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koitsu
Premium,MVM
join:2002-07-16
Mountain View, CA
kudos:23

4 edits

2 recommendations

reply to newview

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

Let me put an end to the nonsense said above:

1. You do not need a an "IPv6-ready" cable modem, for your router or your systems on your LAN to make use of IPv6.

2. DOCSIS 3.0 does not have anything to do with IPv6 capability. You can talk to the Internet using IPv6 with a DOCSIS 2.0 cable modem.

3. An "IPv6-ready" cable modem means that the cable modem's administrative page/management interface supports IPv6. It does not stop Comcast from delegating you an IPv6 prefix (/64) or handing out an individual IPv6 address (/128) to your router. In English: it means that you can access your cable modem via, say, URL »[fe80::230:48ff:fed2:1234]/ rather than »192.168.100.1/.

All of this was debunked in this thread. See posts from ctgreybeard See Profile and netcool See Profile:

»[IPv6] Why does my modem not indicate IPv6?

Anyway, from what I can tell from the OP's screenshot, IPv6 is working fine for him (2nd line; it means Comcast has delegated him an IPv6 prefix (/64) and/or an individual IPv6 address (/128)). I can't tell which because he chose to black out the necessary information.

The 4th line (message about "only being able to reach IPv4 sites") means that the machine he was viewing the Comcast IPv6 readiness page from a machine which has no global (not link-local!) IPv6 address.

So in summary, to me, it looks like the "problem" is with his router firmware. Comcast should be giving you a /64 prefix (in English: a public Internet netblock which you can use on your LAN, as well as your router). My guess is that the router is getting that /64 prefix, but has a bug/issue where IPv6 RAs are not being sent out to the machines on the LAN, thus his Windows 7 machine can't speak IPv6 to the Internet.

If Comcast has confirmed that IPv6 has been rolled out to your area successfully, then its almost certainly a router ordeal (it would help if you could provide some details the router shows, and stop hiding the information with black boxes :P). Otherwise, your area may be an area where Comcast is in the progress of rolling out IPv6 but it might not be fully working/completed yet or maybe it's broken. Comcast can tell you for sure.

I just got done getting familiar with all of this earlier this week, but for the TomatoUSB firmware (which also works on the Linksys E4200, but not sure about the E4200v2 -- the hardware versions often matter greatly, sometimes changing entire CPUs!):

»[IPv6] TomatoUSB and Comcast IPv6 -- bugs found

So don't even for a minute think that consumer router firmwares aren't buggy (even the open-source ones are!). So I would check to see if there's an E4200v2 firmware update and start with that.

Finally, about the 6to4 stuff: I agree with NathanO See Profile -- avoid use of 6to4 if native IPv6 is available. 6to4 absolutely is slow (and that's even shown here -- note the 2.4 second (not millisecond!) response time on one of the tests) because of how it works. It will not get the same response times nor have the same reliability as native IPv6, plus it relies on Comcast's 6to4 anycast relays which could go down. I've used Comcast's 6to4 anycast relays myself and I do see intermittent packet loss + high latency which do not happen with native IPv6. This is understandable; you need to read about how 6to4 anycast works to fully understand why it's slow.
--
Making life hard for others since 1977.
I speak for myself and not my employer/affiliates of my employer.



PGHammer

join:2003-06-09
Accokeek, MD

1 recommendation

Let's tackle your points (and in order).

1. You need both an IPv6-ready cable modem and an IPv6-ready router to give all IPv6-ready hardware on your LAN those benefits without using a IPv6 tunnel service -free OR fee. Tunnel services (both free and fee) can operate without either being true because of how tunneling/encapsulation works. IPv6 tunnels can operate as individual-device clients or at the LAN entry point (usually the router) - most third-party firmware (and some factory firmware) supports tunnel-endpointing - which can extend the IPv6 bennies LAN-wide to all IPv6-ready hardware on the LAN.

2. DOCSIS 3.0 has a great deal to do with IPv6 readiness on the *modem* end if you don't want the additional complexity of using a tunnel service. (Comcast pushed for - and got - IPv6 written into the requirement for DOCSIS 3.0 because their MAN uses NAT - and was getting squeezed in terms of available IPs - and this was before XFINITY and that wave of acquisitions.)

3. IPv6-ready routers - and IPv6-ready cable modems, for that matter - need not show the IPv6 side of their administrative (business/technical) side to the end-user. (The ARRIS crop of IPv6-ready cable modems and EMTAs does not, for example.) Helpful - yes. Required - no.

