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graysonf
Premium,MVM
join:1999-07-16
Fort Lauderdale, FL
kudos:2
reply to NetFixer

Re: [IPv6] Comcast IPv6 Address Assignment/Delegation

Any suggestion for values to try on a router that supports multiple LAN interfaces?

IPv6 Prefix Delegation:

Site-Level Aggregator ID: ?
ISP Prefix Length: /?


NetFixer
Bah Humbug
Premium
join:2004-06-24
The Boro
Reviews:
·Cingular Wireless
·Comcast Business..
·Vonage
said by graysonf:

Any suggestion for values to try on a router that supports multiple LAN interfaces?

IPv6 Prefix Delegation:

Site-Level Aggregator ID: ?
ISP Prefix Length: /?

Sorry, but the only router I have that supported getting a /60 (for a while) was my D-Link DIR655, and I don't have access to the low level configuration in that router (my only choice in its html menu is to either enable/disable DHCP-PD).




When I was getting a /60 from Comcast the config above was also being used, and a secondary router behind the DIR655 was able to get its own /64 IPv6 subnet. I have no idea why I no longer get a /60 from Comcast.

The screen shot below shows what I would get from Comcast when the /60 was working:




The DIR655 would get an IPv6 Network assignment of 2601:5:c80:90::/60, and its LAN would get the IPv6 assignment 2601:5:c80:91::/64. Unfortunately I did not get a screen capture of the secondary router's assignment, but as I recall it was 2601:5:c80:92::/64.

Now that I only get a /64 assignment, I get the same 2601:5:c80:90::/64 for both the Network and LAN.




My secondary (guest network) router is now connected directly (well, actually through a switch), to the modem and it still gets its own /64 assignment (it's just not a subnet of the DIR655's former /60 network).

One interesting thing is that just before I stopped getting the /60 assignment, Comcast changed the Network PD IP address from 2601:5:c80:90::/60 to 2601:5:c80:b0::/60. The next change was to eliminate the /60 assignment (but I went back to the 2601:5:c80:90: subnet again).




I guess that the point of this TLDR reply is to point out that Comcast's IPv6 implementation for dynamic IP address customers is still in flux (and may possibly stay that way), so even if you get something to work today, don't count on it to be working the same way tomorrow. If/when Comcast finally gets IPv6 for static IP business class customers working, I may go back to paying for static IP addresses again.
--
A well-regulated militia, being necessary to the security of a free State, the right of the people to keep and bear arms shall not be infringed.

When governments fear people, there is liberty. When the people fear the government, there is tyranny.


mackey
Premium
join:2007-08-20
kudos:13
reply to graysonf
said by graysonf:

Site-Level Aggregator ID: ?

Whatever you want, but when added to the prefix length the number of bits in it must be less than or equal to 64. I.e. if your prefix length is /64 then this must be 0. If your prefix length is /60 then it must be between 0 and 15 inclusive (0-15 = a 4-bit number. 4 + 60 = 64). This number is added to your prefix to get the subnet for that interface.

said by graysonf:

ISP Prefix Length: /?

The size of the prefix you're requesting from the ISP. Eventually Comcast will support /60-/64 inclusive, but for now only /64 works reliably.

/M