[c-nsp] Load-sharing with two links to the same ISP

[Aftab Siddiqui]

hi Matthew,

Keeping the current internet full feed in view its around 300k routes and
sup720-3BXL should support 1million routes (its cisco though :p). So even if
you terminate the links on 2 different edges coming from the same AS it
should work fine.

If you are trying "bgp bestpath as-path multipath-relax" kindly share the
outcomes because in my opinion it is used to load share between different
as-path. I have never tried it before.

Regards,

Aftab A. Siddiqui


On Tue, Feb 9, 2010 at 12:59 AM, Matthew Melbourne <matt at melbourne.org.uk>wrote:

> Thanks for the pointers towards eBGP Multipath. Can I check that this still
> works if two links are terminated on different edge routers (though with
> iBGP between the edge routers). I assume this will use additional TCAM
> resources (Sup720-3BXL) in maintaining two routes per prefix, which could
> be
> significant for a full BGP feed?
>
> Cheers,
>
> Matt
>
> -----Original Message-----
> From: Erik Cuevas [mailto:ecuevas at fxcm.com]
> Sent: 05 February 2010 12:33
> To: Matthew Melbourne
> Subject: RE: [c-nsp] Load-sharing with two links to the same ISP
>
> Did you check out BGP multipath?
>
>
> http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094431
> .shtml
>
>
> or is the AS Path is different try...
>
> bgp bestpath as-path multipath-relax(its hidden)
>
> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net
> [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Matthew Melbourne
> Sent: Friday, February 05, 2010 6:33 AM
> To: cisco-nsp at puck.nether.net
> Subject: [c-nsp] Load-sharing with two links to the same ISP
>
>  Hi,
>
> What techniques are available to load-share traffic on two links (of
> equal bandwidth) to the same ISP  (same AS) given that BGP only enters
> the best path into the RIB? We could announce our prefixes over both
> links, but splitting the preferred path announcements over the two
> links, either using MED or ISP communities, but this only really
> addresses inbound traffic. More of an issue is trying to load-share
> outbound traffic; we assume we'll learn the same set of prefixes over
> both links from the same ISP - one technique may be to simple split
> the IPv4 address space in half and local-pref accordingly to prefer
> one link or the other depending on the destination IP prefix?
>
> Cheers,
>
> Matt
>
> --
> Matthew Melbourne
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