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Author Topic: Comcast IPv6  (Read 8776 times)

jimb

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Comcast IPv6
« on: October 25, 2010, 11:23:14 PM »

So...

I have Comcast internet now.  I'm still using HE as my IPv6 tunnel provider, but today I gave Comcast's 6RD service a try.  My results were somewhat surprising, with pings to www.kame.net being slower through 6RD than through HE's 6in4 tunnel.

Comcast 6RD:
PING www.kame.net(2001:200:dff:fff1:216:3eff:feb1:44d7) 56 data bytes
64 bytes from 2001:200:dff:fff1:216:3eff:feb1:44d7: icmp_seq=1 ttl=47 time=231 ms
64 bytes from 2001:200:dff:fff1:216:3eff:feb1:44d7: icmp_seq=2 ttl=47 time=236 ms
64 bytes from 2001:200:dff:fff1:216:3eff:feb1:44d7: icmp_seq=3 ttl=47 time=236 ms
64 bytes from 2001:200:dff:fff1:216:3eff:feb1:44d7: icmp_seq=4 ttl=47 time=250 ms
64 bytes from 2001:200:dff:fff1:216:3eff:feb1:44d7: icmp_seq=5 ttl=47 time=251 ms

--- www.kame.net ping statistics ---
5 packets transmitted, 5 received, 0% packet loss, time 4016ms
rtt min/avg/max/mdev = 231.683/241.382/251.609/8.037 ms


Remove the route through 6RD interface:
{root@gtoojimb/pts/2}~# ip -6 route del 2001:200:dff:fff1:216:3eff:feb1:44d7/128 via 2001:55c:45fc:5042::


HE:

{root@gtoojimb/pts/2}~# ping6 -c5 -n www.kame.net
PING www.kame.net(2001:200:dff:fff1:216:3eff:feb1:44d7) 56 data bytes
64 bytes from 2001:200:dff:fff1:216:3eff:feb1:44d7: icmp_seq=1 ttl=57 time=127 ms
64 bytes from 2001:200:dff:fff1:216:3eff:feb1:44d7: icmp_seq=2 ttl=57 time=127 ms
64 bytes from 2001:200:dff:fff1:216:3eff:feb1:44d7: icmp_seq=3 ttl=57 time=128 ms
64 bytes from 2001:200:dff:fff1:216:3eff:feb1:44d7: icmp_seq=4 ttl=57 time=129 ms
64 bytes from 2001:200:dff:fff1:216:3eff:feb1:44d7: icmp_seq=5 ttl=57 time=127 ms

--- www.kame.net ping statistics ---
5 packets transmitted, 5 received, 0% packet loss, time 4016ms
rtt min/avg/max/mdev = 127.615/128.293/129.305/0.767 ms


I repeated similar ping tests with ip6.me and google via IPv6 with similar results.  In fact, google through HE averaged 22.556ms where Comcast 6RD was 216.237ms!

Granted, this isn't an apple-to-apples test, since there's lots of variables like HE's peering relationships vs. Comcast's.  But I'm somewhat surprised that Comcast's 6RD was slower than my HE tunnel, since Comcast's BR is closer hop-wise than HE's 6in4 router, and both use Comcast's IPv4 infrastructure to get to their IPv6 gateways.  HE's TS is physically closer though, even though there are more hops, and Comcasts last few hops are slower (60+ms) where HE's are all below 30ms, which could be part of the explanation.

Either that, or I screwed up.  Here's how I set up the 6RD:

ip tun add c6rd mode sit remote 69.252.80.66 local 75.144.xx.xx dev eth1
ip -6 addr add 2001:55c:4b90:xxxx::1/32 dev c6rd
ip link set c6rd mtu 1280 up


Then I set routes to the various things I was pinging through the Comcast 6RD BR address in IPv6 format like this (for kame):
ip -6 route add 2001:200:dff:fff1:216:3eff:feb1:44d7/128 via 2001:55c:45fc:5042::

I believe this is the right way to set it up.  But not sure.

It also appears that Comcast doesn't use any "IPv4 address compression" in setting up their 6RD prefixes, so you must use the entire 32 bit IPv4 address in your 6RD prefix (e.g.: 2001:55c:4b90:xxxx::/32 in my case [sanitized of course]), leaving you with only a /64 to work with (since the 6rd prefix is 32 bits, the and IPv6 encoded IPv4 address is another 32 bits).  A bit lame.  But I guess they didn't have enough commonality in high order bits of all their IPv4 space to "compress" any.  And they'd probably have a hard time getting say a /24 for 6RD.  :P

Anyway, I'll probably try out their 6to4 now that they have anycasted 6to4 routers up on their network.  But that will probably be worse than 6RD, since you are at the mercy of the internet 6to4 infrastructure for return traffic.

I've also heard you can get native dual-stack on my service, but haven't figured out how to request that yet.

So has anyone else played with any of this?

-Jim
« Last Edit: October 25, 2010, 11:30:07 PM by jimb »
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cholzhauer

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Re: Comcast IPv6
« Reply #1 on: October 26, 2010, 05:09:11 AM »

I haven't had the chance to; none of the ISP's around me know what IPv6 is.  My employer does have a plant located in the valley in CA, and we're going to be getting Internet through Clear, so I'll have to ask them and see if they are doing any IPv6 trials yet.

