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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 ad

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.
- technofiend 5y ago
  Excellent! An informative post with examples. Thank you very much. I look forward to trying this.
- Dylan16807 5y ago
  Is there a problem with handing out /60s like candy? A /48 isn't even unreasonable as a baseline, and personally I'd say home users should always get at least /56 if they want it.
  - ArchOversight 5y ago
    Comcast used to provide /56's but they tightened that down to just a /60. I personally don't think there is an issue with handing out /60's like candy, but I am not Comcast and can't speak for their network engineering team which made the decisions they made for their millions of customers.

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.

technofiend 5y ago
Excellent! An informative post with examples. Thank you very much. I look forward to trying this.
Dylan16807 5y ago
Is there a problem with handing out /60s like candy? A /48 isn't even unreasonable as a baseline, and personally I'd say home users should always get at least /56 if they want it.
- ArchOversight 5y ago
  Comcast used to provide /56's but they tightened that down to just a /60. I personally don't think there is an issue with handing out /60's like candy, but I am not Comcast and can't speak for their network engineering team which made the decisions they made for their millions of customers.