Ecmp Static Routes; Ospf Integration; Ecmp Route Hashing - Lenovo RackSwitch G8264 Application Manual

ECMP Static Routes

OSPF Integration

ECMP Route Hashing

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G8264 Application Guide for ENOS 8.4
Equal‐Cost Multi‐Path (ECMP) is a forwarding mechanism that routes packets
along multiple paths of equal cost. ECMP provides equally‐distributed link load
sharing across the paths. The hashing algorithm used is based on the destination IP
and source IP (DIPSIP) addresses or only on the source IP address (SIP). ECMP
routes allow the switch to choose between several next hops toward a given
destination. The switch performs periodic health checks (ping) on each ECMP
gateway. If a gateway fails, it is removed from the routing table, and an SNMP trap
is sent.
When a dynamic route is added through Open Shortest Path First (OSPF), the
switch checks the route's gateway against the ECMP static routes. If the gateway
matches one of the single or ECMP static route destinations, then the OSPF route is
added to the list of ECMP static routes. Traffic is load‐balanced across all of the
available gateways. When the OSPF dynamic route times out, it is deleted from the
list of ECMP static routes.
You can configure the parameters used to perform ECMP route hashing, as
follows:
sip: Source IP address

dipsip: Source IP address and destination IP address (default)

Note: The sip and dipsip options enabled under ECMP route hashing or in port
LAG hashing (portchannel thash) apply to both ECMP and LAG features (the
enabled settings are cumulative). If unexpected ECMP route hashing occurs,
disable the unwanted source or destination IP address option set in LAG hashing.
Likewise, if unexpected LAG hashing occurs, disable any unwanted options set in
ECMP route hashing.
The ECMP hash setting applies to all ECMP routes.