4. IPv6-ready modem and IPv6-hostile router - this is, in fact, a major obstacle to IPv6 deployment in residential LANs. (It can even be argued that router hostility is the second-biggest such obstacle.) Older routers that lack IPv6 firmware options (whether factory or third-party) are the one consumer-end fix that should be done - and now. (This is something I pointed out - and to - in a different thread; specifically in reference to the various IPv6-hostile older NETGEAR routers that Comcast supplied to customers via various promotions.) The biggest issue there is, despite Comcast not charging even a lease fee for these routers generally, they are still considered the property of Comcast; thus, while this is *technically* a Comcast problem, unless a serious stink gets raised, Comcast won't exactly be in any hurry to replace these routers with IPv6-friendly models. (Comcast has not one, but two reseller/remarketer deals that include IPv6-friendly routers - LinksysByCisco and NETGEAR. The routers that Comcast could remarket already have SKUs assigned by the respective OEMs - EA3500-1VCNAS (Linksys/Cisco) and WNR3500L-1VCNAS (NETGEAR). These are, in fact, direct replacements for the routers that Comcast provided under the *free wireless router* promotions, and support IPv6 via not just third-party firmware, but support it in *factory* firmware.)

5. IPv6 readiness on the LAN itself - If you're worried about IPv6 readiness on the rest of your hardware, that is going to be an issue with non-computer devices used to access the Internet (gaming consoles, Internet-enabled TVs, etc.) as opposed to desktops/notebooks/tablets/smartphones (iOS may be an exception). Windows has been dual-stack as it shipped since XP Service Pack 1, and can be patched to support dual-stack since Windows 2000's Service Pack 4. All Linux distributions since the 2.4.5 series of kernels are also dual-stack by default (as is OS X back to Tiger) - therefore, so much for PCs and Macs. Android (which is basically a Linux fork) is also dual-stack by default. That leaves game consoles and other non-computing devices as the final non-IPv6-ready frontier.



plencnerb
Premium
join:2000-09-25
Carpentersville, IL
kudos:3

said by PGHammer:

1. You need both an IPv6-ready cable modem and an IPv6-ready router to give all IPv6-ready hardware on your LAN those benefits without using a IPv6 tunnel service -free OR fee.

So, if I understand you correctly, Comcast has a list of all the modems that they currently support on their network. This URL has been posted many times in these forums, but to make sure we are both on the same page, I'm posting it again.

»mydeviceinfo.comcast.net/?s=v&so···1&sc=284

Now, if you look at that list, there is a column for "IPv6".

Does that mean that the modem out of the box supports IPv6, or does that mean that Comcast has tested that modem for IPv6 on its network, and had no issues? The reason I ask that, is the list I see shows 76 modems, however only 17 have a check mark in the IPv6 column. If those 17 are the ONLY ones that support IPv6 (and not the only ones so far tested by Comcast to support IPv6 on its network), then I think Comcast has quite a task ahead of them to switch out the other 59 brands of modems that their customers may have so that everyone can be "ready" for IPv6 in that regard.

If however, the ones that do not have a check mark next to them, do we know if Comcast has plans to test these, or apply some kind of firmware update to them so they can support IPv6, and if so, what is that timeframe?

I ask this as I am now on my 3rd modem since May. And, each time I switch it out, I do NOT get a D3 modem, or one that (according to the list) has a check mark in the IPv6 column. I can see why Comcast does not give me a D3 modem, as my package does not require it directly (I'm on the performance tier).

My current modem is "Arris Touchstone Telephony Modem TM402P". By the way, what is the difference between

Arris Touchstone Telephony Modem TM402P (IMS)
and
Arris Touchstone Telephony Modem TM402P (NCS)

I looked all over my modem, and I don't see the (IMS) or (NCS) wording on it, so just wondering why Comcast lists it that way.

Really, I'm just trying to make sure that the modem I have now will be able to pull a IPv6 IP from Comcast, when the time comes. If I do have to go back to the local office and get a 4th modem, I will. However, I really am getting a bit tired of going back and forth switching out modems, only to find the one they give me does not have a green check in the IPv6 column.

Sorry for the long post, but I just want to make sure that I understand that list, in reference to what you said about the modem and it supporting IPv6.

--Brian
--
============================
--Brian Plencner

E-Mail: CoasterBrian72Cancer@gmail.com
Note: Kill Cancer to Reply via e-mail


koitsu
Premium,MVM
join:2002-07-16
Mountain View, CA
kudos:23

2 recommendations

reply to PGHammer

@ PGHammer See Profile --

Sorry, but this is the reality of the situation with IPv6:

Fact: you do not need an "IPv6-ready" cable modem for a router to issue DHCPv6 requests (to get both a /64 prefix and/or a /128 IPv6 address from Comcast) to Comcast. The modem is a bridge, thus it shoves IPv4 and IPv6 packets out the coax interface (technically a lot more happens than just that, but I'm trying to keep it simple).

