Re: Multiple ISP Load Balancing

[Christopher Morrow <morrowc.lists () gmail com>]

On Wed, Dec 14, 2011 at 2:28 PM, Drew Weaver <drew.weaver () thenap com> wrote:
> 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-streams is to do it manually (i.e. set preference for your top N AS/prefix destinations) 
> or don't do it at all (let BGP figure it out..?).

seems the feeling is that if you have multiple full feeds and need to
loadshare, you really don't want (in most cases) ispa=500mbps +
ispb=500mbps.

you really want destinationA to be reached across the 'best path'
(best ... in some form, distance? packetdrop%? jitter? cost?)  you'll
most likely have to tweak things in order to achieve what you want
since only distance is really used in the stock bgp calculation
(distance by as-hops, presuming you don't listen to closely to med
from your providers)

> Suggesting that a "route optimization system" has any value generally makes people cranky.

ha! :)

-chris

> Thanks,
> -Drew
>
> -----Original Message-----
> From: Holmes,David A [mailto:dholmes () mwdh2o com]
> 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 such as the old Routescience Pathcontrol 
> device are still around, and if not what have others found to replace that function. I have used the Routescience 
> 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 been bought by Avaya, then discontinued, and other competitors such as Sockeye, Netvmg 
> have been acquired by other companies.
>
> Doing some research on how load balancing can be accomplished in 2011, I have come across Cisco's performance routing 
> feature, and features from load balancing companies such as F5's Link Controller. I have always found BGP to be easy 
> to work with, and an elegant, simple solution to load balancing using 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 found this to lead to a deterministic Internet routing architecture. This required a knowledge 
> only of IETF standards (common BGP concepts and configurations), required no specialized scripting, or any other 
> knowledge lying outside IETF boundaries, and it seemed reasonable to expect that network engineers should eagerly and 
> enthusiastically want to master this technology, just as any other technology must be mastered to run high 
> availability networks.
>
> 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 methods 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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