Running IPv6 on a large L2 network

Dan White dwhite at
Tue Sep 9 17:36:33 CEST 2008

Tim Chown wrote:
> I'm about to do a revision of this draft:
> so any feedback is timely.
> We also have a modified rafixd that I'll see if we can put up somewhere
> for people to fetch/use if they wish.


A scenario you may want to consider for section 3 is layer two separation.

A common layer two technology in broadband networks is rfc1483 bridging, 
or RBE in cisco terminology:

which uses ATM, DSL or other protocols to create a point to point 
connection between the customer's CPE/modem back to a BRAS router:

which will enforce IPv4 static assignment, or observe/proxy DHCPv4 
requests to enforce DHCP lease times. It uses proxy arp an other 
'tricks' to allow multiple customers to share the same IPv4 subnet while 
enforcing layer two separation.

Some vendors have also implemented IPv6 functionality into this 
scenario. This link has some examples:

Another scenario along the same point-to-point strain is VLAN 
separation, where each customer's traffic gets tagged to a specific VLAN 
(or their DSL/ATM traffic gets converted to a VLAN) and hauled back to a 
router that performs the same type of RBE work on a VLAN interface (one 
VLAN interface per customer on the router).

The advantage is that all traffic gets routed between customers, and no 
two customers see each other's RAs. The downside is that is requires 
manual configuration on the router for each customer.

- Dan

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