Re: [v6ops] MAC table shortage in IPv6 networks caused by multiple IPv6 prefixes/addresses//FW: New Version Notification for draft-liu-v6ops-running-multiple-prefixes-01.txt

["Liubing (Leo)" <[e-mail]>]

Hi Andrew,

> > Now there are some enterprise/campus networks under real use or
> >considering using L2 networks. Some are aiming at better user isolation
> >through VLANs (some even consider QinQ mechanism); while some are
> >aiming less configuration/management than the traditional L3 networks.
> >So there would be thousands of hosts aggregated to the core switch
> >(normally there are two core switches stacked together, but only share one
> cache space).
> >As IPv6 is beginning real use, for example, some of the campus networks
> >are already dual-stack, and the majority of the hosts are Win 7, we
> >once observed in one campus that DHCPv6/SLAAC are both enabled, each
> >Win 7 host had 4 IPv6 addr (SLAAC+DHCPv6+Privacy+link-local)+1 IPv4 addr.
> 
> If the majority of the hosts are Win 7, and are under the control of the
> administrator, this looks more like a misconfiguration rather than anything
> else: clear the "A" bit on the prefix, and they'll half the address usage - down
> to just link-local and DHCPv6-based.

[Bing] I can hardly say SLAAC and DHCPv6 co-existing is a misconfiguration, but I agree DHCPv6-only deployment can partly relieve the problem.
However, even DHCPv6-only would have 2 IPv6 addr+1 IPv4 addr, which would cause approximately 5~8 times cache space than IPv4-only.

Best regards,
Bing