If you are running frame-relay now, unless you have an asymmetrical configuration (which cisco CAN do) where one end is configured to look like a f/r switch, you probably have your carrier's f/r switch in the middle. Whoever configured it that way in the router did it because that is the king of circuit that was ordered. It may well be that there was a much better price especially if there was a lot of mileage and the cir was set low. f/r can look good sometimes. If it is a real point to point t3, don't use f/r ----- Original Message ----- From: "Gyorfy, Shawn" <sgyorfy@elinkny.com> To: <nanog@merit.edu>; <cisco-nsp@puck.nether.net> Sent: Thursday, February 21, 2002 1:46 PM Subject: Cisco DS3 Questions..
Since the topic exploded, what are your opinions on encapsulation of
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
leased 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.