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NetFixer
Snarl For The Camera Please
Premium
join:2004-06-24
The Boro
Reviews:
·Cingular Wireless
·Comcast Business..
·Vonage
reply to newview

Re: [IPv6] IPv6 not implemented in my area yet?

said by newview:

SUCCESS!

Purchased a new Motorola SB6121 today ...

Are you actually getting a native IPv6 connection, or are you using a 6to4 tunnel? Since you have totally redacted the IPv6 IP address, there is no way to know. I am in an area that does not yet support native IPv6, nor does my SMCD3G-CCR support IPv6, but I can post a Comcast IPv6 test page that looks just like yours.




Shown below is that same page without the redacting that shows that I am using a 6to4 tunnel instead of native IPv6 (the "2002:" prefix is the clue).



--
History does not long entrust the care of freedom to the weak or the timid.
-- Dwight D. Eisenhower


newview
Ex .. Ex .. Exactly
Premium
join:2001-10-01
Parsonsburg, MD
kudos:1
Reviews:
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1 edit

Click for full size
I must be getting a native IPv6 connection because I have no clue how to even use or setup a 6to4 tunnel ... I've never even tried.

I sent a PM to NetDog See Profile some days ago asking if IPv6 had been implemented in my area yet and he replied ...
quote:
The CMTS your on supports IPv6 and I can see leases going out to other customers on the DHCP server.


NetFixer
Snarl For The Camera Please
Premium
join:2004-06-24
The Boro
Reviews:
·Cingular Wireless
·Comcast Business..
·Vonage

1 edit

Good to hear that you have a fully functional dual stack native IPv4/IPv6 connection (I wish I could say the same thing here).

Your router could have been automatically setting up a 6to4 tunnel if IPv6 support was enabled, but native IPv6 was not available. The primary reason for my previous post was just to make sure that you had what you thought you had.

it is also good for other users of the SB5100 to know that it is actually blocking Comcast's DHCPv6 instead of acting as a simple bridge (time to replace that modem if you want to get native IPv6 connectivity).
--
History does not long entrust the care of freedom to the weak or the timid.
-- Dwight D. Eisenhower



rchandra
Stargate Universe fan
Premium
join:2000-11-09
14225-2105
reply to koitsu

Sorry, I beg to differ with you.

It's not a "fact" that IPv6 support isn't necessary in a cable modem in order for it to bridge IPv6 frames to the radio. In the other direction, that's debatable. They're not simple bridges, they're firewalled bridges. There's no guarantee that if you put IPv6 frames on the Ethernet port that they'll be forwarded to the radio. D3 makes it clear that in order to be D3 compliant, if the operator has thus configured the modem to use IPv6, it must then forward/bridge IPv6 frames. In other words, it must be capable to be D3 compliant, but the operator might not utilize that capability. Yes, D2 modems can do so also, but only if their firmware deals with the IPv6 extensions to D2; it wasn't part of the original D2 spec to do that, and for most of them, it means a firmware upgrade. For example, I have little doubt that if the firmware were updated on my SB5100, it'd probably work just fine with native IPv6. The only way it wouldn't is if there was something built into the Ethernet hardware to reject the IPv6 frame type. If you've found other examples of D2 modems which have IPv6 capabilities, bully for you, but it's definitely not a given that D2 modems will do (native) IPv6.

You don't believe me on that one, think of the implications of me answering DHCP DISCOVERs with OFFERs. No, they're not simple radio to Ethernet and Ethernet to radio bridges. They don't understand much more than that of layer 3, but to be CableLabs certified, what's allowed to be bridged onto the radio is pretty much very tightly controlled. Before CL clamped down on this, people used to give themselves a speed boost by making up their own config files and having the customer side of the modem provide a TFTP server which would then load that doctored config file into the modem.

Also, it's not a "fact" that the operator side of the modem does not use DHCP. That's a fundamental part of initialization. It doesn't receive a customer address, no. However, it must receive some address (among other parameters) to TFTP its configuration.

You said it yourself. Go research at CableLabs. I did when I was looking for IPv6 connectivity last year. It's by no means easy reading, but it's very explicit about what's not allowed to be passed to the CMTS side, and how the modem iniitializes.
--
English is a difficult enough language to interpret correctly when its rules are followed, let alone when a writer chooses not to follow those rules.

