SUP720 with C6513 or C6509

[a12288]

SUP720 can only stay in slot7 or 8 in C6513, while Slot 7 and 8 are single channel, on the other hand C6509 supports dual channels in each channels, Can I see deploying Sup720 in C6513 will NOT fully utilized its horsepower?

[Jon Marshall]

It's more to do with driving the line cards. Generally speaking you cannot put any 6500 CEF 720 interface modules into any slots other than 9 - 13 although you can use the WS-X6724-SFP module in any slot as it only has one 20GB connection to the switch fabric.

On a 6509 all the slots as you say support dual channels so you can connect more 720 modules into that chassis. It really all depends on how much throughput you actually need. if you must have all fabric only cards with dual channels for performance and you need more slots than the 6513 provides then you need 6509-E chassis's.

Bear in mind that any other combination of cards can go in slots 1 -6 ie. classic line cards and CEF256 cards. The Sup720 will auto-sense the card and provide the correct amount of connectivity to the switch backplane.

HTH

[a12288]

Thanks, still like to know what is the difference to SUP720 itself then, between inserting into single-channel or dual-channel chassis.

[Jon Marshall]

I believe the sup720 only has one dedicated 20Gb connection to the switch backplane regardless of the chassis.

Taken from one of our data centre switches:-

DC-XXX-XXX-DS1#sh fabric status

slot channel speed module fabric

status status

1 0 20G OK OK

2 0 20G OK OK

2 1 20G OK OK

5 0 20G OK OK

Slot 1 has a WS-X6724-SFP which only has 1 20Gb channel.

Slot 5 is the Supervisor 720

Slot 2 is the WS-X6748-GE-TX which has 2 x 20Gb channels.

HTH

[Jean-Noel Poulet]

in chassis 6509 and lower all slots have 2 channels of 20GB for connection to the sup720.

in chassis 6513, slot 1 to 8 have a single channel of 20GB, slot 9 to 13 have a dual ...

This concerns only line cards. Not the supervisor. Sup720 has a capacity of 720GB.

In a 6509 chassis it is used as 9(slots) *20GB *2(channels)*2(fullduplex)=720.

IN 6513, you may use classic as well as switch fabric enabled line card in any slot, but dual channel switch fabric enabled line cards (like 6748) should be installed only in slots 9 to 13.

[Jon Marshall]

One further thing. The output shown was from a 6509. However we do have some service modules in that switch which are fabric-enabled ( not fabric only like the CEF 720 modules ). However due to a "bug" we have had to force the switching mode to bus mode for these service modules. This forcing only affects the service modules but i'm not 100% sure if it could affect the output from the previous e-mail.

It would be interesting to see the output of the "sh fabric status" command on a 6509 running a Sup720 and only CEF 720 modules.

[autobot130]

With a SUP720, you are able to get full non-blocking with the proper linecards on a 6509.

I believe on a 6513, the bottom 4 linecards are unable to perform full non-blocking if it's fully loaded.

[a12288]

any suppportings? I am seriously considering to replace our C6513 with C6509 actually. thanks.

[b.shoresh]

Have one question about the issue: is there any throughput/capacity difference between a 1G SFP installed on the SUP720 module and 1G SFP intalled on WS-X6724-SFP, provided that both modules installed on 6509E.

Thanks.

[wochanda]

The sup720 supports 18 fabric channels, and they are all terminated on the supervisor slots themselves. These fabric channels are distributed differently on different chassis, but the number of channels doesn't change. Each Sup720 itself uses a single fabric channel for the frontlink ports and communications to/from the CPU. Some linecards, such as 6748 and 6704 use dual-fabric connectors, so care needs to be taken to put these into slots that have 2 fabric channels.

The 9 or less slot chassis each have 2 fabric channels per slot. Since all other slots have 2 fabric channels, you're free to use any linecard in any slot.

On the 6513 chassis, slots 1-8 have a single fabric channel, while 9-13 have dual fabric channels. You'll notice this adds up to 18 total fabric channels. Since the Sup720's only use a single fabric channel each, there is no throughput loss by using a 6513 chassis.

So, in conclusion, there isn't any "less bandwidth" in a 6513 than a 6509 chassis, it is just distributed differently among linecards.

Also, to answer the last question about 6724 GE linecard: no, they are both non-blocking gig ports. There are, however, about 3x the amount of interface buffers with the 6724 GE port versus the front panel GBIC port on the SUP, so you may see better performance.