Fact: you do not need an "IPv6-ready" cable modem for a router to see the IPv6 RAs being announced across the wire by Comcast at all times. The router is what cares about these, not the modem.

Fact: DHCPv6 requests are initiated from the device attached to the RJ45/Ethernet jack on the cable modem -- e.g. a router. The cable modem itself does not do any kind of DHCP for the Internet-facing portion or have anything to do with it.

Remember: a cable modem (like the SB51xx and SB612x) is a bridge, not a router. There are devices on the market (possibly those Arris units?) which are both -- that is to say, they have a cable modem bridge in them as well as IPv4/IPv6 routing capabilities. It's important to understand the difference between a bridge and a router.

As for the DOCSIS 3.0 and IPv6 -- sigh, this gets into a semantics argument. Again: a cable modem is a bridge, not a router. However, even bridges need IP addresses so that they can be managed. As you know Comcast needs a way to do things like firmware updates, reboot the modem, pull stats, etc. -- all of these are done via SNMP. A cable modem "being IPv6-ready" means its administrative interface on the carrier side (as you said, not necessarily the customer side) supports IPv6. This has absolutely zero bearing on what I said in preceding paragraphs prefixed with "Fact:". You can verify this on Wikipedia or cablelabs.com if you want. There are also DOCSIS 2.0 cable modems which support IPv6 too (imagine that), such as the DPC2100R2.

So again: if a customer wants an IPv6 address on his home computer, or for his LAN to have native IPv6 addresses (read: not using a tunnel), he does not need an "IPv6-ready" cable modem. He simply needs to make sure his ISP has IPv6 deployed in his area, and that his router correctly supports IPv6. That's it.

@ plencnerb See Profile --

It's a tricky question that's hard to answer, because some devices act as a router as well as a cable modem. A simple "IPv6 yes/no" checkbox does not provide the granularity needed; it could mean "we (Comcast) can talk to the cable modem piece with IPv6", but it could also mean "the router piece was able to speak IPv6". A binary checkbox, again, does not answer that question, so that's a bad decision on Comcast's part.

I'm inclined to think it means the former, and here's why: there is a completely separate page for routers. So, devices which are both a cable modem and router should really be listed on both pages (the former to indicate it supports an administrative IPv6 interface, and the latter to indicate it supports getting an IPv6 prefix and/or address from Comcast for Internet connectivity).
--
Making life hard for others since 1977.
I speak for myself and not my employer/affiliates of my employer.



plencnerb
Premium
join:2000-09-25
Carpentersville, IL
kudos:3

Ok, I'm a bit confused on what you said. It might just be terminology and wording, but hear me out.

First, we have this statement

said by koitsu:

There are also DOCSIS 2.0 cable modems which support IPv6 too (imagine that), such as the DPC2100R2.

So, we have Docsis 2.0 (or D2) cable modems that supports IPv6.

My question then is with the next statement

said by koitsu:

So again: if a customer wants an IPv6 address on his home computer, or for his LAN to have native IPv6 addresses (read: not using a tunnel), he does not need an "IPv6-ready" cable modem. He simply needs to make sure his ISP has IPv6 deployed in his area, and that his router correctly supports IPv6.

So, if I have a D2 cable modem that does not support IPv6, but my router does, then it will pull an IPv6 IP from Comcast. Would it not be better to get a cable modem that supports it?

Example: Say I had a D1 (Docsis 1.0) modem from say 1998. It has no idea what IPv6 is. However, if I read what you said, it won't matter, as my router (brand new in 2012) will be able to get an IPv6 IP from Comcast, as that is what actually gets the IP from Comcast, as the modem acts as a bridge. See all along, I thought the Cable Modem is what got the IP from Comcast, not the router.

I'm just a bit confused...first you say there are cable modems that support IPv6, then you say that we don't need an "IPv6-ready" cable modem.

Isn't "support" and "IPv6-ready" the same thing? Again, just trying to follow what you are saying here.

--Brian
--
============================
--Brian Plencner

E-Mail: CoasterBrian72Cancer@gmail.com
Note: Kill Cancer to Reply via e-mail


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

3 edits

1 recommendation

said by plencnerb:

However, if I read what you said, it won't matter, as my router (brand new in 2012) will be able to get an IPv6 IP from Comcast, as that is what actually gets the IP from Comcast, as the modem acts as a bridge. See all along, I thought the Cable Modem is what got the IP from Comcast, not the router.

IPv4 or IPv6, it is the attached device(s) that get the IP address(es) used for Internet access (I use plural because it is possible to pay Comcast for multiple IP addresses). If you don't believe me, then use another router, or connect your PC directly to the modem (then power cycle the modem) and see if your Internet IP address changes (hint: it will change unless you have cloned a PC's MAC address to the router's WAN interface, and it is that PC that you connect to the modem). IPv6 is slightly different in that a connected device's MAC address is not necessarily part of the DUID that is used to identify a device to the DHCPv6 provider, but many vendor's do still use a device's MAC address as part of the algorithm used to generate a DUID.

