[j-nsp] include-mp-next-hop

Daniel Roesen dr at cluenet.de
Sat Oct 9 13:52:03 EDT 2004

On Tue, Sep 28, 2004 at 09:23:04AM -0700, Pedro Roque Marques wrote:
> w/ mp-bgp the actual next-hop is part of the MP_REACH_NLRI
> attribute. However the BGP spec used to say that an update msg that
> contains rechable information must include the NEXT_HOP attribute.
> Specs changed back and forth on this... the current versions say that
> the NEXT_HOP attribute (which doesn't really make much sense in this
> context) should not be included. The knob is there to interop w/ old
> equipment that requires this attribute althought it ignores the value. 

Thanks. That explains it perfectly. Can you get your explanation
added to the JUNOS docs please? :-)

Do you know which vendors and which software releases are known to
expect the NEXT_HOP attribute?

I wonder wether enabling/disabling include-mp-next-hop affects only
direct peers or wether it is transitive throughout IBGP. To be more
specific: will disabling the option on one router affect also
routers on the other end of the network, across at least one level
of route reflection? I fear that some BGP implementations might
"cache" somehow wether a NEXT_HOP attribute was received or not and
will re-announce accordingly.

> Seems like a new check that has been added...

I'm hearing that people saw this with 12.2(14)S* and 12.2(18)S*
too. So 12.2S is completely "affected".

Best regards,

CLUE-RIPE -- Jabber: dr at cluenet.de -- dr at IRCnet -- PGP: 0xA85C8AA0

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