1msec RTT to ipv6.google.com?
Hi all Anyone had any issues with wrong RTTs on IPv6 probes? I've setup a ping probe (ID#2143865) to ipv6.google.com and it's consistently giving 1msec RTT on the seismograph and the json file. It is physically impossible. This is the RTT I get on the CPE the probe is connected to: SEQ HOST SIZE TTL TIME STATUS 0 2a00:1450:4003:806::200e 56 59 12ms echo reply 1 2a00:1450:4003:806::200e 56 59 12ms echo reply 2 2a00:1450:4003:806::200e 56 59 12ms echo reply 3 2a00:1450:4003:806::200e 56 59 12ms echo reply 4 2a00:1450:4003:806::200e 56 59 12ms echo reply 5 2a00:1450:4003:806::200e 56 59 12ms echo reply Regards, Alexandre Abreu
Hi, I didn't observe this exact thing, but I've seen some weird traceroute outputs on a Windows box behind a Comtrend ADSL router. The PTRs returned were completely wrong and I think there were some other issues too.Once we replaced the CPE everything went back to normal, so I'd check that first, maybe it's doing something funny to the IPv6 traffic. Best regardsTomáš Hetmer
From: alexandre.abreu@vodafone.com To: ripe-atlas@ripe.net Date: Tue, 21 Jul 2015 08:51:41 +0000 Subject: [atlas] 1msec RTT to ipv6.google.com?
Hi all
Anyone had any issues with wrong RTTs on IPv6 probes? I've setup a ping probe (ID#2143865) to ipv6.google.com and it's consistently giving 1msec RTT on the seismograph and the json file. It is physically impossible. This is the RTT I get on the CPE the probe is connected to:
SEQ HOST SIZE TTL TIME STATUS 0 2a00:1450:4003:806::200e 56 59 12ms echo reply 1 2a00:1450:4003:806::200e 56 59 12ms echo reply 2 2a00:1450:4003:806::200e 56 59 12ms echo reply 3 2a00:1450:4003:806::200e 56 59 12ms echo reply 4 2a00:1450:4003:806::200e 56 59 12ms echo reply 5 2a00:1450:4003:806::200e 56 59 12ms echo reply
Regards, Alexandre Abreu
Hi Based on your feedback I've built a probe with the IP address instead of the hostname and I now get "normal" results. There's something weird about the DNS resolution that is leading to these results. Thanks for your help. AA From: th@outlook.cz [mailto:th@outlook.cz] On Behalf Of Tomáš Hetmer Sent: Tuesday, 21 de July de 2015 10:08 To: Abreu, Alexandre, Vodafone Portugal; ripe-atlas@ripe.net Subject: RE: [atlas] 1msec RTT to ipv6.google.com? Hi, I didn't observe this exact thing, but I've seen some weird traceroute outputs on a Windows box behind a Comtrend ADSL router. The PTRs returned were completely wrong and I think there were some other issues too. Once we replaced the CPE everything went back to normal, so I'd check that first, maybe it's doing something funny to the IPv6 traffic. Best regards Tomáš Hetmer
From: alexandre.abreu@vodafone.com<mailto:alexandre.abreu@vodafone.com> To: ripe-atlas@ripe.net<mailto:ripe-atlas@ripe.net> Date: Tue, 21 Jul 2015 08:51:41 +0000 Subject: [atlas] 1msec RTT to ipv6.google.com?
Hi all
Anyone had any issues with wrong RTTs on IPv6 probes? I've setup a ping probe (ID#2143865) to ipv6.google.com and it's consistently giving 1msec RTT on the seismograph and the json file. It is physically impossible. This is the RTT I get on the CPE the probe is connected to:
SEQ HOST SIZE TTL TIME STATUS 0 2a00:1450:4003:806::200e 56 59 12ms echo reply 1 2a00:1450:4003:806::200e 56 59 12ms echo reply 2 2a00:1450:4003:806::200e 56 59 12ms echo reply 3 2a00:1450:4003:806::200e 56 59 12ms echo reply 4 2a00:1450:4003:806::200e 56 59 12ms echo reply 5 2a00:1450:4003:806::200e 56 59 12ms echo reply
Regards, Alexandre Abreu
On Tue, 21 Jul 2015 09:37:13 +0000 "Abreu, Alexandre, Vodafone Portugal" <alexandre.abreu@vodafone.com> wrote:
Based on your feedback I've built a probe with the IP address instead of the hostname and I now get "normal" results. There's something weird about the DNS resolution that is leading to these results.
