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Difficulty: Very hardIPv6 Static Routing

A network engineer needs to manually configure a backup route on Router R1 toward the remote prefix 2001:db8:cafe:40::/642001:\text{db8}:\text{cafe}:40::/64. The primary route to this subnet is learned via OSPFv3 with an administrative distance of 110. The engineer must use the neighboring router's link-local address fe80::250:56ff:fe9a:12ab\text{fe80}::250:56ff:\text{fe9a}:12ab reachable through interface GigabitEthernet0/0/1. What complete Cisco IOS global configuration command must be entered to establish this route as a floating static route with an administrative distance of 130?

Answer:R1(config)# 【ipv6 route 2001:db8:cafe:40::/64 GigabitEthernet0/0/1 fe80::250:56ff:fe9a:12ab 130】

Answer

The complete command required is 'ipv6 route 2001:db8:cafe:40::/64 GigabitEthernet0/0/1 fe80::250:56ff:fe9a:12ab 130'.
To route IPv6 traffic using a link-local address (FE80::/10) as the next hop, Cisco IOS requires a fully specified static route syntax that defines the local exit interface followed by the link-local address. Without specifying the exit interface, the router cannot determine which local physical or logical link reaches that link-local address. Additionally, appending the administrative distance value 130 ensures the static route remains inactive in the routing table until the primary OSPFv3 route (AD 110) fails.

Step-by-Step Solution

1
Identify the base global configuration command for IPv6 static routing.
The command structure starts with 'ipv6 route'.
Cisco IOS requires 'ipv6 route' in global configuration mode to declare static routes for IPv6.
2
Append the destination IPv6 prefix and prefix-length.
Add '2001:db8:cafe:40::/64' after the command keyword.
Static routing requires specifying the exact destination prefix using CIDR slash notation.
3
Identify the mandatory parameters when utilizing a link-local address as the next hop.
Specify the local exit interface 'GigabitEthernet0/0/1' immediately followed by the link-local address 'fe80::250:56ff:fe9a:12ab'.
Because link-local addresses (FE80::/10) are only unique on a per-link basis, Cisco IOS requires a fully specified static route containing both the outbound interface and the next-hop link-local IP.
4
Set the administrative distance for floating route behavior.
Append '130' at the end of the command.
A primary OSPFv3 route has an administrative distance of 110. To function as a backup floating static route, the static route's administrative distance must be higher than 110.

Key Concept

Fully Specified IPv6 Floating Static Route Configuration
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Topics

IPv6 Static Routing

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