[147545] in North American Network Operators' Group
RE: Multiple ISP Load Balancing
daemon@ATHENA.MIT.EDU (Drew Weaver)
Wed Dec 14 14:29:32 2011
From: Drew Weaver <drew.weaver@thenap.com>
To: "'Holmes,David A'" <dholmes@mwdh2o.com>, "nanog@nanog.org"
<nanog@nanog.org>
Date: Wed, 14 Dec 2011 14:28:34 -0500
In-Reply-To: <922ACC42D498884AA02B3565688AF9953402D4EF13@USEXMBS01.mwd.h2o>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
I've asked several times about this in the past; although I learned quickly=
to stop asking.
It seems that the consensus has generally been that the best way to handle =
traffic engineering in networks where you have multiple full-feed up-stream=
s is to do it manually (i.e. set preference for your top N AS/prefix destin=
ations) or don't do it at all (let BGP figure it out..?).
Suggesting that a "route optimization system" has any value generally makes=
people cranky.
Thanks,
-Drew
-----Original Message-----
From: Holmes,David A [mailto:dholmes@mwdh2o.com]=20
Sent: Wednesday, December 14, 2011 2:07 PM
To: nanog@nanog.org
Subject: Multiple ISP Load Balancing
From time to time some have posted questions asking if BGP load balancers s=
uch as the old Routescience Pathcontrol device are still around, and if not=
what have others found to replace that function. I have used the Routescie=
nce device with much success 10 years ago when it first came on the market,=
but since then a full BGP feed has become much larger, Routescience has be=
en bought by Avaya, then discontinued, and other competitors such as Sockey=
e, Netvmg have been acquired by other companies.
Doing some research on how load balancing can be accomplished in 2011, I ha=
ve come across Cisco's performance routing feature, and features from load =
balancing companies such as F5's Link Controller. I have always found BGP t=
o be easy to work with, and an elegant, simple solution to load balancing u=
sing a route-reflector configuration in which one BGP client (Routescience =
Pathcontrol in my background) learns the best route to destination networks=
, and then announces that best route to BGP border routers using common and=
widely understood BGP concepts such as communities and local pref, and fou=
nd this to lead to a deterministic Internet routing architecture. This requ=
ired a knowledge only of IETF standards (common BGP concepts and configurat=
ions), required no specialized scripting, or any other knowledge lying outs=
ide IETF boundaries, and it seemed reasonable to expect that network engine=
ers should eagerly and enthusiastically want to master this technology, jus=
t as any other technology must be mastered to run high availability network=
s.
So I am wondering if anyone has experience with implementing load balancing=
across multiple ISP links in 2011, and if there have been any comparisons =
between IETF standards-based methods using BGP, and other proprietary metho=
ds which may use a particular vendor's approach to solving the same problem=
, but involves some complexity with more variables to be plugged in to the =
architecture.
David
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