© Copyright IBM Corp. 2011 Chapter 15. Basic IP Routing 187
6. Configure the default gateway to the routers’ addresses.
The default gateway allows the switch to send outbound traffic to the router:
7. Enable IP routing.
8. Verify the configuration.
Examine the resulting information. If any settings are incorrect, make the
appropriate changes.
ECMP Static Routes
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 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.
OSPF Integration
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.
ECMP Route Hashing
You can configure the parameters used to perform ECMP route hashing, as follows:
• sip: Source IP address (default)
• dipsip: Source IP address and destination IP address
The ECMP hash setting applies to all ECMP routes.
RS G8000(config)# ip gateway 1 address 205.21.17.1
RS G8000(config)# ip gateway 1 enable
RS G8000(config)# ip routing
RS G8000(config)# show vlan
RS G8000(config)# show interface information
RS G8000(config)# show interface ip
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