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Cisco Content Services Switch Routing and Bridging Configuration Guide
OL-8241-02
Chapter6 Configuring the Internet Protocol
Configuring IP Equal-Cost Multipath
Configuring IP Equal-Cost Multipath
To set the equal-cost multipath (ECMP) selection algorithm and the preferred
reverse egress path, use the ip ecmp command. The CSS supports a maximum of
15 ECMP paths.
The syntax for this global configuration command is:
ip ecmp [address|no-prefer-ingress|roundrobin]
The options for this global configuration mode command are as follows:
•address - Choose among alternate paths based on IP addresses. For example:
(config)# ip ecmp address
•no-prefer-ingress - Do not prefer the ingress path of a flow for its reverse
egress path. By default, the ingress path for a flow is the preferred egress path.
This means that the preferred interface over which to reply to a client is the
interface on which the CSS originally received the request from the client.
Note that this command option has no effect on UDP traffic.
For example:
(config)# ip ecmp no-prefer-ingress
To reset the ingress path of a flow for its preferred reverse egress path, enter:
(config)# no ip ecmp no-prefer-ingress
•roundrobin - Alternate between equal paths in roundrobin fashion. For
example:
(config)# ip ecmp roundrobin
Note The CSS applies the ECMP selection algorithm for non-TCP/UDP packets (for
example, ICMP) on a packet-by-packet basis. Multipath selection for TCP and
UDP is performed on a per-flow basis, and all packets for a particular flow take
the same path.