GNS3 switching setup and options Part 6: Etherswitch, Wireshark, 802.1Q, InterVLAN routing

Key Takeaways

[Music] this is one of multiple videos discussing switching options available in gns3 in previous videos which I've linked below I discussed Cisco IOS avi layer 2 which is the recommended way of implementing switching with gns3 I've also discussed the junus three built-in switch in this video I'm going to demonstrate the ether switcher module which is a module that you insert into rodders to provide switching capability this once again provides basic switching capabilities if you want to use a more advanced searching capabilities rather use iOS V layered two images but for basic switching the ether switch rudder is sufficient in this video I'm going to show you how to configure a router on a stick integrated with the ether switch router I'll then do why shock captures on the Slinker so that we can see the attitude at 1q frames sent it between the rider acting as the rod on the stick and the ether switch Radha previously I configured the ether switch Radha with ports Faust Ethernet 1 / 0 1 / 1 & 1/2 in VLAN - and Faust Ethernet 1/3 in veal and 3 in other words these interfaces are in VLAN 2 and this interface is in veal and 3 what we want to do now is configure editor 1q crunking on fast ethernet 1/4 and then configure router 5 as a rudder on a stick so firstly show run interface F 1 / of for the ether switch has a default config on this interface so we're going to tap switch port mode trunk show run interface F 1 / 4 again we can see that the port is configured for trunking so now let's configure router 5 for inter VLAN routing I'll sort up the Rotter and open up a console so on router 5 go into interface f 0/0 no shut it create a sub interface of dot 1 notice what happens if I try and configure an IP address on the sub interface we told that configuring IP routing on al and sub interfaces only allowed if after sub interface is already configured as part of an attitude at one cue trunk or ISL trunk so we need to set the encapsulation to dot1q I'm going to specify a VLAN of 1 and make that the native VLAN and now I can configure an IP address on the sub interface the Fast Ethernet interface has now come up so interface F 0 / 0.2 encapsulation dot1q this will be for VLAN 2 IP address 10 dot one dot 2 to 254 specify the subnet mask interface F 0 / 0.3 encapsulation dot1q this will be veal and 3 IP address 10 dot one dot dot 254 / 24 show run allows us to see the config URIs our physical interface and here are the sub interfaces on the Radha now this number doesn't have to be the same as this number I've only made them the same to be consistent this is the VLAN tag that the Radha will receive so if it receives VLAN 3 it's gonna process it using this sub interface if it receives VLAN to tag frames it's going to process those frames using this sub interface if it receives untagged frames it's going to process them using this sub interface now in the previous demo are configured multiple routers in the same subnet even though they are in different VLANs and that was done to prove a point about the factor that a layer 2 switch can separate traffic including broadcast traffic by using VLANs so at the moment F 1 slash 0 1/1 1/2 on VLAN 2 and if 1/3 is configured in VLAN 3 so what I'll do is configure these 3 brothers in subnet 10120 and this router in subnet 10 1 3 0 so I'm right a 1 on the first Ethernet interface I'll change the IP address to 10 1 to 1 I'll also set a default route to write a 5 acting as the inter VLAN router ping 10 dot one dot to 54 now we should be able to ping the default gateway let's ping ourselves that works ping the default gateway that's not working let's check if it works here paying 10 1 2 2 5 4 we can ping ourselves but we can't ping write a 1 back on the switch show run interface F 1/4 show CDP neighbors show interface F 1/4 so this is a problem the interface is down at the moment what I'll do is delete that link and I'll add it back again F 1/4 should be connected to F 0/0 on router 5 back on router 5 show interface F 0 / 0 it says the interface is up but on the switch faces showing down so what I'll do is shut it down and no shirt see if that makes any difference so we told it's now become a trunk interface has come up so show CDP neighbor we can now see router 5 and we can see that it's available on Fast Ethernet 0 / 0.1 so back on Radha 1 can be paying the default gateway yes we can can we paying the other sub interface on the default gateway yes we can so that looks a lot better let's go into write a for which is in a separate subnet IP address ten dot one dot dot for now what I'll do here something different I'll disable IP routing to make this become like a PC so the IP rot command won't have any effect we need to use this command IP default gateway notice the IP routing table doesn't show