Re: [Pce] PCE port number

[Vishwas Manral <vishwas.ietf at gmail.com>]

Hi Adrian,

What do you suggest the path forward from here regarding this issue?
Should we just put it in an Errata?

Thanks,
Vishwas

On Fri, Sep 11, 2009 at 10:01 AM, Vishwas Manral <vishwas.ietf at gmail.com> wrote:
> Hi Adrian,
>
> It would have been ok if it was a connectionless transport like UDP.
>
> However I notice a problem when I want multiple sockets to use the
> same port number in particular cases. I figured that I cannot have a
> server socket (accepting connections) as well as a client socket
> trying to connect having the same port number, though I can allow same
> port to be shared across multiple sockets in some cases by using the
> socket option SO_REUSEPORT.
>
> Thanks,
> Vishwas
>
> On Fri, Sep 11, 2009 at 9:33 AM, Adrian Farrel <adrian at olddog.co.uk> wrote:
>> Hi,
>>
>> For my part (I only worked as an author quite late in the process, but I was
>> helping to get this through the IESG review that raised issued about TCP
>> ports) I think Julien has not captured the point.
>>
>> The RFC is not silent about source ports because it does intend to limit the
>> scope.
>>
>> As Julien says, it does matter which port is listened on, and this is
>> deliberately a well-known port number so that it is not necessary to
>> configure (or advertise) the port that must be called.
>>
>> But in Section 4.2.1 you will find...
>>
>>  Only one PCEP session can exist between a pair of PCEP peers at any
>>  one time.  Only one TCP connection on the PCEP port can exist between
>>  a pair of PCEP peers at any one time.
>>
>> One way to help ensure this is to reduce the number of available ports to
>> use as the source port.
>>
>> Does restricting the source port cause any implementation or deployment
>> problems?
>>
>> Thanks,
>> Adrian
>>
>> ----- Original Message ----- From: <julien.meuric at orange-ftgroup.com>
>> To: <vishwas.ietf at gmail.com>; <jpv at cisco.com>;
>> <jeanlouis.leroux at orange-ftgroup.com>
>> Cc: <pce at ietf.org>
>> Sent: Thursday, September 10, 2009 9:57 AM
>> Subject: Re: [Pce] PCE port number
>>
>>
>> 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: pce-bounces at ietf.org [mailto:pce-bounces at ietf.org] 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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