There is the RTCP roundtrip network propagation delay. If the necessary reports are present and properly formatted, there will be an expert info item for any calculations that may be made. You will need to enable this calculation in the RTCP dissector preferences.
Here is the extract from RFC 3550, section 6.4.1, that describes how the calculation should be done:
delay since last SR (DLSR): 32 bits
The delay, expressed in units of 1/65536 seconds, between
receiving the last SR packet from source SSRC_n and sending this
reception report block. If no SR packet has been received yet
from SSRC_n, the DLSR field is set to zero.
Let SSRC_r denote the receiver issuing this receiver report.
Source SSRC_n can compute the round-trip propagation delay to
SSRC_r by recording the time A when this reception report block is
received. It calculates the total round-trip time A-LSR using the
last SR timestamp (LSR) field, and then subtracting this field to
leave the round-trip propagation delay as (A - LSR - DLSR). This
Schulzrinne, et al. Standards Track [Page 40]
RFC 3550 RTP July 2003
is illustrated in Fig. 2. Times are shown in both a hexadecimal
representation of the 32-bit fields and the equivalent floating-
point decimal representation. Colons indicate a 32-bit field
divided into a 16-bit integer part and 16-bit fraction part.
This may be used as an approximate measure of distance to cluster
receivers, although some links have very asymmetric delays.
[10 Nov 1995 11:33:25.125 UTC] [10 Nov 1995 11:33:36.5 UTC]
n SR(n) A=b710:8000 (46864.500 s)
---------------------------------------------------------------->
v ^
ntp_sec =0xb44db705 v ^ dlsr=0x0005:4000 ( 5.250s)
ntp_frac=0x20000000 v ^ lsr =0xb705:2000 (46853.125s)
(3024992005.125 s) v ^
r v ^ RR(n)
---------------------------------------------------------------->
|<-DLSR->|
(5.250 s)
A 0xb710:8000 (46864.500 s)
DLSR -0x0005:4000 ( 5.250 s)
LSR -0xb705:2000 (46853.125 s)
-------------------------------
delay 0x0006:2000 ( 6.125 s)
Figure 2: Example for round-trip time computation
