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

[Jon Lewis]

The "supervisor" is actually a split brain system...with the MSFC handling 
routing calculations/manipulation and the PFC handling packet switching. 
I expect your new setup will handle things just fine...and at least for 
the moment, a Sup720-3BXL can handle full tables.

One annoyance, probably minor, is that none of cisco's GigE ports for the 
6500 have a whole lot of output buffer, so if you're doing much traffic, 
you will likely see some output drops, but not enough to cause problems.

On Wed, 29 Jun 2011, Chris Evans wrote:

> Its all forwarded by the supervisor.  I wouldn't be worried about that too
> much.  I'd be more worried about the full internet table being on the 6500.
>
> It will probably be okay but 6500s aren't great high scale routers. They
> don't have much CPU power.
> On Jun 29, 2011 11:17 AM, <Matthew.Coleman-Hamilton at servicebirmingham.co.uk>
> wrote:
>> Hi,
>>
>> 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?
>> I appreciate that using a WS-X6408A-GBIC means that the classic 32Gbps
>> shared bus will be used (with a max of 15Mpps per system) but in raw
>> performance numbers this is a significant increase on the 7206VXR/NPE-G1s
>> ~2Gbps backplane and ~1Mpps forwarding rate.
>> 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"
>> 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"
>> 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?
>> Thanks in advance,
>> Matthew
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  Jon Lewis, MCP :)           |  I route
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