PeterBlatherwic
Enthusiast
Enthusiast

VMware and Nexus vSwitch internal support for layer 2 priority (802.1p)?

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Hi,

Can anyone provide a definitive answer on whether the various types of vSwitch internally support layer 2 priority handling (i.e. 802.1p).  That is, do these switches internally generate seprate queues, based on the received 802.1p priority tag, then handle each of these queues at the specified priority (highest priority transmitted first). Or, is it just one queue internally, so efectively not prioritized inside the vSwitch, just passing tagging on to any external (physical) switch in the path.

Interested in the answer for each of: standard vSwitch, Distributed vSwitch, Nexus vSwitch.  In vSphere 5 and above.

I have asked similar questions before, and no real clear answer.  Appologies if I have just not spotted it, but I have searched the various VMware and Nexus docs, and of course googled it pretty hard too.

Thanks for any answers or pointers,

PeterB

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chriswahl
Virtuoso
Virtuoso

The Nexus 1000v uses CB-WFQ

With Cisco Nexus 1000V Series Switches Release 4.2(1)SV1(4) and higher, virtualization environments can now also take advantage of Class-Based Weighted Fair Queuing for congestion management.

Here is a white paper.

http://www.cisco.com/en/US/prod/collateral/switches/ps9441/ps9902/white_paper_c11-704041.html

VCDX #104 (DCV, NV) ஃ WahlNetwork.com ஃ @ChrisWahl ஃ Author, Networking for VMware Administrators

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mcowger
Immortal
Immortal

vSS and vDS definitly do not.

Not sure about Nexus.

--Matt VCDX #52 blog.cowger.us
PeterBlatherwic
Enthusiast
Enthusiast

Thanks for the quick and concise answer on the VMware switch front.

Anyone out there know the answer for Nexus vSwitch?

-- PeterB

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weinstein5
Immortal
Immortal

According to this doc it appears with vSphere 5 Network I/O Control  it is supported - http://www.vmware.com/files/pdf/techpaper/Whats-New-VMware-vSphere-50-Networking-Technical-Whitepape...

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PeterBlatherwic
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Yes, saw that doc (and several others), and investigated.  The section on 'IEEE 802.1p Tagging' is about the ability to *set* the priority field at port group level.  But not the ability of the dvSwitch internals to actually repect the priority tagging, i.e. to maintain separate queues actually handled at the different priorities inside the vSwitch.  Hence the question here...

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rickardnobel
Champion
Champion

I have read (somewhere) that while Distrubuted vSwitch 5.x has the ability to tag outgoing frames it will ignore the 802.1p bits on incoming frames.

My VMware blog: www.rickardnobel.se
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chriswahl
Virtuoso
Virtuoso

The Nexus 1000v uses CB-WFQ

With Cisco Nexus 1000V Series Switches Release 4.2(1)SV1(4) and higher, virtualization environments can now also take advantage of Class-Based Weighted Fair Queuing for congestion management.

Here is a white paper.

http://www.cisco.com/en/US/prod/collateral/switches/ps9441/ps9902/white_paper_c11-704041.html

VCDX #104 (DCV, NV) ஃ WahlNetwork.com ஃ @ChrisWahl ஃ Author, Networking for VMware Administrators

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PeterBlatherwic
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Hi Richard.

Your comment confirms others above.  Yes, dvSwitch can tag layer 2 priority, at port group level.  No, neither flavour of VMware vSwitch actually handles the tagging on priority basis, either incoming from outside world or internally to the vSwitch.

-- PeterB

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PeterBlatherwic
Enthusiast
Enthusiast

Thanks Chris!

I actually found this late last eve, wading through the very copious documentation on Nexus 1000V.  It is in the 1000V Quality of Service Configuration Guide.  There sure it a LOT to dig through.

Appears Class-Based Weighted Fair Queuing can use layer 2 priority tags to do multiple queue prioritization of traffic.  L2P is one of several ways to manage the queuing.

One thing I still have not confirmed is whether Nexus allows L2 priority to be set, at port group level.  This would be feature equivalence with VMware dvSwitch capability.

I do know that L3 priority / Diffserv Code Point can be used to map L2 priority values on incoming packets, i.e. set L2P based on incoming DSCP.  That's VERY useful.  Unfortunately, VMware dvSwitch does not have this capability. 

-- PeterB

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chriswahl
Virtuoso
Virtuoso

I actually found this late last eve, wading through the very copious documentation on Nexus 1000V.  It is in the 1000V Quality of Service Configuration Guide.  There sure it a LOT to dig through.

Glad to hear it. Part of the CCIE-DC track is having to dive through thousands of pages of that (and the Smug Cisco Guy).

VCDX #104 (DCV, NV) ஃ WahlNetwork.com ஃ @ChrisWahl ஃ Author, Networking for VMware Administrators
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