To troubleshoot these kind of issues we used pages Top Clients, Top Client Zones and Custom Charts. We also see some common failure cases that can be diagnosed easily with Skylight. In this first article, we saw a short presentation of TCP performance metrics and how the TCP protocol handles the connections with SYN / SYN+ACK / ACK packets. Figure 5 – Troubleshoot connections with Connection Times and SYN rates Conclusion Skylight provides the RTT in the Network Performance s metric theme. The network latency – RTT (Round Trip Time) – can give you another indication that the issue is on the network side. Finally, if the ‘ SYN’ ratio is huge, then you can have security issues, like a DDOS attack. However, if the Connection Time is high, the issue is on the server side, it is overloaded and cannot answer to all clients. You can check this assumption by looking at the Connection Time. If it remains low and impacts several hosts, then it’s probably a network issue. Thus the misconnections are caused by packet loss or contingency. Figure 4 – Skylight custom chart SYN/ConnĪ bad ‘ SYN’ efficiency is sometimes a network issue. You can also graph its evolution over time in Application → Custom charts.
This metric is available in the ‘details’ tables by using the TCP theme. Skylight provides a metric to see this connection efficiency, it is an ‘ SYN’ per Connection rate (which corresponds to the number of SYN packets compared to the number of TCP sessions set up). In a perfect world, you should have 1 ‘ SYN’ per TCP connection. This happens frequently when a server IP is changed, yet some clients continue to query the old one. The server does not exist anymore or is not available.In this case, you could apply the same query to client zones (in the same menu) to see if the IPs are in the same zone. To query only the ‘ SYN’ without connections and only them, use a custom filter: Figure 3 – Skylight finds unilateral flows and sorts them.Īs you see on the results above, there are several IPs which demand to connect to a server ( SYN > 0) but they cannot connect to them ( Connections = 0). We set the filters to see unilateral flows, and this shows mostly ‘ SYN‘ issues, however, you could also get other types of flows. This means that you want to see top client IPs with flows from the client only and without any responses. Figure 2 – Filter on Unilateral Flows Only The pattern is that we only see traffic from the client to the server and no response from the server.
#Handshaker app issues how to#
How to Diagnose TCP Connection Faults 1 – SYN Without ConnectionsĪ first case you can easily diagnostic with Skylight is: “ Could my clients connect to my servers?” In the Skylight navigation menu, go to Application → Clients, then choose the TCP theme and set the Filter called “ Only Unilateral Flow”.
#Handshaker app issues series#
In this series of articles, we will explain TCP meta information and explain why it is important for performance troubleshooting and how to measure it easily with Skylight™. TCP is used under a number of application protocols, such as HTTP, so it is important to know how to diagnostic TCP issues. To do so TCP has features such as Handshake, Reset, Fin, Ack, Push packets, and other types of flags to keep the connection alive and to not lose any information. TCP provides reliable, ordered, and error-free transmission. TCP works with the Internet Protocol (IP). The TCP protocol is a connection-oriented protocol, which means that a connection is established and maintained until the application programs at each end have finished exchanging messages. Let’s have a look at how TCP sessions are established… and what can go wrong!
#Handshaker app issues full#
(See the bottom of this article for a full list) In this article, we will consider the TCP connection setup. This is the first article in a series of articles covering all you need to know to troubleshoot performance issues impacting applications relying on the TCP Protocol. How to Diagnose TCP Connection Setup I ssues?