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RE: Cisco PPP DS-3 limitations - 42.9Mbpbs?
Assuming this utilization figure is correct the other way to milk a higher utilization out of the link is by using Random Early Detect (RED) or Weighted RED. This will eliminate jagged utilization pattern you see in fully consumed link which is caused by TCP window synchronization. RED will give you a smoother utilization line that is closer to maximum theoretical throughput of the link. - Dustin - -----Original Message----- From: Ehud Gavron [mailto:[email protected]] Sent: Wednesday, February 20, 2002 9:24 AM To: [email protected] Cc: [email protected] Subject: Cisco PPP DS-3 limitations - 42.9Mbpbs? At a recent consulting opportunity, a client was only getting 40.9Mbps on their DS-3 (clearchannel DS3 over OC12 to the IP provider). (PA-2T3 to PA-2T3, unloaded CPU, drops occur when peak octets out per sec/8=40.9M) The client asked us why 40.9 was less than 44.210. The IP provider indicated that "Cisco told us the maximum theoretical rate of an interface doing DS-3 with PPP encapsulation is 42.9." I can't find documentation to the 42.9. I can't find documentation that indicates that the PPP overhead is somehow magically excluded from the IfOctetsIn and Out... I can't find documentation as to why 40.9 is the observed rate. Frankly, all my DS-3s (HDLC encap) go up to 44.210, so I was hoping I could share in the collective wisdom of NANOG readers who have DS-3s to IP providers, and can provide real observed feedback. Please reply privately. Please let me know privately if you want a summary. Thanks! Ehud Gavron [email protected]