PSH, ACK flag while application is not working

asked 2022-09-08 12:40:22 +0000

atifjauhar80
1 ●1 ●1 ●1

We are providing internet to servers, Application running on that Server will use Internet to show some articles to users.

We are facing issue that sometime Application get internet and show articles and videos to users but sometime no.

we get packet Capture on both Scenario and get following difference.

Lot of packets with PSH, ACK flag once application facing issue with Internet but no PSH, ACK Packet once it's working fine.

My queries are:

What is purpose of PSH, ACK flag why it cause this issue
How to troubleshoot it further to get reason of this PSH, ACK flag.

answered 2022-09-14 14:45:49 +0000

DavidB
1

From my understanding the PSH flag in the TCP segment is set by the sender to tell the receiver to immediately process the data received to that point. As frames move back and forth between sender and receiver, each TCP Segment has a field called the "Acknowledgement Number", which is a message back to the 'other side' indicating how much data has been received to that point. This is denoted by the "ACK" label in Wireshark. If an Ethernet frames is 'lost' on the network, the receiver will keep the Acknowledgement number the same in subsequent segments sent - a note to the sender to resend data from that point.

I am not sure the PSH and ACK are the root cause of your issue. When the server fails to connect to a web site, are you seeing the server perform a DNS lookup for web site? Are you seeing the server try to open a new TCP connection to the internet web site?

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