Tracert's to ntp.plus.net
I decided that is was worth starting a thread on this topic as a result of several queries that have cropped up recently, the most recent was http://community.plus.net/forum/index.php/topic,115182.msg993273.html#msg993273
I'm currently on a different Gateway and get the following -
>ping ntp.plus.net
Pinging ntp.plus.net [212.159.6.10] with 32 bytes of data:
Ping statistics for 212.159.6.10:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
>tracert ntp.plus.net
Tracing route to ntp.plus.net [212.159.6.10]
over a maximum of 30 hops:
1 <1 ms <1 ms <1 ms dsldevice.lan [192.168.1.254]
2 34 ms 35 ms 50 ms lo0-central10.ptw-ag02.plus.net [195.166.128.196]
3 35 ms 34 ms 34 ms link5-central10.ptw-gw01.plus.net [84.93.248.40]
4 34 ms 41 ms 33 ms 56.core.plus.net [212.159.1.56]
5 34 ms 33 ms 33 ms te9-4.ptn-gw01.plus.net [195.166.129.33]
6 34 ms 34 ms 34 ms vl55.ptn-lb02.plus.net [212.159.2.125]
7 34 ms 33 ms 34 ms cdns02.plus.net [212.159.6.10]
Trace complete.
>tracert 212.159.6.10
Tracing route to cdns02.plus.net [212.159.6.10]
over a maximum of 30 hops:
1 <1 ms <1 ms <1 ms dsldevice.lan [192.168.1.254]
2 34 ms 40 ms 34 ms lo0-central10.ptw-ag02.plus.net [195.166.128.196]
3 35 ms 35 ms 40 ms link5-central10.ptw-gw01.plus.net [84.93.248.40]
4 67 ms 34 ms 38 ms 56.core.plus.net [212.159.1.56]
5 34 ms 34 ms 34 ms te9-4.ptn-gw01.plus.net [195.166.129.33]
6 35 ms 34 ms 34 ms vl55.ptn-lb02.plus.net [212.159.2.125]
7 34 ms 34 ms 34 ms cdns02.plus.net [212.159.6.10]
Trace complete.
>tracert 212.159.6.9
Tracing route to cdns01.plus.net [212.159.6.9]
over a maximum of 30 hops:
1 <1 ms <1 ms <1 ms dsldevice.lan [192.168.1.254]
2 34 ms 35 ms 38 ms lo0-central10.ptw-ag02.plus.net [195.166.128.196]
3 35 ms 34 ms 35 ms link3-central10.ptw-gw01.plus.net [84.93.248.36]
4 34 ms 34 ms 33 ms 56.core.plus.net [212.159.1.56]
5 34 ms 34 ms 34 ms te9-4.ptn-gw01.plus.net [195.166.129.33]
6 34 ms 34 ms 35 ms vl55.ptn-lb02.plus.net [212.159.2.125]
7 34 ms 34 ms 34 ms cdns01.plus.net [212.159.6.9]
Trace complete.
>tracert 212.159.13.50
Tracing route to cdns02.plus.net [212.159.13.50]
over a maximum of 30 hops:
1 <1 ms <1 ms <1 ms dsldevice.lan [192.168.1.254]
2 45 ms 37 ms 38 ms lo0-central10.ptw-ag02.plus.net [195.166.128.196]
3 34 ms 34 ms 34 ms link5-central10.ptw-gw01.plus.net [84.93.248.40]
4 34 ms 34 ms 34 ms 56.core.plus.net [212.159.1.56]
5 34 ms 35 ms 34 ms te9-4.ptn-gw01.plus.net [195.166.129.33]
6 34 ms 34 ms 34 ms vl55.ptn-lb02.plus.net [212.159.2.125]
7 34 ms 33 ms 46 ms cdns02.plus.net [212.159.13.50]
Trace complete.
>tracert 212.159.13.49
Tracing route to cdns01.plus.net [212.159.13.49]
over a maximum of 30 hops:
1 <1 ms <1 ms <1 ms dsldevice.lan [192.168.1.254]
2 42 ms 97 ms 45 ms lo0-central10.ptw-ag02.plus.net [195.166.128.196]
3 34 ms 34 ms 34 ms link11-central10.ptw-gw01.plus.net [84.93.248.52]
4 34 ms 34 ms 34 ms 56.core.plus.net [212.159.1.56]
5 34 ms 34 ms 33 ms te9-4.ptn-gw01.plus.net [195.166.129.33]
6 104 ms 33 ms 34 ms vl55.ptn-lb02.plus.net [212.159.2.125]
7 33 ms 34 ms 34 ms cdns01.plus.net [212.159.13.49]
Trace complete.
