No address in the results when ping or traceroute fail?
When a ping or traceroute emasurement fails, we do not know the IP address of the probe (empty "from" and no "src_addr"), which is annoying when you want to analyze the possible causes of the failure: { "size": 20, "addr": "2620:0:2d0:200:0:0:0:7", "min": -1, "rcvd": 0, "from": "", "dst_name": "2620:0:2d0:200:0:0:0:7", "af": 6, "timestamp": 1374395985, "fw": 4520, "proto": "ICMP", "name": "www.icann.org", "prb_id": 3953, "result": [ { "error": "sendto failed: Network is unreachable" }, { "error": "sendto failed: Network is unreachable" }, { "error": "sendto failed: Network is unreachable" } ], "max": -1, "dup": 0, "avg": -1, "type": "ping", "dst_addr": "2620:0:2d0:200::7", "sent": 0, "msm_id": 1013576 },
Hi Stephane, On 2013/07/21 21:34 , Stephane Bortzmeyer wrote:
When a ping or traceroute emasurement fails, we do not know the IP address of the probe (empty "from" and no "src_addr"), which is annoying when you want to analyze the possible causes of the failure:
The most likely cause for this is that the probe has no IPv6 default router. The from field is filled with the address that is used to connect to the controller. If a probe doesn't have IPv6 connectivity then that is address is unknown. The src_addr is not there because of the way the linux kernel works. Most measurements use the bind system call to find out which local address will be used for outgoing packets. But if there is not route to the destination then bind will fail. Probes also report their network configuration but at the moment that is done in a format that is not easy to parse. The next firmware should fix that. Then we can see how to make that information available. Philip
On Mon, Jul 22, 2013 at 11:43:39AM +0200, Philip Homburg <philip.homburg@ripe.net> wrote a message of 25 lines which said:
The most likely cause for this is that the probe has no IPv6 default router.
Well, IMHO, probes without a router should not be eligible for IPv6 measurements.
Probes also report their network configuration but at the moment that is done in a format that is not easy to parse. The next firmware should fix that. Then we can see how to make that information available.
It would not solve the problem since the probe may renumber between the moment you fetch the (semi-static) info and the measurement. And it is even worse for probes with multiple addresses. We really need to know the adress actually used during the measurement.
On 2013/07/22 16:20 , Stephane Bortzmeyer wrote:
On Mon, Jul 22, 2013 at 11:43:39AM +0200, Philip Homburg <philip.homburg@ripe.net> wrote a message of 25 lines which said:
The most likely cause for this is that the probe has no IPv6 default router. Well, IMHO, probes without a router should not be eligible for IPv6 measurements. Yes, but that will be some future change to the system Probes also report their network configuration but at the moment that is done in a format that is not easy to parse. The next firmware should fix that. Then we can see how to make that information available. It would not solve the problem since the probe may renumber between the moment you fetch the (semi-static) info and the measurement. And it is even worse for probes with multiple addresses. We really need to know the adress actually used during the measurement.
That is easy. The probe didn't actually send any packets so there is no point in knowing the source address that wasn't used. :-) Philip
On Mon, Jul 22, 2013 at 04:29:52PM +0200, Philip Homburg <philip.homburg@ripe.net> wrote a message of 23 lines which said:
The probe didn't actually send any packets so there is no point in knowing the source address that wasn't used. :-)
I wanted to reply to Dan Wing's criticism <https://labs.ripe.net/Members/stephane_bortzmeyer/how-many-atlas-probes-believe-they-have-ipv6-but-are-wrong/> "I have a suspicion that many of these failures are IPv6 tunnels that have suffered bit rot. Could you analyze the IPv6 address that the Atlas probe thinks it has and split them into two categories: (a) known tunnels (e.g., Hurricane Electric, SixXS, 6to4, Teredo) versus (b) presumably "native" IPv6 addresses. "
On 2013/07/22 16:39 , Stephane Bortzmeyer wrote:
On Mon, Jul 22, 2013 at 04:29:52PM +0200, Philip Homburg <philip.homburg@ripe.net> wrote a message of 23 lines which said:
The probe didn't actually send any packets so there is no point in knowing the source address that wasn't used. :-) I wanted to reply to Dan Wing's criticism <https://labs.ripe.net/Members/stephane_bortzmeyer/how-many-atlas-probes-believe-they-have-ipv6-but-are-wrong/> "I have a suspicion that many of these failures are IPv6 tunnels that have suffered bit rot. Could you analyze the IPv6 address that the Atlas probe thinks it has and split them into two categories: (a) known tunnels (e.g., Hurricane Electric, SixXS, 6to4, Teredo) versus (b) presumably "native" IPv6 addresses. "
Stephane, Well, if you can give me a list of probes for which you don't have the IPv6 address then I can look them up for you. Philip
On Mon, Jul 22, 2013 at 04:29:52PM +0200, Philip Homburg <philip.homburg@ripe.net> wrote a message of 23 lines which said:
The probe didn't actually send any packets so there is no point in knowing the source address that wasn't used. :-) I wanted to reply to Dan Wing's criticism <https://labs.ripe.net/Members/stephane_bortzmeyer/how-many-atlas-probes-believe-they-have-ipv6-but-are-wrong/> "I have a suspicion that many of these failures are IPv6 tunnels that have suffered bit rot. Could you analyze the IPv6 address that the Atlas probe thinks it has and split them into two categories: (a) known tunnels (e.g., Hurricane Electric, SixXS, 6to4, Teredo) versus (b) presumably "native" IPv6 addresses. " Yes, this is annoying. Many probes have IPv6 tunnels. Probably they show
On 22.07.2013 16:39, Stephane Bortzmeyer wrote: the "real world" view of IPv6, but often I am interested in native IPv6. When selecting probes manually I only use probes that are located in the same AS for IPv4 and IPv6. regards Klaus
participants (3)
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Klaus Darilion -
Philip Homburg -
Stephane Bortzmeyer