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Stunningly poor IPv6 tech support - Modem in Bridge Mode for IPv6 assignment

Frequent Visitor

Stunningly poor IPv6 tech support - Modem in Bridge Mode for IPv6 assignment

I've been on the phone for over 3 hours (3 hours!) trying to get ANYONE who speaks IPv6.   Every "engineer" I speak with has no clue what it is - they all try to "fix" the problem by reseting the modem or taking it out of bridge mode.  The last one transferred me to wifi support.

 

I have a Cisco ASA-5515-x that I've configured the outside interface for IPv6 DHCP client and autoconfig.    If the modem is not in bridge mode, it assigns my IPv6 outside address correctly.  However, since that prefix is for my inside network, assigning it to my outside interface is of no help.   Once I put them modem in bridge mode, the ASA no longer receives its DHCP assignment presumabely from the upstream DHCPv6 server.

 

Any help would be appriciated.

Frequent Visitor

Re: Stunningly poor IPv6 tech support - Modem in Bridge Mode for IPv6 assignment

I give up.  Comcast wins.

Tech support reset my modem no less than 10 times - twice while I was talking to them via WiFi and telling them NOT to reset the modem.

Not a single engineer understood why I needed to have bridge mode enabled.

Not a single engineer could speak to how IPv6 works.

Not a single engineer could transfer me to someone who could help.

So back to IPv4.

Regular Visitor

Re: Stunningly poor IPv6 tech support - Modem in Bridge Mode for IPv6 assignment

It sounds like bridge mode in your modem/router combination isn't as transparent as a should be.   Why not ditch it and buy a straight modem.   Lots of us with our own modems have no problem running over IPv6.   

Connection Expert

Re: Stunningly poor IPv6 tech support - Modem in Bridge Mode for IPv6 assignment

Do you also have their phone service ?




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Frequent Visitor

Re: Stunningly poor IPv6 tech support - Modem in Bridge Mode for IPv6 assignment

I do have their phone service.   

Frequent Visitor

Re: Stunningly poor IPv6 tech support - Modem in Bridge Mode for IPv6 assignment

Because the package I have required their modem.  Package gave me phone service which I didn't use for MONTHS until my wife needed to send a large fax Smiley Happy.  Now its a fax line.

Connection Expert

Re: Stunningly poor IPv6 tech support - Modem in Bridge Mode for IPv6 assignment

O/k so if you want to keep and use their phone service, and you want to "ditch" their device (as suggested by others) and purchase your own device, (it can't be a "straight cable modem" as others have suggested). Bear this in mind;

 

FWIW, there *may still* be one caveat to owning your own eMTA or gateway device that supports their phone service. YMMV. I always advise (until I'm told otherwise officially) that the first thing you should do is to call in or go to your local CC service center (the better choice) and inquire / confirm as to whether or not customer owned eMTA's (modems with phone support) are allowed to be used on the local system. Some local franchises still do not allow it and require you to rent one from CC. The personnel that work there seem to better know what the actual local franchise's policies really are than do support reps at the national 800 number.

If allowed, there are five devices available at retail that they will activate for service are the Arris TG862G, the Arris SVG2482AC, the Netgear C7100V, the Arris TM822G, and the Arris TM722G. The 862 is a combo cable modem / router / eMTA gateway device but it is a piece of junk. But it can be put in to bridge mode so that it acts only as a cable modem with phone support. You would the use your own high quality stand-alone router with it.

The SVG2482AC and the C7100V are much better performing combo gateway devices that offer 24 downstream channels. The 822 is an eMTA that offers only 8 downstream channels. The 722 is an older eMTA that offers only 4 downstream channel bonding capability so it won't be able deliver their fastest speed tiers like 150 and faster. They are hard to find as they are not being manufactured anymore.