Read about: https://peering.google.com/about/ggc.html Your probe may have resolved ipv6.google.com to the IP of your ISP's Google Global Cache mirror, hence the very low ping. -- With respect, Roman
On Tue, Jul 21, 2015 at 12:33 PM, Roman Mamedov <rm@romanrm.net> wrote:
On Tue, 21 Jul 2015 09:37:13 +0000 "Abreu, Alexandre, Vodafone Portugal" <alexandre.abreu@vodafone.com> wrote:
Based on your feedback I've built a probe with the IP address instead of the hostname and I now get "normal" results. There's something weird about the DNS resolution that is leading to these results.
Read about: https://peering.google.com/about/ggc.html
Your probe may have resolved ipv6.google.com to the IP of your ISP's Google Global Cache mirror, hence the very low ping.
Does not look like that as the address is 2a00:1450:4003:806::200e which is Google VIP in Europe. -- SY, Jen Linkova aka Furry
On Tue, 21 Jul 2015 13:31:33 +0200 Jen Linkova <furry13@gmail.com> wrote:
On Tue, Jul 21, 2015 at 12:33 PM, Roman Mamedov <rm@romanrm.net> wrote:
On Tue, 21 Jul 2015 09:37:13 +0000 "Abreu, Alexandre, Vodafone Portugal" <alexandre.abreu@vodafone.com> wrote:
Based on your feedback I've built a probe with the IP address instead of the hostname and I now get "normal" results. There's something weird about the DNS resolution that is leading to these results.
Read about: https://peering.google.com/about/ggc.html
Your probe may have resolved ipv6.google.com to the IP of your ISP's Google Global Cache mirror, hence the very low ping.
Does not look like that as the address is 2a00:1450:4003:806::200e which is Google VIP in Europe.
From the original message:
I've setup a ping probe (ID#2143865) to ipv6.google.com and it's consistently giving 1msec RTT RTT I get on the CPE the probe is connected to 0 2a00:1450:4003:806::200e 56 59 12ms echo reply
My guess is that maybe the probe was set up to use a different DNS resolver than the CPE, and it got a different IPv6 instead of 2a00:1450:4003:806::200e. -- With respect, Roman
From the original message:
I've setup a ping probe (ID#2143865) to ipv6.google.com and it's consistently giving 1msec RTT RTT I get on the CPE the probe is connected to 0 2a00:1450:4003:806::200e 56 59 12ms echo reply
My guess is that maybe the probe was set up to use a different DNS resolver than the CPE, and it got a different IPv6 instead of 2a00:1450:4003:806::200e.
Indeed the probe pinged 2a00:1450:4004:801::200e and not the address above. I have no idea if that's the root cause for this, but it's certainly a different target. It could be the same DNS resolver but it got different answers at different times? I set up one-off traceroutes 2144086 (ICMP) and 2144089 (UDP) and they seem quite reasonable to me (5 hops, ~1.2ms to target). Robert
Hi I've been reviewing both paths and indeed 2a00:1450:4004:801::200e is 1msec away from the probe (it is answered right at the internet exchange premises by either Google's router or a colocated server/cache) while 2a00:1450:4004:806::200e has to go out to Google DCs hence the ~12msec. Thank you all for your help. AA -----Original Message----- From: ripe-atlas [mailto:ripe-atlas-bounces@ripe.net] On Behalf Of Robert Kisteleki Sent: Tuesday, 21 de July de 2015 12:55 To: Roman Mamedov; Jen Linkova Cc: ripe-atlas@ripe.net; Tomáš Hetmer Subject: Re: [atlas] 1msec RTT to ipv6.google.com?
From the original message:
I've setup a ping probe (ID#2143865) to ipv6.google.com and it's consistently giving 1msec RTT RTT I get on the CPE the probe is connected to 0 2a00:1450:4003:806::200e 56 59 12ms echo reply
My guess is that maybe the probe was set up to use a different DNS resolver than the CPE, and it got a different IPv6 instead of 2a00:1450:4003:806::200e.
Indeed the probe pinged 2a00:1450:4004:801::200e and not the address above. I have no idea if that's the root cause for this, but it's certainly a different target. It could be the same DNS resolver but it got different answers at different times? I set up one-off traceroutes 2144086 (ICMP) and 2144089 (UDP) and they seem quite reasonable to me (5 hops, ~1.2ms to target). Robert
participants (5)
-
Abreu, Alexandre, Vodafone Portugal -
Jen Linkova -
Robert Kisteleki -
Roman Mamedov -
Tomáš Hetmer