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Enthusiast

FCoE Uplink Bandwidth

Folks:

Let's say the scenario is a blade chassis with four (4) 10G CEE uplinks to a ToR FCF....(maybe even a UCS - doesnt matter).

In  such a converged network environment at the server edge, how does one  determine how much uplink bandwidth to dedicate to FCoE traffic? Is  there a standard recommendation to dedicate bandwidth using some sort of  policing or rate limiting mechanism or ....what?

I have read a lot about FCoE lately, but I have never seen anything about this.

Any help would be greatly appreciated.

Regards

4 REPLIES 4
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Beginner

Hey Ex-Engineer -

IEEE DCB is a standard that is passing through the standards body right now (not complete just yet...but close).  It outlines some bandwidth management standards called "ETS: Enhanced Transmission Selection."

ETS allows you to carve up a 10G link based on COS value and assign different traffic classes different amounts of guaranteed bandwidth.  For instance, on a Nexus platform FCoE traffic is by default placed in COS value of 3 (this is common among all FCoE supporting vendors) and given an ETS value of 50% meaning that a 10G link by default will give 50% (5G) of the bandwidth to FCoE when congestion occurs and there is at least 5G of FCoE traffic.  This is meant to insure that no traffic type will be able to starve out another "critical" traffic type.

This IEEE standard isnt just meant for FCoE and can be applied to other types of traffic.

Let me know if this helps or you would like further explanation: estine@cisco.com

Thanks,

Liz

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Liz, thanks. Yes, I am very aware of all of the Ethernet enhancements. I thought by now they were all ratiffied. You mean they're not?? Which ones still remain? Also, in all the documentation I have read about ETS, I have never seen that 50% number or anything about how the BW will be carved up (not with regards to the mechanism, but in terms of BW dedicated to different applications). Great stuff. Do you have a document handy that shows this? If not, no worries...no biggie....

By the way, a nice juicy question still awaits you on yesterdays thread

A steak dinner awaits you in NY, too, not just for Robert!

THANK YOU!

Highlighted

Liz, I found a good document that discusses ETS's default 50/50 settings for IP and FCoE traffic.

http://www.ethernetalliance.org/files/static_page_files/27A08F39-1D09-3519-ADFB673A2A23FF25/ETSNetApp%20final.pdf

Thanks

Highlighted

Ex-Engineer -

The other place you can find some information on how to set these configuration thresholds is the QOS configuration guide for the Nexus 5000: http://www.cisco.com/en/US/docs/switches/datacenter/nexus5000/sw/qos/502_n1_1/Cisco_Nexus_5000_Series_NX-OS_Quality_of_Service_Configuration_Guide_Rel_502_N1_1_chapter3.html#con_1154311

Keep in mind that the 50/50 bandwidth split between FCoE and Native Ethernet is our "default" and is not part of the standard.

Thanks,

Liz

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