TCP
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... many other protocols, SIP can run over a variety of transport
protocols, including TCP, UDP, and SCTP. SIP ...
... TLS.
Currently, use of TLS is defined for TCP only. Thus, clients need to
be able to automatically determine which transport protocols ...
... UDP and TCP, along with TLS over TCP,
so that there is always an intersection of capabilities. Some form
of DNS ...
... client SHOULD use UDP for a SIP URI, and TCP
for a SIPS URI. Similarly, if no transport protocol ...
... was present in the SIP URI. However, another transport, such as TCP,
MAY be used if the guidelines of SIP mandate it for this particular
...
... domain. This
specification defines D2U for UDP, D2T for TCP, and D2S for SCTP. We
also establish an IANA registry ...
... This indicates that the server supports TLS over TCP, TCP, and UDP,
in that order of preference. Since the client ...
... domain. As an example, even
though the SRV record for TCP is _sip._tcp.school.edu, there MUST
also be an SRV record at _sip._tcp.example.com.
...
... If no SRV records are found, the client SHOULD use TCP for a SIPS
URI, and UDP for a SIP URI ...
... SIP URI. However, another transport protocol,
such as TCP, MAY be used if the guidelines of SIP mandate it for this
particular request. That is the case, for example, for requests that
...
... ICMP errors in UDP or connection failures in TCP).
Failure also occurs if the transaction layer ...
... TLS", which
refers to TLS over TCP. When this value is present, the server MUST
use TLS over TCP ...
... TCP. When this value is present, the server MUST
use TLS over TCP to send the response.
If, however, the sent-by field contained a domain name ...
... from the Via (again, a value of TLS refers to TLS over TCP). As in
the client processing, the next entry in the list is tried if the one
...
... transport protocol in the SRV query is TCP). The
resulting list is sorted as described in [2], and the response is
...