[Xorp-users] XORP BGP supports ECMP?

y wu ywuus at yahoo.com
Sun Oct 8 21:41:12 PDT 2006

Hi Vincent,

Thanks for your reply.  It seems that Cisco does
support (some fashion) of ECMP in BGP, indicated
by following quotes from their BGP configuration
instruction manual, regarding E-BGP routes (see
) and I-BGP (see
); so does Juniper (see
for details).  Regards,

BGP Multipath Support

When a BGP speaker learns two identical EBGP paths for
a prefix from a neighboring AS, it will choose the
path with the lowest route-id as the best path. This
best path is installed in the IP routing table. If BGP
multipath support is enabled and the EBGP paths are
learned from the same neighboring AS, instead of
picking one best path, multiple paths are installed in
the IP routing table.

During packet switching, depending on the switching
mode, either per-packet or per-destination load
balancing is performed among the multiple paths. A
maximum of six paths is supported. The maximum-paths
router configuration command controls the number of
paths allowed. By default, BGP will install only one
path to the IP routing table. 

--- Vincent Jardin <vjardin at free.fr> wrote:

> Hash: SHA1
> But, in any cases, ECMP cannot apply to BGP due to
> its policy of
> selection process of the next hop. Only, static
> routes, OSPF, RIP and
> ISIS can support it.
> But, if there are any papers or recommandations that
> show that BGP can
> support ECMP as-is, I'd apprecieate to review it :)
> FYI, it is currently a working draft:
> ~ 
> but right now, no implementation supports it.
> Vincent
> Pavlin Radoslavov wrote:
> |>Does XORP's BGP support multipath ECMP?
> |>I briefly looked at the code and didn't
> |>see any hint.  Nor did other protocols.
> |
> |
> | No, currently XORP doesn't support ECMP.
> | It is on our TODO list:
> |
> | http://www.xorp.org/bugzilla/show_bug.cgi?id=223
> |
> | Regards,
> | Pavlin
> |
> | _______________________________________________
> | Xorp-users mailing list
> | Xorp-users at xorp.org
> |
> Version: GnuPG v1.2.5 (MingW32)
> Comment: Using GnuPG with Thunderbird -
> http://enigmail.mozdev.org
> 1masJOUheGkB7Re8EGhbjgA=
> =BWbt

Do You Yahoo!?
Tired of spam?  Yahoo! Mail has the best spam protection around 

More information about the Xorp-users mailing list