AT&T MPLS / BIB Routers

Mikeal Clark mikeal.clark at gmail.com
Wed Feb 16 17:16:09 CST 2011


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.

On Wed, Feb 16, 2011 at 5:09 PM, Jim Gettys <jg at freedesktop.org> wrote:

> On 02/16/2011 05:44 PM, Mikeal Clark wrote:
>
>> We just put in a AT&T MPLS and are having a pretty negative experience
>> with
>> the "Business in a Box" routers they are using for our smaller sites.  We
>> are seeing extremely high latency under load.  Anyone have any experience
>> with these devices that could shed some light on this?  Are they really
>> this
>> bad?
>>
>>
> There is excessive buffering in all sorts of devices all over the Internet.
> This causes high latency under load (along with higher packet losses, and
> lots of other problems.
>
> It's what I've been blogging about on http://gettys.wordpress.com. These
> buffers fill; and they are so large they have defeated TCP congestion
> avoidance to boot, with horrifying consequences.
>
> So far, I've found this problem (almost) everywhere I've looked:
>        o ICSI has good data that bufferbloat is endemic in DSL, Cable, and
> FIOS.  Delays are often measured in seconds (rather than milliseconds).
>        o some corporate and ISP networks run without AQM, in circumstances
> that they should.
>        o Windows, Mac OSX and Linux all have bufferbloat in their network
> stacks, at a minimum on recent network device drivers, and often elsewhere.
>        o Every home router I've tested is horrifyingly bad.
>        o 3g networks & 802.11 have this in spades.
>
> Why should AT&T's MPLS be any different?
>
> My next topic will be "transient" bufferbloat, having to do with defeating
> slowstart.
>
> Come start helping fix this: please join us at bufferbloat.net, as we
> try to get people to fix it.  Already there are some experimental patches
> for the Linux Intel wireless driver.
>                        Jim Gettys
>                        Bell Labs
>
>



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