Question regarding 6807-XL with Sup2T

[som3awy]

The sup2t in the 6807-xl supports up to 220 Gbps per slot. What does per-slot bandwidth mean?

[Jon Marshall]

It means that each slot can support up to 220 Gbps of bandwidth to whatever is connected into that slot. 

That does not mean that whatever module is connected into that slot can use all of that bandwidth, it just means the bandwidth is available to be used so you need to check the module capabilities before purchasing. 

In addition it is fixed per slot ie. any unused bandwidth in a slot cannot be used in another slot. 

Jon

[Joseph W. Doherty]

To add to what Jon has noted, generally slot bandwidth is duplex, i.e. the sup2T and chassis should support up to 220 Gbps to and from the slot. Further, it's been a while since I looked at the sup2T/6807 specs, but sometimes the bandwidth is split into channels. I.e. not all that bandwidth is available to all ports of a card, which can be an issue if the total ports on a card exceed the overall slot bandwidth capacity. In such cases, like Jon notes, that unused bandwidth cannot be used by other slots, unused slot bandwidth might not be available to every port on a card.

Lastly, the bandwidth to a slot is generally part of the switch fabric, i.e. two slots should be able to intercommunicate regardless of what other slots are doing.

[som3awy]

Thank you both. Last 2 questions, does per slot mean per module?

The 2nd question is, if the C6800 32P10G module is inserted into the 6807-XL chassis with sup2T. The module has a 160 Gbps switch fabric connection, but let's say it has a 320 Gbps switch fabric connection instead, does this mean that it can only use 220 Gbps since that's the max. the sup 2T engine can support?

[Joseph W. Doherty · Accepted solution]

1st question - depends how you define module. If you mean the whole card inserted into the slot, yes, if you mean a component on such a card, maybe not. The 220 Gbps is what the sup2T supports to the card slot. (I recall [?] the chassis supports 880 Gbps to each slot.)

2nd question - yes. However, again, the card and slot might have other limitations. Again, assuming you did have channels, even when you have 160 Gbps slot bandwidth, it may not mean it's all available. Half the ports, in a defined group, might be restricted to 80 Gbps. So, for example, if 10 ports out of the "same" port group wanted 100 Gbps, 80 might only be obtainable, even though the slot supports a total aggregate of 160 Gbps.

[som3awy]

Thanks a lot Jospeh. You've been really helpful. I have another question if you don't mind! 

I'm checking the Nexus 7700 switches, since the hiring manager told me to study them before I come for an interview. It says on the Nexus 7700 switches data sheet that the maximum forwarding capacity Nexus 7700 10-slot switch is 42 Tbps, the max. local switching capacity is 1.2 Tbps and the max. inter switching capacity is 1.2 Tbps. Could you explain what these mean?

[Joseph W. Doherty]

Sorry - not off the top-of-my-head. I would need to read up on them myself.

[som3awy]

Np. Thanks for your help.