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Cisco PPP DS-3 limitations - 42.9Mbpbs?

  • From: Ehud Gavron
  • Date: Wed Feb 20 09:30:19 2002

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]