Load Balancing between multiple BGP peer connections
Tom Sands
tsands at rackspace.com
Wed Sep 14 18:27:27 UTC 2005
Is the connectivity with 1 provider or 3 separate provider? The diagram
and wording would seem like its the same.
Patrick W. Gilmore wrote:
>
> [Wow, operational content - thank you!]
>
> On Sep 14, 2005, at 6:24 AM, Joe Shen wrote:
>
>>
>> How could load on multiple BGP peer links be balanced
>> automatically?
>>
>> The situation we are facing:
>>
>> ---------------------------|
>> | Service provider |
>> | |
>> --R1--------------------R2---
>> |\ |
>> | \ E-BGP |
>> | \ ----------------\ |
>> | \|
>> ----R3--------------------R4-|
>> | Our Network |
>> | (OSPF) |
>> -----------------------------
>>
>> The three links between our network and Service
>> provider network are all 1Gbps. Now, we noticed that
>> load on link R1-R3, R1-R4 is about 50% (in/out), but
>> load on R2-R4 are about 90% ( in/out).
>>
>> How could we balance those load on the three links
>> automatically? or must we tune the route mannually?
>
>
> It's not really clear whether the traffic is going mostly in or
> mostly out. In fact, it looks like you are 1:1 balanced from the
> paragraphs above.
>
> Inbound traffic and outbound traffic need to be balanced separately.
> I'll do inbound here, since that's slightly harder. If you need help
> with outbound too, let us know.
>
>
> First, what are you announcing to your SP? Is it just one big
> block? Or several?
>
> Second, does your SP accept MEDs? (And if not, maybe you need a new
> one? :-)
>
> If you have just one big block, split it up into multiple little
> blocks. Announce them with MEDs or prepend on some links and not
> others or just announce a subset on each link. Be sure to set
> NO_EXPORT on the little blocks, and announce the aggregate prefix on
> all links. You do not want the little blocks making it into the
> global table (wouldn't do any good anyway).
>
> It's not difficult to do, it's just a bit of trial-and-error to get
> right unless you have Flow Stats or something so you know where the
> traffic is going anyway.
>
>
> Outbound is a variation on this theme. Let us know if you need
> outbound help as well.
>
> Good luck.
>
--
------------------------------------------------------
Tom Sands
Chief Network Engineer
Rackspace Managed Hosting
(210)447-4065
------------------------------------------------------
More information about the NANOG
mailing list