4 ms·

Here in Baltimore County, Maryland, Comcast provides my cable modem an IPv4 and IPv6 address. Is that unusual? I'm not sure, but I think Time Warner in New York

Here in Baltimore County, Maryland, Comcast provides my cable modem an IPv4 and IPv6 address. Is that unusual? I'm not sure, but I think Time Warner in New York also allocated IPv6.

ocdtrekkie 5y ago
To my knowledge, actually, by default, Comcast solely provides IPv6 by default... but then if you plug in a device that requires (or is configured to require) IPv4, it'll give you an IPv4 address. During the transition, I'd occasionally find weird things would spontaneously break on consumer PCs, like old Office Click-to-Run versions which didn't support IPv6, and then discover the user no longer had an IPv4 address. Usually happens if the customer's computers connect to the Comcast gateway directly. If they have their own router, it usually gets an IPv4 address.
- throaway46546 5y ago
  Not giving users who connect to the gateway directly a v4 address seems like a decent security feature.
  - ocdtrekkie 5y ago
    That is probably just a side benefit. Your two largest ISPs pushing IPv6 are Verizon and Comcast, because they're also (including wireline and mobile) the largest ISPs. The number of IPv4 addresses they'd need to meet their customers needs would be astronomical if they didn't find any excuse to go IPv6 only where possible.
- ArchOversight 5y ago
  Comcast is dual stack, and will hand out IPv6 and IPv4. There are times when their IPv4 DHCP server is slow or seems to be out to lunch though, and during that time you might get IPv6 only.
mindcrime 5y ago
AIUI, Time Warner had rolled out ipv6 pretty widely before the merger and becoming Spectrum. I have had native dual-stack ipv4/ipv6 from TWC/Spectrum for several years now, in the RTP, NC area.
technofiend 5y ago
Comcast will hand you the smallest routable ipv6 network (/64) by default, however people have had varying success with prefix delegation hints to get larger address spaces. Without passing judgement on a) medium.com articles, b) Comcast or c) pfsense here is an article that covers making IPV6 work in that specific instance. https://circuitguy.medium.com/home-network-virtualized-pfsense-install-f9f3279db446 https://circuitguy.medium.com/home-network-virtualized-pfsen... - Worst case scenario someone can take this and adapt it to opnsense or their OS of choice.
- Akronymus 5y ago
  Better than getting cgnat'ed with a ipv6 address. Mind the address, not address range.
- ArchOversight 5y ago
  Comcast will happily hand out a prefix delegation larger than a /64 if you ask for it, and set the prefix delegation request to 1 instead of 0. This is done because many routers were built with bad IPv6 support that requested a /48 even though they only needed a single /64 for a LAN and Comcast was handing out /60's (their largest size) like candy with almost no use. So my config was to request two prefix delegation, one tagged 0, which would always get a /64, and then one tagged 1 which would get a /60. Not sure if you still can do it or not, but at one point you could continue to ask for prefix delegations (/60's) and get even more address space. Here's the dhcp6c.conf: interface em0 { send ia-pd 0; send ia-pd 1; send ia-na 1; }; id-assoc pd 0 { prefix ::/64 infinity; prefix-interface lagg0 { sla-id 0; sla-len 0; }; }; id-assoc pd 1 { prefix ::/60 infinity; prefix-interface vlan10 { sla-id 1; sla-len 4; }; prefix-interface vlan11 { sla-id 2; sla-len 4; }; prefix-interface vlan20 { sla-id 3; sla-len 4; }; prefix-interface vlan21 { sla-id 4; sla-len 4; }; prefix-interface vlan22 { sla-id 5; sla-len 4; }; }; id-assoc na 1 { }; Note: ia-pd 0 will only ever pull a /64, even if you ask for a /60 all you'll ever get back is a /64. ia-pd 1 on the other hand will allow you to pull anywhere from a /64 to a /60. Yes, this means you get 16 + 1 /64's to use. On top of that I pull a single /128 for the external interface of my router.

Here in Baltimore County, Maryland, Comcast provides my cable modem an IPv4 and IPv6 address. Is that unusual? I'm not sure, but I think Time Warner in New York also allocated IPv6.

ocdtrekkie 5y ago

To my knowledge, actually, by default, Comcast solely provides IPv6 by default... but then if you plug in a device that requires (or is configured to require) IPv4, it'll give you an IPv4 address. During the transition, I'd occasionally find weird things would spontaneously break on consumer PCs, like old Office Click-to-Run versions which didn't support IPv6, and then discover the user no longer had an IPv4 address. Usually happens if the customer's computers connect to the Comcast gateway directly. If they have their own router, it usually gets an IPv4 address.

throaway46546 5y ago
Not giving users who connect to the gateway directly a v4 address seems like a decent security feature.
- ocdtrekkie 5y ago
  That is probably just a side benefit. Your two largest ISPs pushing IPv6 are Verizon and Comcast, because they're also (including wireline and mobile) the largest ISPs. The number of IPv4 addresses they'd need to meet their customers needs would be astronomical if they didn't find any excuse to go IPv6 only where possible.
ArchOversight 5y ago
Comcast is dual stack, and will hand out IPv6 and IPv4. There are times when their IPv4 DHCP server is slow or seems to be out to lunch though, and during that time you might get IPv6 only.

mindcrime 5y ago

AIUI, Time Warner had rolled out ipv6 pretty widely before the merger and becoming Spectrum. I have had native dual-stack ipv4/ipv6 from TWC/Spectrum for several years now, in the RTP, NC area.

technofiend 5y ago

Comcast will hand you the smallest routable ipv6 network (/64) by default, however people have had varying success with prefix delegation hints to get larger address spaces. Without passing judgement on a) medium.com articles, b) Comcast or c) pfsense here is an article that covers making IPV6 work in that specific instance. https://circuitguy.medium.com/home-network-virtualized-pfsense-install-f9f3279db446 https://circuitguy.medium.com/home-network-virtualized-pfsen... - Worst case scenario someone can take this and adapt it to opnsense or their OS of choice.

Akronymus 5y ago
Better than getting cgnat'ed with a ipv6 address. Mind the address, not address range.
ArchOversight 5y ago
Comcast will happily hand out a prefix delegation larger than a /64 if you ask for it, and set the prefix delegation request to 1 instead of 0. This is done because many routers were built with bad IPv6 support that requested a /48 even though they only needed a single /64 for a LAN and Comcast was handing out /60's (their largest size) like candy with almost no use. So my config was to request two prefix delegation, one tagged 0, which would always get a /64, and then one tagged 1 which would get a /60. Not sure if you still can do it or not, but at one point you could continue to ask for prefix delegations (/60's) and get even more address space. Here's the dhcp6c.conf: interface em0 { send ia-pd 0; send ia-pd 1; send ia-na 1; }; id-assoc pd 0 { prefix ::/64 infinity; prefix-interface lagg0 { sla-id 0; sla-len 0; }; }; id-assoc pd 1 { prefix ::/60 infinity; prefix-interface vlan10 { sla-id 1; sla-len 4; }; prefix-interface vlan11 { sla-id 2; sla-len 4; }; prefix-interface vlan20 { sla-id 3; sla-len 4; }; prefix-interface vlan21 { sla-id 4; sla-len 4; }; prefix-interface vlan22 { sla-id 5; sla-len 4; }; }; id-assoc na 1 { }; Note: ia-pd 0 will only ever pull a /64, even if you ask for a /60 all you'll ever get back is a /64. ia-pd 1 on the other hand will allow you to pull anywhere from a /64 to a /60. Yes, this means you get 16 + 1 /64's to use. On top of that I pull a single /128 for the external interface of my router.