Jeopardy! replies and randomcaps REALLY suck!



owlyn
Premium,MVM
join:2004-06-05
Newtown, PA

rchandra,

I suspect somewhere in there is a reason why we can't get to 192.168.100.1 on D2 modems when they have IPV6 on the DOCSIS side. Sounds like an additional firmware update is needed? Or am I on the wrong track?



rchandra
Stargate Universe fan
Premium
join:2000-11-09
14225-2105

You'd have to talk to the manufacturer of your cable modem as to why their firmware behaves like that. The most common reason I could not access my cable modem's status page (it's a Moto SB6120) was that it had no idea how to reply. I had forgotten to set up NAT to the cable modem from my LAN addresses (192.168.1.0/24)...ergo, 192.168.100.1/?? had no idea to what MAC address to reply.

The most certain way I know to access that page is to connect directly to the modem (no router for example), assign the attached interface an address of 192.168.100.2/24 (do NOT use 192.168.100.1 (obviously), do NOT rely on DHCP), and give it a go. If you "know what you are doing," it's possible not to have to rejigger your network connections, and set up your router and LAN so that either they're on the same addresses (192.168.100.0/24 for example) or NAT works. The way I did it is with a post-binding script for dhclient which does ip addr add 192.168.100.21/24 dev $dhcpinterface and iptables --table nat --append POSTROUTING --src 192.168.1.0/24 --jump SNAT --to 192.168.100.21.
--
English is a difficult enough language to interpret correctly when its rules are followed, let alone when a writer chooses not to follow those rules.

Jeopardy! replies and randomcaps REALLY suck!



owlyn
Premium,MVM
join:2004-06-05
Newtown, PA
Reviews:
·Comcast

rchandra,

You are just a bit over my head on this one. I don't know what the /24 means after the IP address. In any event, it worked fine with my router till a few weeks ago (when Comcast did "something" IPV6-related, and I am not the only one reporting it. Comcast is aware of the problem, and apparently understands what is happening, but needs Arris to fix it.



rchandra
Stargate Universe fan
Premium
join:2000-11-09
14225-2105

1 edit

Expressing addresses in that notation is called "classless inter-domain routing", or "CIDR" notation. Instead of having to write out all 4 numbers of the netmask in dotted decimal notation, one writes a "/" and the number of contiguous one bits from the left. So for example, 172.20.190.8/16 is 172.20.190.8 netmask 255.255.0.0. The network part would be 172.20.0.0 and the host part 0.0.190.8. As you can see, it is a crapload easier to write one number rather than four plus three dots.

so...192.168.100.21/24 would be network 192.168.100.0, and the last octet would be the host number.

As for "attached interface" I meant where you have attached your modem to your computer. Every OS is going to call it something different. Mine would be "eth1", some "eri0", some "Local Connection", and so on. By "assigning," I mean not running a DHCP client, the opposite of "Obtain IP address automatically."

The commands I wrote are specific to Linux; if "/24" was not understood, it's less than likely I could concisely explain what those do.

I hope that clarifies most of that though.

--
English is a difficult enough language to interpret correctly when its rules are followed, let alone when a writer chooses not to follow those rules.

Jeopardy! replies and randomcaps REALLY suck!



owlyn
Premium,MVM
join:2004-06-05
Newtown, PA
Reviews:
·Comcast

said by rchandra:

Expressing addresses in that notation is called "classless inter-domain routing", or "CIDR" notation. Instead of having to write out all 4 numbers of the netmask in dotted decimal notation, one writes a "/" and the number of contiguous one bits from the left. So for example, 172.20.190.8/16 is 172.20.190.8 netmask 255.255.0.0. The network part would be 172.20.0.0 and the host part 0.0.190.8. As you can see, it is a crapload easier to write one number rather than four plus three dots.

so...192.168.100.21/24 would be network 192.168.100.0, and the last octet would be the host number.

As for "attached interface" I meant where you have attached your modem to your computer. Every OS is going to call it something different. Mine would be "eth1", some "eri0", some "Local Connection", and so on. By "assigning," I mean not running a DHCP client, the opposite of "Obtain IP address automatically."

The commands I wrote are specific to Linux; if "/24" was not understood, it's less than likely I could concisely explain what those do.

I hope that clarifies most of that though.

Yes, thanks. Still, the problem is in the modem, and according to Comcast, on the DOCSIS side, not the client side. Allegedly, nothing we can do, it seems. I just find that hard to believe.