Configuring an IPv6 Default Gateway to Support OOB Management

A default gateway is the first hop to the network in which management devices are located. In addition to an IPv4 default gateway (whose IP address is configured by means of the ip default-gateway command), an IPv6 default gateway is recommended for the following reasons:

• Although IPv6 discovers neighbors and routes dynamically, in some cases Router Advertisement (RA) and Router Solicitation (RS) operations are disabled and a default gateway is required to send traffic.
• Management devices (for example, TFTP servers, Telnet or SSH clients) are not members of the same subnet as the management IPv6 address.

If a management VLAN is not configured, the device can have only one IPv6 default gateway in the global configuration.

If a management VLAN is configured (by means of the default-ipv6-gateway command in VLAN configuration mode), the device can have a maximum of 5 IPv6 default gateways with a metric (1 through 5) under the management VLAN.

Multiple gateways can have the same metric value.

The best default gateway is first chosen as the device whose neighbors are reachable (in the sequence of metric values). Otherwise, the gateway with the highest priority (the lowest metric value) is chosen.

If a static default gateway is configured, that gateway takes precedence over the best default gateway configured by means of RA. If the static default-gateway configuration is removed, the best default gateway learned by RA is restored.

Configured gateway addresses and the default gateway address must be in same subnet.