All the above were done yesterday. I couldn't recall if pings or tracerts to ntp.plus.net always went to the same cdns server just for hours (which it certainly does) or days or until I change Gateway. Well all the above are the same today (no Gateway change yet).
You'll note that all the routes are identical apart from hop 3, should this happen, is this right/correct?
What happens if any of the Routers in hops 4, 5, & 6 fail - No DNS it would seem
An issue about common subnets and paths was mentioned here -
http://community.plus.net/forum/index.php/topic,110965.msg951189.html#msg951189
but there was no Plusnet response to these specific points.
We'll see what some Gateway hopping yields.
I'm currently on a different Gateway and get the following -
>ping ntp.plus.net
Pinging ntp.plus.net [212.159.6.10] with 32 bytes of data:
Ping statistics for 212.159.6.10:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
>tracert ntp.plus.net
Tracing route to ntp.plus.net [212.159.6.10]
over a maximum of 30 hops:
1 <1 ms <1 ms <1 ms dsldevice.lan [192.168.1.254]
2 34 ms 35 ms 50 ms lo0-central10.ptw-ag02.plus.net [195.166.128.196]
3 35 ms 34 ms 34 ms link5-central10.ptw-gw01.plus.net [84.93.248.40]
4 34 ms 41 ms 33 ms 56.core.plus.net [212.159.1.56]
5 34 ms 33 ms 33 ms te9-4.ptn-gw01.plus.net [195.166.129.33]
6 34 ms 34 ms 34 ms vl55.ptn-lb02.plus.net [212.159.2.125]
7 34 ms 33 ms 34 ms cdns02.plus.net [212.159.6.10]
Trace complete.
>tracert 212.159.6.10
Tracing route to cdns02.plus.net [212.159.6.10]
over a maximum of 30 hops:
1 <1 ms <1 ms <1 ms dsldevice.lan [192.168.1.254]
2 34 ms 40 ms 34 ms lo0-central10.ptw-ag02.plus.net [195.166.128.196]
3 35 ms 35 ms 40 ms link5-central10.ptw-gw01.plus.net [84.93.248.40]
4 67 ms 34 ms 38 ms 56.core.plus.net [212.159.1.56]
5 34 ms 34 ms 34 ms te9-4.ptn-gw01.plus.net [195.166.129.33]
6 35 ms 34 ms 34 ms vl55.ptn-lb02.plus.net [212.159.2.125]
7 34 ms 34 ms 34 ms cdns02.plus.net [212.159.6.10]
Trace complete.
>tracert 212.159.6.9
Tracing route to cdns01.plus.net [212.159.6.9]
over a maximum of 30 hops:
1 <1 ms <1 ms <1 ms dsldevice.lan [192.168.1.254]
2 34 ms 35 ms 38 ms lo0-central10.ptw-ag02.plus.net [195.166.128.196]
3 35 ms 34 ms 35 ms link3-central10.ptw-gw01.plus.net [84.93.248.36]
4 34 ms 34 ms 33 ms 56.core.plus.net [212.159.1.56]
5 34 ms 34 ms 34 ms te9-4.ptn-gw01.plus.net [195.166.129.33]
6 34 ms 34 ms 35 ms vl55.ptn-lb02.plus.net [212.159.2.125]
7 34 ms 34 ms 34 ms cdns01.plus.net [212.159.6.9]
Trace complete.
>tracert 212.159.13.50
Tracing route to cdns02.plus.net [212.159.13.50]
over a maximum of 30 hops:
1 <1 ms <1 ms <1 ms dsldevice.lan [192.168.1.254]
2 45 ms 37 ms 38 ms lo0-central10.ptw-ag02.plus.net [195.166.128.196]
3 34 ms 34 ms 34 ms link5-central10.ptw-gw01.plus.net [84.93.248.40]
4 34 ms 34 ms 34 ms 56.core.plus.net [212.159.1.56]
5 34 ms 35 ms 34 ms te9-4.ptn-gw01.plus.net [195.166.129.33]
6 34 ms 34 ms 34 ms vl55.ptn-lb02.plus.net [212.159.2.125]
7 34 ms 33 ms 46 ms cdns02.plus.net [212.159.13.50]
Trace complete.
