Metro Ring Protocol (Mrp) - HP ProCurve 9304M Installation And Configuration Manual

Metro Ring Protocol (MRP)

NOTE: This feature is not supported in the in software release 07.6.01b.
The Metro Ring Protocol (MRP) is an HP proprietary protocol that prevents Layer 2 loops and provides fast
reconvergence in Layer 2 ring topologies. MRP is especially useful in Metropolitan Area Networks (MANs) where
using STP has the following drawbacks:
• STP allows a maximum of seven nodes. Metro rings can easily contain more nodes than this.
• STP has a slow reconvergence time, taking many seconds or even minutes. MRP can detect and heal a
break in the ring in sub-second time.
Figure 10.1 shows an example of an MRP metro ring.
Figure 10.1 Metro ring – normal state
Customer A
The ring in this example is comprised of four MRP nodes (HP switches). Each node has two interfaces with the
ring. Each node also is connected to a separate customer network. The nodes forward Layer 2 traffic to and from
the customer networks through the ring. The ring interfaces are all in one port-based VLAN. Each customer
interface can be in the same VLAN as the ring or in a separate VLAN.
One of the nodes (switch A) is the master node for the ring. The master node prevents loops by blocking Layer 2
data traffic on one of its interfaces with the ring. Since none of the switches' ring interfaces is running STP, all
ports in the ring except the master node's blocking port are forwarding.
NOTE: When you configure MRP, HP recommends that you disable one of the ring interfaces before beginning
the ring configuration. Disabling an interface prevents a Layer 2 loop from occurring while you are configuring
MRP on the ring nodes. Once MRP is configured and enabled on all the nodes, you can re-enable the interface.
The current software release also supports multiple rings as shown in Figure 10.2.
Customer A
F
F
F
Switch C
This interface b ocks
F
Layer 2 traffic
to prevent a loop
F
Customer A
F
F
Switch B
Switch A Master
Node
l
Switch D
F
F
Configuring Metro Features
F
F
Customer A
B
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