Configuring Summary Addresses - Dell PowerConnect B-RX Configuration Manual

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Configuring IPv4 address family route parameters
For example, if the router has a path from RIP, from OSPF, and IPv4 IS-IS to the same destination,
and all the paths are using their protocols' default administrative distances, the router selects the
OSPF path, because that path has a lower administrative distance than the RIP and IPv4 IS-IS
paths.
Here are the default IPv4 administrative distances on the device:
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Lower administrative distances are preferred over higher distances. For example, if the device
receives routes for the same network from IPv4 IS-IS and from RIP, it will prefer the IPv4 IS-IS route
by default.
To change the administrative distance for IPv4 IS-IS routes, enter the following command at the
IPv4 IS-IS unicast address family configuration level.
BigIron RX(config-isis-router-ipv4u)# distance 100
Syntax: [no] distance <number>
This command changes the administrative distance for all IPv4 IS-IS routes to 100.
The <number> parameter specifies the administrative distance. You can specify a value from 1 –
255. (Routes with a distance value of 255 are not installed in the routing table.) The default for
IPv4 IS-IS is 115.

Configuring summary addresses

You can configure summary addresses to aggregate IS-IS route information. Summary addresses
can enhance performance by reducing the size of the Link State database, reducing the amount of
data the device needs to send to its neighbors, and reducing the CPU cycles used for IS-IS.
When you configure a summary address, the address applies only to Level-2 routes by default. You
can specify Level-1 only, Level-2 only, or Level-1 and Level-2 when you configure the address.
To configure a summary address, enter a command such as the following.
BigIron RX(config-isis-router-ipv4u)# summary-address 192.168.0.0 255.255.0.0
This command configures a summary address for all Level-2 IS-IS route destinations between
192.168.1.0 – 192.168.255.255.
Syntax: [no] summary-address <ip-addr> <subnet-mask> [level-1 | level-1-2 | level-2]
The <ip-addr> <subnet-mask> parameters specify the aggregate address. The mask indicates the
significant bits in the address. Ones are significant, and zeros allow any value. In the command
example above, the mask 255.255.0.0 matches on all addresses that begin with 192.168 and
contain any values for the final two octets.
882
Directly connected – 0 (this value is not configurable)
Static – 1 (applies to all static routes, including default routes)
EBGP – 20
OSPF – 110
IPv4 IS-IS – 115
RIP – 120
IBGP – 200
Local BGP – 200
Unknown – 255 (the device will not use this route)
BigIron RX Series Configuration Guide
53-1002253-01