Router Switch Configuration Using Packet Tracer GNS3

How CDP Works in Cisco Devices Packet Tracer Topology

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<h2 style="text-align: left;">
How CDP works in Cisco Devices Packet Tracer Topology </h2>
<h3 style="text-align: left;">
CDP- Cisco Discovery Protocol</h3>
 
CDP is a Cisco proprietary protocol used by network administrators to discover directly connected cisco devices like Routers, Switches and other devices.
 
 
CDP runs on data link layer and physical media must support SNAP(Sub Network Access Protocol),Frame relay, ATM,Ethernet,Token Ring all supports SNAP.
 
 
CDP discovers neighbor devices regardless of protocol running in neighbor devices.
 
 
It gives summary of directly connected devices only.
 
 
CDP runs on routers with Cisco IOS software releases 10.3 or later releases and Cisco switches.
 
 
CDP exchanges hardware and software device information with its neighbors.We can get information like, 
 
Device ID 
Device Capabilities 
Port ID 
IP address 
Local Interface 
Software version
 
 
 
Now, create a topology like this in a packet tracer and we are going to see how CDP(Cisco Discovery Protocol) learns the neighbor device detail. 
 
 
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjUs_eZtNh_DczoImmxx4nqjKwx4Fh6KhT4-7yYOlFwtLbuFP-vVa4p0p94FMWZ3m5GJarirbRztFtMMIF-_vp3eIs5a-K5foRnfaelGpCYve_RlDNW-UgnFXtZ9riKse3QqLwJYcs74g/s1600/How+we+can+get+neighbor+detials+using+CDP+in+Cisco+Packet+Tracer.PNG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="How we can get neighbor detials using CDP in Cisco Packet Tracer" border="0" data-original-height="362" data-original-width="678" height="339" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjUs_eZtNh_DczoImmxx4nqjKwx4Fh6KhT4-7yYOlFwtLbuFP-vVa4p0p94FMWZ3m5GJarirbRztFtMMIF-_vp3eIs5a-K5foRnfaelGpCYve_RlDNW-UgnFXtZ9riKse3QqLwJYcs74g/s640/How+we+can+get+neighbor+detials+using+CDP+in+Cisco+Packet+Tracer.PNG" title="How we can get neighbor detials using CDP in Cisco Packet Tracer" width="640" /></a></div>
 
 
In above topology Router R1 connected to Switch 0 and Router R2, Interface Fastethernet2/0 of R1 is connecting Switch0 and Interface Serial2/0 of R1 is connecting Router R2. 
 
Ip address Configuration for Router R1 and Router R2 given below, configure devices with this IP address to appropriate interfaces. 
 
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiYcxjmp-QnBrQRj9cVjAgTp7VbKbh3BoyMtz-WdPZAkLL6OU8PTnFOitOhNo8iADWbMce3G8MABS92AyjgyuX6oJ8pKdrB3F-JZbge2-hyahmN-8-w975I7J2t8X-ObsC7tNZ_iGtXSQ/s1600/CDP+Cisco+Devices+Ip+configuration+in+Packet+Tracer.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="CDP Cisco Devices Ip configuration in Packet Tracer" border="0" data-original-height="463" data-original-width="381" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiYcxjmp-QnBrQRj9cVjAgTp7VbKbh3BoyMtz-WdPZAkLL6OU8PTnFOitOhNo8iADWbMce3G8MABS92AyjgyuX6oJ8pKdrB3F-JZbge2-hyahmN-8-w975I7J2t8X-ObsC7tNZ_iGtXSQ/s400/CDP+Cisco+Devices+Ip+configuration+in+Packet+Tracer.png" title="CDP Cisco Devices Ip configuration in Packet Tracer" width="327" /></a></div>
 
 
After we configured the IP address, we are going to see how CDP learns the directly connected device information. 
 
Below image shows CDP Frames forwarded from Switch to Router R1 
 
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjmm9NxVTjqohvCQi0IIvKMYMRXIdgHOzeDWBOkm1omG412C6Y1SIBGCA0ewpil60UEFSMqR0vgPkfGmXZiZfWDgYlucnSyL0hgDl83Waws7RDGezsIrZl-FNzsnYkn67DU1X895EkKsw/s1600/CDP+Frames+from+Switch+to+Router+R1+Packet+Tracer.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="641" data-original-width="627" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjmm9NxVTjqohvCQi0IIvKMYMRXIdgHOzeDWBOkm1omG412C6Y1SIBGCA0ewpil60UEFSMqR0vgPkfGmXZiZfWDgYlucnSyL0hgDl83Waws7RDGezsIrZl-FNzsnYkn67DU1X895EkKsw/s640/CDP+Frames+from+Switch+to+Router+R1+Packet+Tracer.png" width="624" /></a></div>
 
Here,Cisco Discovery Protocol constructs a Frame and the Swich encapsulates the Protocol Data Unit into a ethernet frame.Switch always uses the 0100.0CCC.CCCC as destination MAC address.Physical layer must support SNAP, It was created because all protocols does not work well for 802.3 ethernet frame as 802.3 had no type filed replaced with length field.So, Sub Network Access Protocol(SNAP) is used at layer 2 to bring type field.Frame Relay,Ethernet,ATM,Token Ring all supports SNAP. 
 
CDP frames Sent out to access port FastEthernet 0/24 with source MAC addres 000C.CF95.0E18and Destination MAC address 0100.0CCC.CCCC. 
 
CDP frames received by R1 through the interface Fastethernet 0/0 that was sent from switch.Received frame MAC address matches the with multicast address 0100.0CCC.CCCC then the router decapsulates the PDU from the ethernet frame. 
 
After getting the CDP frame, CDP process received frame and it will get,Neighbor Device ID,Port ID, Neighbor Capabilities,Device Software Version, Platform,etc...If the neighbor is already present in the CDP table,then the CDP resets the hold timer.All devices will do the same. 
 
 
Now, we are going to check CDP details in this topology devices, 
In Router R1 Privileged mode,give this command, 
 
 
<h3 style="text-align: left;">
R1#show CDP neighbors detail</h3>

Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge 
S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone 
Device ID  Local Intrfce   Holdtme  Capability   Platform    Port ID 
Switch           Fas 0/0           175            S               2950         Fas 0/24 
R2                 Ser 2/0           166             R              PT1000    Ser 3/0 
R1#
 
 
 
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Above screenshot shows the information about the directly connected neighbor devices, 
 
Device ID- 'Switch' and 'R2' is the hostname of the neighbor device. 
 
Local Interface- This interafce in which this device Router R1 received the information of neighbor device.Here, 'Serial2/0' and 'Fastethernet0/0' is the interface that received CDP packets from the neighbor device.This two interface belongs to this device. 
 
Holdtime- 179(set to180) is the time the router will keep this neighbor device information before dropping it from the memory.CDP packets will be updated every 60 seconds,if CDP packet not received for the maximum interval of Holdtime then device will drop stored information about neighbor. 
 
Capability- Type of service it is capable of doing.Here 'S' means Switching, 'R' means Routing. 
 
Platform- Hardware platform of the directly equipment.Here '2950'is the switching platform and 'PT1000' is routing platform. 
 
Port ID- Port that sent the CDP packets from neighboring device.Here 'Fastethernet0/24' is the port of neighbor device. 
 
 
Result for Switch and Router R2 given below, 
 
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgTrhU9teLG-lAObhfuQ8-PVEVD_r3LFLH4QWbKxTx5SBiPITlYGwyAIj_eY7Kx93vBUDn42dVnJsb3HDXp9dw4e0DqX4TSmsIq7cZuIbizqb2U_PGQ9QL1v-KuYqfaH5jfYe_02vbE0w/s1600/Router+and+Switch+Cisco+CDP+Command+result+in+Packet+Tracer.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="Router and Switch Cisco CDP Command result in Packet Tracer" border="0" data-original-height="341" data-original-width="639" height="339" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgTrhU9teLG-lAObhfuQ8-PVEVD_r3LFLH4QWbKxTx5SBiPITlYGwyAIj_eY7Kx93vBUDn42dVnJsb3HDXp9dw4e0DqX4TSmsIq7cZuIbizqb2U_PGQ9QL1v-KuYqfaH5jfYe_02vbE0w/s640/Router+and+Switch+Cisco+CDP+Command+result+in+Packet+Tracer.png" title="Router and Switch Cisco CDP Command result in Packet Tracer" width="640" /></a></div>
 
Other show command that gives information is "show cdp entry *".In this command we can get some more information that CDP neighbor command.If we need to find out IP address of neighbor device,Platform,Software Version,etc... this command will be helpful. 
 
<h3 style="text-align: left;">
R1#show cdp entry ?</h3>
  *     all CDP neighbor entries 
  WORD  Name of CDP neighbor entry 
 
In Router R1,Privileged mode give 'show cdp entry *' command to get all directly connected device information. 
 
