I am entirely new to networking. I have a question on testing in this area.

There is a sample testbed as below:

Host server ---- RD ---- WAN Emulation Server --- RD --- Host Server.

I am hoping RD means Route Distinguisher.

Host servers generate netwrok traffic and emulator simulates network conditions (loss, delay etc.)

In this case how to test the functioning of RDs.

Any references on networking will be really helpful.


  • If you aren't sure what RD means, how can you be sure you're using the proper test criteria? – Mike Pennington May 21 '12 at 17:14
  • I am new to networking. From basic googling I figured out RD was route distinguisher but was not completely sure of it. – Sairam Sankaran May 21 '12 at 17:41

The route distinguisher (RD) is used to uniquely identify the provider edge (PE) router originating a given route within an MPLS VPN (RFC 2457bis) network. The RD is a BGP extended community (i.e. 8 bytes) and is typically utilized by remote PE's as a prequel to a standard 32-bit IPv4 route (..or a 128-bit IPv6 route). By convention the RD is supposed to represent a globally assigned BGP ASN and a locally assigned administrative value but there are alternate mechanisms.

How do you test an RD? It's an attribute on a route - traffic generation and such really have no bearing on it at all. To see it in action set up an MPLS-VPN network. The various PE's will need to have a mesh of multiprotocol BGP sessions. Depending on the platform(s) in use you'll need to find the command that lets you look at the raw routes being received from a particular peer. These routes should contain both the RD of said router as well as the route being advertised. One of the novel (and handy) aspects of these sorts of setups is that two routers within a given site can advertise the same route, each with its own RD, which means that the PE's routing table can actually contain parallel routes without actually having enabled multipathing.

I'd strongly suggest taking a step back and familiarizing yourself with both BGP routing and MPLS as well as the particular implementation of your router vendor of choice before embarking on a mechanism to test something like this. The above may make a lot more sense afterwards. There are a number of great books on the topic but one of my favorites is Yakov Rekhter's "MPLS: Technologies and Applications."

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  • Thanks a lot for your answer. I do not understand most of the jargons here. But will take a look at the above book and make myself familiar. I am not implementing this myself, but was asked a question as to how will I write a framework to test the RDs. – Sairam Sankaran May 21 '12 at 17:44

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