Deprecated: Hook custom_css_loaded is deprecated since version jetpack-13.5! Use WordPress Custom CSS instead. Jetpack no longer supports Custom CSS. Read the WordPress.org documentation to learn how to apply custom styles to your site: https://wordpress.org/documentation/article/styles-overview/#applying-custom-css in /var/www/rtoodtoo.net/wp-includes/functions.php on line 6031
TCP fast retransmission – RtoDto.net

TCP fast retransmission

During analysis of my ESX server, vsphere client communication I have encountered the following packet capture. My vsphere client keeps asking for a lost segment with ACK number 1583183 for 9 times after which according to wireshark analysis TCP Fast Retransmission which is one of the ways of handling congestion is engaged.

When I check RFC2581, it says  :

After receiving 3 duplicate ACKs, TCP performs a retransmission of what appears to be 
the missing segment, without waiting for the retransmission timer to expire.

TCP doesn’t wait for the re-transmission timer but isn’t this quite long to engage fast re-transmit? It is 9 duplicate acks in total. Maybe some of my duplicate acks are also lost? It might be. Anyway, it was good to check RFC once again for this retransmit incident.

About: rtoodtoo

Worked for more than 10 years as a Network/Support Engineer and also interested in Python, Linux, Security and SD-WAN // JNCIE-SEC #223 / RHCE / PCNSE


You have a feedback?

Discover more from RtoDto.net

Subscribe now to keep reading and get access to the full archive.

Continue reading