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhGoJoGU48Rh3BX6ckv7CuIPJ6HkrzKZ8axzXOXQKyIdkIXNc9s7Lm3u6wT71thnDRAZgaDhgPe7HyrsAUXA7J3RLMh-YD-Qbnk6q6_J3wreh4W_bwgpbOiHnA1miSrO2xeC5jtcKNJYA/s1600/Show+CDP+entry+in+Cisco+Router+R1+Packet+Tracer+2.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="Show CDP entry in Cisco Router to fing all directly connected devices" border="0" data-original-height="507" data-original-width="662" height="488" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhGoJoGU48Rh3BX6ckv7CuIPJ6HkrzKZ8axzXOXQKyIdkIXNc9s7Lm3u6wT71thnDRAZgaDhgPe7HyrsAUXA7J3RLMh-YD-Qbnk6q6_J3wreh4W_bwgpbOiHnA1miSrO2xeC5jtcKNJYA/s640/Show+CDP+entry+in+Cisco+Router+R1+Packet+Tracer+2.png" title="Show CDP entry in Cisco Router R1 Packet Tracer 2" width="640" /></a></div>
 
 
Switch and Router R2 CDP entry image below, 
 
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjOecideXb1tcPV_H0-w36ibPXFUL0VCxKiKIAjVGUtJVAkckdTDWZSZ4UJI9J0rAcg7ARJGKvtr0FaudlayterA043-tDABhOX-ToWy0Lj-5WICYsknQeUZ0N2xwwS6xTmI6a8sk03Uw/s1600/Show+CDP+entry+in+Cisco+Router+R2+and+Switch+in+Packet+Tracer.PNG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="Show CDP entry in Cisco Router R2 and Switch in Packet Tracer" border="0" data-original-height="578" data-original-width="604" height="611" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjOecideXb1tcPV_H0-w36ibPXFUL0VCxKiKIAjVGUtJVAkckdTDWZSZ4UJI9J0rAcg7ARJGKvtr0FaudlayterA043-tDABhOX-ToWy0Lj-5WICYsknQeUZ0N2xwwS6xTmI6a8sk03Uw/s640/Show+CDP+entry+in+Cisco+Router+R2+and+Switch+in+Packet+Tracer.PNG" title="Show CDP entry in Cisco Router R2 and Switch in Packet Tracer" width="640" /></a></div>
 
 
 
Another CDP show command, 
 
R1#show cdp interface serial2/0 
    Serial2/0 is up, line protocol is up 
     Sending CDP packets every 60 seconds 
     Holdtime is 180 seconds 
 
Above command gives the time interval CDP sends CDP Frames and Hold timer. 
 
 
<h3 style="text-align: left;">
Important Commands in CDP</h3>
To run CDP on all interfaces in cisco devices, we have to give this command in global configuration mode, 
 
R1(config)#cdp run 
 
This command is to Stop CDP on all interface 
 
R1(config)#no cdp run 
 
 
 
To run CDP on particular interfaces,give this command in specific interface mode, 
 
R1(config)#interface serial2/0

R1(config-if)#cdp enable 
 
To stop in particular interface, 
 
R1(config)#interface serial2/0 
 
R1(config-if)#no cdp enable 
 
 
 
R1(config)#cdp timer 60    '60' seconds is the time interval the CDP packets will be updated. 
 
R1(config)#cdp holdtime 180   '180' seconds holdtime interval.How long the neighbor information will be kept in the local CDP table 
 
 
 
CDP is media and protocol independent, it runs on all cisco devices.By using CDP network management applications can get the device type and SNMP agent address of neighbor devices.This enables applications to send SNMP queries to neighbor devices.CDP runs on data link layer so devices that supports different network layer protocols can learn each other.Cisco devices always keep the new received information and it discards the old information. 
 
......... 
 
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How CDP Works in Cisco Devices Packet Tracer Topology

How CDP works in Cisco Devices Packet Tracer Topology CDP- Cisco Discovery Protocol CDP is a Cisco proprietary protocol used by netwo...

Inter-VLAN Routing or Route On a Stick Configuration Using Cisco Packet Tracer

Admin 2 Inter-VLAN, VLAN 14:53

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How to Configure Inter-VLAN Routing or Route On a Stick Using Cisco Packet Tracer and Communication between different VLAN's in a network with layer 2 switches and trunk configuration.</h2>
 
Create a topology like given in below image, 
 
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In above topology, host PC0 and PC1 configured to VLAN2, host PC2,PC3,PC6 and PC7 configured to VLAN3, host PC4 and PC5 configured to VLAN 4. 
 
SWA Fa0/1(PC0)-->VLAN 2 name Red 
SWA Fa0/2(PC1)-->VLAN 2 name Red 
SWA Fa0/3(PC2)-->VLAN 3 name Blue 
SWA Fa0/4(PC3)-->VLAN 3 name Blue 
 
SWB Fa0/1(PC4)-->VLAN 2 name Red 
SWB Fa0/2(PC5)-->VLAN 2 name Red 
SWB Fa0/3(PC6)-->VLAN 3 name Blue 
SWB Fa0/4(PC7)-->VLAN 3 name Blue 
 
 
Link connecting SWA Fa0/23 and SWB Fa0/23 configured as Trunk.<a href="https://www.chennaicisco.com/2020/02/vlan-in-different-switches-and-trunk.html" target="_blank">Configuring VLAN and Trunk</a> already seen in previous post. 
 
Without Inter-VLAN routing, host in same VLAN can communicate,host in different VLAN can't communicate with each other.Link connecting two switches configured as Trunk, So,the host in VLAN3 in SWA can communicate with host in VLAN 3 SWB.What if we need to make host communicate between different VLAN's, we need layer 3 device to make this happen like router or layer 3 switch. 
 
VLAN Cofiguration 
 
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Assigning Ports to VLAN 
 
 
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Above command is to configure range of interfaces to a VLAN.Command to configure each interface interface individually to a vlan is given below, 
 
Example:To configure interface individually. 
SWA(config)#interface fastethernet0/1 SWA(config-if-range)#switchport mode access SWA(config-if-range)#switchport access vlan 2 SWA(config-if-range)#exit 
 
 
Trunk Configuration 
 
 
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Before Inter-VLAN Routing configuration,I am going to check by pinging host in different VLAN with above configuraiton only.We see how it works, 
 
Ping IP-192.168.3.40,192.168.2.60, 192.168.3.80 From host PC3(192.168.2.10). 
 
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Above results shows that, Only host in same VLAN communicates successfully,Here, Source is 192.168.2.10 belongs to VLAN 2.we got reply from host that is in VLAN 2 only. 
 
Here, Router is connected to a switch SWA to attain Inter-VLAN Routing.For that, we have to configure the link connecting router and switch as trunk link.so,the packets from different VLAN can be forwaded through this link.Then, we have to create sub interfaces in a router for each network and configure subinterfaces with IP address, that is going to be act as default gateway for each network. 
 
<ul style="text-align: left;">
<li>Configure link between Router and Switch as trunk.</li>
<li>Create sub-interfaces and configure IP.</li>
<li>Configure sub-interfaces with encapsulation 802.1q</li>
<li> </li>
</ul>
Configuring Link Fastethernet0/22 of SWA Fasthernet0/0 of Router as Trunk. 
 
In SWA Global Configuraion mode, 
 
SWA(config)#interface fastethernet0/22 
SWA(config-if)#switchport mode trunk 
SWA(config-if)#exit 
 
 
 
Creating sub-interfaces and IP address in router. 
 

Router(config)#interface fastethernet0/0 
Router(config-if)#no shutdown 
Router(config-if)#exit 
 
Router(config)#interface fastethernet0/0.1 
Router(config-subif)#encapsulation dot1q 2 
Router(config-subif)#ip address 192.168.2.1 255.255.255.0 
Router(config-subif)# 
 
 
Router(config)#interface fastethernet0/0.2 
Router(config-subif)#encapsulation dot1q 3 
Router(config-subif)#ip address 192.168.3.1 255.255.255.0 
Router(config-subif)#exit 

 
 
After Inter-VLAN configuration just ping and check same host as we pinged before Inter-VLAN Configuration. 
 
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhN5bqYbLYeWDDx-Q4F8YslbgtzgfkjZtv4LZL8R3qhA5gsDOYhelQ6b8Ez7rGMtLEQX0-DucxxCdoWx1iPDVUU_zALrgpTCOaM32-DXqJaPY7tctwTovbVgDIg96r2jT21GPVd967K_w/s1600/After+Inter+VLAN+Configuration+in+Packet+Tracer.PNG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="After Inter VLAN Configuration in a Layer 3 Router Packet Tracer" border="0" data-original-height="677" data-original-width="522" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhN5bqYbLYeWDDx-Q4F8YslbgtzgfkjZtv4LZL8R3qhA5gsDOYhelQ6b8Ez7rGMtLEQX0-DucxxCdoWx1iPDVUU_zALrgpTCOaM32-DXqJaPY7tctwTovbVgDIg96r2jT21GPVd967K_w/s640/After+Inter+VLAN+Configuration+in+Packet+Tracer.PNG" title="After Inter VLAN Configuration in a Layer 3 Router Packet Tracer" width="492" /></a></div>
 
 
All host communicated sucessfully after Inter-vlan configuration,network administrator can manually give an access to user from one vlan to another vlan or restrict the user based on our requirements.Here, different vlan communicates with help of layer 3 router. 
 
