Configuring Default Router Preference - Cisco Catalyst 3750-E Software Configuration Manual

Chapter 41 Configuring IPv6 Unicast Routing
without arguments. To disable IPv6 processing on an interface that has not been explicitly configured
with an IPv6 address, use the no ipv6 enable interface configuration command. To globally disable IPv6
routing, use the no ipv6 unicast-routing global configuration command.
This example shows how to enable IPv6 with both a link-local address and a global address based on the
IPv6 prefix 2001:0DB8:c18:1::/64. The EUI-64 interface ID is used in the low-order 64 bits of both
addresses. Output from the show ipv6 interface EXEC command is included to show how the interface
ID (20B:46FF:FE2F:D940) is appended to the link-local prefix FE80::/64 of the interface.
Switch(config)# sdm prefer dual-ipv4-and-ipv6 default
Switch(config)# ipv6 unicast-routing
Switch(config)# interface gigabitethernet1/0/11
Switch(config-if)# no switchport
Switch(config-if)# ipv6 address 2001:0DB8:c18:1::/64 eui 64
Switch(config-if)# end
Switch# show ipv6 interface gigabitethernet1/0/11
GigabitEthernet1/0/11 is up, line protocol is up
IPv6 is enabled, link-local address is FE80::20B:46FF:FE2F:D940
Global unicast address(es):
2001:0DB8:c18:1:20B:46FF:FE2F:D940, subnet is 2001:0DB8:c18:1::/64 [EUI]
Joined group address(es):
MTU is 1500 bytes
ICMP error messages limited to one every 100 milliseconds
ICMP redirects are enabled
ND DAD is enabled, number of DAD attempts: 1
ND reachable time is 30000 milliseconds
ND advertised reachable time is 0 milliseconds
ND advertised retransmit interval is 0 milliseconds
ND router advertisements are sent every 200 seconds
ND router advertisements live for 1800 seconds
Hosts use stateless autoconfig for addresses.

Configuring Default Router Preference

Router advertisement messages are sent with the default router preference (DRP) configured by the
ipv6 nd router-preference interface configuration command. If no DRP is configured, RAs are sent
with a medium preference.
A DRP is useful when two routers on a link might provide equivalent, but not equal-cost routing, and
policy might dictate that hosts should prefer one of the routers.
Beginning in privileged EXEC mode, follow these steps to configure a DRP for a router on an interface.
Command
Step 1 configure terminal
Step 2
interface interface-id
Step 3 ipv6 nd router-preference {high |
medium | low}
Step 4 end
Step 5 show ipv6 interface
Step 6 copy running-config startup-config
OL-9775-08
FF02::1
FF02::2
FF02::1:FF2F:D940
Purpose
Enter global configuration mode.
Enter interface configuration mode, and enter the Layer 3 interface on
which you want to specify the DRP.
Specify a DRP for the router on the switch interface.
Return to privileged EXEC mode.
Verify the configuration.
(Optional) Save your entries in the configuration file.
Catalyst 3750-E and 3560-E Switch Software Configuration Guide
Configuring IPv6
41-13