The cable modem's IP address is used strictly by the ISP for managing the modem, it is not used by the customer for Internet access (and depending on the modem model and/or firmware, that IP address may not even be visible to the customer).
--
History does not long entrust the care of freedom to the weak or the timid.
-- Dwight D. Eisenhower


plencnerb
Premium
join:2000-09-25
Carpentersville, IL
kudos:3

Ok, I get it now!

But, in some way, the cable modem itself must still be able to "pass" along to whatever device is connected to it (router like Netgear or Linksys, Windows Computer, Mac Computer, etc) the proper IP. If the cable modem itself cannot do that for an IPv6 IP, then you would have to replace the cable modem for one that can, correct?

That is really the basis of my question, and I think what everyone is trying to figure out. I also agree that Comcast may not have "properly" done that on their "approved" cable modem list.

Of course, this is all moot if Comcast has not rolled out IPv6 in your area yet. As far as I can tell, they have not for my area. I had NetDog See Profile look into that for me, and (at least back on the 5th of June), they had not done so yet.

But, I think what everyone is trying to figure out is what they, as customers of Comcast, have to modify or change on their end to get IPv6 to work in their own world once Comcast does roll it out.

Questions like
1) Do I need to buy (or swap) my modem?

2) Do I need to replace my router, or update its firmware? Or, if you are running a Linux router (like I am...Smoothwall), do I need to apply some kind of mod or patch)?

3) What modifications do I need to make to my devices, and are they even supported?

For some, this may require some money...if said user purchased a modem 5 years ago, and it needs to be replaced...that is money to spend..if they also have to replace their 10 year old router..and, if they have a computer running Windows 98, they may need to replace that, purchase a new OS, and so on.

I would hate to find out that what I have currently does not work once things are finally all switched over. Then, trying to figure out what broke after the fact (Hey..I cannot connect..WTF!) would be a lot harder (I would think) then doing the up-front work to figure out if what I have WILL work once things are in place. If I don't have to replace my cable modem, or router, and just modify a few settings, then I'm good. However, if I do need to go purchase a new router (mine may be to old, and not getting an updated firmware from the MFG), I would like to know that ahead of time.

--Brian
--
============================
--Brian Plencner

E-Mail: CoasterBrian72Cancer@gmail.com
Note: Kill Cancer to Reply via e-mail



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

1 recommendation

A simple cable modem is a layer 2 device and media converter, it does not understand IPv4 or IPv6 for traffic passed between your network and the Internet anymore than a simple layer2 switch does. Do a traceroute to an internet server (such as www.google.com) from a device on your network, does your cable modem show up in that traceroute report? I would demonstrate that for you with both IPv4 and IPv6 examples, except that my "modem" does show up because it is a cable gateway, not a simple bridge.

To hell with it, shown below are IPv4 and IPv6 traceroutes to www.google.com from the server that i am currently doing some maintenance on (perhaps it might still be useful):


C:\>tracert www.google.com
 
Tracing route to www.l.google.com [74.125.137.99]
over a maximum of 30 hops:
 
  1    <1 ms    <1 ms    <1 ms  host6.dcs-net.net [75.146.8.46]
  2    32 ms    20 ms    29 ms  96.191.160.1
  3     9 ms     8 ms     9 ms  xe-4-0-0-0-sur01.murfreesboro.tn.nash.comcast.net [68.85.50.125]
  4    10 ms    10 ms    10 ms  xe-3-1-2-0-ar03.nashville.tn.nash.comcast.net [68.85.174.17]
  5    12 ms   127 ms    60 ms  ae-3-0-ar01.goodslettvll.tn.nash.comcast.net [68.86.148.69]
  6    21 ms    29 ms    29 ms  pos-2-1-0-0-cr01.atlanta.ga.ibone.comcast.net [68.86.90.101]
  7    47 ms    18 ms    20 ms  pos-0-1-0-0-pe01.56marietta.ga.ibone.comcast.net [68.86.86.86]
  8    33 ms    19 ms    19 ms  75.149.231.86
  9    18 ms    19 ms    19 ms  64.233.174.2
 10    20 ms    18 ms    19 ms  66.249.94.6
 11    18 ms    19 ms    19 ms  209.85.248.31
 12     *        *        *     Request timed out.
 13    18 ms    20 ms    20 ms  yh-in-f99.1e100.net [74.125.137.99]
 
Trace complete.
 
