Oversubscribing Gb ports on Cisco 6509

[cpals]

Looking into an issue that a HP tech told me about while he was looking at why our HP C7000 blade chassis was causing some discards/overruns on our Cisco 6509 ports. He said that the 48-port blade we're using oversubscribes it's ports 8:1 so only an 8-block of ports at a time could reach 1Gb.

Does this sound accurate? We're using WS-X6548-GE-TX blades on an old 6509 - Sup 2 chassis. We're using the blades for all of our servers, SAN, blades, etc and from what I've read online now about the Cisco blade is that it's more for desktop deployments.

What are the best practices for engineering where to plug all of your servers, SAN, blades?

Also, I found an article online that talked about how to find the oversubscription rate for our blade (sh inter capabilities mod 8) and ours show 'Ports on ASIC: 1-24'. Does this mean we're oversubscribing 24:1???

Thanks.

 

[spidey07]

You upgrade to a sup720 or VSS and use 6748 blades. I don't think that's what the ports on asic command means, not sure though. That normally tells you what ports are bad because of a failed asic.

But the sup2 and 6500 series blades are incredibly old and outdated. Post the "show interface" output into cisco's output interpreter. Also "show fabric switching-mode".

So you have a switch fabric module installed?

-edit-
found this for you...probably relavent.
http://www.cisco.com/en/US/customer...products_tech_note09186a00801751d7.shtml#ASIC

 

[imagoon]

Without looking anything up, that sounds plausable, Sup2 wasn't known for it high fabric speed. I would need to look in to it to be sure.

 

[spidey07]

Without looking anything up, that sounds plausable, Sup2 wasn't known for it high fabric speed. I would need to look in to it to be sure.

no go...you're too slow

 

[imagoon]

no go...you're too slow

I lost.

 

[cpals]

Now, if if all of the ports in an eight-block set talk to each other, will they all get 1Gb between each other or would they still be ruled by the 1Gb total per ASIC? My guess is the second option, but just wondering.

 

[cpals]

Sorry... just keep reading the link Spidey sent... it mentions this:

The WS-X6548-GE-TX, WS-X6548V-GE-TX, WS-X6148-GE-TX, and WS-X6148V-GE-TX modules have a limitation with EtherChannel. For EtherChannel, the data from all links in a bundle goes to the port ASIC, even though the data is destined for another link. This data consumes bandwidth in the 1-Gigabit Ethernet link. For these modules, the sum total of all data on an EtherChannel cannot exceed 1 Gigabit.

So for example, I have a SAN with two 1Gb NICs bonded together in an etherchannel on the 6509 assuming that I could have two active streams totaling 2Gb in bandwidth. From reading the quote above it would make it sound like my two links together could never go over 1Gb combined?

What about if I had a four-port etherchannel with each one of the ports in a separate 8-port ASIC group? I would still be limited to 1Gb total?

 

[spidey07]

That's what I'm reading as well. That blade was never meant to be used in a date center or server farm environment. It's for end stations in a wiring closet to provide cheap gig ethernet.

 

[cpals]

Wow, I've been under some bad assumptions... definitely gotta look into this. Doesn't make sense to be using four-port etherchannels if they can only go over 1Gb anyways!

 

[azev]

Unfortunately with sup1 or sup2 you impose a lot of limitation with the 6509 chassis. There's a backplane command; but I forgot what it is; with that command you can see that some 48 port gig blade only have 8Gb connection to the back plane. If no routing is involved and all is L2 within the blades than you might be ok, but that is almost never the case with serverfarm switches.
If you want high bandwidth speed, you need to look at linerate switches. I believe even with the Sup720gblx your still limited to 32Gig connection to backplane per blade module.

 

[sactwnguy]

We have the a few of the HP 7000 chassis here, we decided it was best to just go 10G for them. If you are going to use 1G a connection you should be using WS-X6748-GE-TX with the DFC module. Even with a SUP720 it is easy to have drops on a 6509.