New Member
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Registered: ‎04-09-2013
Solutions: 1

DHCPv6-PD, Comcast Business, Netgear CG3000DCR temporary working config

Dual-Stack for Comcast Business subscribers has been enabled on the SMC D3G (though I haven't seen anybody make it work, yet, another story) as well as the Netgear CG3000DCR. I am using the latter modem.

 

I am also on an ERPro-8, version 1.6.0. eth0 is WAN, eth1 is LAN, no other interfaces connected.

 

On the WAN interface I have:

dhcpv6-pd {
    pd 1 {
        interface eth1 {
            service slaac
        }
        prefix-length 60
    }
    rapid-commit enable
}

 

What I am seeing - upon initial boot, everything looks fine. Both the router and clients inside the LAN get addresses within a /64 subnet, connectivity is great to ipv6 endpoints.

 

After the first dhcp6c RENEW, there is no connectivity anywhere. So this is about 30 minutes after booting.

  • Clients still have their IPv6 addresses and they do not change
  • Router still has the same WAN and LAN IPv6 addresses, unchanged
  • radvd is still running on the router and new clients will get addresses just fine
  • dhcp6c.log indicates:
Nov/19/2014 23:40:08: ifaddrconf: failed to add an address on eth0: File exists
Nov/19/2014 23:40:08: update_ia: failed to update an address (router_wan_address_here)
  •  The router still has a default v6 route that is unchanged:
default via fe80::6a1:51ff:fe07:629a dev eth0  proto ra  metric 1024  expires 1799sec

 

traceroute6 indicates destination net unreachable, 1 hop past the EdgeRouter. Same story from the router itself, being stopped cold at the modem it seems.

 

I want to separate this issue and find out if it is the Netgear/Comcast, or the EdgeRouter. Sadly I don't have another router, or modem, to try.

 

I CAN try connecting a client to the Netgear's switch, and allowing it to just DHCP everything. I will give that a go.

 

Outside of that test, how can I debug this? What data is useful?

 

Established Member
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Registered: ‎12-10-2009
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Solutions: 16

Re: DHCPv6-PD, Comcast Business, Netgear CG3000DCR temporary working config

As i said in the previous post, I would check routing INTO you lan delagation from an outside source.

 

I suspect that routing is torn down at dhcp renewal.  Why would be a different matter!!! And you may need to speak to comcast.

 

You talked about your next hop being your modem (previously),  I think this is strange.  I would have thougth that your modem should be transparent bridge and your next hop should br a comcast router on the internet.

 

Mark 

New Member
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Registered: ‎04-09-2013
Solutions: 1

Re: DHCPv6-PD, Comcast Business, Netgear CG3000DCR temporary working config

Thanks Mark (again).

 

Comcast provides me with a /56.

The Netgear takes a /64 derived from this, and uses it for devices attached directly to it.

 

I now have a plain Windows machine wired to the Netgear modem. So this client has an address in the Netgear's /64.

 

The EdgeRouter has been rebooted and has its own /64, separate from the Netgear.

 

Indeed under normal conditions my route is:

LAN client -> LAN address of router in /64 space -> 2001:558:4082:37::1

 

The default IPv6 route, on the router according to show ipv6 route is

K>* ::/0 via fe80::6a1:51ff:fe07:aabb, eth0

 show ipv6 neighbors

fe80::6a1:51ff:fe07:aabb dev eth0 lladdr 04:a1:..... router REACHABLE

 

..I can correlate this MAC and lladdr to my cable modem. So indeed it is not as transparent as we would like it to be. This is expected for Comcast Business actually - there is truthfully no concept of a bridged modem, when you have static IPv4 service. Some would say otherwise, I have not seen it work under these specific conditions.

 

I have continuous ping to 2001:558:4082:37::1 going now from my LAN behind the EdgeRouter.

 

I also have it going from my test client.

 

Luckily my work has a fairly robust IPv6 network so I am going to try pinging INBOUND as you suggest.

Established Member
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Solutions: 16

Re: DHCPv6-PD, Comcast Business, Netgear CG3000DCR temporary working config

Googling comcast and both your old modem and the netgear, apparently you have to ask comcast to enbale TRUE bridge mode on the service.  There is a pseudo bridge mode by disabling dhcp, NAT and firewall but that would not solve all issues.

 

If the netgear is already stripping off ranges from the full prefix then you will have issues with trying to run PD on the ERL.

 

The SMC may be easier to work with once they have put it in full bridge mode.  From the sound of it not all comcast engineers know how to do this.