C:\>tracert -6 www.google.com
 
Tracing route to www.l.google.com [2001:4860:800a::67]
over a maximum of 30 hops:
 
  1    <1 ms    <1 ms    <1 ms  2002:4b92:829:0:a221:b7ff:fe9c:602
  2    21 ms    22 ms    22 ms  2002:c058:6301::
  3    21 ms    21 ms    22 ms  ge-7-2-ur02.s3ndigital.ga.atlanta.comcast.net [2001:558:fe12:1::1]
  4    22 ms    24 ms    21 ms  xe-2-0-1-0-ar01.d1stonemtn.ga.atlanta.comcast.net [2001:558:140:22::1]
  5    46 ms    47 ms    47 ms  pos-2-14-0-0-cr01.350ecermak.il.ibone.comcast.net [2001:558:0:f73d::1]
  6    44 ms    46 ms    58 ms  pos-1-1-0-0-pe01.350ecermak.il.ibone.comcast.net [2001:558:0:f589::2]
  7    79 ms    33 ms    33 ms  2001:559::382
  8    40 ms    34 ms    33 ms  2001:4860::1:0:3f7
  9    68 ms    53 ms   144 ms  2001:4860::1:0:5db
 10    56 ms    52 ms    52 ms  2001:4860::8:0:2f04
 11    53 ms    51 ms    52 ms  2001:4860::2:0:a7
 12    62 ms    53 ms    54 ms  2001:4860:0:1::10b
 13    54 ms    53 ms    54 ms  yx-in-x67.1e100.net [2001:4860:800a::67]
 
Trace complete.
 
 


The first hop for the IPv4 traceroute above is my SMCD3G-CCR cable gateway, and it shows up because it is a router, not just a simple bridge modem. That hop would likely be your Smoothwall box for your traceroutes. The second hop is Comcast's gateway for my connection.

The first hop for the IPv6 traceroute above is my Comcast supplied Netgear WNR1000v2-VC wireless router which currently acts as my IPv4 NAT router for non server boxes, and as my IPv6 gateway for all devices. The second hop is Comcast's 6to4 relay server (which I must use because Comcast does not yet offer native IPv6 to my location).

OK, shown below here are the same traceroutes from a Windows XP workstation (that I should have been using to do this anyway). Note that the only differences are that the IPv4 traceroute goes through the Netgear router, and then through the SMC router, and the Google IP addresses are different because Google uses load balancing:


C:\>tracert www.google.com
 
Tracing route to www.l.google.com [74.125.130.103]
over a maximum of 30 hops:
 
  1    <1 ms    <1 ms    <1 ms  ap2.dcs-net [192.168.9.10]
  2     1 ms    <1 ms    <1 ms  host6.dcs-net.net [75.146.8.46]
  3    38 ms    19 ms    29 ms  96.191.160.1
  4    10 ms    10 ms     9 ms  xe-4-0-0-0-sur02.murfreesboro.tn.nash.comcast.net [68.85.50.129]
  5    12 ms    10 ms    11 ms  xe-5-1-3-0-ar01.goodslettvll.tn.nash.comcast.net [68.86.176.105]
  6    18 ms    18 ms    19 ms  pos-2-2-0-0-cr01.atlanta.ga.ibone.comcast.net [68.86.90.189]
  7    19 ms    24 ms    23 ms  pos-0-11-0-0-pe01.56marietta.ga.ibone.comcast.net [68.86.88.186]
  8    18 ms    19 ms    18 ms  75.149.231.86
  9    17 ms    18 ms    18 ms  72.14.239.100
 10    19 ms    21 ms    20 ms  66.249.94.20
 11    19 ms    19 ms    18 ms  209.85.254.247
 12     *        *        *     Request timed out.
 13    19 ms    63 ms    18 ms  gh-in-f103.1e100.net [74.125.130.103]
 
Trace complete.
 
C:\>tracert -6 www.google.com
 
Tracing route to www.l.google.com [2001:4860:800a::93]
over a maximum of 30 hops:
 
  1    <1 ms    <1 ms    <1 ms  2002:4b92:829:0:a221:b7ff:fe9c:602
  2    45 ms    21 ms    21 ms  2002:c058:6301::
  3    22 ms    25 ms    20 ms  ge-7-2-ur02.s3ndigital.ga.atlanta.comcast.net [2001:558:fe12:1::1]
  4    23 ms    23 ms    21 ms  xe-2-0-1-0-ar01.d1stonemtn.ga.atlanta.comcast.net [2001:558:140:22::1]
  5    46 ms    49 ms    52 ms  pos-2-12-0-0-cr01.350ecermak.il.ibone.comcast.net [2001:558:0:f73b::1]
  6    46 ms    44 ms    43 ms  pos-1-1-0-0-pe01.350ecermak.il.ibone.comcast.net [2001:558:0:f589::2]
  7    32 ms    32 ms    35 ms  2001:559::382
  8    34 ms    32 ms    34 ms  2001:4860::1:0:3f7
  9    53 ms    54 ms    58 ms  2001:4860::1:0:5db
 10    53 ms    51 ms    53 ms  2001:4860::8:0:2f04
 11    59 ms    53 ms    53 ms  2001:4860::2:0:a7
 12    58 ms    54 ms    56 ms  2001:4860:0:1::10b
 13    52 ms    87 ms    53 ms  yx-in-x93.1e100.net [2001:4860:800a::93]
 
Trace complete.
 
