Can we have two simultaneous udp streams between two specific pairs of IP addresses and ports?

Question

I am trying to check and analyze my network traffic. Suddenly I found something incomprehensible. I thought that the packets are divided into threads based on them (SRC_IP, DES_IP, SRC_PORT, SRC_PORT , PROTOCOL_NUM) . But now I found two groups of packages with the functions equal above, but interpreted them as two different streams in Wireshark:

As you can see below, RTP packets with even packet numbers represent one stream, and RTP packets with odd packet numbers represent another stream, while both have equal (SRC_IP, DES_IP, SRC_PORT, SRC_PORT , PROTOCOL_NUM) . Why?

To compare statistics:

They are interpreted as two different streams:

Answer 1

You just look at UDP traffic from any direction. UDP stream 2 is from 192.168.1.162 to 192.168.1.159 , and UDP stream 3 is from 192.168.1.159 to 192.168.1.162 .

Although there are two UDP streams, there is only one RTP session. This is because the RFC protocol states that you cannot multiplex on the same port. From RTP RFC Section 5.2 .

 In RTP, multiplexing is provided by the destination transport address (network address and port number) which is different for each RTP session. 

So yes, there are two simultaneous UDP streams, but both hosts talk to each other during an RTP session.