Your results seem surprising though; I would have thought like you that 6RD would have been faster.
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kriteknetworks

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Re: Comcast IPv6
« Reply #2 on: October 26, 2010, 08:59:05 AM »

Show traceroutes please, more information to gather from them than ping, thanks
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jimb

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Re: Comcast IPv6
« Reply #3 on: October 26, 2010, 10:45:22 PM »

Well, I mentioned the traces in my post, but here they are:

To HE:
traceroute to 72.52.104.74 (72.52.104.74), 30 hops max, 60 byte packets
 1  75-144-xx-xx-sfba-ca.hfc.comcastbusiness.net (75.144.xx.xx)  0.760 ms  1.471 ms  1.714 ms
 2  96.157.108.1 (96.157.108.1)  42.540 ms  49.389 ms  56.660 ms
 3  te-4-2-ur04.santaclara.ca.sfba.comcast.net (68.85.191.13)  50.171 ms  50.287 ms  50.368 ms
 4  te-0-9-0-6-ar01.oakland.ca.sfba.comcast.net (68.85.155.74)  51.674 ms  52.579 ms  52.812 ms
 5  pos-0-5-0-0-cr01.sacramento.ca.ibone.comcast.net (68.86.90.137)  53.550 ms  53.840 ms  53.805 ms
 6  pos-0-6-0-0-cr01.sanjose.ca.ibone.comcast.net (68.86.86.202)  54.533 ms  14.310 ms  20.884 ms
 7  pos-0-2-0-0-pe01.11greatoaks.ca.ibone.comcast.net (68.86.87.10)  24.509 ms  19.447 ms  24.977 ms
 8  208.178.58.1 (208.178.58.1)  23.779 ms  24.535 ms  24.780 ms
 9  te4-2-10G.ar3.sjc2.gblx.net (67.17.109.114)  25.073 ms  25.145 ms  25.192 ms
10  te4-2-10G.ar3.sjc2.gblx.net (67.17.109.114)  25.433 ms  25.376 ms  25.361 ms
11  Hurrican-Electric-LLC.Port-channel100.ar3.SJC2.gblx.net (64.214.174.246)  24.490 ms  19.246 ms  22.164 ms
12  10gigabitethernet1-2.core1.fmt2.he.net (72.52.81.177)  29.286 ms  16.083 ms  24.222 ms
13  tserv3.fmt2.ipv6.he.net (72.52.104.74)  22.688 ms  23.826 ms  24.025 ms


To the Comcast 6RD router:

traceroute to 69.252.80.66 (69.252.80.66), 30 hops max, 60 byte packets
 1  75-144-xx-xx-sfba-ca.hfc.comcastbusiness.net (75.144.xx.xx)  0.693 ms  1.469 ms  1.717 ms
 2  96.157.108.1 (96.157.108.1)  45.548 ms  46.315 ms  63.315 ms
 3  te-4-2-ur04.santaclara.ca.sfba.comcast.net (68.85.191.13)  45.432 ms  45.512 ms  45.595 ms
 4  te-0-9-0-3-ar01.oakland.ca.sfba.comcast.net (68.85.155.78)  47.555 ms  48.889 ms  49.009 ms
 5  pos-0-3-0-0-cr01.sacramento.ca.ibone.comcast.net (68.86.90.129)  49.535 ms  49.637 ms  49.667 ms
 6  pos-0-7-0-0-cr01.sanjose.ca.ibone.comcast.net (68.86.85.46)  68.978 ms  65.383 ms  65.391 ms
 7  pos-0-11-0-0-cr01.denver.co.ibone.comcast.net (68.86.86.133)  96.924 ms  61.446 ms  62.305 ms
 8  te-4-1-ar01.potomac.co.ndcwest.comcast.net (68.86.91.10)  62.297 ms  69.178 ms  69.917 ms
 9  te-5-3-ar01.cmc.co.ndcwest.comcast.net (68.86.206.1)  69.762 ms  68.890 ms  69.014 ms
10  te-1-1-ur01.cmc.co.ndcwest.comcast.net (68.86.132.38)  67.377 ms  67.561 ms  68.043 ms
11  6rd.comcast.net (69.252.80.66)  60.037 ms  61.731 ms  68.466 ms


As I said, the distance is greater, so it makes sense that the rtts would get slower as it heads towards Colorado (well I think that's where it is).
« Last Edit: October 26, 2010, 10:47:38 PM by jimb »
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jimb

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Re: Comcast IPv6
« Reply #4 on: February 07, 2011, 10:19:56 PM »

I just a letter from Comcast.  Looks like they're about to start Native Dual Stack trials!  Hopefully this area will be picked as one of the trial areas for NDS. 

They also sent two Comcast IPv6 trial stickers which is pretty cool.  Here's a pic:

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cholzhauer

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Re: Comcast IPv6
« Reply #5 on: February 08, 2011, 05:47:27 AM »

So are you going to attach the stickers to your Sage shirt?
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jimb

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Re: Comcast IPv6
« Reply #6 on: February 08, 2011, 04:15:07 PM »

Maybe stick one on the laptop or something.  But then it's brand new and seems wrong to put a sticker on it.  :)
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