Hi Vishwas.

Interesting comment. We must admit the wording is a bit ambiguous.

RFC 5440 says: "The system listens to the PCEP-registered TCP port" and "Upon 
receiving a TCP connection on the PCEP-registered TCP port"; I do not see any 
behavior description for the source TCP port (good thing!).
My guess is that there is no intend to put constraints on the TCP initiator 
port. I would interpret the sentence you mention as "using the registered TCP 
port on the PCE side, i.e. for the source TCP port for PCE to PCC messages and 
for destination TCP port for PCC to PCE messages"... A little cumbersome, I 
agree.

Authors of RFC 5440, would there be an actual intend to specify otherwise? 
Implementers, any other interpretation?

Thanks,

Julien


-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Vishwas 
Manral

Hi,

I looked at the following in the spec:

“Transport Protocol

  PCEP operates over TCP using a registered TCP port (4189).  This
  allows the requirements of reliable messaging and flow control to be
  met without further protocol work.  All PCEP messages MUST be sent
  using the registered TCP port for the source and destination TCP
  port.”

This has been worrying me a bit. Unlike other protocols like BGP or LDP

In BGP it states clearly:

   A BGP implementation MUST connect to and listen on TCP port 179 for
   incoming connections in addition to trying to connect to peers.

and

   BGP's destination port SHOULD be port 179, as defined by IANA.

Why do we have this restriction on source port? It is becoming a
challenging task
in merchant OS.

Thanks,
Vishwas
Vishwas
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