 


Perhaps my point that a standard cable modem does not show up in a traceroute is somewhat diluted since my cable "modem" does show up (but what shows up is the router's WAN IP address, not a cable modem IP address). But believe me, if I were using a cable modem instead of a cable gateway box, it would not show up, and it should not show up in your traceroutes.

I don't specifically know what versions of Smoothwall do or don't support Comcast's DHCPv6 implementation, but you could probably start a new thread asking that question and get answers from someone using it with native IPv6 (since that is somewhat unrelated to this thread's topic).

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


plencnerb
Premium
join:2000-09-25
Carpentersville, IL
kudos:3

NetFixer,

I understood what you said about a Cable Modem being just a bridge. You did not need to show the trace route to me as you did. But, thanks for sharing anyway!

And yes, any questions I have about my router I'll post in another thread, as that is off topic here.

My question (and you did answer it) was with the cable modem specifically (and one that is not a combo cable modem / router or cable modem / wireless gateway). Are there cable modems out there that could have problems passing a IPv6 IP on to the device that is requesting it? From what you told me, the answer is no, as they are just a simple bridge...whatever data comes in to the Cable Modem via the coax will be passed (without issue) through the cable modem, and out the WAN port to whatever device is connected to it.

With that being said, this statement is then true, correct?

"It does not matter at all what cable modem you have as long as Comcast has it enabled in your area, as its not the cable modem that pulls an IP(be it an IPv4 IP or IPv6 IP)."

If that statement is true, then why all the talk about "Does my cable modem support IPv6", and why has Comcast put up a page showing which Cable Modems "support" IPv6 with that checkmark? Are they just trying to confuse people, or force people to upgrade to new hardware, when they really don't need to?

--Brian
--
============================
--Brian Plencner

E-Mail: CoasterBrian72Cancer@gmail.com
Note: Kill Cancer to Reply via e-mail



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

2 recommendations

My opinion would be that any cable modem that syncs and is supported by Comcast should be able to work with Comcast's DHCPv6 simply because as a layer 2 device it should not know or care what protocol is passing through it. Having said that, I certainly can not guarantee you that every cable modem would indeed function that way, because even though their primary function might be as a layer 2 device, there might be some internal functions that interact with the management interface that could impair its Internet usage. Plus, I suspect that in the not so distant future, Comcast may start requiring all modems to have an IPv6 management interface (since that is one big reason that Comcast is pushing IPv6).

As for exactly what criterion Comcast uses for providing an IPv6 checkmark on their supported devices page, you will have to wait for a Comcast employee in the know for that answer. My best guess is that their primary criterion is management interface IPv6 compatibility, and they want to encourage customers to buy their own modems that have an IPv6 management interface, so that Comcast can pass that expense to the customer (and by indirectly implying that the modem must have the IPv6 checkmark, this goal will be easier to achieve).

As always, [disclaimer]YMMV[/disclaimer].
--
History does not long entrust the care of freedom to the weak or the timid.
-- Dwight D. Eisenhower



jjmb

join:2009-12-01
USA
reply to koitsu

Hello see some comments below, I run the IPv6 program for Comcast and helped specify IPv6 for DOCSIS nearly 7 years ago.

said by koitsu:

Let me put an end to the nonsense said above:

1. You do not need a an "IPv6-ready" cable modem, for your router or your systems on your LAN to make use of IPv6.

[jjmb] the cable must support IPv6, meaning there are cable modems deployed today that will not support LAN side IPv6 connectivity. Many are firmware upgradeable. We have and will continue to work with our vendors to test and deploy firmware updates to introduce support for LAN side support for IPv6.

2. DOCSIS 3.0 does not have anything to do with IPv6 capability. You can talk to the Internet using IPv6 with a DOCSIS 2.0 cable modem.

[jjmb] DOCSIS 3.0 and a subset of pre-DOCSIS 3.0 cable modems support IPv6. Not all pre-DOCSIS 3.0 cable modems support IPv6. Only DOCSIS 3.0 CMTSs support IPv6.

3. An "IPv6-ready" cable modem means that the cable modem's administrative page/management interface supports IPv6. It does not stop Comcast from delegating you an IPv6 prefix (/64) or handing out an individual IPv6 address (/128) to your router. In English: it means that you can access your cable modem via, say, URL »[fe80::230:48ff:fed2:1234]/ rather than »192.168.100.1/.

