Brocade BigIron RX Series Configuration Guide - Manual (Page 292)

214 BigIron RX Series Configuration Guide
53-1002484-04
Configuring forwarding parameters
7
Response to path state changes
If one of the load-balanced paths becomes unavailable, the IP route table in hardware is modified
to stop using the unavailable path. The traffic is load balanced between the available paths using
the same hashing mechanism described above. (Refer to
“How IP load sharing works” on
page 213.)
Default route ECMP
On the BigIron RX, IP load sharing (also known as ECMP load sharing) is done by the hardware. If
there is more than one path to a given destination, a hash is calculated based on the source MAC
address, destination MAC address, source IP address, destination IP address, and IP protocol. This
hash is used to select one of the paths.
If there are multiple next-hop routers for the default route in the IPv4 routing table, routed packets
on the default route would be automatically load-balanced among these next-hops through a
hashing formula, calculated based on (IPv4 Destination Address, IPv4 Source Address, IPv4 Source
Port, IPv4 Destination Port, DA-MAC, and SA-MAC) of the packets received. This feature allows for
load distribution of traffic among the available default route next-hops.
NOTE
This feature is currently not applicable to IPv6 traffic.
To specify the ECMP default route, enter a command such as the following.
BigIron RX(config)# ip load-sharing default-route
Syntax: [no] ip load-sharing [<num> l <default-route>]
The <num> parameter specifies the number of paths and can be from 2 – 8.
The <default-router> parameter specifies the ECMP load sharing.
DIsplaying the ECMP load sharing
Use the show run command to display the ECMP load sharing.
BigIron RX(config)#show run
========show run =====================
!
logging console
hostname RW
ip route 0.0.0.0/0 100.1.1.2
ip route 0.0.0.0/0 100.1.2.2
ip route 0.0.0.0/0 100.1.3.2
ip route 0.0.0.0/0 100.1.4.2
ip route 10.0.0.0/8 10.43.2.1
ip route 40.0.0.0/24 100.1.1.2
ip load-sharing default-route
Use the show ip route command to display the traffic that will now be sent over all 4 links load
balanced instead of being on only 1 link.
BigIron RX#show ip route
Total number of IP routes: 9
Type Codes - B:BGP D:Connected I:ISIS S:Static R:RIP O:OSPF; Cost - Dist/Metric
Destination Gateway Port Cost Type