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Nexus 7k FCoE Traffic Load Balancing

I can't find a clear answer on FCoE traffic load balancing on 7k storage VDC. The following Cisco 7k FCoE reference has obvious configuration mistakes in load-balancing configuration: http://www.cisco.com/en/US/products/ps9670/products_configuration_example09186a0080c13d2f.shtml

It shows load-balancing command being applied under the storage-vdc, which is not possible. Load-balancing can only go under default VDC:

fcoe(config)# port-channel load-balance ethernet source-dest-port

In addition the 7k takes "port-channel load-balance src-dst l4port", not "ethernet source-dest-port".

Based on this example, which is full of mistakes, one would conclude that in order to set load balacing to src-dst-ox id on 7k we have to do:

"port-channel load-balance src-dst l4port" unde the default VDC.

However, the following configuratio guide, tells that the "Traffic is load balanced across equal cost E_Ports and VE_Ports based on SID, DID, and OXID" automatically without the need to configure port-based load balancing for the underlying Ethernet links.

http://www.cisco.com/en/US/docs/switches/datacenter/sw/nx-os/fcoe/configuration/guide/b_Cisco_NX-OS_FCoE_Configuration_Guide_chapter_0100.html#concept_013970837994428BB207A1A79DBFA22A

On Nexus 5k, it is very clear: we have to set Ethernet to "port-channel load-balance ethernet source-dest-port" in order to load balance storage traffic in SID-DID-OXID mode, but I can't find any conclusive documentation on 7k

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New Member

Nexus 7k FCoE Traffic Load Balancing

Well, I see it this way:

-if an interface is allocated to a storage VDC, it will always use src-dst-oxid load balancing

-if an interface is allocated to a "regular" VDC, it will use the load balancing configured for that particular module, or for the system (with the module-level configuration taking precedence).

Now the question is - what happens to shared interfaces (allocated to both a storage and a "regular" VDC)? Well, it looks like Cisco found a very simple solution - according to this, "You cannot configure a shared interface to be part of a port channel"

7 REPLIES
New Member

Nexus 7k FCoE Traffic Load Balancing

The document you linked to (

http://www.cisco.com/en/US/products/ps9670/products_configuration_example09186a0080c13d2f.shtml

) does state that:

On Nexus 7000, by default the "source-destination-oxid" load balancing mechanism is used for FCoE traffic.

Also, I cannot see the "port-channel load-balance" command under the storage VDC (indeed, changing the load balancing method for the storage VDC of a 7K is not possible).

Maybe they updated the documentation?

New Member

Nexus 7k FCoE Traffic Load Balancing

That document was updated Nov. 25 2013 and the FCoE load-balancing section has changed. Now it clearly states that FCoE traffic will automatically be load-balanced using src-dst-oxid. What is not clear however how it affects non FCoE traffic. On Nexus 7k the load-balacing mechanism can be changed only per module or the entire system:

port-channel load-balance [algorithm [module module]]  . If FCoE automatically changes load-balancing scheme, will that also affect other non-FCoE ports on that module?

New Member

Nexus 7k FCoE Traffic Load Balancing

Well, I see it this way:

-if an interface is allocated to a storage VDC, it will always use src-dst-oxid load balancing

-if an interface is allocated to a "regular" VDC, it will use the load balancing configured for that particular module, or for the system (with the module-level configuration taking precedence).

Now the question is - what happens to shared interfaces (allocated to both a storage and a "regular" VDC)? Well, it looks like Cisco found a very simple solution - according to this, "You cannot configure a shared interface to be part of a port channel"

Cisco Employee

Well, I see still the

Well, I see still the question hasn't narrowed down. I hit the same one as ataranen

Say if I don't want the default "src-dst-oxid load balancing" for storage VDC and need to change to a different type. Does this mean, I have to change only on default-vdc? IF so that will have a major hit on rest of the non-fcoe traffic.

While this, can you please post if there is any improved situation from last communication? Hope to see some clarity.

 

VIP Green

Please explain, why you are

Please explain, why you are not happy with default "src-dst-oxid load balancing"

This is widely used in storage, where a out of order FC frame can cause big trouble; this default guarantees, that all FC frames of any read and/or write transcation are sent over the same link (no out of order).

New Member

I think the question is more

I think the question is more about the device capability rather than about advantages of src-dst over src-dst-oxid. It is hard to argue that src-dst-oxid is always better. However we do allow src-dst load balancing on other devices for FCoE. On Nexus 5k there is no issue configuring Ethernet port-channel load balancing to be source-destination-mac, which will provide SID/DID load-balancing to FCoE. Why can't we do the same on 7k ?

What if someone evil-minded set's one side of the FCoE port-channel on 5k to be source-destination-mac, and the other side on 7k is the default source-destination-L4port ? That may have more negative impact .   

Silver

Hi.

Hi.

Could someone get a definitive answer for F1 cards and FCOE load balancing over ethernet port-channels ?

It seems that this src-dst-oxid is not done by default on those cards...

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