[jjmb] just because a modem supports IPv6 does not mean it will be administratively accessible from the LAN side over IPv6. 192.168.100.1 should continue to work even when IPv6 is enabled.

All of this was debunked in this thread. See posts from ctgreybeard See Profile and netcool See Profile:

»[IPv6] Why does my modem not indicate IPv6?

Anyway, from what I can tell from the OP's screenshot, IPv6 is working fine for him (2nd line; it means Comcast has delegated him an IPv6 prefix (/64) and/or an individual IPv6 address (/128)). I can't tell which because he chose to black out the necessary information.

[jjmb] when a home router is installed that supports IPv6 we will issue a /128 address and a /64 prefix by default.

The 4th line (message about "only being able to reach IPv4 sites") means that the machine he was viewing the Comcast IPv6 readiness page from a machine which has no global (not link-local!) IPv6 address.

[jjmb] or has some other software installed on it that prevents the use of IPv6. We have seen this with some anti-virus/firewall applications.

So in summary, to me, it looks like the "problem" is with his router firmware. Comcast should be giving you a /64 prefix (in English: a public Internet netblock which you can use on your LAN, as well as your router). My guess is that the router is getting that /64 prefix, but has a bug/issue where IPv6 RAs are not being sent out to the machines on the LAN, thus his Windows 7 machine can't speak IPv6 to the Internet.

[jjmb] firmware for home routers is still maturing, we still see a good number of issues as well. See »mydeviceinfo.comcast.net for a list of devices we have tested.

If Comcast has confirmed that IPv6 has been rolled out to your area successfully, then its almost certainly a router ordeal (it would help if you could provide some details the router shows, and stop hiding the information with black boxes :P). Otherwise, your area may be an area where Comcast is in the progress of rolling out IPv6 but it might not be fully working/completed yet or maybe it's broken. Comcast can tell you for sure.

[jjmb] we are working on something that customers can use to self validate. Stay tuned.

I just got done getting familiar with all of this earlier this week, but for the TomatoUSB firmware (which also works on the Linksys E4200, but not sure about the E4200v2 -- the hardware versions often matter greatly, sometimes changing entire CPUs!):

[jjmb] the E4200 supports IPv6 out of the box, no need to upgrade or change the firmware.

»[IPv6] TomatoUSB and Comcast IPv6 -- bugs found

So don't even for a minute think that consumer router firmwares aren't buggy (even the open-source ones are!). So I would check to see if there's an E4200v2 firmware update and start with that.

Finally, about the 6to4 stuff: I agree with NathanO See Profile -- avoid use of 6to4 if native IPv6 is available. 6to4 absolutely is slow (and that's even shown here -- note the 2.4 second (not millisecond!) response time on one of the tests) because of how it works. It will not get the same response times nor have the same reliability as native IPv6, plus it relies on Comcast's 6to4 anycast relays which could go down. I've used Comcast's 6to4 anycast relays myself and I do see intermittent packet loss + high latency which do not happen with native IPv6. This is understandable; you need to read about how 6to4 anycast works to fully understand why it's slow.

[jjmb] we agree that 6to4 is not ideal, however, a good number of devices still try to use it by default. As such we deployed 6to4 relays a couple of years ago to improve performance for our customers. The goal is to eventually see the use of 6to4, along with the use of other transition technologies, diminish and become native IPv6.



jjmb

join:2009-12-01
USA
reply to plencnerb

We continue to test and deploy firmware for modems to introduce support for IPv6. Not every modem on mydeviceinfo.comcast.net will support IPv6, largely due to software and/or hardware limitations.

The timeframe for IPv6 support varies per modem. The best advice I can offer is keep watching mydeviceinfo.comcast.net.

We have been working with our vendors for years fortunately. As such we have support for many cable modems in the works. The development, test, and deployment process takes time.

If a modem has the IPv6 check box marked *and* we have launched IPv6 in your area you are ready to go providing you have a computer and/or router that supports IPv6. If you have both and IPv6 is still not enabled then we more than likely have not launched in your area.

Finally, regarding IMS versus NCS. This is an indicator of the different voice technology used to deliver voice services.



jjmb

join:2009-12-01
USA
reply to plencnerb

said by plencnerb:

Ok, I get it now!

But, in some way, the cable modem itself must still be able to "pass" along to whatever device is connected to it (router like Netgear or Linksys, Windows Computer, Mac Computer, etc) the proper IP. If the cable modem itself cannot do that for an IPv6 IP, then you would have to replace the cable modem for one that can, correct?

[jjmb] if your modem does not currently support IPv6 you may need to replace the same. Like I said in an early post we work regularly to update this list based on available firmware from our vendors.

