Subject: RE: From whence they came?

From: "Tom-PT Taylor" <[email-masked]>
Date: Thu, 10 May 2001 18:55:50 -0400

It's partly the difference between a physical and a logical unit in a
load-sharing architecture where the separate units have different addresses.
There's also the possibility that a single physical unit has multiple
network interfaces.  Using the address as received in the header is
important because it gives a beter chnace of the response getting back
through any intervening firewall.

-----Original Message-----
From: Paul Long [mailto:[email-masked]]
Sent: Thursday, May 10, 2001 5:40 PM
To: megaco
Subject: RE: From whence they came?

Tom,
 
Okay, then, and this may be a stupid question, but what is the difference
between "the peer in an association" and the source of a message? IOW, under
what circumstances might they be different? The reason I was confused was
probably because in H.323 the source of a message is of absolutely no
consequence.
 
Paul Long
ipDialog, Inc.

-----Original Message-----
From: Tom-PT Taylor [mailto:[email-masked]]
Sent: Thursday, May 10, 2001 1:50 PM
To: 'Paul Long'; megaco
Subject: RE: From whence they came?

They refer to the source address in the IP header and source port in the
TCP/UDP/SCTP headers.  mID is just a tag to identify the peer in an
association.

> -----Original Message----- 
> From: Paul Long [ mailto:[email-masked] <mailto:[email-masked]> ] 
> Sent: Thursday, May 10, 2001 2:24 PM 
> To: megaco 
> Subject: From whence they came? 
> 
> 
> Item 6.85 got me thinking about the following passages in the spec. 
> 
> 7.2.8: "...replies and pending indications must be sent to 
> the address from 
> which the corresponding requests originated." 
> 9: "...responses ... must always be sent back to the address 
> which was the 
> source of the corresponding request." 
> 
> Are they referring to the source address in the IP header and 
> source port in 
> the UDP and TCP headers, or are they referring to the mID in 
> the message 
> header? 
> 
> Paul Long 
> ipDialog, Inc.

---

From: "Paul Long" <[email-masked]>
Date: Thu, 10 May 2001 19:27:47 -0500

RE: From whence they came?Tom,

Hmmm... Taking a closer look at the spec, I see that the mID in the message
prolog is just used by the receiver as a logical identifier for the sender
and that, in particular, the IP-address forms just have syntactical
value--they are never used as IP addresses, per se. It looks like these mIDs
are only used when paired up with transaction identifiers to uniquely
identify transactions, scoped to the receiver. Is this correct? Scary
thought, but, as long as the sender takes care by using an IP address that
another sender will not use, it appears that the IP address in a message mID
doesn't have to have any relationship to the actual network interface of the
sender. Am I right?

Paul Long
ipDialog, Inc.

    -----Original Message-----
    From: Paul Long [mailto:[email-masked]]
    Sent: Thursday, May 10, 2001 5:40 PM
    To: megaco
    Subject: RE: From whence they came?

    Tom,

    Okay, then, and this may be a stupid question, but what is the
difference between "the peer in an association" and the source of a message?
IOW, under what circumstances might they be different? The reason I was
confused was probably because in H.323 the source of a message is of
absolutely no consequence.

    Paul Long
    ipDialog, Inc.