 
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjKOQXJ6NFYl4AntO_SBp0trPjYxJc4peHuT_ZDMClXmCe2UbhsxqSdkMqd5kSXv_TRiBsp5ZoxhYUVHkosfxrpd3VsqZFjxztVe3hYI8HXPuuLgRQC_kC_PZ0ZBm2BRYjD4QEFsLiNmw/s1600/Inter-VLAN+or+Route+On+a+Stick+Configuration+using+Packet+tracer+chennaicisco.com+12.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="Inter-VLAN or Route On a Stick Configuration using Packet tracer chennaicisco.com 12" border="0" data-original-height="836" data-original-width="900" height="594" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjKOQXJ6NFYl4AntO_SBp0trPjYxJc4peHuT_ZDMClXmCe2UbhsxqSdkMqd5kSXv_TRiBsp5ZoxhYUVHkosfxrpd3VsqZFjxztVe3hYI8HXPuuLgRQC_kC_PZ0ZBm2BRYjD4QEFsLiNmw/s640/Inter-VLAN+or+Route+On+a+Stick+Configuration+using+Packet+tracer+chennaicisco.com+12.png" title="Inter-VLAN or Route On a Stick Configuration using Packet tracer chennaicisco.com 12" width="640" /></a></div>
 
 
If above image is not clear Download the High Resolution Pic <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjENmnOHO4kwacjEBJUc9I8vWiw2Yu_e8gjgz3ejyJjz67eVqMJLfIN7c4sdkzNI1s4dwc98uv5oWrYR0sbHB6h69526OmaY7ZXdSVOWw67SbAhpQHesxhucQZulUxc4THL_vzoxmcHOA/s1600/Inter-VLAN+or+Route+On+a+Stick+Configuration+using+Packet+tracer+chennaicisco.com+1.png" target="_blank">Download Link</a> 
 
 
This image shows ICMP packet activity in this network, after pinging from one host to another host in different VLAN with Inter VLAN Routing configuration. 
 
After pinging the IP 192.168.3.40 of Vlan3 (Blue) from host 192.168.2.10 of vlan2 (Red).ICMP packets forwarded to layer 2 switch SWA through fastethernet 0/1.shown in Figure 1 in above image.. 
 
After receiving packets switch broadcast to all interfaces that is part of vlan2 ,here the packet broadcasted through interface fastethernet 0/2,interface fastethernet 0/23 is a trunk link between SWA and SWB,interface fastethernet 0/22 is a trunk link connected to a router.Packet not forwarded to vlan blue.Refer Fig 2. 
 
Host PC1,PC4 and PC5 will drop the packets,Only router will forward the vlan2 packets through sub-interface that belongs vlan3 (blue).Here, interface fastethernet 0/0 of Router is configured with sub-interfaces, interface fastethernet 0/0.1 with IP address 192.168.2.1 it will act as a default gateway for red vlan.Interface fastethernet 0/0.2 is configured with IP address 192.168.3.1 this act as a default gateway for vlan blue.So, the packet received through sub-Interface belongs to vlan red, that is fastethernet 0/0.1 routed to sub-interface fastethernet 0/0.2 that belongs to vlan 3.Packet received as vlan2 red, goes out as vlan3 blue packet. 
 
Switch gets the packet from router and Switch SWA forwards the received packets from the router through ports that is belongs to vlan3 blue only,Fastethernet0/3,Fastethernet0/4 and Fastethernet0/23.Host PC2,PC3 and SWB receives the packet.SWB forwards the packet to host PC6 and PC7,both host will check destination IP address and they drops the packet.Only host PC3 with IP address of 192.168.3.40 will reply all other host in blue vlan drops the packet.Ref Fig.3&4. 
 
Host PC3 responding to the request and SWA forwards the packet to the default gateway,Packet received through sub-interface fastethernet0/0.2 IP address 192.168.3.1 belongs to vlan3.Rotuer forwards the packet through sub-interface fastethernet0/0.1 to switch SWA,Switch sends the packet to the host PC0 192.168.2.10.This is the complete process going on for Ping in this Inter-vlan topology. 
 
 
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If ARP table already has a MAC address of destination then the packet sends to a default gateway without broadcast and router forwards through sub-interface of destination host vlan(VLAN3 in above example).Then Destination host sends reply packet to the default gateway,router forward the packet through the particular sub-interface that act as default gateway for particular vlan(VLAN2 in this example).Ref Above image. 
 
 
 
You May Interested in: 
 
<a href="https://www.chennaicisco.com/2020/02/vlan-configuration-in-cisco-switch.html" target="_blank">VLAN Configuration in Packet Tracer</a> 
 
<a href="https://www.chennaicisco.com/2020/02/vlan-in-different-switches-and-trunk.html" target="_blank">VLAN Configuration in Multiple Switches</a> 
 
 </div>

Inter-VLAN Routing or Route On a Stick Configuration Using Cisco Packet Tracer

How to Configure Inter-VLAN Routing or Route On a Stick Using Cisco Packet Tracer and Communication between different VLAN's in a netw...

How Spanning Tree Protocol Works If Multiple Links on Same Segment

Admin 1 Spanning Tree Protocol, STP, Switching 19:48

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<h2 style="text-align: left;">
In this topology, we are going to see how Spanning Tree Protocol (STP) selects forwarding port if multiple links present on same segment using packet tracer</h2>
First create a topology like this with two switch connect them with cross cable.Here i have selected Fa0/2,Fa0/4,Fa0/6 in switch A and Fa0/12,Fa0/20,Fa0/18 in Switch B connected with cross cable. 
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Port Fa0/2 of switch A is Connected to Fa0/12 of Switch B, 
Fa0/4 of switch A isconnected to Fa0/20 of switch B and 
Fa0/6 of switch A is connected to Fa0/18 of switch B 
 
Once, we place a switch in packet tracer working area the switch automatically starts and STP will be enabled by default.After we connects two switches STP automatically choose the root switch and it will block redundant links by keeping only one active to avoid loop.
 
 
STP uses lowest bridge ID to choose root switch.Here, Both switches have same Priority so STP will go for MAC address for root switch selection,
 
 
Switch A MAC address : 0002.175B.AD32 
Switch B MAC address : 0001.635C.E32B
 
 
Switch B has the lowest MAC address than Switch A.So, the switch B will become root switch.
 
 
After selecting root switch, then STP will block redundant link that cause loop using received BPDU information. Only one link with lowest port cost will be selected as forwarding port, other than this will be blocked.If current active links fails then STP selects port with lowest port cost of remaining ports.If port costs are same for all links then, port number will be used to select forwarding port.
 
 
In this topology port cost of all ports are same, that is 19 (100 Mbps).So, STP will choose forwarding port by using lowest port number of root switch.Here, switch B is root switch and lowest port number of root switch is Fa0/12. Here, Interface Fa0/12 is connected to interface Fa0/2 of switch A.So, interface Fa0/2 will be root port and other ports in switch A that connects switch B will be in blocking state, that is Fa0/4 and Fa0/6 of Switch A.
 
 
All ports in root switch will be designated port.Here, Fa0/12, Fa0/20 and Fa0/18 of switch B will be designated ports.
 
 
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This how STP selects ports if redundant links connected on same segment.
 
Link status by giving command in Privileged mode, 
 
Switch#Show Spanning-tree 
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg9C2TnVAYst7W7Uk063ZmGyFxU11r3gqWNsJaBVr5l6MFHNP0S_YStloCEZsNedugzOiJsxFyNdnbWyvybhK75Xf8Dub5o_xSyUxc_395GXmKN-vF1Hfh1trVdhRgjAMFi8jo-wF0B8w/s1600/Default+STP+Status.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="How Spanning Tree Protocol Works If Multiple Links on Same Segment" border="0" data-original-height="683" data-original-width="600" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg9C2TnVAYst7W7Uk063ZmGyFxU11r3gqWNsJaBVr5l6MFHNP0S_YStloCEZsNedugzOiJsxFyNdnbWyvybhK75Xf8Dub5o_xSyUxc_395GXmKN-vF1Hfh1trVdhRgjAMFi8jo-wF0B8w/s400/Default+STP+Status.jpg" title="How Spanning Tree Protocol Works If Multiple Links on Same Segment" width="351" /></a></div>
 
 
 
 
<h3 style="text-align: left;">
Now, we see what will happen if current forwarding port fails.</h3>
 
For that, I am going to shutdown interface Fa0/12 of switch B.Give this command in global configuration mode of switch B to shudown the port Fa0/12. 
 
 
Switch(config)#interface fastEthernet 0/12 
Switch(config-if)#shutdown
 
 
After giving this command STP selects forwarding port by lowest cost port of root Switch..If cost is same then the link with lowest port number from other links that is connected to switch A will be selected.For that, port of switch A that is connected to the lowest cost port of switch B will be set as root port.
 
