[c-nsp] Replacing a 7206VXR w/ NPE-G1 with Sup720-3BXL w/ WS-X6408A-GBIC

[Gert Doering]

Hi,

On Wed, Jun 29, 2011 at 04:14:20PM +0100, Matthew.Coleman-Hamilton at servicebirmingham.co.uk wrote:
> Our Internet BGP tier is currently provided by a pair of 7206VXR routers 
> with NPE-G1s which are getting quite long in the tooth. We've recently 
> been able to reclaim a pair of Sup720-3BXLs and the associated 6509 
> chassis'. Its our intention to retire the 7206s and replace them with the 
> 6509s /w Sup720s but we require 6 GigE interfaces per box. We have a pair 
> of WS-X6408A-GBIC 'classic bus' linecards on the shelf (no spare 65XX or 
> 67XX modules unfortunately) but my question is whether using the 
> WS-X6408A-GBIC to provide port capacity is a good or bad idea in this 
> scenario?

It will work just fine, given that you're not going to max out the bus
with a single 8G card :-)

[..]
> My real concern is that I've found two different Cisco documents that 
> describe the Forwarding-Engine Architecture differently for classic 
> linecards.
> This link :- 
> http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps708/product_data_sheet0900aecd801459a7.html
> states that "the Supervisor engine CPU makes forwarding decision"

That's not fully correct - it's "the Supervisor engine" (as opposed to
"the DFC card on a 6700 module+DFC") but not "the CPU".

> and this link:- 
> http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps708/product_data_sheet0900aecd8017376e.html
> states that "Centralized Cisco Express Forwarding engine located on 
> supervisor policy feature card (PFC) makes forwarding decision"

The PFC is part of the Supervisor engine.

> As the 6500 series is a hardware-based platform I'm keen to make use of 
> hardware-supported features where available and not experience unexpected 
> issues from high CPU utilisation.
> Can anyone confirm exactly how traffic will be forwarded by the 
> Sup720-3BXL with a WS-X6408A-GBIC in the chassis?

Bus, PFC, Hardware.  Unless you hit one of the (rare) feature combinations
that require CPU-based CEF on the Sup720.

gert
-- 
USENET is *not* the non-clickable part of WWW!
                                                           //www.muc.de/~gert/
Gert Doering - Munich, Germany                             gert at greenie.muc.de
fax: +49-89-35655025                        gert at net.informatik.tu-muenchen.de
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