RD is local value in MPLS?

[wfqk]

Hi In MPLS and vrf environment, can we say RD is local value? it also means RD is significant locally? If we want to change the RD value, what other do we also need to change accordingly? Thank you

[Mark Malone]

Hi

its not exactly locally significant to say a device , its local to a vrf which can be spread across multiple devices in an MPLS domain , so if your changing it you want to plan it and make sure as they can be used to specify a customer vrf , if you change it one place and not the other you will lose routes as when the MP-BGP exchanges routes the RDs will be different so they wont go into the same vrf

RDs keep track of what routes belong to what customer usually , in an MPLS domain you may have several customers with same subnet space 192.168.10.0/24 , so you tag it to make sure it lands in correct VRF

[mlund]

Hi

I do not agree with that.

What You describe is the RT (route-target), wich is what bgp use to recognize different customer. You set a route-target value for export and if the import route-target matches on the bgp peer it will be installed into the vrf that has the RT configured.

The RD (route distinguisher) is local significant to the router, however it is ditributed to the other bgp peers together with ip adresses. For example if a customer has 10.1.1.0/24 as to be routed, and the RD is specified as rd 1:1 then the router announce this as 1:1:10.1.1.0.

If you at the same time have a redundant router annoncing the same prefix and also is configured with rd 1:1 it will also announce 1:1:10.1.1.0 and the receiving router has to chose one of them. If however the redundant router is configured with rd 1:2 it will announce the router as 1:2:10.1.1.0 and because they are different, the receiving router can accept both.

/Mikael 

[Yashar Toopchi]

Hi Mikael,

Your statement is wrong, RD is used to distinguish the routes of different customers connected to the same service provider, route target is used for route import and export and is typically used for VRF route leaking. RD is locally significant and is unique for each VRF in a PE router (or RR)

Thanks.

[iankihiu1]

is it ? RD locally significant. RT globally significant ?