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Catalyst 3750 SwitchSoftware Configuration Guide
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Chapter39 Configuring IPv6 Unicast Routing
Understanding IPv6
If a new switch becomes the stack master, it recomputes the IPv6 routing tables and distributes them to
the member switches. While the new stack master is being elected and is resetting, the switch stack does
not forward IPv6 packets. The stack MAC address changes, which also changes the IPv6 address. When
you specify the stack IPv6 address with an extended unique identifier (EUI) by using the ipv6 address
ipv6-prefix/prefix length eui-64 interface configuration command, the address is based on the interface
MAC address. See the “Configuring IPv6 Addressing and Enabling IPv6 Routing” section on
page 39-12.
If you configure the persistent MAC address feature on the stack and the stack master changes, the stack
MAC address does not change for approximately 4 minutes. For more information, see the “Enabling
Persistent MAC Address” section on page5-19 in Chapter 5, “Managing Switch Stacks.”
These are the functions of IPv6 stack master and members:
Stack master:
runs IPv6 routing protocols
generates routing tables
distributes CEFv6 routing tables to stack members that use dCEFv6
runs IPv6 host functionality and IPv6 applications
Stack member (must be running the IP services image):
receives CEFv6 routing tables from the stack master
programs the routes into hardware
Note IPv6 packets are routed in hardware across the stack if the packet does not have exceptions
(IPv6Options) and the switches in the stack have not run out of hardware resources.
flushes the CEFv6 tables on master re-election