At 10:50 AM 8/04/2002 +0200, Iljitsch van Beijnum wrote:
load balanced across those links. Some mechanisms (for example Cisco CEF) can do this on a per-destination (flow-based) basis, to prevent packet reordering.
I seem to remember fast switching was per-destination, and CEF was round robin. But it seems CEF is now per-destination as well in IOS 12.2. Round robin is optional.
you remember incorrectly. by default, CEF uses a hash based on both src & dst to determine the path to take. somewhat paradoxically this is referred to as "per-destination" load-balancing (or "deterministic"). on many platforms, you can reconfigure CEF to use a per-packet distribution. "ip load-sharing XX" is the interface command to set the policy. "per-destination" historically is what fast-switching used to do -- and it did a particularly bad job of handling large amounts of traffic sourced to one ip-address (such as a news-server or proxy-server). this was particularly apparent for multiple <E1 links load-balanced using equal cost routes. cheers, lincoln.