 

Mark

 

 

New Member
Posts: 20
Registered: ‎04-09-2013
Solutions: 1

Re: DHCPv6-PD, Comcast Business, Netgear CG3000DCR temporary working config

The wrench thrown into this is static IPv4 addresses. If you have a static block, you cannot do what is called "True Bridge Mode", the modem acts as router for your static block. You are also required to lease equipment from Comcast when you have static addresses, otherwise, I would definitely own my own gear.

New Member
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Registered: ‎04-09-2013
Solutions: 1

Re: DHCPv6-PD, Comcast Business, Netgear CG3000DCR temporary working config

[ Edited ]

A little over 2 hours in and still working, this is a first. I have ICMP flying in and out from multiple sources, none missing a beat yet. Strange. Will keep 'em going.

 

edit=OK, about 5 hours after booting the Netgear it is no longer routing IPv6 traffic. Pings inbound/outbound from all nodes stopped at the same time

 

show ipv6 neighbors

fe80::6a1:51ff:fe07:aabb dev eth0 lladdr 04:a1:... router DELAY

 

Rebooting the Netgear modem restores traffic, so I'll follow up with Comcast, think I have pretty good evidence at this point that the EdgeRouter is not doing anything wrong.

 

Member
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Re: DHCPv6-PD, Comcast Business, Netgear CG3000DCR temporary working config

I am having the same issue; yet dont seem like comast issue.. the EdgeRouter still maintains IPv6 native connectivity, it can ping both internet IPv6's and LAN IPv6's, its just the LAN devices can no longer reach the internet via IPv6 after some time.

 

Comcast Business 75/15 w/Netgear Business Router

New Member
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Registered: ‎04-09-2013
Solutions: 1

Re: DHCPv6-PD, Comcast Business, Netgear CG3000DCR temporary working config

I worked around this by replacing the Netgear business gateway with my own Motorola SB6141. In that process I had to also ditch IPv4 static addresses, but I have had a /56 delegated to me since the new modem got turned up.

 

In case anyone is mulling over this same action, for DNS, I went with ZoneEdit, and the EdgeRouter interaction with its API is just perfect. Had no issues since the switch. If you do not have absolute need for multiple routable v4 addresses I would heavily consider going this direction.

Member
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Registered: ‎06-18-2013
Kudos: 101
Solutions: 4

Re: DHCPv6-PD, Comcast Business, Netgear CG3000DCR temporary working config

thanks for the reply.. unfortunately I cant ditch the static IP's.. I host several servers in-house and it'd cost alot more to move them out to a local datacenter than it costs for business internet.

 

I'll live w/out IPv6 before I give up my /28

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Registered: ‎07-28-2012
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Solutions: 2

Re: DHCPv6-PD, Comcast Business, Netgear CG3000DCR temporary working config

[ Edited ]

This looks alot like the problem i am having, with a different ISP (Canal Digital, Norway)

I am not sure if i lose connectivity on the FIRST renew, but it is definitely related to the renew happening.

 

Same symptoms as the thread starter, everything seeming great (all clients have IPv6es), but just no traffic goes out or in from the ISP on that prefix. The Edgerouter itself is still pinging from its eth1 linknet-address tho, so it's just the PD that stops working.

 

So i guess it means IPv6 works great (from the edgerouter), but the PD doesnt work for very long.. If i restart dhcp6c it works for a while and then goes away again.

 

This just doesn't look healthy?

 