 
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Here, 
Port Fa0/12 is down,remaining ports that is connected to switch A is Fa0/20 and Fa0/18.
 
 
Fa0/20 is connected to Fa0/4 port of switch A
Fa0/18 is connected to Fa0/6 port of switch A
 
 
Cost of all links are same,so Spanning Tree Protocol will choose forwarding port from switch B with lowest port number.Fa0/18 will be selected as forwarding port,Fa0/18 is connected with Fa0/6 of switch A.Then, the port Fa0/6 of switch A will be root port and port Fa0/18 will be designated port.
 
 
Fa0/20 port of switch B will be designated port and Fa0/4 will be in blocking state(Alternate Port).
 
 
Link status by giving command in Privileged mode, 
 
Switch#Show Spanning-tree 
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<h3 style="text-align: left;">
Changing Forwarding port manually</h3>
 
We can manullay choose forwarding port by reducing the speed of the port that we dont want to be a forwarding port.100 Mbps is default speed in all ports.we have to options one is 100 Mbps or 10 Mbps.Cost of 100 Mbps is 19 and cost of 10 Mbps is 100.
 
 
Without shutdown we can make the link that we dont want be primary forwarding port to secondary port by setting speed to lower value.If we set to 10 Mbps to Fa0/12, the cost of this port will be 100.
 
 
 
Switch(config)#interface fastEthernet 0/12 
Switch(config-if)#speed 10 
Switch(config-if)#exit
 
 
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Link status by giving command in Privileged mode, 
 
Switch#Show Spanning-tree 
 
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Now, STP will go for other lowest cost ports for port selection.Here, other ports are Fa0/20 and Fa0/18 and this post cost are same, STP will choose lowest port number from this two ports.That is Fa0/18.Fa0/6 of switch A will be root port.</div>
 
 
How Spanning Tree Protocol Works If Multiple Links on Same Segment STP Full Video 
 
<iframe allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen="" frameborder="0" height="305" src="https://www.youtube.com/embed/zBxEvY9SnCA" width="400"></iframe> 
 
 
 </div>

How Spanning Tree Protocol Works If Multiple Links on Same Segment

In this topology, we are going to see how Spanning Tree Protocol (STP) selects forwarding port if multiple links present on same segment ...

VLAN Configuration in Cisco Switch Using Packet Tracer

Admin 1 Packet Tracer, VLAN 14:37

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<h2 style="text-align: left;">
How to Configure VLAN in Cisco Switch Using Packet Tracer Simulator with a Simple Topology Example.</h2>
<h3 style="text-align: left;">
</h3>
<h3 style="text-align: left;">
VLAN- Virtual Local Area Network</h3>
<ul style="text-align: left;">
<li>VLAN is Virtually grouping of host for Various Purpose.</li>
<li>VLAN reduces the size the of broadcast and collision domain within a layer 2 switched network.</li>
<li>Broadcast frames from one VLAN will not be forwarded to another VLAN.</li>
<li>Logically grouping of host can be done by physical port association.Host from one VLAN cannot communicate with host from another VLAN.It reduces unwanted broadcast traffic in a network.</li>
<li>We can isolate users based on workgroup or users performs similar functions in VLAN.By this we can redcuce unwanted network traffic forwarding to users who is doing different functions.</li>
<li>Layer 2 switching and Layer 3 routing are used to reduce the size of collision and Broadcast domains.</li>
<li>VLAN Provides security by isolating users.Group of users needed high security can be grouped into a seperate VLAN,So, Other users in a network cannot communicate with this users.</li>
<li>Communication between VLAN happens only by using router.It is called as inter VLAN routing.</li>
<li>We need routers to break larger broadcast domain into smaller one,but VLAN do this in Layer 2 Switched network.</li>
</ul>
 
 
 
 
Step:1 Create a topology like in below image,
 
 
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Note:- Here all VLAN host were configured with IP in Same network to make you understand VLAN in better way. In realtime, we have to use different network for each VLAN to achieve Inter VLAN routing. It can be classful network or subnetted network based on our requirement. 
 
Step:2 Configure IP address to all PC. 
 
VLAN not configured in above topology and all PC's are configured with IP address in a same network 10.0.0.0 and subnet mask 255.0.0.0. Switch 2950-24 used in this topology. 
 
PC0 is Connected to Fastethernet0/1,IP address 10.0.0.10 

PC1 is Connected to Fastethernet0/2,IP address 10.0.0.20 

PC2 is Connected to Fastethernet0/3,IP address 10.0.0.30 

PC3 is Connected to Fastethernet0/4,IP address 10.0.0.40 

PC4 is Connected to Fastethernet0/5,IP address 10.0.0.50 

PC5 is Connected to Fastethernet0/6,IP address 10.0.0.60 

PC6 is Connected to Fastethernet0/7,IP address 10.0.0.70 

PC7 is Connected to Fastethernet0/8,IP address 10.0.0.80 

PC8 is Connected to Fastethernet0/9,IP address 10.0.0.90 
 
 
Step:3 Ping hosts in a network without VLAN configuration. 
Only IP address are configured to PC's,VLAN not configured.Now I am going to ping host 10.0.0.30,10.0.0.60,10.0.0.90 from 10.0.0.10 to check whether we are getting reply or not. 
 
Click on PC0->Desktop->Command Prompt.Then give this command in that window, 
 

In,PC0 
 

Ping 10.0.0.30 
Ping 10.0.0.60 
Ping 10.0.0.90 
 
 
 
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiH-XbvwTl-i0UsSlrpeDuNMaPUXSVBxf0v__yOyJcI2yT9cbKNlbEqGg22fekqaQeOkdHp9M3tIoQpYjFbGDPQhTXo02Zp89ytujjYA-NFr1XOxKV0lwciIUW9Oi1GxjN2Q7UtHhZOCw/s1600/Ping+Host+30+60+90+from+host+10+without+VLAN.PNG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="VLAN Configration in Cisco Switch Using Packet Tracer HOST REPLY" border="0" data-original-height="699" data-original-width="559" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiH-XbvwTl-i0UsSlrpeDuNMaPUXSVBxf0v__yOyJcI2yT9cbKNlbEqGg22fekqaQeOkdHp9M3tIoQpYjFbGDPQhTXo02Zp89ytujjYA-NFr1XOxKV0lwciIUW9Oi1GxjN2Q7UtHhZOCw/s640/Ping+Host+30+60+90+from+host+10+without+VLAN.PNG" title="VLAN Configration in Cisco Switch Using Packet Tracer HOST REPLY" width="507" /></a></div>
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We are getting reply from all host, without any restrictions. 
 
Step:4 Configure VLAN in a switch 2950-24, 
 

VLAN 2 for interface fastethernet 0/1,0/2,0/3 
VLAN 3 for interface fastethernet 0/4,0/5,0/6 
VLAN 4 for interface fastethernet 0/7,0/8,0/9 
 
Here 9 host are there, seperated as three groups with three host per group.I am going fastethernet0/1-0/3 to VLAN 2 named as Red, Fastethernet0/4-0/6 to VLAN 3 named as Blue,Fastethernet 0/7-0/9 to VLAN 4 named as Green.Like given in a image below. 
 
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj4vd80E6rVyM_Py-dluc0G7beBzepILUf97DnxIroKR6V9-KprDwhTci7ss2uLlZpP7UbudXvUfVO0WnPaO9Ooyb3LB4-wFLNNZCwZhvqLGXkNv8lEMO91frCI7-En4bn_lYFp37Ibvg/s1600/With+VLAN+Configuration+Using+Packet+Tracer.PNG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="VLAN Configration in Cisco Switch Using Packet Tracer with Three vlan" border="0" data-original-height="449" data-original-width="836" height="339" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj4vd80E6rVyM_Py-dluc0G7beBzepILUf97DnxIroKR6V9-KprDwhTci7ss2uLlZpP7UbudXvUfVO0WnPaO9Ooyb3LB4-wFLNNZCwZhvqLGXkNv8lEMO91frCI7-En4bn_lYFp37Ibvg/s640/With+VLAN+Configuration+Using+Packet+Tracer.PNG" title="VLAN Configration in Cisco Switch Using Packet Tracer with Three vlan" width="640" /></a></div>
 
 
To cofigure VLAN in a Switch,Click on Switch, then go to CLI tab on the switch and give this command. 
 
Creating a VLAN and name for the it.

Switch(config)# 
Switch(config)#vlan 2 
Switch(config-vlan)#name red 
Switch(config-vlan)#exit 
 
 

Switch(config)#vlan 3 

Switch(config-vlan)#name blue 

Switch(config-vlan)#exit 
 
 

Switch(config)#vlan 4 

Switch(config-vlan)#name green 

Switch(config-vlan)#exit 
 
 
 
Assigning interfaces with vlan to the range of interfaces.Here, I am going configure Interfaces 1 to 3 to VLAN 2 so , we can  specify a range start to end that is going to be configured to a single VLAN. 
 