output like you would have when IP writing is enabled so rather one has IP routing enabled output looks like that rather fall doesn't output looks like this hence we need to use the IP default gateway command can be paying ten one two three two five four yes we can can we paying ten one two one Rotter one yes we can debug IP ICMP will prove that ping the Radha there are the echo replies I'll trace to ten one two one notice the traffic is going via the rod on the stick so I'll complete the configuration of router 2 and router three so that we have a fully functioning Network and then I'll do some Wireshark captures so interface F 0/0 on router to ten one two one will be the IP address we need to all they were being correct let's make it ten one two two rather notice we got duplicate IP address warning configure a default route on this Radha pointing to the default gateway ping 10 1 2 1 that's rata 1 rather form Ping's succeeds inter VLAN writing is working and lastly on writer 3 IP address 10.1 dot 2.3 IP write 10 1 2 2 5 4 can it ping writer for yes it can so we have full IP connectivity in this network what I'll do now is start a capture on this link between the switch and router five so we see p vs t plus traffic we see some other traffic being captured already AA filter for ICMP traffic and on brought a fool I'll ping rather one but only send one ping and I'll stop that why shall capture so notice we received an eight atutor 1q frame with the VLAN set to three that's correct because Radha for is in veal and three and the switch is indicating to Radha five that that Radha belongs to veal and three we can see that the source is 10 1 2 3 4 the destination is 10 1 2 1 in other words this is right a 4 in VLAN 3 pinging right a 1 in VLAN 2 we can see that it's an echo request a packet now the right on the stick sends the frame back to the switch but notice the VLAN ID has changed so the packet was sent by rata fall to the switch it was sent by the switch to router 5 and then back from router 5 to the switch but with the VLAN number changed so the VLAN number changed from 3 to 2 as it was sent back to the switch from router 5 notice the source and destination IP addresses are the same but the source and destination MAC addresses are different so the frame from rada for 2 out of 5 has the destination set to this but what you'll notice is that becomes the source of the frame center PI R out of 5 back to the switch so just going back notice the MAC addresses see 2 0 6 1 be 44 and that is the source in the next frame because the frame was sent untagged from router fall to the switch tagged as VLAN 3 by the switch and sent to a destination MAC address of router 5 router 5 then changed the VLAN number and sent it back to the switch but when doing into VLAN routing the rod it changes the source and destination MAC addresses source MAC address is rather for destination MAC addresses are out of five but now the source MAC address is router five destination MAC address is rather one VLAN number has changed IP addresses remain the same this is the reply from Radha one too broad of four so the source MAC addresses router one destination MAC addresses router five it's tagged by the switch as VLAN 2 we can see the source and destination IP addresses of Radha 1 and writer for this is an echo reply router five does the inter VLAN rot so now we've got router five source MAC address sending the traffic to router for destination MAC address the raid has changed the VLAN number to 3 IP addresses our router 1 2 out of 4 it's an echo reply so this is an example of a rod on a stick and you can see how the traffic here is tagged on this link as a veal and three when sent from the switch to route of five but tagged as VLAN to when sent by rider five back to the switch destined to write a 1 when it comes from Rider one it's untagged here tagged here as VLAN to by the switch inter VLAN rotted sent back to the switch as wheel and 3 the tag is then removed when it gets to router for says another test let's prove that I'll do a capture here as well as a capture here so route of fall sends a ping to write a one-off filter for ICMP this is the link between router fall and the switch what you'll notice is the frames are untagged there is no attitude of 1q tagging here however the frames between the switch and router five odd tagged VLAN three VLAN to be lent to the VLAN three now it's not very efficient to send traffic to Rada five and back again every time devices send traffic from one VLAN to another and hence routers on sticks have been replaced by layer 3 switches using switched virtual interfaces or SV eyes so that traffic doesn't have to go to router five and back again every time it's inter VLAN routed I hope you've enjoyed this video if it's been of benefit to you please like it and please subscribe to my youtube channel I wish you all the very best [Music]