Comments on: The Great vSwitch Debate – Part 2 http://kensvirtualreality.wordpress.com/2009/03/29/the-great-vswitch-debate-part-2/ My Ramblings about all things Virtual Sun, 03 Jan 2010 17:52:13 +0000 http://wordpress.com/ hourly 1 By: Ken Cline http://kensvirtualreality.wordpress.com/2009/03/29/the-great-vswitch-debate-part-2/#comment-267 Ken Cline Mon, 30 Nov 2009 23:16:14 +0000 http://kensvirtualreality.wordpress.com/?p=155#comment-267 Hi Pippin, You are correct that if there are two port groups with the same VLAN number on the same vSwitch, the vSwitch can deliver locally. I don't see this as a real problem - as long as the administrators are aware of the fact that the two port groups belong to the same layer two domain and traffic will flow between them without layer three intervention. Using multiple port groups with the same VLAN identifier can provide a nice administrative separation between the VMs - but it is strictly administrative. I have seen users implement this tactic when the know that they WILL be implementing VLANs at some point, but just haven't gotten the network team on-board yet. HTH, KLC Hi Pippin,

You are correct that if there are two port groups with the same VLAN number on the same vSwitch, the vSwitch can deliver locally. I don’t see this as a real problem – as long as the administrators are aware of the fact that the two port groups belong to the same layer two domain and traffic will flow between them without layer three intervention.

Using multiple port groups with the same VLAN identifier can provide a nice administrative separation between the VMs – but it is strictly administrative. I have seen users implement this tactic when the know that they WILL be implementing VLANs at some point, but just haven’t gotten the network team on-board yet.

HTH,
KLC

]]> By: Pippin Wallace http://kensvirtualreality.wordpress.com/2009/03/29/the-great-vswitch-debate-part-2/#comment-264 Pippin Wallace Mon, 23 Nov 2009 15:35:44 +0000 http://kensvirtualreality.wordpress.com/?p=155#comment-264 Ken, first off thank you very much for the terrific articles. I do have a question regarding two port groups sharing the same VLAN number. I am guessing the vSwitch sees all VM's in both port groups as being on the same VLAN and thus can switch/"route" per the vSwitch's ARP table. It would seem that this could produce some odd/undesirable behavior and I would like to know what warnings you would advise with this configuration? Ken, first off thank you very much for the terrific articles. I do have a question regarding two port groups sharing the same VLAN number.
I am guessing the vSwitch sees all VM’s in both port groups as being on the same VLAN and thus can switch/”route” per the vSwitch’s ARP table.
It would seem that this could produce some odd/undesirable behavior and I would like to know what warnings you would advise with this configuration?

]]> By: Ken Cline http://kensvirtualreality.wordpress.com/2009/03/29/the-great-vswitch-debate-part-2/#comment-165 Ken Cline Wed, 13 May 2009 00:45:52 +0000 http://kensvirtualreality.wordpress.com/?p=155#comment-165 If two port groups are defined on the same vSwitch and they both have the same VLAN number (even if that VLAN number is "not defined"), then traffic between the two port groups will be routed locally within the vSwitch and not exit via a vmnic (pNIC). Hope that clarifies things for you - and thanks for stopping by, and especially thanks for asking a question! KLC If two port groups are defined on the same vSwitch and they both have the same VLAN number (even if that VLAN number is “not defined”), then traffic between the two port groups will be routed locally within the vSwitch and not exit via a vmnic (pNIC).

Hope that clarifies things for you – and thanks for stopping by, and especially thanks for asking a question!

KLC

]]> By: Jason http://kensvirtualreality.wordpress.com/2009/03/29/the-great-vswitch-debate-part-2/#comment-164 Jason Tue, 12 May 2009 15:44:43 +0000 http://kensvirtualreality.wordpress.com/?p=155#comment-164 Wow, great damn series Ken. We have been looking for a definitive explanation of some of this stuff for some time. Very helpful. I did have a couple of questions though, and perhaps I missed it and just need clarification. If two port groups reside on the same vSwitch but neither has a VLAN defined, how do they communicate? Does the traffic leave the host? Thanks in advance. Wow, great damn series Ken. We have been looking for a definitive explanation of some of this stuff for some time. Very helpful.

I did have a couple of questions though, and perhaps I missed it and just need clarification.

If two port groups reside on the same vSwitch but neither has a VLAN defined, how do they communicate? Does the traffic leave the host? Thanks in advance.

