SUP720 with 67XX line card

Unanswered Question
Nov 30th, 2008

Hi,

I use SUP720-10G/3BXL with 67xx ( CEF720) line card without DFC , what will be total througput of chassis (6509) with Central forwarding ?

I guess : 15 MPPS or 48 MPPS ??

And if i want to close to 400MPPS , I need DFC on each line card. is that correct ?

Regards

Chintan

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royalblues Sun, 11/30/2008 - 23:19

Using the WS-F6700-CFC, up to 30 Mpps per system for a centralized forwarding configuration.

Using the WS-F6700-DFC3x, up to 48 Mpps per module for dual fabric channel modules.

Using the WS-F6700-DFC3x, up to 24 Mpps for the single fabric channel module

HTH

Narayan

chintan-shah Sun, 11/30/2008 - 23:41

Hi,

Thanks for clarification but below explnation from cisco confuse me to get 48 Mpps (CFC) , 400 MPPS ( Accelerated CEF ???).....

Delivers Scalable and Predictable Performance: centralized forwarding (CEF) at 48Mpps/720Gbps, accelerated CEF at 400Mpps (peak) /720Gbps and, distributed forwarding (dCEF) 400Mpps (sustained)/720Gbps

http://www.cisco.com/en/US/products/hw/modules/ps2797/ps5138/index.html

REgards

Chintan

Giuseppe Larosa Mon, 12/01/2008 - 01:01

Hello Chintan,

to achieve 400 Mpps and 720 Gbps you need the DFC3x in the linecards.

the document contains the sentence:

Delivering scalable forwarding Performance: up to 400 Mpps1 IPv4 and 200 Mpps IPv6 with

dCEF

there is a footnote 1 reference link

note1:

Requires DFC3's

If all your linecards are 67xx it is wise to install the DFC3x where x matches your current PFC3 version to have optimized forwarding.

Hope to help

Giuseppe

Jon Marshall Mon, 12/01/2008 - 01:02

Chintan

Yes it is a little confusing. Had a quick reread of the 6500 architecture white paper, http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps708/prod_white_paper0900aecd80673385.html, and it states that with CFC ie. centralised forwarding you can achieve rates of 30Mpps providing you don't have classic line cards in the chassis. This is known as compact switching mode.

48Mpps is the forwarding rate achieveable per module (with the right module and DFC card as Narayan points out).

Not sure where the 48Mpps for CFC comes from as i can't find any reference to it in any of the tech docs.

Jon

chintan-shah Mon, 12/01/2008 - 01:57

Hi all,

Thanks for all clarification. So, I take CFC =30 MPPS, with DFC 48 Mpps per slot, with DFC 24 MPPS ( with sinlge fabirc module like 6724) for my further work.

Thanks again all,

Chintan

Joseph W. Doherty Mon, 12/01/2008 - 04:20

For clarification, the supervisior 720 provides either 15 or 30 Mpps for the whole chassis. 15 Mpps when it works with non-fabric cards (e.g. 61xx, 63xx) or 30 Mbpps when it works with fabric cards w/o DFCs (e.g. 65xx, 67xx).

If a fabric card has a DFC, the DFC adds to the forwarding rate either 15 Mpps for the CEF 256 (e.g. 65xx) or 48 Mpps for the CEF 720 (e.g. 67xx) per card.

See table 2 in: http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps708/product_data_sheet0900aecd8017376e.html

I'm unsure how Cisco obtains their 400 Mpps rate. A 6509 with 8 6748 cards with DFCs would provide (8 * 48 Mpps) 384 Mpps. If the sup's Mpps was added, this would provide either 399 or 414 Mpps depending whether you add in 15 or 30 Mpps, but with all DFCs, main sup shouldn't be forwarding "normal" packets.

In theory, if you used a 6513 chassis, slots 9-13 could provide 48 Mpps each using 6748s with DFCs, but since slots 1-7 (sup in slot 8) only offer 20 Gbps, max Mpps would require about 30 Mpps, so 5 * 48 Mpps + 7 * 30 Mpps = 450 Mpps.

Interestingly, 450 Mpps is mentioned in http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps9336/product_data_sheet0900aecd806ed759_ps708_Products_Data_Sheet.html, but this is in reference to 720C and VSS and "increasing the supervisor throughput from 48 to 82 Mpps". I suspect this both means the 720C offers 48 Mpps (single) or 82 Mpps (VSS) and they are adding this value to chassis DFC totals.

Joseph W. Doherty Mon, 12/01/2008 - 05:07

Addendum:

Forgot about the 6724-SFP which is only single fabric connection and rated at 26 Mpps. With these and 6748s, all with DFCs, in a 6513 you have (5 * 48 Mpps) + (7 * 26 Mpps) = 422 Mpps.

PS:

BTW: Wirespeed Ethernet requires 1.488095 Mpps per 1 Gbps for 64 byte size packets, so DFCs can't deliver full wire rate. Also, the CEF720 fabric connections, single 20 or dual 40, are oversubscribed for both 24 or 48 gig port 67xx cards, and again, DFC performance isn't enough to guarantee full wire speed for their bandwidth either. Practically, though, unlikely you'll need full wire rate for 64 sized packets.

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