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Regular Contributor

Re: Stunningly poor IPv6 tech support - Modem in Bridge Mode for IPv6 assignment

Does your ASA have setting for DHCPv6 with Prefix Delegation?
Frequent Visitor

Re: Stunningly poor IPv6 tech support - Modem in Bridge Mode for IPv6 assignment

Found 1 issue after HOURS of support from Cisco - the Hop Limit field in the IPv6 header for DHCPv6 packets from Xfinity was set to 0 so all of the DHCPv6 advertisements were bing (correctly) dropped by the ASA.   More hours on the phone trying to find the right comcast "engineer" to fix it.   Finally receiving a /128 address on my outside interface.   However, I'm unable to assign any of my inside interfaces

!

interface GigabitEthernet0/0
nameif Outside
security-level 0
ip address dhcp setroute
ipv6 address dhcp default
ipv6 enable
ipv6 nd suppress-ra
ipv6 dhcp client pd hint ::/56
ipv6 dhcp client pd prefix-from-Comcast
!
interface GigabitEthernet0/1
nameif Inside
security-level 100
ip address 192.168.1.1 255.255.255.0
ipv6 address prefix-from-Comcast ::1:0:0:0:1/64
ipv6 address autoconfig
ipv6 enable
!

 

vpn(config-if)# sh ipv6 int
Outside is up, line protocol is up

IPv6 is enabled, link-local address is fe80::206:f6ff:fe2b:2feb
Global unicast address(es):
2601:681:xxxx:xxxx::7356, subnet is 2601:681:xxxx:xxxx::7356/128
Joined group address(es):
ff02::1:ff00:7356
ff02::2
ff02::1:ff2b:2feb
ff02::1
ICMP error messages limited to one every 100 milliseconds
ICMP redirects are enabled
ND DAD is enabled, number of DAD attempts: 1
ND reachable time is 30000 milliseconds
Hosts use stateless autoconfig for addresses.


Inside is up, line protocol is up
IPv6 is enabled, link-local address is fe80::206:f6ff:fe2b:2fe8
No global unicast address is configured

Joined group address(es):
ff02::1:ff2b:2fe8
ff02::2
ff02::1
ICMP error messages limited to one every 100 milliseconds
ICMP redirects are enabled
ND DAD is enabled, number of DAD attempts: 1
ND reachable time is 30000 milliseconds
ND advertised reachable time is 0 milliseconds
ND advertised retransmit interval is 1000 milliseconds
ND router advertisements are sent every 200 seconds
ND router advertisements live for 1800 seconds
Hosts use stateless autoconfig for addresses.
vpn(config-if)#

 

 

Frequent Visitor

Re: Stunningly poor IPv6 tech support - Modem in Bridge Mode for IPv6 assignment

aaaaannddd we're back to not receiving an IPv6 address on the outside interface.

 

Gota love Comcast...  Briliant engineers there.

Contributor

Re: Stunningly poor IPv6 tech support - Modem in Bridge Mode for IPv6 assignment

Hi Mickey,

 

I feel your pain as well.  I have had my cases closed here in the forums and ignored.  Read here:

 

http://forums.xfinity.com/t5/Your-Home-Network/IPv6-Hop-Limit-0-for-DHCPv6-Advertisement-XID-set-by-...

 

If you are interested in the real technical issue, it is here:

 

http://techsticles.blogspot.com/2017/03/why-your-fancy-routerfirewall-likely.html

 

The bottom line is yes, as you found, Comcast sends a hop limit of 0, which breaks the RFCs.  The crummy routers on the market (and those that Comcast give you) will accept the IPv6 packet.  Any "expensive" routers or firewalls (i.e. Cisco, Juniper, etc) will reject any packet with a hop limit set to 0. I had a tech over to upgrade me to Gigabit and I showed him the problem.  He was surprised and said he would escalate it, but of course, like with all the other tickets that I opened, I got nothing.

 

My frustrations are with you as I have attempted to speak with the bug kahuna (ComcastJohn) on Reddit, here, and via email with zero response.  You would think he would care.

 

The bottom line is Comcast does not care.  Period.  I run a Cisco 5512X, which is not too different from you and will be married to IPv4 on Comcast until they fix that bug and conform the to RFC 2460.

 

 

 

Authorized Vendor

Re: Stunningly poor IPv6 tech support - Modem in Bridge Mode for IPv6 assignment

This is being looked at and has been escalated..

-------------------------------------
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: Stunningly poor IPv6 tech support - Modem in Bridge Mode for IPv6 assignment

Thank you ArrisTuska.  Now I am hopeful we can get this fixed.