]]> By: Welcome to vSphere-land! » Networking Links http://kensvirtualreality.wordpress.com/2009/03/29/the-great-vswitch-debate-part-2/#comment-154 Welcome to vSphere-land! » Networking Links Fri, 08 May 2009 02:39:31 +0000 http://kensvirtualreality.wordpress.com/?p=155#comment-154 [...] Cline’s The Great vSwitch Debate Series: Part 1 Part 2 Part 3 Part 4 Part 5 Part 6 Part 7 Enabling Netflow on Virtual Switches Configuring and [...] [...] Cline’s The Great vSwitch Debate Series: Part 1 Part 2 Part 3 Part 4 Part 5 Part 6 Part 7 Enabling Netflow on Virtual Switches Configuring and [...]

]]> By: Allen http://kensvirtualreality.wordpress.com/2009/03/29/the-great-vswitch-debate-part-2/#comment-116 Allen Tue, 28 Apr 2009 13:31:35 +0000 http://kensvirtualreality.wordpress.com/?p=155#comment-116 Ha, not really. But if you keep feeding us the good content, I'll keep the feedback coming. :-) Ha, not really. But if you keep feeding us the good content, I’ll keep the feedback coming. :-)

]]> By: Ken Cline http://kensvirtualreality.wordpress.com/2009/03/29/the-great-vswitch-debate-part-2/#comment-115 Ken Cline Tue, 28 Apr 2009 03:13:03 +0000 http://kensvirtualreality.wordpress.com/?p=155#comment-115 Hey Allen, Looking for a job as an editor? The pay sucks (you'll make just as much as I do ;) ) -- seriously, I do appreciate your feedback (at least I know you're reading the articles!) KLC Hey Allen,

Looking for a job as an editor? The pay sucks (you’ll make just as much as I do ;) ) — seriously, I do appreciate your feedback (at least I know you’re reading the articles!)

KLC

]]> By: Allen http://kensvirtualreality.wordpress.com/2009/03/29/the-great-vswitch-debate-part-2/#comment-111 Allen Mon, 27 Apr 2009 20:51:50 +0000 http://kensvirtualreality.wordpress.com/?p=155#comment-111 Ken, Are you missing the PG_VGT port group in Figure 3? Table 1 (and the two paragraphs that follow) references this port group, but I don't see it anywhere in Figure 3. I only mention it because I was a bit confused when I read through this initially, though I get the idea still. Thanks, Allen Ken,

Are you missing the PG_VGT port group in Figure 3? Table 1 (and the two paragraphs that follow) references this port group, but I don’t see it anywhere in Figure 3. I only mention it because I was a bit confused when I read through this initially, though I get the idea still.

Thanks,
Allen

]]> By: Ken Cline http://kensvirtualreality.wordpress.com/2009/03/29/the-great-vswitch-debate-part-2/#comment-98 Ken Cline Thu, 23 Apr 2009 18:13:37 +0000 http://kensvirtualreality.wordpress.com/?p=155#comment-98 Mike - I don't see the specific link to which you are referring. Could you please be more specific? The only thing that I see that has anything to do with CCNA is my reference to CIR, which is to a site where copyright is claimed by 2000Trainers.com - and a quick search of that site doesn't reveal any references to the title you're citing. Can you clarify, please? Thanks, KLC Mike – I don’t see the specific link to which you are referring. Could you please be more specific? The only thing that I see that has anything to do with CCNA is my reference to CIR, which is to a site where copyright is claimed by 2000Trainers.com – and a quick search of that site doesn’t reveal any references to the title you’re citing.

Can you clarify, please?

Thanks,
KLC

]]> By: Mike Gough http://kensvirtualreality.wordpress.com/2009/03/29/the-great-vswitch-debate-part-2/#comment-96 Mike Gough Thu, 23 Apr 2009 18:01:56 +0000 http://kensvirtualreality.wordpress.com/?p=155#comment-96 Your link above: CCNA 3 - Module 7 Exam Answers Version 3.1 appears to me to be a link to someone publishing copyright violation of Cisco exam details. I request and recommend you disassociate from and remove you link here. Best regards, Mike Gough Your link above:
CCNA 3 – Module 7 Exam Answers Version 3.1

appears to me to be a link to someone publishing copyright violation of Cisco exam details.
I request and recommend you disassociate from and remove you link here.
Best regards, Mike Gough

]]>