Subject: Re: Implementors' Guide Update Editor's last Call Section 11.2

From: Chuong Nguyen <[email-masked]>
Date: Thu, 10 May 2001 09:38:47 -0500

G'Day Christian
Please see comments below":

G'Day Chuong,

Please see my replies below.

Cheers, Christian

Chuong Nguyen wrote:
>
> Christian
>
>
> Section 11.2 ServiceChange Address and Ports
> There is some confusion on  when to use either ServiceChange Address
> or ServiceChange MGCID. The text below offers some advice on
>
> [Begin Clarification]
> 1) The use of ServiceChangeAddress is not encouraged
>
> <cnn>  Why is the use not encouraged?
[CHG] This was in the approved IG. The issue was that the
ServiceChangeMgcID and the ServiceChangeAddress carried essentially the
same information. So ServiceChangeMgcID was favoured.

<cnn>  Now I am really confused.  As I had quoted below the difference
between
              ServiceChangeAddress and ServiceChangeMgcID.  They both
have different
              purpose.
              For UDP ServiceChangeAddress is used to tell each other
what port# to use
              for further communication.
              ServiceChangeMgcID is for MGC to tell MG to seek another
MGC to service it.

             It is not one is prefer over the other.  It is more like
how it should be used.

             I think that the confusion must have occured when
ServiceChangeAddress was changed
             in the ABNF from VAULE to mID which is something else that
I want to address later.

             Your comment about ServiceChangeMgcId was favoured over
ServiceChangeAddress
              does not make sense to me.

             For example, MG sends ServiceChange Restart to MGC1.

             Case 1:  MGC1 does not want to service MG.
             MGC1 sends Reply back w/ServiceChangeMgcId of MGC2.
             Thus telling MG to try MGC2.

             Case 2: MGC1 will service MG but want MG to use port #
10000 for further communication.
             MGC1 replies w/ServiceChangeAddress containing port#10000.
              Now ServiceChangeAddress ABNF has been changed in IGv6
section B.2

                   serviceChangeAddress = ServiceChangeAddressToken
EQUAL ( mId / portNumber )

               So MGC1 can either specify "ServiceChangeAddress=10000"
or
                "ServiceChangeAddress=10.10.10.10:10000"

            From the above example, I don't see how ServiceChangeMgcId
is favoured over
            ServiceChangeAddress.

>
> 2) MGCs must be able to cope with ServiceChangeAddress with either a
> full address or just a port number in the case of TCP transport.
>
> <cnn>  Do you mean UDP transport?
>                And ServiceChangeAddress does not apply to TCP?
[CHG] ServiceChangeAddress applies to all. The "or" relates TCP to the
port number. I guess you could remove the "in the case of TCP transport"

part.

<cnn>  I think we went over this already on the List and Brian has
indicated the following:
              If TCP is used ServiceChangeAddress would be ignored if
included in the msg.
              And I agree w/him that there is no point in changing port#
for TCP which will
              require a new TCP connection towards the MGC.

              Maybe Brian can clarify this again?

>
>
> <cnn>  I don't see any text regarding the clarification of when one or

> the other should be used.
> The Standard text already has something like:
>
> ServiceChangeAddress
>    and ServiceChangeMgcId parameters must not both be present in the
>    ServiceChangeDescriptor or the ServiceChangeResultDescriptor.  The
>    ServiceChangeAddress provides an address to be used within the
>    context of the association currently being negotiated, while the
>    ServiceChangeMgcId provides an alternate address where the MG
> should
>    seek to establish another association.
[CHG] That's why we put the note in favouring MGcID.

<cnn>  See comments above.
              The only thing that I see wrong is that Section 7.2.8 is
missing the description of
              ServiceChangeMgcId in a separate paragraph like the other
parameters.
              ServiceChangeMgcId description is buried in the
ServiceChangeAddress description
              plus subsequent paragraphs describing ServiceChange
Registration.

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