That is really the basis of my question, and I think what everyone is trying to figure out. I also agree that Comcast may not have "properly" done that on their "approved" cable modem list.

Of course, this is all moot if Comcast has not rolled out IPv6 in your area yet. As far as I can tell, they have not for my area. I had NetDog See Profile look into that for me, and (at least back on the 5th of June), they had not done so yet.

But, I think what everyone is trying to figure out is what they, as customers of Comcast, have to modify or change on their end to get IPv6 to work in their own world once Comcast does roll it out.

Questions like
1) Do I need to buy (or swap) my modem?

[jjmb] see above.

2) Do I need to replace my router, or update its firmware? Or, if you are running a Linux router (like I am...Smoothwall), do I need to apply some kind of mod or patch)?

[jjmb] router upgrades are likely required. We publish a list that we have tested, however, I get email often from folks who have other makes and models that work fine.

3) What modifications do I need to make to my devices, and are they even supported?

[jjmb] most popular operating systems support IPv6, Windows 7/8/Vista, MAC OS X Lion/Snow Leopard, Linux. *BSD. There is different functionality based on the OS.

For some, this may require some money...if said user purchased a modem 5 years ago, and it needs to be replaced...that is money to spend..if they also have to replace their 10 year old router..and, if they have a computer running Windows 98, they may need to replace that, purchase a new OS, and so on.

I would hate to find out that what I have currently does not work once things are finally all switched over. Then, trying to figure out what broke after the fact (Hey..I cannot connect..WTF!) would be a lot harder (I would think) then doing the up-front work to figure out if what I have WILL work once things are in place. If I don't have to replace my cable modem, or router, and just modify a few settings, then I'm good. However, if I do need to go purchase a new router (mine may be to old, and not getting an updated firmware from the MFG), I would like to know that ahead of time.

--Brian



jjmb

join:2009-12-01
USA
reply to newview

Only use 6to4 if you must, our preference (and yours) is native IPv6. If you do not have IPv6 yet you need to check if your modem supports IPv6 on mydeviceinfo.comcast.net. It is possible that we have not launched IPv6 in your area yet. Please watch www.comcast6.net for updates on our deployment.



newview
Ex .. Ex .. Exactly
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Parsonsburg, MD
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said by jjmb:

If you do not have IPv6 yet you need to check if your modem supports IPv6 on mydeviceinfo.comcast.net.

So the modem has to support IPv6 as well as the router?


whfsdude
Premium
join:2003-04-05
Washington, DC
Reviews:
·Comcast

said by newview:

So the modem has to support IPv6 as well as the router?

Yes. I've actually come across an RCA modem that didn't support it. Luckily the person had just gone out and bought a DOCSIS 3 modem the day before. He was just to lazy to call Comcast to activate. Boy was he happy when I told him about the walled garden activation


jjmb

join:2009-12-01
USA
reply to newview

Correct, this is what the checkbox on »mydeviceinfo.comcast.net represents.



plencnerb
Premium
join:2000-09-25
Carpentersville, IL
kudos:3
reply to jjmb

jjmb,

Thanks for all the answers!

Now I have a better understanding, and can properly plan for the deployment of IPv6 on my end.

The last time I checked with NetDog See Profile, IPv6 was not rolled out in my area yet. However, when that has been done, I really wanted to know what modifications or changes I needed to make on my end to take advantage of this, and you finally answered all the questions that I had.

--Brian
--
============================
--Brian Plencner

E-Mail: CoasterBrian72Cancer@gmail.com
Note: Kill Cancer to Reply via e-mail



newview
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reply to newview

Click for full size
SUCCESS!

Purchased a new Motorola SB6121 today ...


dslcreature
Premium
join:2010-07-10
Seattle, WA
reply to SHoTTa35

said by SHoTTa35 :

3 - I have that modem too and you can use Hurricane Electric if you want IPv6. You wont get 6to4 with that router though as it's not one of the supported options. No big deal IMO. 6rd is supported though IIRC.

Until IPv6 comes to town the HE tunnels are amazing. Latency soo low I have trouble believing it's a "tunnel".


Pinging www.l.google.com [74.125.127.103] with 32 bytes of data:
Reply from 74.125.127.103: bytes=32 time=22ms TTL=52
Reply from 74.125.127.103: bytes=32 time=23ms TTL=52

Pinging www.l.google.com [2001:4860:8005::69] with 32 bytes of data:
Reply from 2001:4860:8005::69: time=24ms
Reply from 2001:4860:8005::69: time=23ms


NetFixer
Snarl For The Camera Please
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join:2004-06-24
The Boro
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reply to newview

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
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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
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The Boro
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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
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join:2004-06-05
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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
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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
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join:2004-06-05
Newtown, PA
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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.