IPv6 Prefix on Fiber

[David92]

Is there a way to get a larger prefix than /64 on IPv6 over fiber? I'm trying to figure out if it's something on my end or if it is even supported?

There are many posts all over where other people make reference to using a /56 prefix without issue. Is this something that is only partly implemented and it depends on where you are?

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[-G-]

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@mozerd wrote:

It now looks like Rogers is allowing a mix of /PD's and I am wondering how does Rogers determine who gets what? Depending on your Gateway Model assigned to your account capabilities My speculation is that its selectable ... i.e. if you do not request a PD you might get a /60 but if do request a /56 THROUGH the CLIENT Prefix Hint request - that's what you will get ... 

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First, we are talking about at least 3 different scenarios.

In the most basic case, which probably applies to 99.999% of the people out there, they either run their home networks on Rogers-provided gear or buy a consumer router that only supports a single subnet on the firewall's internal (Wi-Fi + Ethernet) LAN segment.  For those, they request an IPv6 address and /64 PD and (almost certainly) get a /64 PD which, in turn, gets allocated to the internal LAN.

Another thing, that just started happening very recently, is that the Xfinity Gateway now requests something other than a /64 PD.  I have access to an XB6, XB7 and XB8 Gateway and have seen all three obtain a /56 PD in my area.  Why?  I don't know.  Rogers must have plans that require the delegation of additional address space internally.   It might be to support a new service.  It might be to allow another router to connect to the Gateway's internal LAN and request a /64 PD of its own.  Rogers won't say.

As for why some customer's Xfinity Gateways are getting a /60 PD rather than a /56?  It could be because they request a /56 but a /60 is the largest address pool that is available.  It could be a revised provisioning template that specifically requests a /60.  If Rogers only requires a /60 PD not a /56, they why burn through 16 times the address space over and above the amount that goes to waste when requesting a /60?

Then there is the remaining 0.001% that have more advanced networking needs.  Request whatever size PD makes sense for you.  What you get depends on what is available in the address pool.

Why is this a secret? And Why is the Rogers Network not consistent <> FTTH still does not get a PD - shame shame Shame

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It's an implementation issue.  If Rogers has plans that require the Xfinity Gateway to obtain a larger PD than the /64 it has been requesting for years, it will be possible for FTTH customers' equipment to request this in time.  I get the sense that this change is coming, which is why I asked FTTH customers to check whether their Xfinity Gateways are now behaving differently.

As for why?  Rogers implements IPv6 on their wireless, DOCSIS and XGS-PON networks differently.  Most service providers don't implement a consistent architecture across all of their services.  I have been part of developing various reference architectures in my consulting days... and every so often when a telecom or service provider's infrastructure becomes too complex to maintain and their service lifecycle management becomes too onerous, they will finally implement transformation initiatives.  Otherwise, as they grow through mergers and acquisitions, or add new services organically in an ad-hoc manner, they end up with multiple internal architectures that are difficult to manage, and OSS and BSS systems that are not well integrated and/or that limit deployment models.

[-G-]

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@JKnott wrote:

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I've been running pfSense for my firewall/router for over 8 years.  Initially, Rogers provided only a single /64.  However, after they started providing a /56, I was able to select the prefix size I wanted.  As for who gets what, after the initial assignment, your DUID is used to identify what prefix you had been assigned.

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Yes.  Ideally, you do not want the IPv6 address space that you obtain or the size of the PD to change.  There are various ways that service provider gear can maintain that binding, and the DUID is usually part of that.

If you successfully obtain a /56 PD, you should be able to continue to do so for the foreseeable future.  However, it also depends on whether the CPE device has a stable DUID.  You can also always request a smaller PD, if you should ever desire to do so.

[JKnott]

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@-G- wrote:

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As for why?  Rogers implements IPv6 on their wireless, DOCSIS and XGS-PON networks differently.

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I can understand why they'd provide only a single /64 to a cell phone.  However, they're also selling wireless Internet.  I'd hope they'd provide a bigger prefix for that.

[mozerd]

Lets go back to techincal basics and Rogers Gateway in BRIDGE mode:

Your router sends a DHCPv6 solicitation message to your ISPs DHCPv6 server, in which it can request options (»datatracker.ietf.org/doc ··· ction-21) like DNS, desired prefix lenght for delegation; and identify itself [DUID], which consists of two parts: Address Assignment for the on-link address, and Prefix Delegation for its own prefix(es). (»datatracker.ietf.org/doc ··· 2)Within this message, the client can request a specific prefix length for delegation. My router is set to request a /64 and a /56. If your desired prefix length is honored depends on the size your requested prefix, how your ISP allocates its prefixes ...

Following this message, your ISPs DHCPv6 servers actions may vary, as there are various options on how to decide which prefix to delegate. The RFC (»datatracker.ietf.org/doc ··· ion-13.3) states:

"The mechanism through which the server selects prefix(es) for delegation is not specified in this document. Examples of ways in which the server might select prefix(es) for a client include static assignment based on subscription to an ISP, dynamic assignment from a pool of available prefixes, and selection based on an external authority such as a RADIUS server using the Framed-IPv6-Prefix optionas described in [RFC3162]."