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Bronze

Question about configuring Global IPv6 address on interface

It seems when configuring a global IPv6 address on a layer 3 interface, we cannot specify the whole 128 bit address. We can only specify the prefix and leave the last 64 bits to be generated by the router:

http://www.cisco.com/en/US/docs/ios-xml/ios/ipv6/configuration/12-2sx/ip6-addrg-bsc-con.html#GUID-70188E8F-16D2-4DD1-8DE2-70073FF37CC8

Then how can I specify the router address to the client using DHCPv6? Do I have to keep the router RAs while using DHCPv6 together?

Thanks.

zhenning

1 ACCEPTED SOLUTION

Accepted Solutions

Question about configuring Global IPv6 address on interface

From this document, it seems indeed that it is like you says.

My experience is that the eui64 argument is optional.

To my best knowledge you can either type:

ipv6 address 2012:1:1:1:: /64 eui64

or

ipv6 address 2012:1:1:1::1 /64

With all versions that I have tried, both options were possible. I would be surprised if this were no longer the case.

regards,

Leo

7 REPLIES

Question about configuring Global IPv6 address on interface

From this document, it seems indeed that it is like you says.

My experience is that the eui64 argument is optional.

To my best knowledge you can either type:

ipv6 address 2012:1:1:1:: /64 eui64

or

ipv6 address 2012:1:1:1::1 /64

With all versions that I have tried, both options were possible. I would be surprised if this were no longer the case.

regards,

Leo

Bronze

Re: Question about configuring Global IPv6 address on interface

Hi Leo, thanks for your reply. But I tried this on both 6500(12.2.33SXI4a) and 3750 switches with no luck.

(config-if)#ipv6 address 2012:1:1:1::1 ?

  link-local  Use link-local address

(config-if)#ipv6 address 2012:1:1:1::1 /64

% Invalid input detected at '^' marker.

zhenning

Bronze

Re: Question about configuring Global IPv6 address on interface

Sorry, Leo's suggestion actually works. I need to remove the space between before /64:

(config-if)#ipv6 address 2012:1:1:1::1/64

Cisco's doc need to be updated to avoid this confusion.

Question about configuring Global IPv6 address on interface

Its truly amazing what a single space can do. Sorry, I should have left it out.

It is just that I try to do a lot of commands by head (as a practice) and obviously I make mistakes there.

Thnx for putting me right.

Leo

Purple

Question about configuring Global IPv6 address on interface

Hi Leo,

Where is it stated in this doc that you can't configure a /128 ?

Router(config-if)#ipv add 2001::1/128

Router(config-if)#do sh ipv int lo0

Loopback0 is up, line protocol is up

  IPv6 is enabled, link-local address is FE80::9CD7:2EFF:FEF0:99FA

  Global unicast address(es):

    2001::1, subnet is 2001::1/128

  Joined group address(es):

    FF02::1

    FF02::2

    FF02::1:FF00:1

    FF02::1:FFF0:99FA

  MTU is 1514 bytes

  ICMP error messages limited to one every 100 milliseconds

  ICMP redirects are enabled

  ND DAD is not supported

  ND reachable time is 30000 milliseconds

The IOS accepts it on any interface but it will only work for Loopbacks.

I configured a /126 between 2 serials and it worked without any problem but for prefix-advertisement through RA  to work then you must configure a /64.

Regards.

Alain

Don't forget to rate helpful posts.

Question about configuring Global IPv6 address on interface

Hi Alain,

You are entirely correct, any mask > /64 can be configured on an interface.

However, in my perceprton the question was about the ability to specify a full address, regardless of the mask used on it.

In the document the OP linked it appears as if the only options were eui64, link-local or anycast. This was confusing him.

My point was essentially that the ipv6 address command may also be used without one of those.

The notation in the document is misleading. It should be like this:

ipv6 address prefix/mask [eui64]

regards,

Leo

Bronze

Re: Question about configuring Global IPv6 address on interface

Hi Alain,

Look at the document I included in the original post, it says:

Do one of the following:

    ipv6 address ipv6-prefix / prefix-length eui-64

    ipv6 address ipv6-address / prefix-length link-local

    ipv6 address ipv6-prefix / prefix-length anycast

    ipv6 enable

zhenning

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