static ipv6 address from a /64

[paul amaral]

Hi all

I have a cisco 6500 that i configured a /64 on int1/39 that has a linux server connected to it and supressed RAs. On this server i assigned a static ip, 

2001:x:77:4::2. i can ping to/from the server with no issues. However when doing a show ipv6 neighbors i still see the auto config ipv6 on fast1/39.

interface FastEthernet1/39

ip address x.x.x.33 255.255.255.240

ip flow ingress

speed 100

duplex full

ipv6 address 2001:x:77:4::1/64

ipv6 nd ra suppress

spanning-tree portfast edge

My question why is that attached server getting an auto config ipv6 address when i have the supress command under interface. Also is it correct to assign a /64 to an int/vlan and statically assign ips instead or should i move to a /56. I'm not really sure if what im doing is common or if it create issues.

TIA, Paul

[Deepak Ambotkar]

Hi Paul,

Is it possible to debug below things on the Cisco device?

debug ipv6 neighbour

Can you please paste the IP address config and show outputs from the linux server?

I hope you are not getting a random IP assigned from the /64 subnet.

Thanks,

Deepak

[paul amaral]

Deepak, while i assigned a static ip to the server doing a show ipv6 neighbor shows this static ip and it also shows the auto config ip. Again based on my config above shouldnt it jsut show the static ip. Why is SLAAC in play here if i have

ipv6 nd ra suppress on the interface, will this setup cause issues.

sh ipv6 neighbors

IPv6 Address                              Age Link-layer Addr State Interface

2001:x:77:4::2                            1 0019.b9e6.5647  STALE Fa1/39

2001:x:77:4:219:B9FF:FEE6:x     49 0019.b9e6.5647  STALE Fa1/39

FE80::219:B9FF:FEE6:5647                    1 0019.b9e6.5647  STALE Fa1/39

note i can ping the static and auto config ip and the server lists both of them.

[Deepak Ambotkar]

Paul, this behaviour is not normal. Both IP's are from the same subnet though. We are not sure if this autoip is assigned out of SLAAC. The only way is to find this out by removing the server IP address and assign the static IP again using "debug ipv6 nd" / "debug ipv6 packet" to capture the packets.

I am trying to set this in the lab and let you know the results soon.

Regards,

Deepak

[Tomas Fidler · Accepted solution]

This question is more about linux .

Try look here:

http://superuser.com/questions/33196/how-to-disable-autoconfiguration-on-ipv6-in-linux

But if you run "debug ipv6 nd" on cisco, you can see, if router responds to Router Solicitiotion messages...

If cisco is not responding with Router Advertisments, try solve it on linux side.

If cisco is responding send log messages here... with "show ipv6 interface Fa1/39"

[paul amaral]

thanks thomas, thats more or less what i did.