[45789] in North American Network Operators' Group
Re: Cisco PPP DS-3 limitations - 42.9Mbpbs?
daemon@ATHENA.MIT.EDU (Stephen J. Wilcox)
Wed Feb 20 09:41:59 2002
Date: Wed, 20 Feb 2002 14:41:10 +0000 (GMT)
From: "Stephen J. Wilcox" <steve@opaltelecom.co.uk>
To: Ehud Gavron <gavron@wetwork.net>
Cc: nanog@merit.edu, GAVRON@Opus1.COM
In-Reply-To: <01KEHM424UV8935NJ9@Opus1.COM>
Message-ID: <Pine.LNX.4.21.0202201438080.13061-100000@staff.opaltelecom.net>
MIME-Version: 1.0
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Errors-To: owner-nanog-outgoing@merit.edu
we run HDLC on DS3 and we max at about 40.something too
not sure why, i just assume theres either overhead in the frames somewhere
or that the cards arent designed to run at line speed
we run HDLC, c-bit and CRC16 on PA-2T3+.. be interested if anyone knows
how to get the missing 10% :)
Steve
On Wed, 20 Feb 2002, Ehud Gavron wrote:
>
> 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
> gavron@wetwork.net
>
--
Stephen J. Wilcox
IP Services Manager, Opal Telecom
http://www.opaltelecom.co.uk/
Tel: 0161 222 2000
Fax: 0161 222 2008
