Per Service Consistent Hashing - Alcatel-Lucent 7750 SR OS Interface Configuration Manual

LAG
Per Flow Hashing Changes
There have been some changes to the existing per flow behavior described above to better spread
certain types of traffic across various paths.
The hashing procedure that used to be applied for all VPLS BUM traffic (broadcast, unknown
unicast and multicast) would result in PBB BUM trafficbeing sent out on a BVPLS SAP to follow
only one link if MMRP was not used.
Now, only for chassis mode D, traffic flooded out an egress BVPLS SAP is loadspread using the
algorithm described above for the VPLS known unicast.
When H-POL is configured on an Epipe SAP, traffic spraying is the same as for VPLS known
unicast instead of just using the related service id.

Per Service Consistent Hashing

The hashing feature described in this section applies to traffic going over LAG, Ethernet tunnels
(eth-tunnel) in loadsharing mode, or CCAG loadbalancing for VSM redundancy. The feature does
not apply to ECMP.
Per-service-hashing was introduced to ensure consistent forwarding of packets belonging to one
service. The feature can be enabled only in chassis mode D using the [no] per-service-hashing
configuration option under config>service>epipe and config>service>vpls, valid for Epipe,
VPLS, PBB Epipe, IVPLS and BVPLS.
The following algorithm describes the hash-key used for hashing when the new option is enabled:
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If the packet is PBB encapsulated (contains an I-TAG ethertype) at the ingress side, use
the ISID value from the I-TAG
If the packet is not PBB encapsulated at the ingress side
→ For regular (non-PBB) VPLS and EPIPE services, use the related service ID
→ If the packet is originated from an ingress IVPLS or PBB Epipe SAP
−
If there is an ISID configured use the related ISID value
−
If there is no ISID yet configured use the related service ID
→ For BVPLS transit traffic use the related flood list id
−
Transit traffic is the traffic going between BVPLS endpoints
−
An example of non-PBB transit traffic in BVPLS is the OAM traffic
The above rules apply regardless of traffic type
→ Unicast, BUM flooded without MMRP or with MMRP, IGMP snooped
7750 SR OS Interface Configuration Guide