Switch(config)#interface range fastethernet0/1-3 
Switch(config-if-range)#switchport mode access 
Switch(config-if-range)#switchport access vlan 2 
Switch(config-if-range)#exit 
 
Switch(config)# 
Switch(config)#interface range fastethernet0/4-6 
Switch(config-if-range)#switchport mode access 
Switch(config-if-range)#switchport access vlan 3 
Switch(config-if-range)#exit 
 
Switch(config)# 
Switch(config)#interface range fastethernet0/7-9 
Switch(config-if-range)#switchport mode access 
Switch(config-if-range)#switchport access vlan 4 
Switch(config-if-range)#exit 
 
 
Or, we can configure each individual interfaces like this,but it takes time.But, I just showing you how to configure single interfaces in case if you want to do. 
 
Switch(config)# Switch(config)#interface fastethernet0/1 Switch(config-if-range)#switchport mode access Switch(config-if-range)#switchport access vlan 2 Switch(config-if-range)#exit 
 
Above command is to configure VLAN to a single interface. 
 
 
After configuring VLAN and assigning ports to a Vlan,Only host in same Vlan can communicate with each other,Host from different Vlan can't communicate each other. 
 
To check VLAN configuration details, give this command in Privileged Mode.It will give the configured VLAN information in Cisco Switch 
 

Switch#show vlan brief 
 
VLAN      Name        Status Ports 
---- -------------------------------- --------- ------------------------------- 
1               default       active Fa0/10, Fa0/11, Fa0/12, Fa0/13                                     Fa0/14, Fa0/15, Fa0/16, Fa0/17                                     Fa0/18, Fa0/19, Fa0/20, Fa0/21                                     Fa0/22, Fa0/23, Fa0/24 
2                  red          active Fa0/1, Fa0/2, Fa0/3 
3                  blue        active Fa0/4, Fa0/5, Fa0/6 
4                  green      active Fa0/7, Fa0/8, Fa0/9 
1002 fddi-default active 
1003 token-ring-default active 
1004 fddinet-default active 
1005 trnet-default active 
Switch# 
Switch# 
 
A 
 
To check, how vlan works based on our configuration in this topology, I am going ping same host that already pinged without VLAN configuration with current configuration. 
 
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjGGoJED04xlWdCewEAcOu0uxYJ6x4zz_1fXOWnlSVRWbe7V44v24Drb5XBs_XRE7F3uKuYWzv2gKN4kMeUzVQsDoB8Sh1nNckkaZi6uL6hVluqU2DvjK3HhboVBRUfwKrZBtGPLuGaMw/s1600/Ping+Host+30+60+90+from+host+10+After+vlan+configuration+chennaicisco.com.PNG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="VLAN Configration in Cisco Switch Using Packet Tracer with Three vlan" border="0" data-original-height="660" data-original-width="503" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjGGoJED04xlWdCewEAcOu0uxYJ6x4zz_1fXOWnlSVRWbe7V44v24Drb5XBs_XRE7F3uKuYWzv2gKN4kMeUzVQsDoB8Sh1nNckkaZi6uL6hVluqU2DvjK3HhboVBRUfwKrZBtGPLuGaMw/s640/Ping+Host+30+60+90+from+host+10+After+vlan+configuration+chennaicisco.com.PNG" title="VLAN Configration in Cisco Switch Using Packet Tracer with Three vlan" width="484" /></a></div>
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10.0.0.10 belongs to VLAN 2 
10.0.0.30 belongs to VLAN 2 
10.0.0.60 belongs to VLAN 3 
10.0.0.90 belongs to VLAN 4 
 
 
Above screen shows that host from same vlan can communicate other host from different Vlan failed to Communicate.In this method we can virtually break the large broadcast domain to smaller one.Most secured host can be assigned to a seperate vlan from others, it will isolate users. 
 
We can ping other host to check how it works, I am going ping 10.0.0.20 and 10.0.0.50 from 10.0.0.10. 
 
Here, 
 
10.0.0.10 belongs to VLAN 2 
10.0.0.20 belongs to VLAN 2 
10.0.0.50 belongs to VLAN 3 
 
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We get reply successfully from the host in same VLAN,Failed in Different VLAN 
 
 
 
 
 
VLAN Troubleshooting Commands. 
 
 
Switch#show vlan id 2            (This command will give us information about particular Vlan ID 
                                                            Here, I am checking the information of VLAN 2) 
VLAN     Name          Status Ports 
---- -------------------------------- --------- 
  2             red              active Fa0/1, Fa0/2, Fa0/3 
 
 
 
 
Switch#show vlan brief       (This command will give us information about all vlans in the                                                                 switch.) 
 
 
 
 
Switch#show vlan name blue     (This Command Gives information based on Vlan Name)

VLAN     Name          Status Ports 
---- -------------------------------- --------- 
  2             blue              active Fa0/4, Fa0/5, Fa0/6       
 
 
 
Switch#show vlan ? 
 brief VTP all VLAN status in brief 
 id VTP VLAN status by VLAN id 
 
 name VTP VLAN status by VLAN name 
 
 
<iframe allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen="" frameborder="0" height="300" src="https://www.youtube.com/embed/8yu60yYWUbQ" width="400"></iframe>

<ul style="text-align: left;">
<li>VLAN Configuration in Packet Tracer</li>
<li>VLAN in Cisco Packet Tracer</li>
<li>Assigning name for the VLAN</li>
<li>Configuring VLAN to an interfaces.</li>
<li>CCNA and CCNP Free Online Course Lab</li>
</ul>
 
 
 
 
 
 
 </div>

VLAN Configuration in Cisco Switch Using Packet Tracer

How to Configure VLAN in Cisco Switch Using Packet Tracer Simulator with a Simple Topology Example. VLAN- Virtual Local Area Network ...

How Spanning Tree Protocol (STP) works in Packet Tracer Topology

Admin 0 Spanning Tree Protocol, STP, Switching 15:05

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<h2 style="text-align: left;">
Understanding Spanning Tree Protocol (STP) in Packet Tracer with Simple topology using 2950-24 Switch.</h2>
Spanning Tree Protocol (STP) presents in layer 2 Switches and Bridges to keep the network loop free,Its IEEE Standard is IEEE 802.1D. Redundant links between layer 2 devices are very important in the network,it prevents total network failure.Single link between devices fails, there will be network failure. So, multiple links are very important.
 
 
At the same time multiple links often cause many problems in the network, Switches forwards and receives same frames again and again in a looped network and it will take entire bandwidth and it makes the network unstable, and there will be a problem in maintaing stable MAC address table.STP is uses Spanning Tree Algorithm (SPA) to construct the loop free network.
 
 
<h2 style="text-align: left;">
Default Spanning Tree Timers</h2>
Blocked Port (Loss of BPDU) Max Age = 20 sec
 
 
By deafault, All the ports are in blocking state when the switch starts,Blocking ports just listen to Bridge Protocol Data Units (BPDU).Looped path will be in blocking state, if any links fails the STP recalculate the paths.
 
 
Listening Port (Forward Delay = 15 sec)
 
 
Listening port will listen to Bridge Protocol Data Units (BPDU) to make sure there is no loops in the network.Listenting port prepares frames to foward but it won't populate the MAC address table. 
 
Learning Port (Forward Delay = 15 sec)
 
 
Learning port learns all path in a Switched network by using received Bridge Protocol Data Units (BPDU).Learning state generates the MAC address table, but it won't forward the data frames.
 
 
Forwarding Port 
 
Forwarding port sends and receives all the data frames.Forwarding port will be either designated or Root port.
 
 
Disabled Port 
 
Disabled port is administratively disabled, it won't participate in this process,
 
 
 
<h3 style="text-align: left;">
Terms Using by Spanning Tree Protocol</h3>
BPDU : Bridge Protocol Data Units contains the information of the Switches to use in the root switch selection process.When switch starts the spanning tree is used to find the root switch.BPDU will be sent to all devices in network with BID. 
 
Bridge ID BID : STP tracks all switches in switched network. Bridge ID is the combination of Bridge Priority(32768) and Switch base MAC address.By default 32768 is the priority in all cisco Switches. 
 
Designated Port: Designated port of the switch will be in the forwarding state.All ports of the Root Switch will be designated port. 
 
Non designated Port: Non Designated port will be in blocking to avoid loop.This port cost will be higher than the designated port.One or more port in Non root bridge will be in blocking state to avoid looped path. 
 
Root Bridge : Switch with lowest BridgeID(BID) will become the root bridge.
 
 
Non root Bridge : Other than Root bridge with higher cost will becomes non root bridge. 
 
Forwarding Port: Forwarding port will be either designated port or Root port. 
 
Blocked Port: Blocket port will not forward the frames. 
 
 
 
Port cost based on Link speed IEEE Specification 
 
Link speed            Link Cost (IEEE) 
 
 10 Gbps - 2 
 1 Gbps- 4 
 100 Mbps -19 
 10 Mbps -100 
 
 
<h3 style="text-align: left;">
Spanning Tree Timers</h3>
Hello: By default hello time between each BPDU is 2 secs.We can set hello time between 1 to 10 seconds 
 
Forward Delay: Time spent in the lestening and learning state.By default, it is 15 sec. We can set this time between 4 to 30 seconds. 
 
