Quick Reference Guide

600 PowerConnect B-Series TI24X Configuration Guide
53-1002269-02
Configuring IP parameters – Layer 3 Switches
21
PowerConnect(config)# ip route 209.157.22.0 255.255.255.0 null0
PowerConnect(config)# write memory
Syntax: ip route <ip-addr> <ip-mask> null0 [<metric>] [distance <num>]
or
Syntax: ip route <ip-addr>/<mask-bits> null0 [<metric>] [distance <num>]
To display the maximum value for your device, enter the show default values command. The
maximum number of static IP routes the system can hold is listed in the ip-static-route row in the
System Parameters section of the display. To change the maximum value, use the system-max
ip-static-route <num> command at the global CONFIG level.
The <ip-addr> parameter specifies the network or host address. The Layer 3 Switch will drop
packets that contain this address in the destination field instead of forwarding them.
The <ip-mask> parameter specifies the network mask. Ones are significant bits and zeros allow
any value. For example, the mask 255.255.255.0 matches on all hosts within the Class C subnet
address specified by <ip-addr>. Alternatively, you can specify the number of bits in the network
mask. For example, you can enter 209.157.22.0/24 instead of 209.157.22.0 255.255.255.0.
The null0 parameter indicates that this is a null route. You must specify this parameter to make
this a null route.
The <metric> parameter adds a cost to the route. You can specify from 1 – 16. The default is 1.
The distance <num> parameter configures the administrative distance for the route. You can
specify a value from 1 – 255. The default is 1. The value 255 makes the route unusable.
NOTE
The last two parameters are optional and do not affect the null route, unless you configure the
administrative distance to be 255. In this case, the route is not used and the traffic might be
forwarded instead of dropped.
Configuring load balancing and redundancy using multiple static routes to the
same destination
You can configure multiple static IP routes to the same destination, for the following benefits:
• IP load sharing – If you configure more than one static route to the same destination, and the
routes have different next-hop gateways but have the same metrics, the Layer 3 Switch load
balances among the routes using basic round-robin. For example, if you configure two static
routes with the same metrics but to different gateways, the Layer 3 Switch alternates between
the two routes. For information about IP load balancing, refer to “Configuring IP load sharing”
on page 605.
• Backup Routes – If you configure multiple static IP routes to the same destination, but give the
routes different next-hop gateways and different metrics, the Layer 3 Switch will always use the
route with the lowest metric. If this route becomes unavailable, the Layer 3 Switch will fail over
to the static route with the next-lowest metric, and so on.