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Webcast-Catalyst9k
New Member

IPV6 addressing "shortcut"

Is there some sort of shortcut one can use when doing basic troubleshooting with IPV6?  In the old days it wasn't terribly difficult to remember a few key IPV4 address and be able to relatively easily ping them or telnet to them. 

For the moment I am experimenting with IPV6 and have purposely choosen a very simple (read: lots of zeros) address scheme.  For instance right now I can fairly easily ping fd::1 and fd::2 and so on.  But what happens when I get a "real" IPV6 from an ISP?

It would be great if one could skip the network portion of the IPV6 address using something like DNS suffix search order to ping host1 rather than host1.mydomain.com.  In this case instead of pinging 2008:6ce5:0e6b:f561:aaaa:bbbb:cccc:dddd I would simply ping aaaa:bbbb:cccc:dddd because the network part was somehow configured or implied.  Does something like this exist?

Thanks,

Diego

6 REPLIES
Purple

IPV6 addressing "shortcut"

Hi,

Is this feature available in IPv4, No of course because you must specify the entire IP address to communicate so the same goes for IPv6.

The first /48 are assigned by ISP then the bits from 49 to 64 are used to subnet so you ar going to use a simple to remember scheme and the host part unless you staically configure it is derived from the MAC address so it is the most complicated part to remember not the prefix part.

Regards.

Alain.

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Cisco Employee

IPV6 addressing "shortcut"

Diego,

There technically isn't a way to do this yet, I say yet as you could always raise a feature request.

There are 2 options / workarounds that come to mind depending on what you want to acheive.

1) Leverage the 'ipv6 general prefix feature' This feature is used as a config shortcut to simplify static interface addressing

e.g.

ipv6 general-prefix BOB 2001:db8:1:1::/64

!

interface Ethernt1/0

ipv6 address BOB ::1/127

!

You cannot use the general prefix however for any debugging (pings and traceroutes to BOB fail)

2) You could configure an IPv6 host on each device which represents the test endpont (assuming this is static) that you want to test against

!

ipv6 host BOB 2001:db8:1:1::1

!

ping BOB

I hope this helps

New Member

IPV6 addressing "shortcut"

Thank you sir.  Those suggestions are very helpful.  I have to think some "shortcuts" will be developed as IPV6 becomes more and more prevalent.

Thanks,

Diego

Bronze

Re: IPV6 addressing "shortcut"

Mark, this may be untimely for your use but perhaps others may find this helpful.

Keep in mind since there are NO RFC 1918 type addresses in IPv6, this tip may not work in a production environment (with Internet Access).

:

LAB setup:

Interface f0/0

ip address 172.16.1.1 255.255.255.0

ipv6 address 172:16:1::1/126

Now you don't have to remember different addresses, just remember to put a colon ":" instead of a period ".".

HTH

Frank

Cisco Employee

Re: IPV6 addressing "shortcut"

Frank,

Just a point of correction. There are RFC 1918 style address in IPv6 they are called Unique-Local (fc00::/7)

So a way to adapt your shortcut proposal would be to preface the intended IPv6 address with the FD00 prefix.

e.g.

Interface f0/0

ip address 172.16.1.1 255.255.255.0

ipv6 address fd00:172:16:1::1/126

However, the purpose of Unique-Local is to provide an expectation of private uniqueness within a network and not have addressing overlap should there be a merger at some point in the future. If people were to adopt this shortcut in production it would defeat the purpose of this address space, this is best kept to a lab setup / environment.

Regards

Stephan

Bronze

Re: IPV6 addressing "shortcut"

Ahhh, The unique-local!!!

Good information, Thanks

Frank

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