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Re: Frame Relay encap vis-a-vis point-to-point at UUNET

  • From: Nathan Stratton
  • Date: Mon Sep 21 20:57:01 1998

On Mon, 21 Sep 1998, Barry L James wrote:

> Hey all,
> 
> 	We just got a third T1, this time through UUNet and when I looked
> at their router configuration I got a little surprise.  We ordered a
> point-to-point circuit that is being terminated at their detroit POP.  The
> configuration, however, sets up the line as a frame relay encap on a
> sub-interface (on a Cisco, of course :).  When I talked to my UUNet rep he
> advised that this was the way "every large ISP did it" which I knew wasn't
> exactly true since our MCI and AT&T (just recently transitioned from the
> BBN backbone to the AT&T network) does not use this configuration.  He
> insisted that it was still a point to point and that the frame relay
> encapsulation was used to enhance the connection.

Well I don't know that this is the way every large ISP does it, but
several do. That is at least how I did it with NetRail. You take all your
T1 customers into CT3 cards on Cascade 9000s and then connect the 9000 to
your routers.

> Well, I had him grab an engineer (he was an SE) that could possibly
> explain it better to me (since the SE said F/R was used to decrease RIP
> broadcasts across their backbone) and the engineer said this (basically):
> the circuit is terminated in a cascade 9000 f/r switch (used for port
> density) which went to a HSSI interface in a Cisco 7xxx series router
> which connected directly to their ATM network.  Therefore, the f/r encaps
> were needed to speak with the cascade.  The engineer advised we had a full
> CIR and would not suffer any bandwidth loss from using f/r encap.

Correct. 

> Now, I guess my question is: am I getting sold the brooklyn bridge here?

Well no, but it does have some problems. A lot of the Cascades at UUNet
are the old HSSI cards and have problems over 30 megs. 

> I mean, not that I wouldn't like to *own* the brooklyn bridge (well, I'd
> rather have the triboro or the washington, but anyway...).  Is this f/r
> encap going have any adverse affect on the quality of this connection
> (assuming that this is *NOT* a point-to-point into a frame cloud) or am I
> getting shoveled a load of copralite?

Well you should be ok. Sure you MAY run into congestion issues, but you
should be ok. 

> Thanks!

><>
Nathan Stratton				Telecom & ISP Consulting
www.robotics.net	 		nathan@robotics.net
--
"No king is saved by the size of his army; no warrior escapes by
his great strength."                               - Psalm 33:16
 
> Barry
> 
> Barry L James		| Mikrotec Internet Services, Inc (AS3801)
> Director R & D		| 1001 Winchester Rd
> bjames@mis.net		| Lexington KY 40505
> http://www.mis.net/	| 606/266.5925   800/875.5095
> Member AAAI, IEEE # 40277528
> ---
> Man will occasionally stumble over the truth, but most of the time he
> will pick himself up and continue on. -- Winston Churchill
> 





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