Max age: Maximum length of time that waits before a bridge port saves received BPDU Information. 
 
 
 
 
 
We are going to see how Spannig Tree Protocol (STP) works on this this simple packet tracer topology. 
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In this topology, we are using three switches Switch A, Switch B and Switch C. I have chosen 2950-24 switch in packet tracer.when we place switch in working space switch will turn on in packet tracer and STP starts running once the switch is ON by default,then STP will choose Root Bridge and block looped paths. 
 
 
Choosing Root Bridge 
 
When switches powered ON, all the switches in network decides themselves as a root switch and sends BPDU to other neighbour switches.After receiving Bridge Protocol Data Unit (BPDU) that contains Bridge ID with the information of switch priority (32768) by default and Base MAC address of Switch, The Switch will select root bridge by choosing switch with lowest priority value. If all switches have same priority then switch with lowest MAC address will be chosen as Root Switch.
 
 
In this, topology all switches have same bridge priority, So Spanning Tree Protocol will check for the MAC address in received BPDU. Here Switch A has the lowest MAC so Switch A becomes root switch, switch B and Switch C are Non-Root switches. 
 
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All ports of root switch become designated ports(forwarding Port), the best port that connects Non-Root Switch to the Root switch becomes root port.Here Switch A Port Fa0/1 and Fa0/3 becomes designated Ports.Switch B fa0/1 and Switch C fa0/3 becomes root port.Check above Image 
 
But there is another link connects switch B and Switch C that Creates loop.So Spanning tree will block one of the port in this switches.Either Fa0/2 Port of Switch B or Fa0/2 port of Switch C. 
 
Here two switches are directly connected to the root switch,so The port of the switch with highest bridge ID will be blocked, spanning tree choose designated port from the switch with lowest bridge ID.Here Switch B has higher Bridge ID value than Switch C. So, Fa0/2 of switch C becomes designated port and Fa0/2 port of Switch B will be made as Blocking port (Alternate port).Check above image. 
 
 
 
<h3 style="text-align: left;">
Let's See what happens when we shutdown one of the links in this topology.</h3>
If any link fails the spanning tree will re calculate the path.Here consider the link between switch A and Switch B fails.For that a im going to shutdown the port of switch C fa0/3 by giving command in global configuration mode in Swich C. 
 
 
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Switch(config)# 
Switch(config)#int fa0/3 
Switch(config-if)#shutdown 
 
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Then the link between switch B and Switch c become active.Switch B fa0/2 port becomes designated port from blocking port,even though it has higher Bridge ID value than Switch C.Because Only Switch B connects to root Switch, So port fa0/3 becomes designated and port fa0/3 changes to root port. 
 
 
Spanning Tree Table comparison Before and After Shutdown. 
 
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How Spanning Tree Protocol (STP) works in Packet Tracer Topology Full Video
 
<iframe allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen="" frameborder="0" height="305" src="https://www.youtube.com/embed/rNEPHdd8owo" width="400"></iframe> 
 
 
 
 
How Spanning Tree Protocol (STP) works in Packet Tracer Topology Full Video
 
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<h3 style="text-align: left;">
<a href="https://www.chennaicisco.com/2020/01/how-spanning-tree-protocol-works-if.html">How Spanning works if Multiple links present on same segment</a></h3>
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How Spanning Tree Protocol (STP) works in Packet Tracer Topology

Understanding Spanning Tree Protocol (STP) in Packet Tracer with Simple topology using 2950-24 Switch. Spanning Tree Protocol (STP) prese...

Configure a Site to Site VPN in Cisco Routers Using GNS3

Admin 2 VPN 17:11

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How to configure a IPSEC Site to Site VPN (Virtual Private Network) in Cisco routers using GNS3 with simple seven steps 
 
Step 1:Create topology like this 
 
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjXntSTwt74WnHVKFVfNWANx_wSSlzplR6QrCdj8yvR_Ge2AwrfvZMPAH_BK3u4POeNxwHkY50AHNzIMXQuD2TYedz9TjT159Flpomydts9yplXCFql35N2EF_Hinkc0jZvhSljOlxk9w/s1600/VPN+Topology.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="Configure a Site to Site VPN in Cisco Routers Using GNS3 CCNA CCNP" border="0" height="368" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjXntSTwt74WnHVKFVfNWANx_wSSlzplR6QrCdj8yvR_Ge2AwrfvZMPAH_BK3u4POeNxwHkY50AHNzIMXQuD2TYedz9TjT159Flpomydts9yplXCFql35N2EF_Hinkc0jZvhSljOlxk9w/s640/VPN+Topology.jpg" title="Configure a Site to Site VPN in Cisco Routers Using GNS3 CCNA CCNP" width="640" /></a></div>
 
 
 
Step 2:Configure routers and host with ip address like i have given in topology 
 
 
In Router HO global config mode, 
 
HO(config)#interface fastethernet 2/0 
HO(config-if)#ip address 192.168.1.1 255.255.255.0 
HO(config-if)#no shutdown 
HO(config-if)#exit 
 
HO(config)#interface serial 1/0 
HO(config-if)#ip address 20.0.0.1 255.0.0.0 
HO(config-if)#clock rate 64000 
HO(config-if)#encapsulation ppp 
HO(config-if)#no shutdown 
HO(config-if)#exit 
 
 
In Router ISP1 global config mode, 
 
ISP1(config)#interface serial1/0 
ISP1(config-if)#ip address 20.0.0.2 255.0.0.0 
ISP1(config-if)#encapsulation ppp 
ISP1(config-if)#clock rate 64000 
ISP1(config-if)#no shutdown 
ISP1(config-if)#exit 
 
ISP1(config)#interface serial1/1 
ISP1(config-if)#ip address 30.0.0.1 255.0.0.0 
ISP1(config-if)#encapsulation ppp 
ISP1(config-if)#clock rate 64000 
ISP1(config-if)#no shutdown 
ISP1(config-if)#exit 
 
 
In Router ISP2 global config mode, 
 
ISP2(config)#interface serial 1/0 
ISP2(config-if)#ip address 30.0.0.2 255.0.0.0 
ISP2(config-if)#encapsulation ppp 
ISP2(config-if)#clock rate 64000 
ISP2(config-if)#no shutdown 
ISP2(config-if)#exit 
 
ISP2(config)#interface serial 1/1 
ISP2(config-if)#ip address 40.0.0.1 255.0.0.0 
ISP2(config-if)#encapsulation ppp 
ISP2(config-if)#clock rate 64000 
ISP2(config-if)#no shutdown 
ISP2(config-if)#exit 
 
 
In Router BO global config mode, 
 
BO(config)#interface fastethernet2/0 
BO(config-if)#ip address 192.168.2.1 255.255.255.0 
BO(config-if)#no shutdown 
BO(config-if)#exit 
 
BO(config)#interface serial1/0 
BO(config-if)#ip address 40.0.0.2 255.0.0.0 
BO(config-if)#clock rate 64000 
BO(config-if)#encapsulation ppp 
BO(config-if)#no shutdown 
BO(config-if)#exit 
 
Qemu1 
 
tc@box:~$ 
tc@box:~$ sudo su 
root@box:~#ifconfig eth0 192.168.1.10 netmask 255.255.255.0 up 
root@box:~#route add ip default gw 192.168.1.1 
root@box:~#route add default gw 192.168.1.1 
 
Qemu2 
 
tc@box:~$ 
tc@box:~$ sudo su 
root@box:~#ifconfig eth0 192.168.2.10 netmask 255.255.255 up 
root@box:~#route add ip default gw 192.168.2.1 
root@box:~#route add default gw 192.168.2.1 
 
 
 
Step 3:Configure ISP1 and ISP2 routers with any routing protocols.I am going to use RIP. 
 
ISP1(config)#router rip 
ISP1(config-router)#network 20.0.0.0 
ISP1(config-router)#network 30.0.0.0 
ISP1(config-router)#exit 
 
ISP2(config)#router rip 
ISP2(config-router)#network 30.0.0.0 
ISP2(config-router)#network 40.0.0.0 
ISP2(config-router)#exit 
 
This will isolate the ISP1 and ISP2 from HO and BO Routers, So it will work like a real time Site to site network topology.In real time ISP can use any routing protocol. 
 
