Switch Meshing

Operating Notes for Switch Meshing

traffic patterns, including the situation where multiple VLANs are configured and a broadcast path through the mesh domain leads only to ports that are in the same VLAN as the device originating the broadcast.

Unicast Packets with Unknown Destinations

A meshed switch receiving a unicast packet with an unknown destination does not flood the packet onto the mesh. Instead, the switch sends a query on the mesh to learn the location of the unicast destination. The meshed switches then send 802.2 test packets through their non-meshed ports. After the unicast destination is found and learned by the mesh, subsequent packets having the same destination address will be forwarded. By increasing the MAC Age Time in the System Information screen (page 6-10)you can cause the switch address table to retain device addresses longer. Because the switches in a mesh exchange address information, this will help to decrease the number of unicast packets with unknown destinations, which improves latency within the switch mesh. Also, in an IP environment, HP recommends that you configure IP addresses on meshed switches. This makes the discovery mechanism more robust, which contributes to decreased latency.

Spanning Tree Operation with Switch Meshing

Using STP or RSTP with several switches and no switch meshing configured can result in unnecessarily blocking links and reducing available bandwidth. For example:

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