IPv6 Address and Host Identifier

[CSCO11177789]

Hi;

Are we have to use 64bit prefix for host addresses ?

For example we gave 2001:xxx:xxx:100::10/56 address to one of our servers and everything is fine. Also on another subnet of firewall we use  2001:xxx:xxx:200::10/56 for another server etc.

Is this configuration wrong or not ? 

Thanks,best regards

[blau grana]

Hi,

If this addressing is fine with you, it is OK. You don't have to use 64bit for host address.

64bit range for hosts is recommendation because of some techniques of dynamic obtaining of IPv6 address.

[WSLH OIS NOC - OIS Infrastructure]

For routing purposes, prefixes vary from /9 to /127; routing a /56 is fine.  However, there is a very strong bias toward in 64 bit:64 bit split in subnet and host parts of addresses, and it's best practice to make all regular vlans be /64 except for making point to point links be /127.  Well written IPv6 stacks should cope with other sizes, but do you trust all your device vendors to have gotten that right yet?

In IPv4 it's really hard to have all your subnets be the same size, and it makes for a documentation and adminstration nightmare to keep track of the variations.  In IPv6 you can make them all the same size, and none of them will be too small, and it is just so much simpler.

-- Jim Leinweber, WI State Lab of Hygiene

[CSCO11177789]

Thank you.

We go on with /56 for static servers and /64 for end users.

Best regards