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Difficulty: Very hardIPv6 Static Routing

An engineer is configuring a secondary backup route on core router R1 to reach remote subnet 2001:db8:89ab:2000::/562001:\text{db8}:89\text{ab}:2000::/56 through neighboring router R2. The primary route is learned dynamically via OSPFv3 with an Administrative Distance of 110110. The interconnecting segment between R1 and R2 uses GigabitEthernet0/0/1. R2's interface on this link uses the link-local address fe80::211:22ff:fe33:4455\text{fe80}::211:22\text{ff}:\text{fe33}:4455. Which Cisco IOS command must be configured on R1 to create a valid floating static route with an Administrative Distance of 130130 using R2's link-local address?

  1. ipv6 route 2001:db8:89ab:2000::/56 GigabitEthernet0/0/1 fe80::211:22ff:fe33:4455 130Answer
  2. B
    ipv6 route 2001:db8:89ab:2000::/56 fe80::211:22ff:fe33:4455 130
  3. C
    ipv6 route 2001:db8:89ab:2000::/56 GigabitEthernet0/0/1 fe80::011:22ff:fe33:4455 130
  4. D
    ipv6 route 2001:db8:89ab:2000::/56 GigabitEthernet0/0/1 130

Answer

The command 'ipv6 route 2001:db8:89ab:2000::/56 GigabitEthernet0/0/1 fe80::211:22ff:fe33:4455 130' correctly specifies both the exit interface and link-local next-hop address with an Administrative Distance of 130.
When configuring an IPv6 static route using a link-local next-hop address (fe80::/10\text{fe80}::/10), Cisco IOS strictly mandates a fully specified route. This format includes the local exit interface followed by the link-local address of the adjacent router. Appending the value 130 at the end of the syntax correctly sets the Administrative Distance higher than OSPFv3 (110), successfully forming a floating static route.

Step-by-Step Solution

1
Identify the mandatory components of an IPv6 static route using a link-local address as the next hop.
Because link-local addresses (fe80::/10\text{fe80}::/10) are shared across multiple local links, Cisco IOS requires a fully specified route syntax: 'ipv6 route <prefix/mask> <exit-interface> <link-local-next-hop> [AD]'.
Without the local exit interface, the router cannot determine which physical or logical link to use to reach the target link-local address.
2
Verify Administrative Distance manipulation for floating static route capability.
The primary path is learned via OSPFv3 with AD = 110110. Setting the static route AD to 130130 ensures it remains inactive in the IPv6 routing table until the primary OSPFv3 route disappears.
Floating static routes require an Administrative Distance higher than the active primary routing protocol.
3
Validate the exact command string structure.
The target prefix is 2001:db8:89ab:2000::/562001:\text{db8}:89\text{ab}:2000::/56, the local exit interface is GigabitEthernet0/0/1, the next-hop link-local address is fe80::211:22ff:fe33:4455\text{fe80}::211:22\text{ff}:\text{fe33}:4455, and the metric parameter is 130.
This matches the exact fully specified static route configuration requirements in Cisco IOS.

Key Concept

Fully Specified IPv6 Static Routes and Link-Local Next-Hop Requirements
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Topics

IPv6 Static Routing

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