AT&T MPLS / BIB Routers

George Bonser gbonser at
Thu Feb 17 00:02:40 CST 2011

> From: Mikeal Clark 
> Sent: Wednesday, February 16, 2011 3:16 PM
> To: Jim Gettys
> Cc: nanog at
> Subject: Re: AT&T MPLS / BIB Routers
> I'm building up to 3000-4000ms latency with these BIB routers.  We
> never had
> this issue on the old point to points using Cisco gear.

Something I might try, assuming that the BIB unit plugs into a switch
port, is to try bandwidth limiting that port to whatever the CIR is of
the MPLS link.  If buffering in that path is the problem, limiting the
input bandwidth to the box to the maximum of the output bandwidth should
eliminate any buffering in the path or the BIB box.  Assuming your old
Cisco gear was using the same network infrastructure, that might rule
out excessive buffering in the MPLS path as the cause, unless AT&T can't
actually deliver the advertized bandwidth across the path they are

What is the CIR?  If you have a 10Meg path and have a GigE jacked into
the box, yeah, it's going to get into buffers pretty quick.  Maybe even
taking the ethernet port down to 10Meg might help, depending on what you
are expecting the bandwidth of the path to be.  

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