Thursday, 25 August 2011

IPv6 routers: Thomson step up their game

We have something of a race on to get a working, entry level, IPv6 DSL router, and we are today one step closer.

Thomson ("IPv6 Ready") do have some test s/w on one of their routers (yes, the high end one, grrr) and testing today has gone well - it works! This bodes well for the small (technicolor) router having working IPv6 soon as it is the same base s/w. Thanks to the man from Thomson for driving to see us today.

But will they beat zoom or zyxel? Who knows. We are still testing.

Now, for the technical bit. This is not done using PPP (why why why why why) but using RA and DHCPv6. It seems the Billions cope perfectly well without any RA even in response to a router solicitation. However the Thomson expects an answer to a router solicitation. What is worse is it does fully honour the lifetime setting sent. This has a max time of 18 hours, so we are having to send periodic router announcements to keep the router working. Frustrating, but according to spec I suppose. We need this in PPP really.

Needless to say the FireBrick FB6202 LNS handles all this, and we have a Thomson working on our test LNS right now - yay!

So, the race is still on.

7 comments:

  1. "This is not done using PPP (why why why why why)"

    Because, Despite the rumors, the people that do this stuff just haven't a sodding clue!

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  2. Have you checked out TP-Link? they are dirt cheap and support ipv6 if you flash them with dd-wrt. They can also do cool things like run asterisk.

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  3. As we have said before, many times, there are ways to re-flash many boxes to do this - but we are looking for a simple, out of the box, cheap, DSL router to provide with the service that can be used easily be both techies and non techies alike.

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  4. Rev/Jason,

    The decision behind not doing assignment of Global IPv6 addressing via PPP is one of timing; back in the mists of time, there was no such thing as link-local addresses and PPP was the only mechanism available to negotiate an IPv4 address during connection setup.

    IPCP via PPP (what the Rev is talking about and that I describe above) and DHCP.

    In an attempt to simplify address assignment across Ethernet and PPP, the folks who came up with the RFC decided that the only addressing-related thing which should be negotiated over PPP would be the link-local address.

    (technically, the link-local address isn't even negotiated, the PPP server simply offers IPv6 as part of the session setup and the PPP client either ignores the advertisement - because it has no knowledge of IPv6 - or says, "Yes, I can do IPv6" - with the PPP server sticking a link-local address on its' side of the link and expecting the PPP client at the other end to do exactly the same thing)

    The idea was that once you have a link-local address, you can receive router advertisements and can also communicate with an upstream DHCPv6 server - just as you can on an Ethernet-based network.

    It does sort of make sense once you twist your head around to their way of thinking, it means that attributes which would have been handed out via PPP such as nameservers, NTP servers, etc can be handed out via DHCP akin to their Ethernet brethren.

    Unfortunately, there are some design issues with the use of RA on the WAN-side of an ADSL router; notably, the ISP chooses the first 64 bits of the address but the client is free to choose the latter 64 bits of the address and there is no way for the ISP to influence this.

    So, you can't assign all your IPv6 users with an address out of the same /64 for the WAN side of their router; someone could easily spoof their address to that of another subscriber and cause the equivalent of an IPv4 address conflict - which is why we assign a unique /64 to each of our users' WAN interfaces and a /48 routed over the PPP link; only way to avoid that scenario.

    I think it is clear for now that any ISP which claims full IPv6 support must ensure they are sending RAs and also replying to DHCPv6 requests with sane attributes; only when that doesn't work should we blame the RFC folks.

    As I re-iterated to the Rev in a private mail, the current IPv6 router situation is rather dire and the standards, while somewhat questionable when viewed from certain angles, do leave something to be desired.

    Rev: I plan on attending the January 2012 UKNOF and would love to bash heads and compare notes with you on this topic.

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  5. See the BBF's TR-124i2 for more details on what's required by the standards:
    http://www.getipv6.info/index.php/Broadband_CPE#Standards_and_Standard_Organizations
    Page 90 seems to suggest that the WAN ought to send an Router Solicitation.

    Incidentally, I test the ZyXEL VSG-1432 in routed mode on our VDSL2 access vendor's beta IPv6 code and it worked.

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  6. My Fritz!box 7390 has just had a firmware update (not beta) and seems to work now

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