Lsr Hashing - Alcatel-Lucent 7750 SR OS Interface Configuration Manual

Interface Configuration

LSR Hashing

The LSR hash routine operates on the label stack only. However, there is also the ability to hash
on the IP header if a packet is IP. An LSR will consider a packet to be IP if the first nibble
following the bottom of the label stack is either 4 (IPv4) or 6 (IPv6). This allows the user to
include an IP header in the hashing routine at an LSR for the purpose of spraying labeled IP
packets over multiple equal cost paths in ECMP in an LDP LSP and/or over multiple links of a
LAG group in all types of LSPs.
The user enables the LSR hashing on label stack and/or IP header by entering the following
system-wide command: config>system>lsr-load-balancing lbl-ip | ip-only.
By default, the 7x50 LSR falls back to the hashing on label stack only as in existing
implementation behavior. This option is referred to as lbl-only and the user can revert to this
behavior by entering one of the two commands:
config>system>lsr-load-balancing lbl-only
config>system>no lsr-load-balancing
The user can also selectively enable or disable the inclusion of label stack and IP header in the
LSR hash routine on a specific network interface by entering the following command:
config>router>interface>lsr-load-balancing lbl-ip | ip-only
This provides some control to the user such that this feature is disabled if labeled packets received
on a specific interface include non IP packets that can be confused by the hash routine for IP
packets. These could be VLL and VPLS packets without a PW control word.
When you exclude label stack and IP header from the hash routine on an interface, the 7x50 LSR
falls back to the hashing on label stack only as in existing implementation behavior.
7750 SR OS Interface Configuration Guide Page 109