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Beginner

Is it possible to talk eachother without RT?

Hi there. 

If there were two customer, and RD is set the same both side on the each PE device. 

what if we don't set the RT, is it working? or without RT, they can't talk each other?

IF they can talk, it means we only need to set the RT when we need to talk different VPN site(different custoemer). Am i right ?

Thank you. 

Best regards, 

1 ACCEPTED SOLUTION

Accepted Solutions
Hall of Fame Cisco Employee

Hello,

Hello,

"Without RT" means "no export RT" and "no import RT", right?

In that case, if two PE routers have a VRF defined without any route-target commands whatsoever then the communication will not be possible, and here is why:

  • Any route sent out from one PE to the other within this VRF will have no RT assigned, because there was no route-target export command configured.
  • On the receiving PE, this route will not be imported into any of the existing VRFs because:
    • VRFs having the route-target import command configured won't see this particular RT value in the received route, as it does not have any RT
    • VRFs without the route-target import command deny all incoming routes because the lack of this command says that regardless of the RT value, this VRF is not interested in importing routes

Best regards,
Peter

4 REPLIES 4
Hall of Fame Cisco Employee

Hello,

Hello,

"Without RT" means "no export RT" and "no import RT", right?

In that case, if two PE routers have a VRF defined without any route-target commands whatsoever then the communication will not be possible, and here is why:

  • Any route sent out from one PE to the other within this VRF will have no RT assigned, because there was no route-target export command configured.
  • On the receiving PE, this route will not be imported into any of the existing VRFs because:
    • VRFs having the route-target import command configured won't see this particular RT value in the received route, as it does not have any RT
    • VRFs without the route-target import command deny all incoming routes because the lack of this command says that regardless of the RT value, this VRF is not interested in importing routes

Best regards,
Peter

Highlighted
Beginner

Thank you very much !! 

Thank you very much !! 

Beginner

There is the exception of a

There is the exception of a VRF Lite configuration. With this method the VRF is declared on all routers from end to end including the routing protocols. The drawback is the extra configuration and management needs so it isn't practical for large networks.

Participant

as a side note you can do

as a side note you can do this on junipers using policies rather than route targets

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