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Vlans between more routers (is it possible?)


What i am trying to do is to ping pc2 from question it possible for pc1 to ping through more routers? will it work if i enter the command encapsulation 802.1q  for r1,r2,r3?

PC1(vlan 10)----------SW2950-----------R1------------R2---------R3--------SW2950-------PC2(vlan 10)

5 Replies 5

Jon Marshall
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VIP Community Legend

If you are using the same IP subnet for vlan 10 on both sides then no this won't work because you can't route within a subnet, only between subnets.

There are some ways of extending the vlan across L3 hops such a L2TPv3 but they require extra configuration and may or may not be supported on your devices.

Note I said extending the vlan but really it is the same IP subnet ie. if you use different IP subnets then you could reuse the vlan number.



I agree with Jon,

You can have the same vlan on both extremes but with different subnets, the routers are going to limit the broadcast domains. 

Now if you are going to implement L2TPv3 you should configure:

*Configuration on R1 and R3 under the interfaces facing the switches. 

pseudowire-class VLAN10
encapsulation l2tpv3
ip local interface Loopback0

interface fa0/0
description FACING-TO-SWITCH

interface fa0/0.10
encapsulation dot1q 10
xconnect <remote loobpack IP> <VC ID> pw-class VLAN10

But As John mentioned, Im not really sure if your devices support L2TPv3. Other option is EoMPLS but you need to configure MPLS between R1, R2 and R3.

Best regards. 

>> Marcar como útil o contestado, si la respuesta resolvió la duda, esto ayuda a futuras consultas de otros miembros de la comunidad. <<

So in a way it`s not possible:(. Another question would be...does it happen often in the real world? for l2 switches (vlan) to go through routers?

It does not happen by default ie. you need to use additional technologies etc.

It does not happen that often so in your setup it would  be far more common to have different subnets at either end even if you used the same vlan number but there are certain cases where it is needed.



You can configure 2 router interfaces to work like layer 2 using bridges, I have made it on 1 router only, but please check if it is supported on your routers. 


>> Marcar como útil o contestado, si la respuesta resolvió la duda, esto ayuda a futuras consultas de otros miembros de la comunidad. <<
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