Need Comcast IPv6 routing assistance please

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1

Hello NANOG,

Could someone from Comcast IPv6 routing team please contact me directly? I
am both a business and residential comcast customer and my employer is a
Level(3) HSIP customer at multiple sites.

I'm seeing *consistent* 46.1% packet loss between Comcast Res/Bus services
in Northern CA and Pixar (Level 3 customer) also in Northern CA. I have
ticket open with Level (3) but the problem appears to be on Comcast's
network.

Sample trace:

                                       My traceroute [v0.85]
ipv6testhost.ddv.com (::slight_smile:
Mon May 23 10:56:05 2016
Keys: Help Display mode Restart statistics Order of fields quit
                                                           Packets
      Pings
Host Loss% Snt Last
  Avg Best Wrst StDev
1. 2601:647:280:23::1 0.0% 464 0.6
  0.4 0.3 8.7 0.4
2. 2001:558:4000:3d::1 0.2% 463 13.0
10.3 8.2 27.4 2.1
3. te-0-7-0-5-sur03.sanrafael.ca.sfba.comcast.net 10.2% 463 9.6
10.7 8.5 34.8 2.4
4. be-207-rar01.rohnertpr.ca.sfba.comcast.net 44.7% 463 10.6
11.7 9.4 25.9 2.1
5. he-0-18-0-0-ar01.santaclara.ca.sfba.comcast.net 51.6% 463 15.2
14.1 12.0 26.2 1.9
6. 2001:1900:4:3::439 46.0% 463 13.3
14.4 11.8 50.2 3.6
7. vl-80.edge1.SanJose1.Level3.net 44.9% 463 12.1
13.9 11.7 28.5 2.3
8. vl-4045.edge5.LosAngeles.Level3.net 45.4% 463 21.2
21.5 19.2 39.4 2.6
9. vl-4044.bar1.LasVegas1.Level3.net 46.4% 463 24.9
27.7 24.4 88.3 6.8
10. vl-5.car1.LasVegas1.Level3.net 46.2% 463 104.3
46.3 24.5 318.2 48.0
11. PIXAR-ANIMA.car1.LasVegas1.Level3.net 44.9% 463 27.6
27.4 25.0 37.7 2.1
12. 2620:79:0:b04d::249 45.1% 463 46.4
48.9 46.0 114.2 4.9

And pings back from Pixar:

Type escape sequence to abort.Sending 500, 100-byte ICMP Echos to
2601:647:0:1900:242:DEA1:FEC9:FFAE, timeout is 2 seconds:
Packet sent with a source address of
2620:79:0:B04D::249%internet.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!..!.!!!!!!!!!!!!..!!!!!!!!!...!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!..!!!!!!!!!!!!!!!...!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!..!!!!!.!!!!!!!!!!!!!!!!!!!!!!!..!.!!!!!!!!!!!!!!!!!!..!!!!!!!!!!!!!!!!!!!!...!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!..!!.!!!!..!!!!!!!!!...!!!!!!!!!!!!!....!!!!!!!!..!!!!!!!!!....!!!!!..!!!!!!!!!!!!!!!!!!!!!!...!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!Success rate is 90 percent (452/500), round-trip min/avg/max =
12/30/68 ms

Any help really appreciated as you can imagine how painful remote access
for our employees with Comcast connections into Pixar over IPv6 is right
now.

Many Thanks,
David

2

David Sotnick wrote:

I'm seeing *consistent* 46.1% packet loss between Comcast Res/Bus services
in Northern CA and Pixar (Level 3 customer) also in Northern CA. I have
ticket open with Level (3) but the problem appears to be on Comcast's
network.

5/12 = 41.6%

Someone's got a 12-way LAG / ECMP path with either 5 links broken or
else with a hashing algorithm which is dumping your packets into one or
more broken paths 5/12 of the time.

Nick

3

Nick Hilliard wrote:

David Sotnick wrote:

I'm seeing *consistent* 46.1% packet loss between Comcast Res/Bus services

5/12 = 41.6%

and 5/12 != 46.1%, so scratch that. Anyway, the mtr output shows the
likely position of where the problem is.

Nick

4

Will get appropriate folks engaged. Thanks.