Configuration Guide User guide

1004 FastIron Configuration Guide
53-1002494-02
Configuring IP parameters – Layer 3 Switches
• If the IP load forwarding cache does not contain a forwarding entry for the destination, the
software selects a path from among the available equal-cost paths to the destination, then
creates a forwarding entry in the cache based on the calculation. Subsequent traffic for the
same destination uses the forwarding entry.
Response to path state changes
If one of the load-balanced paths to a cached destination becomes unavailable, or the IP route
table receives a new equal-cost path to a cached destination, the software removes the
unavailable path from the IP route table. Then the software selects a new path.Disabling or
re-enabling load sharing
To disable IP load sharing, enter the following commands.
Brocade(config)# no ip load-sharing
Syntax: [no] ip load-sharing
Changing the maximum number of ECMP (load sharing) paths
You can change the maximum number of paths the Layer 3 Switch supports to a value from 2
through 8. Table 170 shows the maximum number of paths supported per device.
For optimal results, set the maximum number of paths to a value at least as high as the maximum
number of equal-cost paths your network typically contains. For example, if the Layer 3 Switch you
are configuring for IP load sharing has six next-hop routers, set the maximum paths value to six.
NOTE
If the setting for the maximum number of paths is lower than the actual number of equal-cost paths,
the software does not use all the paths for load sharing for RIP routes. Run the clear ip route
command to fix this issue.
To change the number of IP load sharing paths, enter a command such as the following.
Brocade(config)# ip load-sharing 6
Syntax: [no] ip load-sharing [<num>]
The <num> parameter specifies the number of paths and can be from 2 through 8, depending on
the device you are configuring.
ICMP Router Discovery Protocol configuration
The ICMP Router Discovery Protocol (IRDP) is used by Brocade Layer 3 Switches to advertise the IP
addresses of its router interfaces to directly attached hosts. IRDP is disabled by default. You can
enable the feature on a global basis or on an individual port basis:
• If you enable the feature globally, all ports use the default values for the IRDP parameters.
TABLE 170 Maximum number of ECMP load sharing paths per device
FESX
FSX 800
FSX 1600
FWS FCX
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