 
Step 4:Configure the HO and BO routers with VPN Configurations 
 
In Router HO global config mode, 
 
HO(config)#crypto isakmp enable 
HO(config)#crypto isakmp policy 10 
HO(config-isakmp)#authentication pre-share 
HO(config-isakmp)#hash md5 
HO(config-isakmp)#encryption des 
HO(config-isakmp)#group 2 
HO(config-isakmp)#lifetime 3600 
HO(config-isakmp)#exit 
 
 
HO(config)#crypto isakmp key security address 40.0.0.2 255.0.0.0 
HO(config)#crypto ipsec transform-set hoset esp-des esp-md5-hmac 
HO(cfg-crypto-trans)#exit 
 
 
HO(config)#access-list 101 permit ip 192.168.1.0 0.0.0.255 192.168.2.0 0.0.0.255 
 
 
HO(config)#crypto map homap 10 ipsec-isakmp 
% NOTE: This new crypto map will remain disabled until a peer 
        and a valid access list have been configured. 
HO(config-crypto-map)#set peer 40.0.0.2 
HO(config-crypto-map)#set transform-set hoset 
HO(config-crypto-map)#match address 101 
HO(config-crypto-map)#exit 
 
 
HO(config)#interface serial 1/0 
HO(config-if)#crypto map homap 
HO(config-if)#exit 
 
 
In Router BO global config mode, 
 
 
BO(config)#crypto isakmp enable 
BO(config)#crypto isakmp policy 10 
BO(config-isakmp)#authentication pre-share 
BO(config-isakmp)#hash md5 
BO(config-isakmp)#encryption des 
BO(config-isakmp)#group 2 
BO(config-isakmp)#lifetime 3600 
BO(config-isakmp)#exit 
 
 
BO(config)#crypto isakmp key security address 20.0.0.1 255.0.0.0 
BO(config)#crypto ipsec transform-set boset esp-des esp-md5-hmac 
BO(cfg-crypto-trans)#exit 
 
 
BO(config)#access-list 101 permit ip 192.168.2.0 0.0.0.255 192.168.1.0 0.0.0.255 
 
 
BO(config)#crypto map bomap 10 ipsec-isakmp 
% NOTE: This new crypto map will remain disabled until a peer 
        and a valid access list have been configured. 
BO(config-crypto-map)#set peer 20.0.0.1 
BO(config-crypto-map)#set transform-set boset 
BO(config-crypto-map)#match address 101 
BO(config-crypto-map)#exit 
 
 
BO(config)#interface serial 1/0 
BO(config-if)#crypto map bomap 
BO(config-if)#exit 
BO(config)# 
 
 
Step 5:Configure the default static route in HO and BO to forward all packets to the Internet Service Provider Router.Peer address for HO router is 40.0.0.2 it is a public ip address when packet forwarded to 20.0.0.2 from HO router it is ISP responsible to take packet to 40.0.0.2 same for the BO router. 
 
 
HO(config)#ip route 0.0.0.0 0.0.0.0 20.0.0.2 
 
BO(config)#ip route 0.0.0.0 0.0.0.0 40.0.0.1 
 
 
Step 6:Now give debug command to HO and BO router in privileged mode to see VPN process. 
 
 
In priveleged mode on HO and BO Routers 
 
HO#debug crypto ipsec 
Crypto IPSEC debugging is on 
 
HO#debug crypto isakmp 
Crypto ISAKMP debugging is on 
 
 
BO#debug crypto ipsec 
Crypto IPSEC debugging is on 
 
BO#debug crypto isakmp 
Crypto ISAKMP debugging is on 
 
 
Step 7:Now go to host in 192.168.1.0/24 network and ping ip address 192.168.2.10 in 192.168.2.0/24 Network, then go to router HO and BO to see what is happening while you ping. 
 
 
Ping 192.168.2.10 
 
 
 
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiEs5mR4M5UzwCq5yN7qi3RCifd6N4sVY9h-JwsbvLeJqPFQ88e6eJoVJcSWV6QaYUxEBgR9Ay-bobjfP7AGripERSzXanpbG7Ln91DWvP7fG54jHixbsla7NXtZ-iWn6NcITJAix2PLQ/s1600/responses+.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em; text-align: center;"><img alt="Configure a Site to Site VPN in Cisco Routers Using GNS3 CCNA CCNP" border="0" height="376" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiEs5mR4M5UzwCq5yN7qi3RCifd6N4sVY9h-JwsbvLeJqPFQ88e6eJoVJcSWV6QaYUxEBgR9Ay-bobjfP7AGripERSzXanpbG7Ln91DWvP7fG54jHixbsla7NXtZ-iWn6NcITJAix2PLQ/s640/responses+.jpg" title="Configure a Site to Site VPN in Cisco Routers Using GNS3 CCNA CCNPConfigure a Site to Site VPN in Cisco Routers Using GNS3 CCNA CCNP" width="640" /></a></div>
 
 
 
 
Trouble Shooting Commands: 
 
 
 
HO#show crypto isakmp ? 
  key      Show ISAKMP preshared keys 
  policy   Show ISAKMP protection suite policy 
  profile  Show ISAKMP profiles 
  sa       Show ISAKMP Security Associations 
 
HO#show crypto isakmp key 
HO#show crypto isakmp policy 
HO#show crypto isakmp profile 
HO#show crypto isakmp sa 
 
HO#show crypto ipsec ? 
  profile               Show ipsec profile information 
  sa                    IPSEC SA table 
  security-association  Show parameters for IPSec security associations 
  transform-set         Crypto transform sets 
 
HO#show crypto ? 
  ca           Show certification authority policy 
  dynamic-map  Crypto map templates 
  engine       Show crypto engine info 
  identity     Show crypto identity list 
  ipsec        Show IPSEC policy 
  isakmp       Show ISAKMP Security Associations 
  key          Show long term public keys 
  map          Crypto maps 
  mib          Show Crypto-related MIB Parameters 
  optional     Optional Encryption Status 
  sockets      Secure Socket Information 
 
HO#debug crypto ? 
  ber      decode ASN.1 BER data 
  engine   Crypto Engine Debug 
  ipsec    IPSEC processing 
  isakmp   ISAKMP Key Management 
  mib      IPSEC Management Transactions 
  pki      PKI Client 
  socket   Crypto Secure Socket Debug 
  verbose  verbose decode 
 
 </div>

Configure a Site to Site VPN in Cisco Routers Using GNS3

How to configure a IPSEC Site to Site VPN (Virtual Private Network) in Cisco routers using GNS3 with simple seven steps Step 1:Create top...

How Switch Learns MAC Address of Connected Devices in LAN

Admin 1 ARP, ICMP, MAC Table, Packet Tracer, Switching 13:45

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<h2 style="text-align: left;">
How Switch Learns MAC Address of Connected Devices to It in a LAN example using Packet tracer
</h2>
 
 
In this post, we are going to see how the switch learns MAC(Media Access Control) address and how Switch makes forward , filter decision.
 
 
.Create a topology with switch and 5 PC connected to it,like below example.I have shown IP address and MAC(Hardware) address of each PC connected to switch.
 
 
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjNtdhkl9k4DWMzQAbXzK6qkPeyMcl5DLyxwfJosaY8ZuPnctWmvLIOJR1wHgM4Z09I82ZCiDHlLoK_N4BhMxfW6I_ywPy-ktWR9WeTJO0zrRxrbA1fBWPI6H3sg0YP7RKRc8w5dzLORw/s1600/1.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em; text-align: center;"><img border="0" data-original-height="341" data-original-width="603" height="360" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjNtdhkl9k4DWMzQAbXzK6qkPeyMcl5DLyxwfJosaY8ZuPnctWmvLIOJR1wHgM4Z09I82ZCiDHlLoK_N4BhMxfW6I_ywPy-ktWR9WeTJO0zrRxrbA1fBWPI6H3sg0YP7RKRc8w5dzLORw/s640/1.jpg" width="640" /></a>
 
 
PC1 is connected to Switch Port Fastethernet0/1 (Fa0/1) 
PC2 is connected to Switch Port Fastethernet0/1 (Fa0/2) 
PC3 is connected to Switch Port Fastethernet0/1 (Fa0/3) 
PC4 is connected to Switch Port Fastethernet0/1 (Fa0/4) 
PC5 is connected to Switch Port Fastethernet0/1 (Fa0/5) 
 
.Initially there won't be any MAC address present in PC ARP Cache and Switch MAC address table.I am going to check ARP cache of PC2,PC5 and MAC address table of switch.
 
 
.I am going to check ARP cache of PC2,PC5 and MAC address table of switch.Give this command "arp -a" in command promt to check if any saved MAC address present in a PC ARP Cache.To check MAC address table of switch give this command in Privileged mode of the switch "show mac-address-table".Initially it won't have any MAC address present in it.

<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg_ODaUIBxVNtCs6ZqyxMdn_ICZqhckqaUrkTY2pBCVtPdloS27FR74TtHnCKDPEa0vdjgavoVG7BbHcTc_BuEKh77lCpgA-Yu3GPVXQ6RarwIYXIa2n_IE2m3yMTVV9cbTdnt9KrzoVQ/s1600/2.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em; text-align: center;"><img border="0" data-original-height="768" data-original-width="1366" height="358" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg_ODaUIBxVNtCs6ZqyxMdn_ICZqhckqaUrkTY2pBCVtPdloS27FR74TtHnCKDPEa0vdjgavoVG7BbHcTc_BuEKh77lCpgA-Yu3GPVXQ6RarwIYXIa2n_IE2m3yMTVV9cbTdnt9KrzoVQ/s640/2.jpg" width="640" /></a> 
 
 
 
 
 
 
.Now, Ping from any PC in a LAN to any other PC connected to that switch.I'm going to ping PC5 from PC2, then we see what happens. Go to PC2 command prompt and give this command "ping 192.168.1.50".Now the device PC2 will send a echo request payload to PC5 or we can create a complex PDU.I am going to use complex PDU to show what will happen after we give ping commandand we have to select simulation mode in bottom right corner.

