Compressed Routes

Compressed routes allow you to reduce the number of routes that are installed in the hardware routing tables. The switch uses hardware routing tables to improve packet forwarding performance. The switch can use both hardware and software to forward packets, but packet forwarding without software processing is faster. The hardware routing tables have less storage space than the software, so compressed routes conserve resources and improve scaling

The compressed route feature allows you to install less specific routes in the table, when overlapping routes with same next-hop exist. This route pruning technique is implemented as part of the Route Manager (RtMgr) process.

When a route is added, deleted or updated, the pruning algorithm is applied to see if the new route and/or its immediate children can be compressed or uncompressed as follows:

If the parent node (immediate less specific route) of the newly added IP prefix has the same gateway as the new IP prefix, the newly added prefix is compressed.
If the gateways of the newly added IP prefix and its immediate children are the same, the child nodes are compressed.
If the gateways of the newly added IP prefix and its immediate children are not the same, and the child nodes had been previously compressed, the child nodes are uncompressed.

Published March 2020prev | next

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