RE: T1 bonding

["Scott Morris" <swm () emanon com>]

If you're treating them as two separate links (e.g. two POPs, etc.) then
that's correct, it'll be done by the routers choice of load-balancing (L3).
If you are going to the same POP (or box potentially) you can do MLPPP and
have a more effective L2 load balancing.

Otherwise, it's possible to get an iMux DSU (Digital Link is a vendor as I
recall, but there may be others) that allow that magical bonding to occur
prior to the router seeing the link.  At that point, the router just sees a
bigger line coming in (some do 6xT-1 and have a 10meg ethernet output to
your router).

If you're seeing the balancing the way that you are, most likely that vendor
(I have no specific knowledge about the A-vendor) is doing usage-based
aggregation which isn't exactly a balancing act.  The ones at some of my
sites are MLPPP which is a vendor-agnostic approach for the most part.

Scott 

-----Original Message-----
From: owner-nanog () merit edu [mailto:owner-nanog () merit edu] On Behalf Of
Elijah Savage
Sent: Tuesday, January 24, 2006 7:28 PM
To: Matt Bazan
Cc: nanog () merit edu
Subject: Re: T1 bonding


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Matt Bazan wrote:
> Can someone shed some technical light on the details of how two T1's 
> are bonded (typically).  We've got two sets of T's at two different 
> location with vendor 'X' (name starts w/ an 'A') and it appears that 
> we're really only getting about 1 full T's worth of bandwidth and 
> maybe 20% of the second.
>
> Seems like they're bonded perhaps using destination IP?  It's a vendor 
> managed solution and I need to get some answers faster than they're 
> coming in.  Thanks.
>
>   Matt
More than likely they are not bonded t1's they are just load balanced by the
router which by default on Cisco is per session. Meaning pc1 to t1#1, pc2to
t1#2, pc3 to t1#1. If they are truly bonded with some sort of MUX for a 3
meg port then you would not see the results you are seeing.

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