New Poster

Re: Stunningly poor IPv6 tech support - Modem in Bridge Mode for IPv6 assignment

This is incredibly annoying. I have a Juniper SRX 210 and I couldn't obtain a prefix delegation from Comcast either. Some quick monitoring showed that DHCPv6-Advertise were being sent back with hlim = 0 and JunOS correctly dropped the packet and responsed with ICMPv6 hop-limit-exceeded.

 

Some JunOS devices can use no-ipv6-reject-zero-hop-limit to accept such apckets, unfortunately SRX products does not support it.

 

Comcast, please fix this.

Authorized Vendor

Re: Stunningly poor IPv6 tech support - Modem in Bridge Mode for IPv6 assignment


dndx wrote:
 

Comcast, please fix this.


I am going to PM you I want to know what CMTS your on..  and check some things..

-------------------------------------
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: Stunningly poor IPv6 tech support - Modem in Bridge Mode for IPv6 assignment

Hi ArrisTuska,

 

I had sent you some items a couple of weeks ago... do you have any update to this problem?

Frequent Visitor

Re: Stunningly poor IPv6 tech support - Modem in Bridge Mode for IPv6 assignment

I too have this issue.  Hop Limit 0 DHCPv6 Advertise responses from Comcast.  Using an ASA 5506-X running 9.8(2) with a Motorola MB8600.  I'm in the Atlanta area.

 

I'm not sure why the outside interface is not doing SLAAC.  The firewall is receiving RAs, but it is not assigning an address.  The RAs contain 4 ::/64 prefixes.

 

fw1(config)# show ipv6 routers
Router fe80::201:5cff:fe67:6846 on outside, last update 0 min, CONFLICT
  Hops 0, Lifetime 1800 sec, AddrFlag=1, OtherFlag=1
  Reachable time 3600000 msec, Retransmit time 1000 msec
  Prefix 2001:558:xxxx:xxxx::/64
    Valid lifetime 604800, preferred lifetime 302400
  Prefix 2001:558:xxxx:xxxx::/64
    Valid lifetime 604800, preferred lifetime 302400
  Prefix 2001:558:xxxx:xxxx::/64
    Valid lifetime 604800, preferred lifetime 302400
  Prefix 2001:558:xxxx:xxxx::/64
    Valid lifetime 604800, preferred lifetime 302400

Frequent Visitor

Re: Stunningly poor IPv6 tech support - Modem in Bridge Mode for IPv6 assignment


ipv6bob wrote:

I too have this issue.  Hop Limit 0 DHCPv6 Advertise responses from Comcast.  Using an ASA 5506-X running 9.8(2) with a Motorola MB8600.  I'm in the Atlanta area.

 

I'm not sure why the outside interface is not doing SLAAC.  The firewall is receiving RAs, but it is not assigning an address.  The RAs contain 4 ::/64 prefixes.



Replying to myself, it's correctly not doing SLAAC because the RAs tell it not to.

Contributor

Re: Stunningly poor IPv6 tech support - Modem in Bridge Mode for IPv6 assignment

Those are Comcast routers.  They are publicly known (no need to XX out their addresses).  Your IP addresses will come in the ADVERTISE XID.  Thats the packet that your Cisco is correctly dropping (as well as your REPLY XID if you were to get that far) due to the hop limit = 0.

 

You can fix your CONFLICT on the routers with this on your interface:

 

ipv6 nd reachable-time 3600000

 

But that CONFLICT has no issue or impact.  Its the hop limit = 0 that is causing your problems.

Authorized Vendor

Re: Stunningly poor IPv6 tech support - Modem in Bridge Mode for IPv6 assignment


M0untainman wrote:

Hi ArrisTuska,

 

I had sent you some items a couple of weeks ago... do you have any update to this problem?


I will ping the DHCP OPS again about this..

-------------------------------------
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: Stunningly poor IPv6 tech support - Modem in Bridge Mode for IPv6 assignment



I will ping the DHCP OPS again about this..


Thank you.  I've been working through escalations with support trying to get resolution or acknowledgement.  The last answer I got in residential was that they couldn't gaurantee IPv6 addressing.  When I spoke with business a potential work-around is using a static assignment, and they assign a /56.

 

I just switched to xfinity for speed and price, but I've since realized IPv6 is a requirement as well.

 

Thanks

Regular Visitor

Re: Stunningly poor IPv6 tech support - Modem in Bridge Mode for IPv6 assignment


ArrisTuska wrote:

M0untainman wrote:

Hi ArrisTuska,

 

I had sent you some items a couple of weeks ago... do you have any update to this problem?


