Specifications

ip l3-hash
278 SSR Command Line Interface Reference Manual
ip l3-hash
Purpose
Changes the hashing algorithm used for the L3 lookup table.
Format
ip l3-hash channel <num>|all variant <num>
Mode
Configure
Description
The SSR’s L3 Lookup table is organized as a hash table. The hash function reduces the
destination and source MAC addresses to 16-bit quantities each. The hashing algorithm
generates a uniform distribution within the MAC address space. However, given a
particular set of addresses, the distribution may cause addresses to clump together in the
table. To minimize the risk of thrashing in the tables, three variations to the basic hashing
algorithm are defined. Only one variation is in effect on a line card at any given time. You
can use the ip l3-hash command to control which variation is in effect for a line card.
To see the effect changing the hashing algorithm has on the hash bucket, use the statistics
show l3-stat command in the SSR’s Diag mode.
Parameters
channel <num>|all
Is a slot number on the SSR. Valid slot numbers are 0-3 on the SSR 2000, 0-7 on the SSR
8000, and 0-15 on the SSR 8600. The hashing algorithm change affects all ports on the
line card in the slot. The all option causes the hashing algorithm to change on all ports
on all slits.
variant <num>
Causes a variation to the basic hashing algorithm to be made. Valid variant numbers
are 1-3. If you specify 0, the default hashing algorithm is used.