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Re: AGIS Route Flaps Interrupting its Peering?

  • From: Dave Siegel
  • Date: Mon Jul 08 14:35:00 1996

> This actually works reasonably well as long as you don't try to cram 20Mbps 
> of data through it in aggregate.
> 
> The problem that one particular provider had was trying to do this
> full-mesh AND ignoring the fact that Ethernet isn't really 10Mbps; its 
> more like 5-6Mbps when you take the duplexing issues into account.  Now add
> the collision domain problems to this (you really don't have a 3000-mile
> collision domain; its "faked" in the translation) and limited buffering and
> you can see where some problems show up really quickly, especially when you
> sell resale T1s to people and don't upgrade the backbone to meet the
> increasing sales of circuits......
> 
> If you only mesh the places you need to talk to from one point to another
> and use a better exit technology at exchange points (allowing an aggregate
> data rate > 10mbps) it works quite well.  Try to go "cheap" and use the AUI
> interface everywhere and you get a different result.

And I know a provider that despite realistic expectations of the technology,
still experience serious problems with everything that Sean mentioned.  50%
of all problems were caused by inadequate buffering, and the other 50% were
caused by PVC's either dissappearing, or being re-routed around the wrong
end of the country.

(Gee, 250ms from San Francisco to San Jose...it's taking the east coast route
again...)

> > 	-- mixed-media bridging (NetEdges, FDDI/Ethernet bridges)
> 
> Netedge <> Ethernet works quite well (far better than RETIX<>Ethernet.)  

No argument on the Retix's.

> Netedge<>FDDI has been reported to have the problems you listed, and more.

not quite there yet, no.

> > Finally, why is it that most vendors never test their products in
> > a serious battlefield environment like an ISP of size medium to huge?
> > These places tend to be excellent worst-case testing grounds.
> 
> That's a good question...

What are you talking about?  They do a series of stress tests designed to
push the equipment to it's utmost capabilities in their state-of-the-art

  ...laboratory.

heh.

Dave

-- 
Dave Siegel		     Sr. Network Engineer, RTD Systems & Networking
(520)623-9663 x130	     Network Consultant -- Regional/National NSPs
dsiegel@rtd.com		     User Tracking & Acctg -- "Written by an ISP, 
http://www.rtd.com/~dsiegel/					for an ISP."
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