[45821] in North American Network Operators' Group
Re: Cisco DS3 Questions..
daemon@ATHENA.MIT.EDU (Christopher A. Woodfield)
Thu Feb 21 14:11:34 2002
Date: Thu, 21 Feb 2002 14:12:43 -0500
To: "Gyorfy, Shawn" <sgyorfy@elinkny.com>
Cc: "'nanog@merit.edu'" <nanog@merit.edu>,
"'cisco-nsp@puck.nether.net'" <cisco-nsp@puck.nether.net>
Message-ID: <20020221141243.A24614@semihuman.com>
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In-Reply-To: <ED659EFBBAB8D511AE3E00508BD9392B272631@EXNY1>
From: "Christopher A. Woodfield" <rekoil@semihuman.com>
Errors-To: owner-nanog-outgoing@merit.edu
There's no reason to use frame-relay encapsulation unless you're actually going
through a frame network.
For point-to-point circuits, from Cisco to Cisco, HDLC is the best choice, but
it's proprietary (although Juniper has a Cisco HDLC mode). For
anything else, I'd recommend PPP.
-C
On Thu, Feb 21, 2002 at 01:46:44PM -0500, Gyorfy, Shawn wrote:
>
> Since the topic exploded, what are your opinions on encapsulation of leased
> line DS3s. We currently use Frame Relay for out Point to Point DS3
> connections. Personally, I don't know why we use FR as our encapsulation,
> and so the question to all. If you are running Cisco to Cisco, would it be
> wise to run HDLC or PPP? Our DS3s' here are hardly maxed out, 15% or so, so
> I'm not complaining about the few extra bits I can squeeze out them but
> maybe that 15% can shrink to 10% with less overhead. Opinions or examples
> of life appreciated.
>
> Thanks
>
> shawn
>
> -----Original Message-----
> From: Iljitsch van Beijnum [mailto:iljitsch@muada.com]
> Sent: Wednesday, February 20, 2002 4:28 PM
> To: Jon Mansey
> Cc: nanog@merit.edu
> Subject: Re: Cisco PPP DS-3 limitations - 42.9Mbpbs?
>
>
> On Wed, 20 Feb 2002, Jon Mansey wrote:
>
> > OMG! Arent we missing the point here? What about never running links above
> > 60% or so to allow for bursts against the 5 min average, and <shudder>
> > upgrading or adding capacity when we get too little headroom.
>
> > And here we are, nickel and diming over a few MBps near to 45M on a DS3...
>
> And why not? Obviously there is a reason why they're not upgrading,
> because there is plenty of traffic to fill up a second or faster circuit
> if packets are being dropped because of congestion. (Which has not been
> confirmed so far.)
>
> There shouldn't be any problems pushing a DS3 well beyond 99% utilization,
> by the way. With an average packet size of 500 bytes and 98 packets in the
> output queue on average, 99% only introduces a 9 ms delay. The extra RTT
> will also slow TCP down, but not in such a brutal way as significant
> numbers of lost packets will. Just use a queue size of 500 or so, and
> enable (W)RED to throttle back TCP when there are large bursts.
--
---------------------------
Christopher A. Woodfield rekoil@semihuman.com
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