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IPv6 prefix size and home routing

Authorized Vendor

Re: IPv6 prefix size and home routing


@hardtarget459 wrote:

I think I'm running into this issue in the Pacific Northwest (which was recently rolled out at the end of September according to comcast6.net).

 

My firewall is set to send a prefix-hint of '/60', so I can assign different IPv6 subnets to my backend networks. If I run a tcpdump capture on my WAN interface on my firewall, I can see two offers coming back:

 

1) Prefix delegation of /60, preference 0

2) Prefix delegation of /64, preference 255

 

This makes my firewall choose the /64 offer, which means I then can't route anything unless I only enable IPv6 on a single interface.  I could split up the /64, but that would be a nightmare to manage on the backend (and would sort of defeat a lot of the usefulness of the protocol).

 

How do I make my connection give me a /60 prefix delegation?


Can you PM me the sniffer trace of this or logs you have..  I would like to see both of the prefixes..

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Network Engineer, IP Engineer, Docsis..; the views expressed on this post are mine and do not necessarily reflect the views of my employer..

Gamer.. Living the dream one catastrophe at a time Smiley Happy ..
Frequent Visitor

Re: IPv6 prefix size and home routing


@ComcastTuska wrote:

Can you PM me the sniffer trace of this or logs you have..  I would like to see both of the prefixes..


Info sent via PM.

New Poster

Re: IPv6 prefix size and home routing

I'd also like to get a /60 prefix.  I've currently got a working IPv6 /64 prefix from Comcast.  I've tried setting my IA_PD to 60 but I don't seem to get any IPs delegated that way.  I'm wondering if prefixes larger than /64 are available in the City of Alexandria, VA area.  I can PM my info if you need it. 

Frequent Visitor

Re: IPv6 prefix size and home routing

i'm wondering when comcast will release the firmware update for the motorola sbg6782 so it will accept ipv6 protocols. as it is now, it won't accept that and i'm stuck at ipv4....

Authorized Vendor

Re: IPv6 prefix size and home routing


@SalemsLotto wrote:

I'd also like to get a /60 prefix.  I've currently got a working IPv6 /64 prefix from Comcast.  I've tried setting my IA_PD to 60 but I don't seem to get any IPs delegated that way.  I'm wondering if prefixes larger than /64 are available in the City of Alexandria, VA area.  I can PM my info if you need it. 


All areas support the /60..

-------------------------------------
Network Engineer, IP Engineer, Docsis..; the views expressed on this post are mine and do not necessarily reflect the views of my employer..

Gamer.. Living the dream one catastrophe at a time Smiley Happy ..
Regular Visitor

Re: IPv6 prefix size and home routing

I've been working around my /64 prefix for some months, and would love to obtain a /60 to subnet on my internal interfaces (linux host).  I've released my /64 several times (checked the packets, and release was acknowledged), and even waited overnight, but even with a fresh lease file I still pickup the same /64 prefix.

 

The RAs I see are for /64 too (unlike others here).  Could my dhcp server still be an old config?

 

Authorized Vendor

Re: IPv6 prefix size and home routing

I can help with this..  Keep your IA_PD hit to a /60, PM me your CM-MAC, Prefix, and DUID.  I will have your /64 removed, then you can do a release renew for a /60..

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Network Engineer, IP Engineer, Docsis..; the views expressed on this post are mine and do not necessarily reflect the views of my employer..

Gamer.. Living the dream one catastrophe at a time Smiley Happy ..
Contributor

Re: IPv6 prefix size and home routing

I've noticed what seems to be a routing issue on Comcast's network. Can some of you other folks with IPv6 connections take a look at my post here http://forums.comcast.com/t5/Home-Networking-Router-WiFi/IPv6-Routing-Issue/m-p/2038619 and see if the problem is reproducible?

Frequent Visitor

Re: IPv6 prefix size and home routing

I'm still running in to the same issue I was having in message #48.  My machine is sending out the prefix hint for a /60, but I'm getting a /64 and /60 back, with the /60 being preference 255.  Because of this, my firewall ignores the /64 since it asked for the /60.

Contributor

Re: IPv6 prefix size and home routing

Without thinking too hard about it I think that's the way it's supposed to work. The /64 should go on your WAN interface and then the /60 gets used internally. Remember you're not doing NAT now so each interface needs to be on a different network and then the router will actually route between the networks. The /60 network is for your use inside your router so you still need another address on your WAN interface thus the /64. If your router is setup correctly it should handle this automatically.

