Switched Redundant Network

Many different network solutions exist for switched redundant networks. Redundant networks are usually used in the backbone of a network, but could also be used for user access.

Redundancy for switched networks are handled on link level, for Ethernet that is on Ethernet level.

A switched redundant user access is normally in the form active/backup or active/active. Some kind of link aggregation (bonding) is normally used.

In an active/backup solution one link at a time is used by the user. If the active link fails the backup link will take over. Fail-over is normally handled by the link layer. For Ethernet that is on Ethernet level. The active and backup link normally shares the same IP- and MAC-address. In an active/active solution both links are sending and receiving data at the same time. The most common way when connecting to shared networks is to use the same IP address and MAC address on both interfaces. The outgoing traffic from the server is distributed over the links by some hash algorithm. With an active/active solution the switches in the network have to support this way of working. For more information on SMLT, see Spanning Tree Protocol (STP).

Below different ways to build switched redundant networks are described:

Parent topic: Basic Network Techniques for Redundant Networks
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