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Catalyst 4500 series SUP7E perfomance comparision question

Alexey Stytsenko
Beginner
Beginner

Hi folks!

I have few questions about SUP7E perfomance. There are they:

Catalyst 4500 SUP7e switching capacity is 848 Gbps

Catalyst 6500 Sup720 backplane is 720 Gbps

So this is mean that SUP7E has capability to switch more traffic than SUP720 ?

Second question - what size pakets must be to gain bandwidth of 848 gbps when SUP7E IPv4 throughput is 250 mpps? 1500 byte packets give us only about 375 Gbps.

And last question -

Catalyst 4500 SUP7e IPv4 throughput is 250 mpps

Catalyst 6500 Sup720 without using distributed forwarding (NO DFC3!!!) is 30 mpps

SUP7E has so poferful architecture that dominate over Sup720 architecture 8 times???

What purpose of using such distributed architectures(as Sup720) if centralized can offer such perfomance?

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Accepted Solutions

Joseph W. Doherty
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Hall of Fame Master

Disclaimer

The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

Liability Disclaimer

In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

Fabric bandwidths are generally defined for both in and out.  So, for example a 2 gig port switch, to support wire-speed or line-rate, would need a 4 Gbps fabric.  The fabric bandwidth requirement is independent of frame size.

Forwarding rates are defined for traffic flowing unidirectionally through the device, so the same 2 gig port switch, to guarantee Ethernet line rate would need to provide about 2.976 Mpps.  (NB: this for minimal size frames, the pps requirement would decrease for larger frames.  For example, 1518 byte frame for the same 2 gig would only require .162 Mpps)  (NB: for one gig, Ethernet min frames need 1.488 Mpps, 1518 byte frames need 81 Kpps.)

"So this is mean that SUP7E has capability to switch more traffic than SUP720 ?"

Yes, it does.  More fabric bandwidth, and much, much, much more forwarding performance for the supervisor itself. 

"Second question - what size pakets must be to gain bandwidth of 848 gbps  when SUP7E IPv4 throughput is 250 mpps? 1500 byte packets give us only  about 375 Gbps."

Packet size doesn't matter. To fully utilize 848 Gbps, you would need a Ethernet forwarding rate of about 285 Mpps to guarantee line-rate or wire-speed for all frame sizes.

"Catalyst 6500 Sup720 without using distributed forwarding (NO DFC3!!!) is 30 mpps"

That's for fabric line cards - half that for non-fabric line cards.

"SUP7E has so poferful architecture that dominate over Sup720 architecture 8 times???"

Correct for just for supervisor forwarding performance.

"What purpose of using such distributed architectures(as Sup720) if centralized can offer such perfomance?"

That's how the 6500 architecture offers additional forwarding performance.

dCEF720 line cards, with their DFCs, offer 48 Mpps (per card).

PS:

As the other posters have noted, the SUP7E is very recent, and its performance outclasses a SUP720 but the even more recent SUP2T with its newer corresponding line cards offers about twice the performance; 1 Tbps fabric and up to 720 Mpps in a 6513 chassis.  (NB: the Mpps performance doesn't guarantee wire-speed/line-rate performance for all Ethernet packet sizes, but real-world packets generally aren't all minimum sized.)

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Disclaimer

The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

Liability Disclaimer

In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

Why? Mpps is value given for a whole system not only one direction of  traffic, and 720 Gbps (sup 720) is bidirectional bandwidth as well.

Yes, pps is given for the whole system, but you only need to account for one direction of traffic; fabric specifications tend to account for duplex bandwidth.  It's really the same bandwidth, but the pps and fabric account for them differently; similar to a 100 Mbps (duplex) link might be noted as providing 200 Mbps of bandwidth.

For example:

Assuming we have a 4x gig (duplex) port switch, how much bandwidth do we have 4 gig or 8 gig?  Since each port is duplex, we must have 8 gig, yet one port's input is another's output, so there's only 4 gig being transferred.  The fabric bandwidth, if it can support all the ports at their full rate, would be noted as 8 gig.  The forwarding pps, would only need to account for 4 gig.  For Ethernet 64 bytes this would be 4 x 1.488 Mpps, for Ethernet 1,518 bytes this would be 4 x 81 Kpps.

And throughput in 64 bytes packets - is maximum throughput system can  grant, then for 1518 bytes packets thoughput will significantly differs  in decreasing side?

No, just the opposite.  Bigger packets required pps rates, for same transfer rate, decrease.  (Again, for gig Ethernet, 1.488 Mpps @ 64 vs. 81 Kpps @ Kpps.)

PS:

A 6513's slots 1-8 provide 20 (duplex), slots 9-13 provide 40 (duplex).  Fabric bandwidth would be 8*40=320 Gbps, 5*80=400 Gbps; 320 + 400 = 720 Gbps

PPS:

4500 series provides 6, 24 (SUP6) or 48 (SUP7E) Gbps per slot (with corresponding line cards).

6500 series provides 20 or 40 (SUP720), or 80 (SUP2T) Gbps per slot (with corresponding line cards).

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11 REPLIES 11

Leo Laohoo
VIP Community Legend VIP Community Legend
VIP Community Legend

Hi Alexey,

I'm no expert with the Sup7E, however, I would like to request if you can compare the performance of the Sup7E with the  Sup2T (link included).

The reason why is because the Sup720 is a 5 year old technology.  The Sup7E for the 4500 is less than a year old.  The Sup2T, however, is also new (officially released last week).

SUP2T use PFC4 card which offers 60 mpps of centralized forwarding.

So last question as well can be applied to Sup2T architecture

But first two questions is still topical cos it seems to me that i misunderstood smth in them.