VRID Question


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Hi - I have a question regarding when to use a single VRID and when to use differnet VRIDs. As I understand it, a VRID designates a virtual router pair - when 2 routers have the same VRID they are able to exchange VRRP messages.

In my example above - If I have CORE A and CORE B in the same buildling with the same 3 VLANs on - should I use a different VRID for each VLAN or the same VRID for all VLANS. Historically we have always used 1 VRID for all vlans across the cores and it has worked as we would expect.

The only reason I ask the question is when configuring ports on the core with multiple VLANs we often get the following warning from the switch;

WARNING : Port belongs to multiple VLANs with the same VRID

I'm not sure why the switch warns of this - why is this a problem/warning?

Thanks

6 replies

Userlevel 6
The VRRP message is a bit misleading. Up till 16.1 you can only use 7 vrid's on a switch, newer versions can use more but there is no need to use difference vrid's on different vlans.
I would just keep the same VRID on all vlans, no problem with that.
Userlevel 6
Leo,

VRID can be reused in different VLAN's, the warning messages are not seen in latest software versions, i tested it in 22.x and 21.x , what is the EXOS version you have tested this?
Still i would say this could be a cosmetic issue which is not seen in latest EXOS versions.

please let me know if this helps. I should have refreshed before posting 🙂
Karthik Mohandoss wrote:

Leo,

VRID can be reused in different VLAN's, the warning messages are not seen in latest software versions, i tested it in 22.x and 21.x , what is the EXOS version you have tested this?
Still i would say this could be a cosmetic issue which is not seen in latest EXOS versions.

please let me know if this helps. I should have refreshed before posting :)

Thanks Karthik, We're currently using 16.1. We're due to be configuring VVRP sometime next week so I'll keep you posted on if we get the warning in this release. 🙂
Userlevel 6
Hi Leo,

You can define priority based on VRID to select the Master and Backup role between Core A and Core B.

Let's say you have 4 vlans (A1, A2, B1, B2). You can configure the same VRID (let's say "1" for A1 and A2 vlans; and VRID "2" for B1 and B2 vlans).

Then you can set a better priority (higher than 100) to A1 and A2 on Core A and to B1 and B2 to Core A.

Then you would have A1/A2 vlans being routed through Core A and B1/B2 vlans routed through Core B.
Henrique wrote:

Hi Leo,

You can define priority based on VRID to select the Master and Backup role between Core A and Core B.

Let's say you have 4 vlans (A1, A2, B1, B2). You can configure the same VRID (let's say "1" for A1 and A2 vlans; and VRID "2" for B1 and B2 vlans).

Then you can set a better priority (higher than 100) to A1 and A2 on Core A and to B1 and B2 to Core A.

Then you would have A1/A2 vlans being routed through Core A and B1/B2 vlans routed through Core B.

Hi Henrique, Thanks for your reply. So I understand what you're saying there but I have a question. In your example there's no reason why I couldn't have A1, A2, B1, B2 all in the same VRID - say VRID 1 and still use the priority to have the A masters one side and the B masters the other.

Are there any benefits to using different VRIDs other than the VRRP communication traffic being separate?
Userlevel 6
Henrique wrote:

Hi Leo,

You can define priority based on VRID to select the Master and Backup role between Core A and Core B.

Let's say you have 4 vlans (A1, A2, B1, B2). You can configure the same VRID (let's say "1" for A1 and A2 vlans; and VRID "2" for B1 and B2 vlans).

Then you can set a better priority (higher than 100) to A1 and A2 on Core A and to B1 and B2 to Core A.

Then you would have A1/A2 vlans being routed through Core A and B1/B2 vlans routed through Core B.

Hi Leo, I believe the only difference here would be using different "VRRP:VRID_number" MAC addresses and would help for a better troubleshooting insight.

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