During my time in the field, I’ve seen a lot of different network configurations. Some networks I see are thoughtfully designed, others not so much.

I have noticed that the majority of the deployments I have witnessed have under utilized many of the features that make the equipment worth the price tag in the first place.

Why spend thousands of dollars on enterprise networking equipment if you aren’t going to use the knobs and dials that you paid for? There are many examples of this, but today I wanted to bring attention to one that I find especially useful. Multiple VLAN Registration Protocol (MVRP)



What is MVRP?

In short, MVRP allows one switch to dynamically advertise its VLANs to other switches. Rather than manually defining VLANs everywhere, switches can learn which VLANs exist and where they are needed.

It’s a simple protocol, but one that can drastically streamline deployments and, in many cases, make future network expansion far less painful.

Let’s get a little bit more involved

MVRP is built on top of the Multiple Registration Protocol (MRP), which was introduced as part of the IEEE 802.1ak amendment to the 802.1Q standard back in 2007. While the name might make it sound complicated, the important takeaway is MRP provides a standardized way for switches to dynamically share information with one another at Layer 2. MVRP is simply the VLAN specific application.

This means MVRP isn’t proprietary or tied to a single vendor. It’s an open standard, and it’s supported across a wide range of enterprise switching platforms.

Since I’ll be releasing a configuration guide focused Aruba CX, I found this explanation from the folks at HPE helpful.


“MVRP makes use of the Multiple Registration Protocol (MRP). Each MRP-enabled interface is called an MRP participant, and each MVRP-enabled interface is called an MVRP participant. When the VLAN configuration on an MVRP participant changes, it sends a Protocol Data Unit (PDU) to notify other MVRP participants to register and deregister the changed VLAN. MRP rapidly propagates the configuration information of an MRP participant throughout the layer 2 network.”

PDUs probably sound familiar if you have ever studied in your networking journey. In spanning tree these were BPDUs. MVRP works on the same principal, but instead of sending bridge PDUs, it works by Sending PDUs to update the status and need of devices for certain VLANs.

If BPDUs tell the network how to build the topology, MRP PDUs tell it which VLANs actually belong on it.

Juniper has a great guide that shows these messages available here: https://www.juniper.net/documentation/us/en/software/junos/mvrp/multicast-l2/topics/concept/mvrp-mx-series-understanding.html

Juniper breaks down in their guide:

New—VLAN information is new and possibly not previously registered.
JoinIn—VLAN information is being declared and is registered.
In—VLAN information is not being declared but is registered.
JoinEmpty—VLAN information is being declared but not registered.
Empty—VLAN information is not being declared and is not registered.
Leave—VLAN information that was previously registered is being withdrawn.
LeaveAll—All registrations will be de-registered. Participants that want to participate in MVRP will need to re-register.

This post is already getting a bit long winded, but the goal was to demystify what MVRP actually does and why it matters.

In the next post, I’ll focus on configuring MVRP on Aruba CX switches and discuss design considerations so you can decide if it’s a good fit for your next deployment.