The 3GE will never run all 3 ports at line rate what ever the packet size
(ie/ you do not overload the forwarding ASIC). This is because the usable
bandwidth from the card into the fabric is ~2.8Gbps (full-duplex). The line
cards on a GSR do not switch packets internally - all traffic between cards
(even on the same card) is via the switch fabric.
Matt.
-----Original Message-----
From: Mikael Abrahamsson [mailto:swmike@swm.pp.se]
Sent: 19 July 2002 09:47
To: Cisco-NSP
Subject: RE: [nsp] Gigabit Ether Channel on Cisco 12000s
On Fri, 19 Jul 2002, Matt Ryan wrote:
> LOL - having work in the OIBU with Chris (albeit for only 18 months) I'd
> have to agree with his version as well. While in other places Cisco use
> Cabletron maths (as I believe is the right place to lay this blame) the
GSR
> switching fabric is not one of them.
So, on a 12012 with:
1 Route Processor Card
1 Clock Scheduler Card
3 Switch Fabric Cards
What is the available aggregate useful packet bandwidth in the backplane
to a 3GE card?
Will a 3GE be able to run all three ports full (if the pps limit is not
reached) or not? If there is a backplane limit, is this leveraged in case
some packets can be forwarded between the ports on a single 3GE (ie the
card have higher "internal" capacity than the backplane can support) and
then it can run all three ports full?
-- Mikael Abrahamsson email: swmike@swm.pp.se------------------------------------------------------------------------------ Live Life in Broadband www.telewest.co.uk
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