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Fwd: MPLS acceptable latency?



---------- Forwarded message ----------
From: david peahi <davidpeahi at gmail.com>
Date: Thu, Nov 15, 2012 at 12:15 PM
Subject: Re: MPLS acceptable latency?
To: Mikeal Clark <mikeal.clark at gmail.com>



Assuming no configuration errors, this underscores the need to negotiate
SLAs, and serious SLA penalties, with the telcos, and to always request a
telco network map, with the telco path that data will be transitting
end-to-end.. My rule of thumb in network design is that data over copper or
fiber takes 10 ms per 1000 miles, which is governed by the speed of light.
Network devices along the path add serialization/de-serialization delay,
but with modern network devices this delay is negligible. So according to
this rule of thumb 85 ms is almost enough time for data to traverse the USA
3 times.
I have found that telcos have been setting round trip SLAs so high that
they are meaningless (e.g. 50 ms for a GigE MEF ELAN service, 20 ms for
"Gold" MEF EVPL service), and border on being  fraudulent. In one case I
also noted 100 ms round trip times between sites less than 1 mile away, and
discovered that every packet was being sent back to east Texas from
Southern California, almost a 5000 mile detour.




On Thu, Nov 15, 2012 at 10:54 AM, Mikeal Clark <mikeal.clark at gmail.com>wrote:

> Hello!
>
> I have some AT&T MPLS sites under a managed contract with latency
> averaging 75-85 ms without any load.  These sites are only 45 minutes
> away.  What is considered normal/acceptable?
>
> Thanks,
>
>