Link Aggregation and GVRP

Question

I've been toying with the idea of using Link Aggregation between our 5324 and 5316M switches. We are currently using ESX and VLAN's extensively.   The whitepapers I've read about mention that for it to work properly GVRP cannot be enabled.   Does this mean on the specific ports that are going to be members of a LAG as well as the Global GVRP enable setting?   Is GVRP worthwhile or should I just tag the ports / LAG's that are connected to other switches so it always knows what VLAN traffic to expect?   Cheers Troy

tester25 · Answer

Have you found out anything since posting this last week?

Box293 · Answer

I always get such pleasure answering my own question (can you feel the sarcasm). At least if I answer it then I'm helping someone like you. Also I'm no expert, I only know this stuff from playing around and it's possible that my understanding of the concepts is wrong / different to the norm.

In my environment we heavily use VLAN's. We have approx 60 VLAN's setup so everything I talk about focuses around them.

It's pretty straight forward stuff. Basically on the ports that you want to aggregate you need to turn off GVRP. GVRP can still be left on globally as this works OK when the aggregated ports are working.

You need to assign these ports to a LAG on the 5316M. On the 5324 you don't need to create a lag but it does mean you need to tag each indivual port on the switch with these VLAN's (or GVRP will take care of this). Using a LAG on the 5324 is recommended. It does not need to be the same LAG number on each end (ie 3 on the 5316M and 7 on the 5324 is fine).

Here are the commands used to configure it all. On the 5316M I do all the configuring through the DRAC serial port on the blade chassis and the serial port on the 5324 (I use the serial port becuase I will more than likely loose connectivity if I am using telnet through this process).

When I mention VLAN 2100 this is just the VLAN we use for our management VLAN. All the bold and large fonts is from our documentation, as soon as I work something out it is documented; this is a very important habbit to get into (particuarly handy when trying to remember a command)

Link Aggregation Using Three Ports

On the 5316M it will be ports g11-g13

On the connecting switch 5324 it will be ports g1-g3

LAG = port-channel or channel-group

LAG on the 5316M will be 1

LAG on the 5324 will be 2 (this varies depending on how many existing LAG’s you have)

DO NOT CONNECT the switches together until advised

Clear All Settings On The Ports To Be Link Aggregated

interface range ethernet g11-13
switchport mode general

switchport general acceptable-frame-type tagged-only
switchport general allowed vlan remove 1-4094 (ignore the errors, make take two minutes)
no gvrp enable
switchport general pvid 4095

Repeat the above steps on ports g1-g3 on the 5324 switch

Set Link Aggregation Defaults

interface range port-channel 1-8
switchport mode general
switchport general pvid 4095
switchport general acceptable-frame-type tagged-only

Repeat the above steps on the 5324 but use the following command for the first line

interface port-channel 2

Aggregate The Ports On The Switches

interface range ethernet g11-13
channel-group 1 mode auto

Repeat the above steps on ports g1-g3 on the 5324 switch

Configure the Aggregation

interface port-channel 1
gvrp enable

Repeat the above steps on the 5324 but use the following command for the first line

interface port-channel 2

Connect one cable from port g11 (5316M) to g1 (5324). Wait about 30 seconds and a lot of text should flow on the screen. Once this happens connect the other two ports.

Configure The LAG On The 5316M

You will need to configure on the LAG on the 5324 switch to say that LAG 2 has tagged traffic for VLAN 2100. This will then allow you to telnet to it etc.

telnet to the main switch
configure
interface port-channel 1
switchport general allowed vlan add 2100 tagged

tester25 · Answer

Thanks much.  So basically you just need to delete any existing port channel, then disable GVRP on the ports that were/are going to be members of that port channel, then re-add the ports to the port channel, and then re-enable GVRP on the port channel.   After that, all the Dynamic VLANs will show up on the switch that doesn't have those 60 Static VLANS configured on it.   Did I get that right?   I've never configured GVRP via port channels that are connected between two switches so this is a good lesson for me.  I'm sure that others will see this posting in the future and it will help them as well.  Thanks again.

Box293 · Answer

That's pretty much well exactly right.

Some notes on GVRP that I've noticed.

If I'm setting up a new blade chassis with the 5316M switches and I have no blades connected or turned on the GVRP doesn't work immediately. Let me explain:

I tag ports g1-10 on the 5316M to indicate vlan 2100 is in use.
I also specify the management ip address for this switch is on vlan 2100 (192.168.100.44)
I then setup the LAG and that all connects to the main switch OK (setup LAG on main switch as 5 for example).
From the main switch I am unable to ping the .44 ip address on the 5316M.
From the main switch if I tag LAG 5 as having 2100 vlan then I am able to ping the .44 address from the main switch.
If I untag the 2100 vlan on LAG 5 and then plug in and power on a blade in the chassis in a short while (usually 30 seconds) the GVRP detects 2100 on LAG 5 and you can then ping the .44 address.

I discovered this when I was adding a second 5324 switch connected to our original 5324 switch. I was not using LAG's to connect them however the GVRP behaviour is the same. I had no network cables plugged into any of the ports on the new switch, only the cable connecting the two switches. If I tagged a port as 2100 vlan and then connected a PC to it (just needs a link light to come up) then shortly there after I was able to ping and connected to the management IP of the second switch.

When configuring GVRP for the first time I highly recommend using a serial cable. The reason for this is that you will see all the system messages flooding the screen, particuarly when GVRP VLAN's are detected. Also learn how to use the command line interface of the switch, it's particularly handy for tagging multiple vlan's across multiple ports with one command.

Any more questions let me know. I knew nothing about this stuff and the manuals weren't the most helpfull so I documented everything I know along the way. It's pretty easy once you understand the key concepts and the order in which steps should be taken.

Message Edited by Box293 on 02-07-2007 04:03 PM

tester25 · Answer

Very good info. Thanks for sharing with everyone here.

Yep, that's exactly how GVRP works. It adds/removes dynamic VLANs when ports are connected/disconnected. I saw that behaviour on my PC6024/PC5324/PC5324 setup.

Box293 wrote:

When configuring GVRP for the first time I highly recommend using a serial cable. The reason for this is that you will see all the system messages flooding the screen, particuarly when GVRP VLAN's are detected. Also learn how to use the command line interface of the switch, it's particularly handy for tagging multiple vlan's across multiple ports with one command.

You also get these messages when you're in a telnet session to the switch.

Message Edited by tester25 on 02-07-2007 04:16 PM

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Link Aggregation and GVRP

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