Re: Question on Ipv6 address

[Owen DeLong <owen () delong com>]

On Mar 26, 2013, at 8:39 AM, Joe <sj_hznm () hotmail com> wrote:

> I'm new to Ipv6 and trying to understanding something about IPv6 in service provider network.
> I've got the following questions , could anybody do some helps?
> 1. In a dial-up network (Q-in-Q for each customer who dials in )      Should each customer be assigned to ipv6 subnet 
> prefix like /64 unique universily?  I've read   a rfc which stated point-to-point like should be assigned /64. But to 
> my

> understanding, in dial-up   network , each user should only needed to be assigned a single ipv4 address, with wich 
> customer   could used in his PC or his home router. 


IPv6 is very different from IPv4.

In IPv6, there should be a /64 assigned to the point to point link over which a  /48 should be delegated to the 
customer.

If the customer doesn't have a router and is just attaching a single PC, he will not make the Prefix Delegation request 
and just the point-to-point /64 will be adequate.

> 2. In dial-up network,  could each vlan's ipv6 link-id  be planned with its vlan number?     if so,  IP v6 address 
> confliction could be avoided when  BAS is assigned a /64 or longer prefix.

Why would you ever assign a longer prefix?
I'm not sure what you mean by "link-id", so I'm not sure what you are attempting to resolve here.

> 3. we are testing some BAS with IPv6 accessing, in radius accouting packets, there is     IP-v6-prefix, 
> Ip-v6-link-id, Ip-v6-delegated-prefix.    how could dial-up PC's  IPv6    address be calculated with above 
> information?

It probably can't. Why do you need to?

> 4. should it be necessary to plan  different IP-v6-prefix(IP-v6-delegated-prefix) for each dial-up customers  in BAS?

There are multiple ways to structure this.

If you put all of the customers into a common NBMA network, then you can use a single /64 prefix to number all of the 
link addresses from a given BAS to the customer sites. All of the CPE routers will use the same address on the BAS as 
their default gateway.

If you put the customers into individual VLANs, then each VLAN should have a /64 prefix assigned to it.

Beyond that, if the customer has a router, you should plan on having a /48 delegated prefix for each customer.

> 5. How could delegated IPv6 prefix be used in service provider's network? is this useful in dial-up access network?

The delegated prefix isn't used in the service provider's network. It is delegated to the customer for them to number 
their network. It can be used by the customer regardless of attachment method, though the low speeds of dialup make a 
complex topology on the far side less likely.

Owen