EIGRP - RTP's reliable message exchange process

The EIGRP protocol uses Reliable Transport Protocol (RTP) to exchange update and other EIGRP messages. RTP is a reliable protocol, and requires that messages sent are acknowledged using RTP’s reliability mechanisms.

RTP may attempt up to 16 retries when EIGRP messages are unacknowledged. In fact, this retry mechanism operates at the Transport layer (i.e. within the RTP protocol itself).

The retries that are attempted by an EIGRP router using RTP will typically take place based on the retransmission timeout (RTO) used by RTP, which is dynamically calculated based on network conditions. By default the RTO is set to 200 milliseconds.

Links:

https://forum.networklessons.com/t/eigrp-queries-and-stuck-in-active/914/63?u=lagapidis