I will ping the DHCP OPS again about this..


ArrisTuska:

 

I am a Comcast user and own a Cisco ASA 5508-X and am having the same problem obtaining an ipv6 prefix due to the hop limit exceeded. How can I get in touch with you with info needed to resolve this?

 

Thanks.

 

 

Authorized Vendor

Re: Stunningly poor IPv6 tech support - Modem in Bridge Mode for IPv6 assignment

This is NOT confirmed yet but it is looking more and more like it is a CMTS issue and not a DHCP server issue..  So if that would be the case then it woudnt be a Comcast issue but a ARRIS issue..  Once I get it confirmed I will point it out, I also need to confirm if this issue is on the latest code on the CMTS that is getting pushed out to the field shortly..

 

So those CM-MAC's you all have sent me is a great help; so far the only people that have seen this issue is on a E6000 and not the "other" CMTS..

-------------------------------------
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: Stunningly poor IPv6 tech support - Modem in Bridge Mode for IPv6 assignment

Thanks for your help on this, Arris!

Contributor

Re: Stunningly poor IPv6 tech support - Modem in Bridge Mode for IPv6 assignment

Thanks ArrisTuska.  Your attention to this is outstanding.

 

Unfortunately this IS a Comcast issue in that they are running Arris equipment.  So it falls on them to tell customers they are looking at this.

 

It is my sincere hope that after you get this working that a Comcast representative can come in this thread and apologize for the "stunningly bad support", whereby they closed tickets on us, tried to state untrue reasons for these problems, and hand waving away the issue.  Their support is atrocious.

 

I want to thank you with my own sincerety for giving us your attention to fix this.  Obviously we were not crazy. Smiley Happy

 

That "other" CMTS wouldn't happen to be "Cisco" would it?... you know...the one that works?

Regular Visitor

Re: Stunningly poor IPv6 tech support - Modem in Bridge Mode for IPv6 assignment

Are there any updates on this? I noticed my modem rebooted on the evening of 10/4.

Frequent Visitor

Re: Stunningly poor IPv6 tech support - Modem in Bridge Mode for IPv6 assignment


ArrisTuska wrote:

This is NOT confirmed yet but it is looking more and more like it is a CMTS issue and not a DHCP server issue.. 

Thank you for continuing to drive this to resolution.

Contributor

Re: Stunningly poor IPv6 tech support - Modem in Bridge Mode for IPv6 assignment

Yes... any updates would be great.  Its been a week since I emailed my CM-MAC info and I have had no reboots or anything.  Advertisement XIDs still report a hlim=0, so I am not seeing any differences.

Regular Visitor

Re: Stunningly poor IPv6 tech support - Modem in Bridge Mode for IPv6 assignment

In the absence of a real solution to this problem I have connected my Catalyst L3 switch (which does not check RFC compliance in RAs) upstream from the firewall in order to get this working. Really stinks that I need to increase the routing overhead to compensate for Comcast's lack of attention to this matter.

Contributor

Re: Stunningly poor IPv6 tech support - Modem in Bridge Mode for IPv6 assignment

I reached out to ArrisTuska via email a few times and received nothing.  Has anyone seen this work where they saw the problem before?

 

On my blog on this issue, I had a guy recently report to me that this is also happening on TWC/Spectrum and thinks its the Arris CMTS as well since it doesn't appear to be a problem only on Comcast.

 

It would be nice to get an update or at least a ticket number under Comcast that we can call and track.  The silence is deafening.

New Poster

Re: Stunningly poor IPv6 tech support - Modem in Bridge Mode for IPv6 assignment

How can I update the firmware for my arris wbm 760 router? Please help

Connection Expert

Re: Stunningly poor IPv6 tech support - Modem in Bridge Mode for IPv6 assignment


kunziepro wrote:

How can I update the firmware for my arris wbm 760 router? Please help


You can't do it manually. Comcast pushes out the updates automatically through the system when they are available.




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I am not a Comcast employee, I am a paying customer just like you!
I am an XFINITY Forum Expert and I am here to help. For information on the program click here.
We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Mark it as an accepted solution!solution Icon
Community Icon
I am not a Comcast employee. I am a paying customer just like you!
I am an XFINITY Forum Expert and I am here to help.
We ask that you post publicly so people with similar questions may benefit.
Was your question answered? Mark it as an accepted solution!solution Icon
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I am not a Comcast employee.