Dec/06/2014 20:27:45: client6_recvadvert: unexpected advertise
Dec/06/2014 20:27:46: update_ia: T1(900) and/or T2(1440) is locally determined
Dec/06/2014 20:27:46: update_ia: T1(900) and/or T2(1440) is locally determined
Dec/06/2014 20:42:46: ifaddrconf: failed to add an address on eth1: File exists
Dec/06/2014 20:42:46: update_ia: failed to update an address 2001:466f:f000:a:e2ad:c1a5:a71f:cfbf
Dec/06/2014 20:42:46: update_ia: T1(900) and/or T2(1440) is locally determined
Dec/06/2014 20:42:46: update_ia: T1(900) and/or T2(1440) is locally determined
Dec/06/2014 20:57:46: client6_recvadvert: unexpected advertise
Dec/06/2014 20:57:46: update_ia: T1(900) and/or T2(1440) is locally determined
Dec/06/2014 20:57:47: update_ia: T1(900) and/or T2(1440) is locally determined
Dec/06/2014 21:12:46: update_ia: T1(900) and/or T2(1440) is locally determined
Dec/06/2014 21:12:47: ifaddrconf: failed to add an address on eth1: File exists
Dec/06/2014 21:12:47: update_ia: failed to update an address 2001:466f:f000:a:e2ad:c1a5:a71f:cfbf
Dec/06/2014 21:12:47: update_ia: T1(900) and/or T2(1440) is locally determined
Dec/06/2014 21:27:47: update_ia: T1(900) and/or T2(1440) is locally determined
Dec/06/2014 21:27:47: client6_recvadvert: unexpected advertise
Dec/06/2014 21:27:48: update_ia: T1(900) and/or T2(1440) is locally determined
Dec/06/2014 21:42:47: update_ia: T1(900) and/or T2(1440) is locally determined
Dec/06/2014 21:42:48: ifaddrconf: failed to add an address on eth1: File exists
Dec/06/2014 21:42:48: update_ia: failed to update an address 2001:466f:f000:a:e2ad:c1a5:a71f:cfbf
Dec/06/2014 21:42:48: update_ia: T1(900) and/or T2(1440) is locally determined
Dec/06/2014 21:57:47: update_ia: T1(900) and/or T2(1440) is locally determined
Dec/06/2014 21:57:49: client6_recvadvert: unexpected advertise
Dec/06/2014 21:57:50: update_ia: T1(900) and/or T2(1440) is locally determined
Dec/06/2014 22:12:47: update_ia: T1(900) and/or T2(1440) is locally determined
Dec/06/2014 22:12:50: ifaddrconf: failed to add an address on eth1: File exists
Dec/06/2014 22:12:50: update_ia: failed to update an address 2001:466f:f000:a:e2ad:c1a5:a71f:cfbf
Dec/06/2014 22:12:50: update_ia: T1(900) and/or T2(1440) is locally determined
Dec/06/2014 22:27:47: update_ia: T1(900) and/or T2(1440) is locally determined
Dec/06/2014 22:27:51: client6_recvadvert: unexpected advertise
Dec/06/2014 22:27:52: update_ia: T1(900) and/or T2(1440) is locally determined
Dec/06/2014 22:42:48: update_ia: T1(900) and/or T2(1440) is locally determined
Dec/06/2014 22:42:52: ifaddrconf: failed to add an address on eth1: File exists
Dec/06/2014 22:42:52: update_ia: failed to update an address 2001:466f:f000:a:e2ad:c1a5:a71f:cfbf
Dec/06/2014 22:42:52: update_ia: T1(900) and/or T2(1440) is locally determined
Dec/06/2014 22:57:48: update_ia: T1(900) and/or T2(1440) is locally determined
Dec/06/2014 22:57:52: client6_recvadvert: unexpected advertise
Dec/06/2014 22:57:53: update_ia: T1(900) and/or T2(1440) is locally determined
Dec/06/2014 23:12:48: update_ia: T1(900) and/or T2(1440) is locally determined
Dec/06/2014 23:12:53: ifaddrconf: failed to add an address on eth1: File exists
Dec/06/2014 23:12:53: update_ia: failed to update an address 2001:466f:f000:a:e2ad:c1a5:a71f:cfbf
Dec/06/2014 23:12:53: update_ia: T1(900) and/or T2(1440) is locally determined
Dec/06/2014 23:27:48: update_ia: T1(900) and/or T2(1440) is locally determined
Dec/06/2014 23:27:53: client6_recvadvert: unexpected advertise
Dec/06/2014 23:27:54: update_ia: T1(900) and/or T2(1440) is locally determined
Dec/06/2014 23:42:48: update_ia: T1(900) and/or T2(1440) is locally determined
Dec/06/2014 23:42:54: ifaddrconf: failed to add an address on eth1: File exists
Dec/06/2014 23:42:54: update_ia: failed to update an address 2001:466f:f000:a:e2ad:c1a5:a71f:cfbf
Dec/06/2014 23:42:54: update_ia: T1(900) and/or T2(1440) is locally determined
Dec/06/2014 23:57:49: update_ia: T1(900) and/or T2(1440) is locally determined
Dec/06/2014 23:57:55: client6_recvadvert: unexpected advertise
Dec/06/2014 23:57:56: update_ia: T1(900) and/or T2(1440) is locally determined

 

Member
Posts: 205
Registered: ‎06-18-2013
Kudos: 101
Solutions: 4

Re: DHCPv6-PD, Comcast Business, Netgear CG3000DCR temporary working config

yeah im getting much the same errors as you

 