Frequent Visitor

Re: IPv6 prefix size and home routing


@BFranske wrote:

Without thinking too hard about it I think that's the way it's supposed to work. The /64 should go on your WAN interface and then the /60 gets used internally. Remember you're not doing NAT now so each interface needs to be on a different network and then the router will actually route between the networks. The /60 network is for your use inside your router so you still need another address on your WAN interface thus the /64. If your router is setup correctly it should handle this automatically.


Yes, but I'm not getting any IPv6 addresses assigned to any interfaces (WAN or internal), which is what I had seen previously.  It could be something on the firewall too, I can check with them in the interim.

Expert

Re: IPv6 prefix size and home routing


@BFranske wrote:

Without thinking too hard about it I think that's the way it's supposed to work. The /64 should go on your WAN interface and then the /60 gets used internally. Remember you're not doing NAT now so each interface needs to be on a different network and then the router will actually route between the networks. The /60 network is for your use inside your router so you still need another address on your WAN interface thus the /64. If your router is setup correctly it should handle this automatically.


FWIW the WAN interface get's a /128.



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Contributor

Re: IPv6 prefix size and home routing

Yes, of course you're correct. This is what happens when I post before thinking it thorugh. The fe80 is a /64 but the routable address is a /128.

Authorized Vendor

Re: IPv6 prefix size and home routing


@hardtarget459 wrote:

I'm still running in to the same issue I was having in message #48.  My machine is sending out the prefix hint for a /60, but I'm getting a /64 and /60 back, with the /60 being preference 255.  Because of this, my firewall ignores the /64 since it asked for the /60.


PM me your CM-MAC and your Prefix you have assigned right now, I will work to have your current PD disabled.  When you do a renew you will get the /60.. 

-------------------------------------
Network Engineer, IP Engineer, Docsis..; the views expressed on this post are mine and do not necessarily reflect the views of my employer..

Gamer.. Living the dream one catastrophe at a time Smiley Happy ..
Authorized Vendor

Re: IPv6 prefix size and home routing


@BFranske wrote:

Yes, of course you're correct. This is what happens when I post before thinking it thorugh. The fe80 is a /64 but the routable address is a /128.


I think you got what was going on here right?  If not I can explain..

-------------------------------------
Network Engineer, IP Engineer, Docsis..; the views expressed on this post are mine and do not necessarily reflect the views of my employer..

Gamer.. Living the dream one catastrophe at a time Smiley Happy ..
Frequent Visitor

Re: IPv6 prefix size and home routing


@hardtarget459 wrote:

I'm still running in to the same issue I was having in message #48.  My machine is sending out the prefix hint for a /60, but I'm getting a /64 and /60 back, with the /60 being preference 255.  Because of this, my firewall ignores the /64 since it asked for the /60.


I think my issue is fixed.  I seem to be getting a /60 delegated to me, and all my machines are getting IPv6 assignments on each of my interfaces.  Thanks!

Frequent Visitor

Re: IPv6 prefix size and home routing

Removed comment--I confused myself.  It's working fine, as far as I can tell.

New Poster

Re: IPv6 prefix size and home routing

I'm also getting a /64 when I request a /60. I did a packet dump of the request, and I see my box releasing my /64, then requesting a /60. Comcast's server (fe80::201:5cff:fe66:3246) responds with the same /64.

 

I'm happy to PM packet captures, configuration information, or identifying info (MAC, DUID, etc etc).

Regular Visitor

Re: IPv6 prefix size and home routing

Lachesis, I found when I was setting up my system that after I had initially gotten the /64, I had to release and shut down my IPv6 for about 30-60 minutes before the server would accept the hint and give me the /60.

New Poster

Re: IPv6 prefix size and home routing

Zelouki,

 

That worked, thanks! Smiley Happy

 

 

For anyone else reading along, I'm using openwrt, so I just did:

 

ifdown wlan6

 

(wait 1 hour)

 

ifup wlan6

 

Now I have a /60 prefix.

Frequent Visitor

Re: IPv6 prefix size and home routing

I recently got a new cable modem from Comcast, and my IPv6 /60 delegation went away.  Is there something I need to do to get it back (other than rebooting my CM and firewall)?  I did a trace, and I can see a bunch of DHCPv6 solicits with a /60 prefix delegation hint, but no responses back offering the /60 prefix (the only router advertisements are for /64, which won't work).