Click on PC2 and select complex PDU, then a window will open.

we have to give this details, 
 
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj6kXBtK5TTCWVoxpl3LUtpTVDOHIViU8uPOoB8JB0_eXcMO8gy09g7HVO36H5Fh_7-0_7xckJcChSSIlqQNMJ6bRSo23M2xm_Dh1lq83nSrUqUQUP9qKYslF99NvmGX-ED-gxhHPtc8w/s1600/Complex+PDU+from+192.168.1.20+to+192.168.1.50+Ping.PNG" imageanchor="1" style="margin-left: 1em; margin-right: 1em; text-align: center;"><img border="0" data-original-height="632" data-original-width="663" height="608" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj6kXBtK5TTCWVoxpl3LUtpTVDOHIViU8uPOoB8JB0_eXcMO8gy09g7HVO36H5Fh_7-0_7xckJcChSSIlqQNMJ6bRSo23M2xm_Dh1lq83nSrUqUQUP9qKYslF99NvmGX-ED-gxhHPtc8w/s640/Complex+PDU+from+192.168.1.20+to+192.168.1.50+Ping.PNG" width="640" /></a> 
 
 
click on "Create PDU" and ckick on "Play" button. 
 
 
 
 
 
 
 
PC will check ARP cache for the destination MAC address, if MAC address is not present ARP Packet will be sent from PC2 with,PC will check the subnet mask to findout the destination host IP is present in same network or different network.If destination IP present in different network,packet will be forwarded to default gateway.Here, the destination IP present in same network, so switch will broadcast throughout the LAN. 
 
Source IP address - 192.168.1.20 
Destination IP address- 192.168.1.50 
Source MAC address - 0001.96DD.75DC 
Destination MAC address- FFFF.FFFF.FFFF 
 
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjt6soFEPrraSv4_U9gFcjL0-PTFE-YFkNYvnB_rB9-VX7zw21A_76gP6CkzQj1CZKhxQnx5N0nSdC4qJQww_rnfm8BrE630EM-VFzifz6-QeIQGIIVx7zImvlFkUgBMc433e_5DG9uDw/s1600/Packet+at+Switch+from+PC2+to+Switch.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em; text-align: center;"><img border="0" data-original-height="668" data-original-width="1050" height="407" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjt6soFEPrraSv4_U9gFcjL0-PTFE-YFkNYvnB_rB9-VX7zw21A_76gP6CkzQj1CZKhxQnx5N0nSdC4qJQww_rnfm8BrE630EM-VFzifz6-QeIQGIIVx7zImvlFkUgBMc433e_5DG9uDw/s640/Packet+at+Switch+from+PC2+to+Switch.jpg" width="640" /></a> 
 
Once the packet reached the switch, it will check received frames source hardware address and destination address.If the source hardware address not found in MAC Address table then,
Switch will save the Source hardware address (MAC) to the MAC address table with port number information on which frames has been received.Here,Source MAC address is 0001.96DD.75DC this information will be saved to MAC address table, Check above image.
 
 
 
 
 
 
 
 
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhimJTvNIGhGZpOpk3V4ePgfTOHl_l5a4YwZJQIKnnFgswpC79sjSAnAUiAH0dTEMdipcc6rD7CVbllvNQYUJRqfykrufTxwUk5JrnuO6g_F_xeXzR0ivivOXN4Wj-QsyT3M7icA-XZDg/s1600/PC+5+Packet+and+ARP+Cache+After+Receiving+PDU.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em; text-align: center;"><img border="0" data-original-height="720" data-original-width="609" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhimJTvNIGhGZpOpk3V4ePgfTOHl_l5a4YwZJQIKnnFgswpC79sjSAnAUiAH0dTEMdipcc6rD7CVbllvNQYUJRqfykrufTxwUk5JrnuO6g_F_xeXzR0ivivOXN4Wj-QsyT3M7icA-XZDg/s640/PC+5+Packet+and+ARP+Cache+After+Receiving+PDU.jpg" width="540" /></a> 
 
If the destination hardware address (MAC ) not present in MAC address table of switch , then switch will broadcast the frames through out all interface connected to it, Except the port in which the frame has been received. 
 
.All Devices connected to this switch will get this frames and the devices will check destination hardware address "FFFFFFFFFFFF" it is broadcast address and it will check IP address of the received packet.If it not matched then it will drop the packet, if IP matched then Source MAC address of received frame will be saved to ARP cache and It will send a echo payload reply with its MAC address ,Only PC5 IP will get a match and it will send a reply to PC2. All other device will drop the frames.check above image. 
 
 
 
 
 
 
 
 
 
 
Now PC5 will reply with its source MAC and IP address, Destination address as PC2 MAC Address and IP address. 
 
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiNCMjJv88Th6mFQC65ZL-dTauLIKBdjnedrWUB0-Txn2JE2TvuUs5uxk3SXdWsAuu6ifdQMWNJrXUlOaZQCihKb8GJx2Fr_tbasn-dLjmsVJuWXvnsxSXsU0IQC4EnKg4zqhNlCTzDAg/s1600/Packet+from+PC5+to+Switch+and+MAC+address+Table.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em; text-align: center;"><img border="0" data-original-height="720" data-original-width="483" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiNCMjJv88Th6mFQC65ZL-dTauLIKBdjnedrWUB0-Txn2JE2TvuUs5uxk3SXdWsAuu6ifdQMWNJrXUlOaZQCihKb8GJx2Fr_tbasn-dLjmsVJuWXvnsxSXsU0IQC4EnKg4zqhNlCTzDAg/s640/Packet+from+PC5+to+Switch+and+MAC+address+Table.jpg" width="428" /></a> 
 
Now,switch will receive frame from PC5 and it will check received frames source hardware address and destination address.
If the source hardware address not found in MAC Address table then Switch will save the Source (MAC) hardware address 0060.5CAA.AA16  to the MAC address table with port number information on which frames has been received. 
 
 
 
 
 
 
 
 
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhPAx7McVjLvc1iJYFMPb3FIthb130YbzSTSXhv4iZIMCWc2BU6G5fktz6DPkcqrPHG71XScC_iRzNBqwK5y4f3V4Xwlt4qGQNhEhrWEIfAe2tppdfmN3X9q3lnGA1jK-i4dRcj1Rcxzg/s1600/PC2+Packet+and+ARP+Cache+Table.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em; text-align: center;"><img border="0" data-original-height="720" data-original-width="575" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhPAx7McVjLvc1iJYFMPb3FIthb130YbzSTSXhv4iZIMCWc2BU6G5fktz6DPkcqrPHG71XScC_iRzNBqwK5y4f3V4Xwlt4qGQNhEhrWEIfAe2tppdfmN3X9q3lnGA1jK-i4dRcj1Rcxzg/s640/PC2+Packet+and+ARP+Cache+Table.jpg" width="510" /></a> 
 
In this case PC2 hardware address already present in Switch MAC address table.So, switch will forward packet Only thorough FastEthernet0/2.Finally, it reaches PC2 with Source MAC address of PC5.PC2 will save the MAC address of PC5 in it's ARP Cache.
 
 
 
 
 
 
 
 
 
 
 
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjiUSyEXGk-1yXLQP7dmIVgsTs2mf1Rfen_q8ceyJI2f3C5ZcPtqUv3iDHarL0Xt8f3rn4oibDdwmKwTUOKpsTNtFNtbK0m-nqfWVGT0MenSEeUVEvjuWqjYEbs0qZduJ1fbITWUqBp-g/s1600/ICMP+Packet+after+ARP+Process.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em; text-align: center;"><img border="0" data-original-height="720" data-original-width="1200" height="384" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjiUSyEXGk-1yXLQP7dmIVgsTs2mf1Rfen_q8ceyJI2f3C5ZcPtqUv3iDHarL0Xt8f3rn4oibDdwmKwTUOKpsTNtFNtbK0m-nqfWVGT0MenSEeUVEvjuWqjYEbs0qZduJ1fbITWUqBp-g/s640/ICMP+Packet+after+ARP+Process.jpg" width="640" /></a> 
 
.Now, PC2 knows the MAC address for the IP address of 192.168.1.50. PC2 will send ICMP packets with Source MAC and IP of PC2 and destination address as PC5 MAC and IP.This time when the frames reaches switch, the switch will forward frames only on port FastEthernet0/5. Because the MAC address already present in MAC address table.

Once the frames reached PC5 .PC5 will send a reply.Once the switch learned MAC address then it won't broadcast again. It will send packet only on particular port on that destination device connected to it. 
 
 
 
 
 </div>

How Switch Learns MAC Address of Connected Devices in LAN

How Switch Learns MAC Address of Connected Devices to It in a LAN example using Packet tracer In this post, we are going to see how the...