Was your question answered?
Mark it as a solution!solution Icon

Frequent Visitor

Re: Stunningly poor IPv6 tech support - Modem in Bridge Mode for IPv6 assignment


ArrisTuska wrote:

This is NOT confirmed yet but it is looking more and more like it is a CMTS issue and not a DHCP server issue..  So if that would be the case then it woudnt be a Comcast issue but a ARRIS issue..  Once I get it confirmed I will point it out, I also need to confirm if this issue is on the latest code on the CMTS that is getting pushed out to the field shortly..

 

So those CM-MAC's you all have sent me is a great help; so far the only people that have seen this issue is on a E6000 and not the "other" CMTS..


Any update on this?  It appears to still not be working.

 

Thanks

New Poster

Re: Stunningly poor IPv6 tech support - Modem in Bridge Mode for IPv6 assignment

Having the same issue, DHCP packets arriving with zero hop limit at my Juniper SRX240 (which can't be set to ignore that). Am in Santa Cruz, California.

Contributor

Re: Stunningly poor IPv6 tech support - Modem in Bridge Mode for IPv6 assignment

Over a month since anyone heard a thing about this issue.

 

*TAP* *TAP* *TAP*.... is this microphone working?

 

Anyone?  Anyone?  Beuller?

Contributor

Re: Stunningly poor IPv6 tech support - Modem in Bridge Mode for IPv6 assignment

Since ArrisTuska has gone silent, can somone from Comcast please give an update?

Authorized Vendor

Re: Stunningly poor IPv6 tech support - Modem in Bridge Mode for IPv6 assignment


M0untainman wrote:

Since ArrisTuska has gone silent, can somone from Comcast please give an update?


I dont have much of an update just that we are looking into this..  I will ping some people on my side to see what we have seen so far..

-------------------------------------
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: Stunningly poor IPv6 tech support - Modem in Bridge Mode for IPv6 assignment

Sorry for going silent.  All of the posts were notifying my comcast email address - which I check maybe once a year - so I didn't know anybody else was following the post.

 

I've given up.   I just don't have the time, nor patience, to deal with Comcast "support".   Its like spending a 3 day weekend at the dentist having all of your teeth root canaled.... then finishing it up with a vasectomy chaser.

 

Good luck getting it to work - please post here if they ever remove their collective heads from their collective undercarriages. 

Frequent Visitor

Re: Stunningly poor IPv6 tech support - Modem in Bridge Mode for IPv6 assignment

Maybe I'll just start posting in #comcastcares on twitter how bad their IPv6 support is Smiley Happy

Frequent Visitor

Re: Stunningly poor IPv6 tech support - Modem in Bridge Mode for IPv6 assignment

Tried posting on twitter to #comcastcares #fail and lo and behold, an "engineer" wants to fix my IPv6 problem (he's an expert apparenly).

Gota give -TS credit for trying to help.  His suggestion that I reinstall my personal Arris modem was a bit weak, since I'm in bridge mode, but I went with it.  Unfortunately, the next day when I had time to switch modems, -JC picked up the DM thread.   He got the old modem up and running, and as soon as I verified that, indeed, DHCPv6 advertisement packets were being sent with a Hop Limit of zero, he vapor locked.   Told me it was a Cisco problem (asa-5515) and that they don't have the ability to help me.   After that, he just plain refused to respond.   Does Twitter tell you when you're blocked?   I'm pretty sure he blocked me. Smiley Happy  Not that it wasn't deserved - I had the audacity to explain that it was in fact an Xfinity problem and to ask for additional help.
Actual tweets from -JC:  

"My apologies, I was researching this and unfortunately, the ASA issue is beyond something we would be able to address or fix from here.-JC"

"understand unfortunately, this is not an issue we would be able to assist with further here if your internet is working properly.-JC".

 

No response after that... nothing.   #comcastdoesntgiveas***

 

Now even my tweets to #comcastcares go unresponded to.   If I have about 4-5 hours to kill tomorrow, I may call their tech support...  That's always good for a laugh - after I've pulled out my hair.

 

I'll try again later Smiley Happy