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Difficulty: MediumIPv6 Static Routing

A network administrator is configuring IPv6 static routing on router R1 to reach network 2001:db8:89ab:10::/642001:\text{db8}:89\text{ab}:10::/64. The directly connected neighbor router interface is configured with global unicast address 2001:db8:1234:1::22001:\text{db8}:1234:1::2 and link-local address fe80::2\text{fe80}::2. Router R1 uses local interface GigabitEthernet0/1 to reach this neighbor. Which TWO Cisco IOS commands represent valid IPv6 static route configurations on R1?

  1. ipv6 route 2001:db8:89ab:10::/64 GigabitEthernet0/1 fe80::2Answer
  2. ipv6 route 2001:db8:89ab:10::/64 2001:db8:1234:1::2Answer
  3. C
    ipv6 route 2001:db8:89ab:10::/64 fe80::2
  4. D
    ipv6 route 2001:db8:89ab:10::/64 GigabitEthernet0/1 fe80::fffe:2

Answer

The two valid Cisco IOS static route commands are 'ipv6 route 2001:db8:89ab:10::/64 GigabitEthernet0/1 fe80::2' and 'ipv6 route 2001:db8:89ab:10::/64 2001:db8:1234:1::2'.
In Cisco IOS, IPv6 static routes configured with a link-local address as the next hop MUST include the local egress interface (fully specified route). Alternatively, a global unicast next-hop address can be configured directly without an egress interface specified.

Step-by-Step Solution

1
Identify valid next-hop options for Cisco IOS IPv6 static routes
IPv6 static routes can use a global unicast next-hop address alone, an outbound local interface with a global unicast address, or a fully specified combination of local exit interface and link-local next-hop address.
Link-local addresses have link-local scope and exist on multiple interfaces simultaneously, making the exit interface strictly mandatory when using link-local next hops.
2
Evaluate the option using local exit interface and link-local address
The command specifying GigabitEthernet0/1 alongside link-local address fe80::2 is valid.
It fulfills the mandatory requirement of declaring the local egress interface when referencing link-local IPv6 addresses.
3
Evaluate the option using global unicast next-hop address
The command specifying next-hop global unicast address 2001:db8:1234:1::2 is valid.
Global unicast addresses are globally unique and routable without explicit interface identification.

Key Concept

IPv6 Static Route Next-Hop Requirements
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Topics

IPv6 Static Routing

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