ISP reachability

[ankitohc]

Hello Experts,

We are having some intermittent issue with internet.

When I did traceroute the ISP IP 

I found the below sometime I get RTO on 7 hop. What does it mean? Can anyone please explain?

[liviu.gheorghe]

Hello @ankitohc ,

the traceroute command is one of the tools used in troubleshooting IP connectivity issues in a network. It works by sending ICMP or UDP packets to every host along a route to the destination host you entered in the traceroute command. It starts sending the packets with TTL=1 so the packets don't go beyond the first hop which will send back to the source a TTL Exceeded message.

For each hop, the source send 3 packets and record the round trip time for each of the packets.

If a hop on the route doesn't send a reply back to the source, for example icmp is restricted by an access-list, a * is printed instead of the round trip time.

Hope this helps.

[ankitohc]

Thank you for the answer however why it replies sometime and sometime it does not- as you see in the image

[liviu.gheorghe]

It can happen that some of the probes sent will timeout and other ones don't.

[Ruben Cocheno]

@ankitohc 

You see that behaviour often when devices out there don't allow tracerouteso you do see those * on it