CCIE Pursuit Blog

December 5, 2007

LFU 11: Interfaces Can Have Multiple IPv6 Addresses

I ran into an issue this weekend with an IPv6 address that I thought that I had removed showing up in my routing table. 

r1(config)#ipv6 unicast-routing
r1(config)#int s1/0
r1(config-if)#ipv6 address 2001::11/64
r1(config-if)#do sh ipv6 int br | e down|unass
Serial1/0                  [up/up]
    FE80::CE00:12FF:FE10:0
    2001::11

Oh crap!  I wanted to configure 2001::1/64 not 2001::11/64.

r1(config-if)#ipv6 address 2001::1/64
r1(config-if)#do sh ipv6 int br | e down|unass
Serial1/0                  [up/up]
    FE80::CE00:12FF:FE10:0
    2001::1
    2001::11

r1(config-if)#do sh run int s1/0
Building configuration…

Current configuration : 262 bytes
!
interface Serial1/0
 ip address 10.0.0.1 255.0.0.0
 encapsulation frame-relay
 ipv6 address 2001::1/64
 ipv6 address 2001::11/64
 serial restart-delay 0
 no dce-terminal-timing-enable
 frame-relay map ip 10.0.0.2 102 broadcast
 no frame-relay inverse-arp
end

Unlike IPv4, configuring a different IPv6 address on an interface will NOT overwrite the existing IPv6 address with the new IPv6 address.  This is because an interface can have multiple IPv6 addresses.

You can use the “no ipv6 address” to remove all IPv6 addreses on an interface.  Then you can configure the new IPv6 address.

interface Serial1/0
 ip address 10.0.0.1 255.0.0.0
 encapsulation frame-relay
 ipv6 address 2001::1/64
 ipv6 address 2001::11/64
 ipv6 address 2001::111/64
 ipv6 address 2001::1111/64
 serial restart-delay 0
 no dce-terminal-timing-enable
 frame-relay map ip 10.0.0.2 102 broadcast
 no frame-relay inverse-arp
end

r1(config-if)#no ipv6 address
r1(config-if)#do sh run int s1/0
Building configuration…

Current configuration : 211 bytes
!
interface Serial1/0
 ip address 10.0.0.1 255.0.0.0
 encapsulation frame-relay
 serial restart-delay 0
 no dce-terminal-timing-enable
 frame-relay map ip 10.0.0.2 102 broadcast
 no frame-relay inverse-arp
end

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1 Comment »

  1. […] that took me WAY too long to complete.  I made a couple of really stupid fat-finger mistakes (covered in this LFU).  Part of the problem is that I still have a hard time reading IPv6 addresses.  Otherwise, this […]

    Pingback by Internetwork Expert Volume II: Lab 2 - Section 7 « CCIE Pursuit — December 10, 2007 @ 8:52 am | Reply


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