Route /64 for internal use?

[jmaurin12]

Hi!

I'm not so familiar with IPv6, so sorry if I say something dumb.

Today, I have this scenario:  ISP------------>(home)BridgeModem---->Cisco 2801------>local Lan.

In this scenario, I'm using my router (2801) to connect my PPPoE and get IP (which is static, but got from PPPOE) and do NAT for my local network (192.168.22.X).

I just got and /64 IPv6 block from my provider and I would like to know if I route these ipv6 for my lan users instead of doing NAT like ipv4? If yes, How do I do this? This is my block: 2804:07f0:8402:1269::/64

Should I split this /64 into 2x /32, put first network in my Dialer interface (WAN) and the second network in my LAN interface?

[Philip D'Ath]

The ISP should have given you a /56 or a /48.  The /64 they have given you is fine for the link between them and you, buy you need another prefix to put behind your router.

[johnd2310]

Hi,

The /64 you were given is for your internal network. A /64 is the smallest you should use for your internal network. It is not advisable to use anything smaller than a /64 for a Lan. We normally use smaller than a /64 for point to point links.

Your provider should give you another ipv6 address for the link to the ISP.

thanks

John

[timway001]

I was going to type a really long reply but then I replied the nice person that writes on PacketPushers wrote this exact issue up just for you!

http://packetpushers.net/ipv6-home-prefix-delegation/

In a nutshell on the provider facing interface you are going to use DHCPv6 Prefix-Delegation client to request and hopefully receive a prefix from your ISP. You then setup your LAN facing interface(s) with an IPv6 based address (subnet) on the prefix delegated to you. Depending on how big of a prefix your provider gives you will determine how many subnets you can make of /64's.

Like the others that have responded have mentioned you shouldn't use anything smaller than a /64 if you need to use SLAAC and it's associated functions. In some cases you may see smaller ranges used for point-to-point links or other special cases. I'm not sure what the Cisco design guides say but from what I recall they suggest using /64 even for point-to-point if possible. That said in my network I currently have a /64 carved up int /126 (yes technically a /127 woudl work too ... legacy equipment complained or something like that) for my point-to-point links.