Participant

Some General Questions re. TWC's IPv6

I  just bought an Arris SB6190, reportedly IPv6 capable, and wasn't getting an IPv6 address assigned to any of our Linux computers, although a call to TW tech support did turn up two pieces of information, which I'd like to have verified by someone from TWC who knows about their IPv6 deployment:

 

I get EITHER a v4 OR a v6 address assigned to my WAN IF, but not both. I was using a DHCP (v4) client so my aquisition of a v4 address precluded assignment of a v6 address. Use of an IPv6 DHCP client would probably result in assignement of a v6 address. Is this correct ???

 

IPv6 addresses are dynamically assigned by TWC. Yes ???

 

A couple of questions ......

 

If v6 addresses are dynamically assigned, am I assigned only a single address, or a /64 prefix as is commonly done by ISPs? A dynamicly assigned prefix is somewhat less that fully useful, except insofar as it can be used to configure LAN hosts using stateless autoconfiguration.

 

If the above is true, what would it take to get a static /64 prefix from TWC?

 

9 REPLIES 9
Seasoned Contributor

Re: Some General Questions re. TWC's IPv6


@fmouse wrote:

I get EITHER a v4 OR a v6 address assigned to my WAN IF, but not both. I was using a DHCP (v4) client so my aquisition of a v4 address precluded assignment of a v6 address. Use of an IPv6 DHCP client would probably result in assignement of a v6 address. Is this correct ???

 

...

 

If v6 addresses are dynamically assigned, am I assigned only a single address, or a /64 prefix as is commonly done by ISPs? ...

If the above is true, what would it take to get a static /64 prefix from TWC?

 


No, IPv6 and IPv4 aren't mutally exlusive.  If you can get both but not at the same time it's probably your client/gateway behavior but there have been a couple of subtle problems.

 

You get a /56 but you might have to hint to get one otherwise a /64.

 

If you have to ask about a static you can't afford it.  However my prefix, like my IPv4 address rarely changes.  I've had the same one as long as I've kept the request ID consistent.  Of course I use HE for fixed addresses.  This does require policy based routing.

Participant

Re: Some General Questions re. TWC's IPv6

The reason I asked was becuase I read on the TWC website that static v6 addressing wasn't available in many service areas. Whether or not I can afford it, or whether or not it's a good value is another matter altogether. I run my online business on a Linode VM and have, in addition to an IPv4 address and a single SLAAC unicast v6 address, I have a routable /56 and a /64 which were free for the asking from Linode - all for less than the cost of our TWC residential connection. If TWC wants to charge monopoly prices for a static v6 address group then they can (edited)  themselves. I can subnet my Linode /56 through a 6to4 tunnel to our LAN and get what I need that way.  My wife and I run much of our businesses over the Internet and have so far gotten by on residential service, but this year the service has been rather less than stellar, what with packet loss problems during peak times of day and clueless tech support. I really don't mind a tech support person telling me that they don't know something, but I really object to people who try to (edited) me into thinking they do, and give me mis-information, or just hang up if they don't understand my questions - which has happend with TWC on several occasions.

 

It looks as if I have several TWC-owned /64 prefixes in the routing table on my gateway box, so it seems that my Linux gateway is probably sending out a router solicitation at boot time and getting a reply, even though I'm not seeing any periodic router advertisements from the TWC side on the box. I'm also getting a couple of TWC-owned v6 addresses in my DNS resolver list, which don't work (and are unreachable) if I don't have a v6 connection through TWC, and I'd like to find a way to turn these off until I get other issues solved, such as our excessive packet loss during peak times of day. As it is, I have to manually delete these addresses after every boot to get DNS resolution to work.

 

Right now, I'm using a /64 address assignment  from SixXS on our LAN,  which works fine, but I've been advised that SixXS may be discontinuing their services.

 

Seasoned Contributor

Re: Some General Questions re. TWC's IPv6


@fmouse wrote:

It looks as if I have several TWC-owned /64 prefixes in the routing table on my gateway box, so it seems that my Linux gateway is probably sending out a router solicitation at boot time and getting a reply, even though I'm not seeing any periodic router advertisements from the TWC side on the box. I'm also getting a couple of TWC-owned v6 addresses in my DNS resolver list, which don't work (and are unreachable) if I don't have a v6 connection through TWC

 I'm not sure your experience is typical.  As far as I know if you don't see router advertisements from a head-end link-local address you don't have IPv6.  I'm not aware of any TWC resolvers that are dual-stack.  What IPv6 addresses do you have that you think are resolvers?  Perhaps it's a service area difference but I've not seen it come up on DSLreports.

Participant

Re: Some General Questions re. TWC's IPv6

Router advertisements can be broadcast peridocally, or only in response to a router solicitation.

 

I didn't keep track of the DNS resolver v6 IPs, but I did verify that they belonged to TWC.  I configured my dhclient to not request them. I'm having enough trouble with TWC's DNS and their "Search Guide" alternative to sending a proper NXDOMAIN response to a non-resolving DN resolution request. This majorly interfered with DHCP on my router and broke connectivity altogether a couple of days ago.  I'm posting that saga separately. I'll post a link to it here if you wish.

Seasoned Contributor

Re: Some General Questions re. TWC's IPv6


@fmouse wrote:

Router advertisements can be broadcast peridocally, or only in response to a router solicitation.


Of course but while I'm not sure must is applied to RA it's essentially a fatal error to not send them at a regular interval to propagate default router information.  In my service area it's sent every three seconds.  It's how you can tell your 6183 is blocking transiting IPv6 traffic.

 


@fmouse wrote:

I didn't keep track of the DNS resolver v6 IPs, but I did verify that they belonged to TWC

 The point being I'm not sure those addresses are resolvers but if they are and are only reachable from TWC IPv6 space then I can reach them.  I've not seen any mention of them and, in fact, TWC fails the IPv6 only DNS test because the advertised resolvers only have IPv4 connectivity.  There's a thread here about it.

Participant

Re: Some General Questions re. TWC's IPv6

Thanks, bodosom. Good information Smiley Happy

Participant

Re: Some General Questions re. TWC's IPv6

While I'm not seeing IPv6 RAs from TWC on my router, apparently (I can listen for them with radvdump) I know that our SB6190 is passing IPv6 traffic. We had a problem yesterday and today, now resolved, with the router and my wife connected directly to the SB6190 with her Windows 8.1 system. I checked my website (http://www.fmp.com) which identifies the browser's connecting address and it shows a TWC IPv6-assigned unicast address.

 

At this point I don't care about IPv6 on the router since I have a SixXS tunnel and will hopefully also have one from my server, which as a /56 subnet from Linode on which I'll be setting up a tunnel to replace the SixXS tunnel.

Newcomer

Re: Some General Questions re. TWC's IPv6

I have IPv6 working for my home network, but I don't see router advertisements on my router's WAN link.  The way it seems to work for me is that when my router starts up, it sends a DHCPv6 request on the WAN in order to get an IPv6 prefix from Time Warner.  I've been able to successfully request either a /64 prefix or a /56 prefix, though I wasn't able to get anything in between.  Once the router has the prefix, it starts sending out router advertisements to the internal network, and all my devices pick up an address via SLAAC.  I suspect that your windows computer plugged directly into the modem worked with IPv6 because Windows will try both SLAAC and DHCPv6 to get an address.  Time Warner will happily assign your computer a /128 IPv6 address with DHCPv6.

Participant

Re: Some General Questions re. TWC's IPv6

My Ubuntu Linux laptop also gets a v6 address from TWC. The configuration, from a system point of view, is a bit hard to untangle since it's done through a GUI.