RE: Newbie network upgrade question, apologies in advance to NANOG

["Vandy Hamidi" <vandy.hamidi () markettools com>]

I would agree only under certain limited situations.
Per packet load balancing COULD increase jitter, and if you're running VOIP (or similar protocols) could degrade 
performance.  It could also affect TCP performance (on OSes not SACK enabled) as well.
This would only really happen if you're T1's are near capacity (~above 80% or so).  Near when queues start causing 
noticeable delays.

If were talking about 2 identically configured T1's, on the same router, through the same loop provider, connected to 
one ISP--I highly doubt a situation where packet reordering would arise.  It's not impossible, but unlikely as all the 
circuits would be utilized the same, thus queue delays should be similar across the board.

I've done this on a private network with 4 T1's and never had a problem.  We were pushing 100GB database dumps across 
it and performance did quadruple over the single T1.


        -=Vandy=-

-----Original Message-----
From: prue [mailto:prue () usc edu]
Sent: Wednesday, July 02, 2003 1:21 PM
To: Vandy Hamidi
Cc: nanog () merit edu
Subject: RE: Newbie network upgrade question, apologies in advance to
NANOG


Vandy,

> Also, you may want to set your border router (the one with the serials to your 
> ISP) to route "per packet" as opposed to allowing the routes to cache.  This 
> will distribute the bandwidtch evenly across your T1's.  If you don't, then a 
> single high traffic session or destination can consume an uneven amount of 
> bandwidth on one of your lines.  You can ask your ISP to do this as well for 
> incoming packets.

That is not such a good idea generally.  If you do this then you get packet 
reordering.  This can be detrimental to TCP performance.

Walt