>tracert 212.159.13.49
Tracing route to cdns01.plus.net [212.159.13.49]
over a maximum of 30 hops:
1 <1 ms <1 ms <1 ms dsldevice.lan [192.168.1.254]
2 42 ms 97 ms 45 ms lo0-central10.ptw-ag02.plus.net [195.166.128.196]
3 34 ms 34 ms 34 ms link11-central10.ptw-gw01.plus.net [84.93.248.52]
4 34 ms 34 ms 34 ms 56.core.plus.net [212.159.1.56]
5 34 ms 34 ms 33 ms te9-4.ptn-gw01.plus.net [195.166.129.33]
6 104 ms 33 ms 34 ms vl55.ptn-lb02.plus.net [212.159.2.125]
7 33 ms 34 ms 34 ms cdns01.plus.net [212.159.13.49]
Trace complete.
All the above were done yesterday. I couldn't recall if pings or tracerts to ntp.plus.net always went to the same cdns server just for hours (which it certainly does) or days or until I change Gateway. Well all the above are the same today (no Gateway change yet).
You'll note that all the routes are identical apart from hop 3, should this happen, is this right/correct?
What happens if any of the Routers in hops 4, 5, & 6 fail - No DNS it would seem
An issue about common subnets and paths was mentioned here -
http://community.plus.net/forum/index.php/topic,110965.msg951189.html#msg951189
but there was no Plusnet response to these specific points.
We'll see what some Gateway hopping yields.
I always thought i was special 
ok i'll get me coat..
ok i'll get me coat..
With your ping, you certainly are 
Flushing the DNS Cache sorted the cdns IP address point, it became random if flushed each time, however no change to the hops on the current gateway.
Flushing the DNS Cache sorted the cdns IP address point, it became random if flushed each time, however no change to the hops on the current gateway.
Quote from: Anotherone
You'll note that all the routes are identical apart from hop 3, should this happen, is this right/correct?
What happens if any of the Routers in hops 4, 5, & 6 fail - No DNS it would seem
An issue about common subnets and paths was mentioned here -
http://community.plus.net/forum/index.php/topic,110965.msg951189.html#msg951189
but there was no Plusnet response to these specific points.
We'll see what some Gateway hopping yields.
In answer to your question about hop 3, yes thats fine and expected. In summery you have 12 links to pick from and route hashing will just send you off down one of them. All the other hops are resilient in one format or another and will be routed around.
In regards to the DNS servers. We have them (cluster) located in two sites, both responding to the same VIP ranges so in theory you should just go to the cloest one, if one site goes away the same VIP will just work at the other site.
Hopefully that helps a little, if I've missed the point in some way or there is an issue I'm sure the DC guys will pick it up and/or get it logged internally.
Quote from: townman
Quote from: paulmh5 In regards to the DNS servers. We have them (cluster) located in two sites, both responding to the same VIP ranges so in theory you should just go to the cloest one, if one site goes away the same VIP will just work at the other site.
Paul,
Is the point you are trying to make here, is that the IP addresses we see in trace routes to PN services are virtual, not the real addresses of the servers?
I'm not Paul but yes, the IP's you see in traceroutes are not those of the physical caching DNS servers themselves. They are virtual IP's. The physical caching servers themselves are clustered across two sites for resiliency. I think BGP or something similar is used to route you to the closest cluster which is the basis for the question jelv asked here.
I could be wrong but last I knew there were four physical boxes in each cluster (each with their own IP that you'll not see in traceroutes).
Quote from: Anotherone But that does not explain what happens if for example xe-10-0-0.ptw-cr01.plus.net in the tracert in my previous post fails/fails to respond!
That's a core router (Juniper MX kit I think). The rDNS of that hop represents one of multiple interfaces on the device itself. There will be redundancy within the unit itself e.g. multiple line cards as well as there being another physical unit i.e. ptw-cr02. I don't know a huge amount about our core network but I do know there's sufficient resiliency should a network interface unexpectedly fall over.
I'm going to bow out now before I get out of my depth, however if this thread is a question of whether or not we've sufficient network redundancy then I don't think people have anything to worry about
