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typhoon and tomahawk line cards pps performance



Im trying to work out the performance data for the ASR9k and want to be sure im getting it right


RSP440 does 220G in + 200G out worth of fabric per slot with typhoon

and on a typhoon card per NPU we get

60G in + 60G out and 45Mpps in + 45Mpps out

so for 24x10GE running on a box with single rsp440 we get

220 in, 220 out, which would make for 22 ports at line rate

however since we loose 5G per FIA on this card, we effectively have

5x10GE per FIA, or total 20x10GE ports to keep line rate, which works out as

3x10GE for one NPU, and 2x10GE on the other NPU per FIA

so if we have 45Mpps bidirectional per FIA, we get

for 3x10GE group: 83 bytes at line rate 

for 2x10GE group: 55 bytes at line rate

Is this correct ?

im also assuming that on the 9912 where fabric is separate from the RP, if we have 4+1 fabric cards but we lose an RP we still have the full fabric bandwidth ie 400 in + 440 out per slot when running with one RP, right ?


but if we want to maintain line rate even with small packet sizes, having fabric separate from RP doesnt help much right ?

would be great if numbers can be shared for tomahawk line cards with RSP880/RP2 too, as i havent figured this one out


Cisco Employee

Your math and understanding

Your math and understanding here are correct with one small correction:

in a single RSP440 system, using a 24x10 LC, you could only use 20 ports at linerate.

that is because each of the 4 FIA's gets backpressured. which means that out of the groups of 6 interfaces the FIA serves, only 5 of the 6 can be run at linerate. Since there are 4 FIA's 4x1 is 4 minus 24 ports on the card leaves you with 20 ports at linerate. and then making sure that you skip every 6th interface so: using interfaces 0-1-2-3-4 (skip 5) 6-7-8-9-10 (skip 11) etc

TH does 250 Mpps and the RSP provides 880G per slot per direction.




thanks Xander, Nicolas for

thanks Xander, Nicolas for your replies and clarifications


so if tomahawk NPU does 250Mpps and 240Gbps in+out, and I want to keep linerate at small packet sizes, the math looks like

250Mpps x 64byte x 8bits = 128Gbps


So I need to be looking at a TH card having 12-13 10GE ports per NPU, correct ?  

even if this is far from the 240Gbps per NPU....


Also I cant seem to find anything about the 4x100GE architecture, I only see the 8x100GE on the ciscolive pres






Cisco Employee

Regarding the 9912 part of

Regarding the 9912 part of your question, you have 5 SFC of 110Gbps per fabric cards in Typhoon and 230Gbps per fabric cards in Tomahawk. If you lose on RP, it doesn't change this math (no switching in the RP-1 or RP-2 in 9912 or 9922 chassis, only the control plane).

Losing one SFC will still give you linerate capability.



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