Tracing an internet connection

[woody1]

Have you logged a ticket yet?

It hasn't played up for the past week or so. I have bought another router, which I'd been meaning to do anyway, so I can at least rule this out if the problem reoccurs.

[woody1]

According to this, the <40ms average ping times I'm currently getting do appear to be at the limits of what is achievable with 4G.

https://www.4g.co.uk/news/4g-injecti...#Lower_latency

Hopefully, it continues like this.

[Lance]

According to this, the <40ms average ping times I'm currently getting do appear to be at the limits of what is achievable with 4G.

https://www.4g.co.uk/news/4g-injecti...#Lower_latency

Hopefully, it continues like this.

latency isn't an issue unless you have particularly time sensitive apps. And even if you do, 250ms is generally considered acceptable for a worst case scenario.

TCP/IP was designed to cope with packet loss and variable latencies. It's why you have TCP sliding windows. It's why you can have large bandwidths with high latency (the two are not directly related).

When using voice, jitter is a bigger problem than latency.

You youngsters have been spoiled. A reliable, low jitter, 2Mb/s connection is bloody amazing. I'd rather have that than a Talktalk 70Mb/s lossy, unreliable bag of sh1te.

If you want to learn some more read up about TCP sliding windows, and QoS. All QoS does is determine which packets get dropped in a congested network (it's nothing fancy, but is very effective).

[woody1]

latency isn't an issue unless you have particularly time sensitive apps. And even if you do, 250ms is generally considered acceptable for a worst case scenario.

I'm only using latency (ping) as a measure of the health of the connection. I now know that 40ms is v.good.

BTW, I learned something new the other day; that you can deduce quite a lot from the TTL in the ping output.

[Lance]

I'm only using latency (ping) as a measure of the health of the connection. I now know that 40ms is v.good.

BTW, I learned something new the other day; that you can deduce quite a lot from the TTL in the ping output.

only if you assume that every router decrements the TTL by 1. Which is a fair assumption on business LAN/WAN., but not on an internet provider who want their network obscure. If they block the ICMP response to stop you trace routing, why would they play nicely with the TTL?
I've seen some ISPs actually add numbers to the TTL

[woody1]

only if you assume that every router decrements the TTL by 1. Which is a fair assumption on business LAN/WAN., but not on an internet provider who want their network obscure. If they block the ICMP response to stop you trace routing, why would they play nicely with the TTL?
I've seen some ISPs actually add numbers to the TTL

Yes I read this. But I also hadn't realised that the TTL varies depending on the OS of the target host.

BTW, do you know if there is any way of discovering the IP addresses of the hops which appear as "* * *" in traceroute? Or would I need to consult a hacker for that?

[Lance]

Yes I read this. But I also hadn't realised that the TTL varies depending on the OS of the target host.

BTW, do you know if there is any way of discovering the IP addresses of the hops which appear as "* * *" in traceroute? Or would I need to consult a hacker for that?

there is no way to get the IP address, or even to know if it exists.
The TTL might be being decremented by more than one by a device. What will show as a 'missing' hop.

All you know is that the ICMP packet that was sent with a TTL for that hop number didn't get a response.

this explains it quite well Traceroute (networklessons.com)