North American Network Operators Group|
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Re: Load balancing in routers
On 8 Apr 2002, Paul Vixie wrote: > > 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. > CEF is flow-hashed, and the hash seems to include both source and > destination, and seems to include the port numbers. This is by observing > the behaviour of flows hitting various members of the F.ROOT-SERVERS.NET > set, each of whom sends F's address to several upstream routers using OSPF. > CEF works like a charm -- the load is never split by more than 45-55 and > that's damn good for wire speed hashing in my view. > We used CEF in 11.x and it behaved the same way. It was never round-robin > in any way we could observe. You're right. I was thinking of process switching. According to: http://www.ils.unc.edu/dempsey/186s00/reorderingpaper.pdf packet reordering at MAE East was extremely common a few years ago. Does anyone have information whether this is still happening?