What do you do if a particular website or a particular web service is crawling and yet pings, mtr traceroutes come back perfect? Or what if you can’t ping at all because of firewall in the way? Is something throttling this specific connection on the remote end?
The way to look under the hood is to look at the specific TCP session and see how it’s performing. This is where wireshark comes to the rescue with the following metrics:
- Packet Loss: Filter by criteria “tcp.analysis.lost_segment”
- Up/down throughput: Go to statistics -> Conversations -> scroll all the way right for “bps” stats
- Latency: Select TCP packet in question -> Expand TCP SEQ/ACK analysis -> look for RTT to ACK