Significance RD and RT in MPLS context

ashutosh_pateriya · ‎03-08-2007

Hi,

I wanted to know what are situations where we can reuse RTs and RDs in our network or they should not be reused at all. What will happen if I am reusing same RTs and/or RDs somewhere else in the network . Theoritically they should not be duplicated but what is the logical ground of that assunption .

mheusinger · ‎03-08-2007

Hi,

in short:

RD makes unique VPNv4 prefixes. If you have one customer and his routes differ in the IPv4 part (they usually should), then you get unique VPNv4 prefixes with ONE RD for this customer. In this case you can reuse the RD - it is even recommended.

RT defines VPN membership. So on one PE you mark routes with a specific RT and on another PE you insert routes based on this RT. If you have to build an any-to-any VPN for ONE customer, all his routes could be marked with one RT. This RT has then the meaning "Customer X" in your environment. In this case RTs can be reused - indeed once again it is recommended.

If you have a second customer, it should most likely never get to see routes of customer X. So you need a different RT for your second customer and so on.

For a more detailed description you could read f.e. through

http://www.cisco.com/en/US/products/sw/iosswrel/ps1830/products_feature_guide09186a00800e977b.html#wp11131

Hope this helps! Please use the rating system.

Regards, Martin