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Cisco 1921 IPv6 wrong RA, using link-local address

Posted on 2014-04-07
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Last Modified: 2014-05-23
We have a Cisco 1921 that is giving out its link-local address in it's router advertisements, rather than the global uni-cast address assigned to its internal interface.  DHCP config on the router works fine, and is handing out the proper subnet and dns information, but hosts are configuring their gateways to the link-local fe80:: address given in the router's RA.  How can I change this?

Thanks,
Robert
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Question by:Robert Davis
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4 Comments
 
LVL 10

Expert Comment

by:Rafael
ID: 39984613
I don't know how your config looks so this is off the hip. You may have to configure two VLANs. One for inside and one for outside.

First configure the outside interface using the public address as well as the link local address and use the ipv6 nd suppress-ra command.

Second do the same thing for your other  VLAN and use the ipv6 nd prefix command. This will generate the advertisements.

Fro more details go to this site on cisco.

http://www.cisco.com/c/en/us/td/docs/ios/ipv6/command/reference/ipv6_book/ipv6_07.html#wp2359793
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Author Comment

by:Robert Davis
ID: 39984655
Sorry, here's the config, any thoughts after taking a look?

ip cef
!
ipv6 unicast-routing
ipv6 dhcp pool v6-pool
 address prefix 2001:omitted:1001::/64
 dns-server 2001:4860:4860::8888
!
ipv6 inspect name ipv6-firewall icmp
ipv6 inspect name ipv6-firewall udp
ipv6 inspect name ipv6-firewall ftp
ipv6 cef
!
!
interface Tunnel0
 description Hurricane Electric IPv6 Tunnel Broker
 no ip address
 ipv6 address 2001:470:1F04:omitted::2/64
 ipv6 enable
 ipv6 inspect ipv6-firewall out
 ipv6 traffic-filter outside-in6 in
 tunnel source publicv4address
 tunnel mode ipv6ip
 tunnel destination he.ipv4.address
!
interface Embedded-Service-Engine0/0
 no ip address
 shutdown
!
interface GigabitEthernet0/0
 description $ETH-LAN$$ETH-SW-LAUNCH$$INTF-INFO-GE 0/0$$FW_OUTSIDE$
 ip address public.v4. address
 ip nat outside
 ip virtual-reassembly in
 zone-member security out-zone
 duplex auto
 speed auto
!
interface GigabitEthernet0/1
 no ip address
 duplex auto
 speed auto
!
interface GigabitEthernet0/1.1
 description $ETH-LAN$
 encapsulation dot1Q 1 native
 ip address ipv4.internal.address
 ip nat inside
 ip virtual-reassembly in
 zone-member security in-zone
 ipv6 address 2001:omitted:1001::1/64
 ipv6 enable
 ipv6 nd prefix 2001:omitted:1001::/64
 ipv6 nd managed-config-flag
 ipv6 nd other-config-flag
 ipv6 nd router-preference High
 ipv6 dhcp server v6-pool
!
ip forward-protocol nd
!
ipv6 route 2001:omitted:1001::/64 GigabitEthernet0/1.1
ipv6 route ::/0 Tunnel0
!
!
!
ipv6 access-list outside-in6
 permit tcp any any established
 permit icmp any any

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Host is also on 2001:omitted:1001::/64 and can ping6 other hosts on the same network.  Router can ping out to the Internet on v6.
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Accepted Solution

by:
TimotiSt earned 500 total points
ID: 39996134
As weird as it is, I think that's the way IPv6 was designed to work.

The use of link-local addresses to uniquely identify routers (for
      Router Advertisement and Redirect messages) makes it possible for
      hosts to maintain the router associations in the event of the site
      renumbering to use new global prefixes.
https://tools.ietf.org/html/rfc4861
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Author Closing Comment

by:Robert Davis
ID: 40087522
Additionally the firewall had to be completely disabled.
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