If the host is using the same port for 2 different applications, wouldn't
the applications get confused? Dont the applications need 2 different
streams of traffic going with 2 different ports?
>From: [EMAIL PROTECTED]
>To: [EMAIL PROTECTED], [EMAIL PROTECTED]
>Subject: RE: Question about Napt
>Date: Thu, 25 Jan 2001 10:07:30 -0500
>
>Here's my 2cents
>
>All TCP/UDP sessions can be uniquely identified using four pieces of
>information
>source tuple
>1) source ip address
>2) source socket
>destination tuple
>3) destination ip address
>4) destination socket
>
>The router would keep a table of inside connections and map those to a
>table
>of outside connections that it originates.
>On the outside connections it has to be able to pick the source socket to
>originate from. This allows the router to create unique connections
>without
>duplication. As to the multiplexing part, the router really wouldn't be
>involed. The host would be doing the multiplexing. If I understand what
>you have written the host would be using the same unique information to
>create the second session: same source ip address, same source socket, same
>destination ip address, and the same destination socket. So the router
>really wouldn't care that there were two sessions, it only keys on the
>source and destination tuples.
>
>
>-----Original Message-----
>From: Fred Danson [mailto:[EMAIL PROTECTED]]
>Sent: Thursday, January 25, 2001 9:07 AM
>To: [EMAIL PROTECTED]
>Subject: Question about Napt
>
>
> Hi, I was reading RFC3022 about Napt last night, and I still dont
>understand one thing about it. From what I understand is that Napt allows
>you to use one single globally unique IP address on the WAN interface of
>your router, and then a large number of local addresses inside your network
>which aren't globally unique.
> Now the router will be able to translate the different traffic
>streams
>coming from the WAN according to the port on the packet. So if host A
>inside
>
>the network wanted to communicate with Host B which is on a different
>outside network, it would directly address the outside site, and the router
>would catch the packet enroute and change the source IP address to the
>router WAN interface IP address and also change the source port to a port
>of
>
>the router's discretion.
> Normally, from what I understand, ports are used to multiplex streams
>of traffic across a link. If Host A was using two applications and wanted
>to
>
>start a second session with Host B. Would the router allow this? The RFC
>states "While not a common practice, it is possible to have an application
>on a private host establish multiple simutaneous sessions originating from
>the same tuple of (private address, private TU port). In such a case, a
>single binding for the tuple of (private address, private TU port) may be
>used for translation of packets pertaining to all sessions originating from
>the same tuple on a host. How exactly would the applications know which
>traffic stream was for itself?
> Also, how many local hosts can the router assign to a single IP
>address
>before it has to use a second IP address? Could a company of 100000 use a
>single IP address for NAPT? or would it need to use more than one?
>
>
>Thanks in advance,
>
>Freddy
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