Hello! Cogent operates a machine on 2600::. IIRC there was also a route to sprint for that net, but that seems to be gone. I can ping that via my ISP (AS8820) that uses Cogent as its current default uplink. Although, I cannot ping that from various other ISPs, e.g. HE AS6939 or DTAG 3320 (no route). Some other people reported issues years ago: https://www.reddit.com/r/ipv6/comments/1bzfqzn/2600_is_no_longer_pingable/ Do some people know more about that case? -- kind regards Marco Send unsolicited bulk mail to 1768504259muell@stinkedores.dorfdsl.de
On 1/15/26 14:30, Marco Moock via NANOG wrote:
Hello!
Cogent operates a machine on 2600::. IIRC there was also a route to sprint for that net, but that seems to be gone.
I can ping that via my ISP (AS8820) that uses Cogent as its current default uplink.
Although, I cannot ping that from various other ISPs, e.g. HE AS6939 or DTAG 3320 (no route).
Some other people reported issues years ago: https://www.reddit.com/r/ipv6/comments/1bzfqzn/2600_is_no_longer_pingable/
Do some people know more about that case?
Cogent is well known for having incomplete global IPv6 connectivity. Does your network have a route to 2600::? Does Cogent have a route to your network? If you're on AS6939, the answer to both of those is probably "no". Obviously in that case, you're not going to be able to ping it even if there's a host there listening and willing to respond. Back when it was Sprint, the routing policy would have been different, but Cogent has completely absorbed the Sprint IP network and turned it into "more Cogent". -- Brandon Martin
nanog@lists.nanog.org (Marco Moock via NANOG) wrote:
Some other people reported issues years ago: https://www.reddit.com/r/ipv6/comments/1bzfqzn/2600_is_no_longer_pingable/
Do some people know more about that case?
Cogent. 'nuff said.
Some other people reported issues years ago: https://www.reddit.com/r/ipv6/comments/1bzfqzn/2600_is_no_longer_pingable/ Cogent. 'nuff said.
some times actual engineering tells more than politicl theory $ traceroute6 2600:: traceroute6 to 2600:: (2600::) from 2001:418:1::62, 64 hops max, 28 byte packets 1 r2.sea.rg.net 76.805 ms 0.387 ms 0.319 ms 2 r1.sea.rg.net 0.335 ms 0.297 ms 0.253 ms 3 2001:550:2:13::16d:2e 1.406 ms 1.337 ms 1.271 ms 4 be2579.ccr22.sea02.atlas.cogentco.com 1.153 ms 1.046 ms 1.007 ms 5 be5823.ccr31.slc01.atlas.cogentco.com 21.332 ms 6 be6640.ccr82.slc03.atlas.cogentco.com 21.874 ms 23.092 ms * 7 be9563.ccr82.den01.atlas.cogentco.com 31.272 ms 31.689 ms be2353.ccr81.den01.atlas.cogentco.com 32.385 ms 8 * * * 9 * * * 10 port-channel2717.ccr91.cle04.atlas.cogentco.com 55.437 ms 55.553 ms 55.502 ms 11 port-channel9258.ccr91.dca04.atlas.cogentco.com 67.533 ms port-channel9259.ccr92.dca04.atlas.cogentco.com 67.553 ms 67.528 ms 12 * * * 13 be2713.agr61.iad02.atlas.cogentco.com 69.661 ms * 14 te0-0-0-12.nr61.b014476-2.iad02.atlas.cogentco.com 69.179 ms 69.284 ms 69.097 ms 15 2600.cogentco.com 70.695 ms !P 70.168 ms !P 71.392 ms !P similarly via ntt then on to cogent randy
[Thanks Randy for calling me out there; it is not political for me, more like a continued nuisance. I shouldn't have been so sloppy as not to call out *both* knuckleheads, 6939 and 174.] I also wanted to confirm reachability from 8412 in Vienna, AT. ( ^174 201011 22927 3891 8412$ ) ...and a whole lot of other places that don't use 6939... Elmar, distracted by a cat.
hi elmar, yes, it is the old issue of HE and Cogent not peering over IPv6. the only aspect that bothers me is that it indicates a lack of business pressure for IPv6 routability. IPv6 has farther to go than we might like. randy
It's definitely a long standing issue. While HE provides a fair amount of primary uplinks for me in various capacities, I often find myself needing to bring another blended provider into the mix just to cross the 'cogent bridge' so to speak. I run a fair bit of v6 only stuff these days, but only a small amount of traffic comes from that bridge area, so unless you're on cogent directly it's almost a non-issue. While I can't really speak to cogent's motivations for not doing this, HE is more than happy and willing to, and they DO peer on v4, so it's definitely a .... interesting subject, to say the least. -----Original Message----- From: Randy Bush via NANOG <nanog@lists.nanog.org> Sent: Thursday, January 15, 2026 6:28 PM To: Elmar K. Bins via NANOG <nanog@lists.nanog.org> Cc: Randy Bush <randy@psg.com> Subject: Re: pingability of 2600:: hi elmar, yes, it is the old issue of HE and Cogent not peering over IPv6. the only aspect that bothers me is that it indicates a lack of business pressure for IPv6 routability. IPv6 has farther to go than we might like. randy _______________________________________________ NANOG mailing list https://lists.nanog.org/archives/list/nanog@lists.nanog.org/message/L5SRNW5S...
While I can't really speak to cogent's motivations for not doing this
my memory is that cogent said publicly that they treat IPv6 the same as IPv4 business wise, i.e. with respect to transit and peering
HE is more than happy and willing to, and they DO peer on v4
do they really peer over IPv4? the above would seem to hint otherwise randy
On 15.01.2026 14:56 Brandon Martin via NANOG wrote:
Cogent is well known for having incomplete global IPv6 connectivity.
Does your network have a route to 2600::? Does Cogent have a route to your network? If you're on AS6939, the answer to both of those is probably "no". Obviously in that case, you're not going to be able to ping it even if there's a host there listening and willing to respond.
This is not limited to HE. E.g. AS3320 doesn't have a route to 2600::/29 - and they peer on IPv6 - e.g. 2001:550::/32 is being in their table directly connected to AS174. Are there some people form Cogent here who can clarify that?
participants (5)
-
Brandon Martin -
Elmar K. Bins -
Gary Sparkes -
Marco Moock -
Randy Bush