Spoiler

Dec/08/2014 22:29:48: ifaddrconf: failed to add an address on eth0: File exists

Dec/08/2014 22:29:48: update_ia: failed to update an address 2601:1:8d01:5e00::1

Dec/08/2014 22:44:48: ifaddrconf: failed to add an address on eth0: File exists

Dec/08/2014 22:44:48: update_ia: failed to update an address 2601:1:8d01:5e00::1

Dec/08/2014 23:14:48: ifaddrconf: failed to add an address on eth0: File exists

Dec/08/2014 23:14:48: update_ia: failed to update an address 2601:1:8d01:5e00::1

Dec/08/2014 23:29:48: ifaddrconf: failed to add an address on eth0: File exists

Dec/08/2014 23:29:48: update_ia: failed to update an address 2601:1:8d01:5e00::1

Dec/08/2014 23:44:49: ifaddrconf: failed to add an address on eth0: File exists

Dec/08/2014 23:44:49: update_ia: failed to update an address 2601:1:8d01:5e00::1

Dec/09/2014 00:14:49: ifaddrconf: failed to add an address on eth0: File exists

Dec/09/2014 00:14:49: update_ia: failed to update an address 2601:1:8d01:5e00::1

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Re: DHCPv6-PD, Comcast Business, Netgear CG3000DCR temporary working config

But is it working?  I think that messages just means I'm trying to set address X, but address X is already set on that interface.

EdgeMAX Router Software Development
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Re: DHCPv6-PD, Comcast Business, Netgear CG3000DCR temporary working config

no its not working, unless I restart dhcp6c then it works for ~15mins.. not really logging anything when its working, and then all subnets loose IPv6 connectivity and these errors start appearing.

 

The router still has IPv6 connectivity upstream and the router can also reach devices on all the subnets via IPv6, its simply no longer doing any routing between the two after the first renewal. 

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Re: DHCPv6-PD, Comcast Business, Netgear CG3000DCR temporary working config

One thing you could try to do is run dhcp6c forground with debug enabled to see if there are any additional error messages when it stops working after 15 minutes.  To run forground, first find and kill the exsisting daemon:

ubnt@ubnt:~$ ps aux | grep dhcp6c
root      1272  0.3  0.1   2208   856 ttyS0    S+   11:17   0:00 /usr/sbin/dhcp6c -c /var/run/dhcp6c-eth0-pd.conf -p /var/run/dhcp6c-eth0-pd.pid -df eth0
ubnt      1295  0.0  0.1   2388   588 ttyS0    S+   11:17   0:00 /bin/busybox grep dhcp6c

ubnt@ubnt:~$ sudo kill 1272

 Then copy the command line above and add a 'D' such as:

ubnt@ubnt:~$ sudo /usr/sbin/dhcp6c -c /var/run/dhcp6c-eth0-pd.conf -p /var/run/dhcp6c-eth0-pd.pid -dDf eth0

Jun/01/2014 11:20:44: get_duid: extracted an existing DUID from /var/lib/dhcpv6/dhcp6c_duid: 00:01:00:01:1b:1d:c8:3f:dc:9f:db:17:13:8c
Jun/01/2014 11:20:44: cfdebug_print: <3>comment [# This file was auto-generated by /opt/vyatta/sbin/dhcpv6-pd-client.pl] (70)
Jun/01/2014 11:20:44: cfdebug_print: <3>comment [# configuration sub-system.  Do not edit it.] (44)
Jun/01/2014 11:20:44: cfdebug_print: <3>[interface] (9)
Jun/01/2014 11:20:44: cfdebug_print: <5>[eth0] (4)
Jun/01/2014 11:20:44: cfdebug_print: <3>begin of closure [{] (1)
Jun/01/2014 11:20:44: cfdebug_print: <3>[send] (4)
Jun/01/2014 11:20:44: cfdebug_print: <3>[ia-na] (5)
Jun/01/2014 11:20:44: cfdebug_print: <3>[0] (1)

 

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Re: DHCPv6-PD, Comcast Business, Netgear CG3000DCR temporary working config

[ Edited ]

by the time I got arround to testing this further the problem had resolved its self, I presume Comcast made some changes on there end because I left it in a broken state and noticed it had been working fine for an unknown time.

 

the config originally posted now seems to work without trouble on Comcast Business w/Static IPs, though IPv6 speeds leave alot to be desired:

SpeedTest

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Posts: 1
Registered: ‎02-16-2015

Re: DHCPv6-PD, Comcast Business, Netgear CG3000DCR temporary working config

Checking for ongoing issues with Comcast IPv6 & IPv4 and their provided Netgear CG3000DCR DOCSIS 3.0 Commercial Cable Modem and Router.

 

My Comcast Business service is supposed to be 150/20 without any static IPs.

I note consistent difference between IPv4 & IPv6

Comcast Speedtest

I am not a network technician, but it would seem that Comcast should be giving me the same class of service over both, as not eveyone is on IPv6.  

 

The above in addition to the general instability of my service with Comcast.

Your thoughts on this matter will be appreciated.