[Xorp-hackers] BGP MED attributes

[Štefan Gula]

Hi,

In current implementation I believe that it is not possible to send
MED attribute to IBGP neighbors for routes learned from EBGP
neighbors. For example:
We have got 3 routers: R1, R2, R3
R1 is in AS 100
R2 and R3 are in AS 200
they are connected through links L1, L2, L3 like this:
L1: R1 <->R2
L2: R2 <->R3
L3: R3 <->R1

Now want I want to achieve is set MED attribute for routes in AS100 on
R1 for link L1 to 100 and for link L2 to 200. This can be accomplished
without problems. The problem is that routers R2 and R3 doesn't send
MED attribute in their updates about the routes learned from R1.
According to RFC 1771 MED is optional non-transitive and "If received
over external links, the MULTI_EXIT_DISC attribute may be propagated
over internal links to other BGP speakers within the same AS". So why
not enable to sending this attribute to other IBGP neighbors?

There is also one other limitation about NEXT_HOP attribute. In
current implementation every router changes NEXT_HOP attribute to
itself (or the IP set in configuration). Sometimes this behaviour is
not required and I would like to see the option to disable this
behavior.

Best regards.

-- 
Stefan Gula, CCNP