On May 14, 2010, at 11:57 AM, Christopher Morrow wrote: > On Fri, May 14, 2010 at 2:29 PM, Franck Martin <fra...@genius.com> wrote: >> I said somewhere in here... wierd quoting happened. >> On Thu, May 13, 2010 at 6:18 PM, Michael Ulitskiy <mulits...@acedsl.com> >> wrote: >>> Hello, >>> >>> We're in the early stage of planning ipv6 deployment - >>> learning/labbing/experimenting/etc. We've got to the point when we're >>> also planning to request initial ipv6 allocation from ARIN. >>> So I wonder what ipv6 transit options I have if my upstreams do not >>> support native ipv6 connectivity? >>> I see Hurricane Electric tunnel broker BGP tunnel. Is there anything >>> else? Either free or commercial? >> >> 1) see gblx/ntt/sprint/twt/vzb for transit-v6 >> 2) tunnel inside your domain (your control, your MTU issues, your >> alternate pathing of tunnels vs pipe) >> 3) don't tunnel beyond your borders, really just don't >> >> tunnels are bad, always. >> -chris >> >> I see so many times, that tunnels are bad for IPv6, but this is the way IPv6 >> has been designed to work when you >> cannot get direct IPv6. So I would not say tunnels are bad, but direct IPv6 >> is better (OECD document on IPv6 >> states the use of tunnels). > > Tunnels promote poor paths, they bring along LOTS of issues wrt PMTUD, > asymmetry of paths, improper/inefficient paths (see example paths from > several ripe preso's by jereon/others), longer latency. If the tunnel > exits your border you can't control what happens and you can't affect > that tunnels performance characteristics. it's 2010, get native v6. > I will point out that most of these issues apply to 6to4 and Teredo auto- tunnels and not as much to GRE or 6in4 statically configured tunnels.
There is a juniper bug which makes PMTU-D a problem if your tunnel is Juniper<->Juniper. >> If the issue with tunnel is MTU, then a non-negligible part of IPv4 does not >> work well with MTU different of 1500. >> With IPv6 we bring the concept of jumbo packets, with large MTU. If we >> cannot work with non standard MTUs in >> IPv6 tunnels, how will we work with jumbo packets? > > a non-negligible part of the ipv6 internet doesn't work at all with >> 1280 mtu... due to tunnels and some other hackery :( jumbo packets > are a fiction, everyone should stop 10 years ago believing they will > ever work end-to-end between random sites. > Jumbo packets do work end to end in some random cases and PMTU-D works in most others. All of the tunnels I am using have at least a 1280 MTU, so, I'm not sure why you would think a tunnel wouldn't support 1280. Owen
