Subject: RE: deprecated address handling for inbound TCP

From: Richard Draves <[email-masked]>
Date: Wed, 8 Nov 2000 19:57:48 -0800

I think the rule is: if an application or upper-layer protocol specifies the
address, then you can use a deprecated address. So if an application
explicitly binds to a deprecated address, then you use it. If an existing
TCP connection is using a deprecated address, then you continue to use it.
If you receive TCP SYN sent to a deprecated address, then you can send a SYN
ACK and establish a TCP connection. If you receive an Echo Request, then you
can send an Echo Reply. Etc.

If the IPv6 layer is in the position of selecting a source address (because
an address was not specified by the application or upper-layer), then you
avoid using a deprecated address. See
draft-ietf-ipngwg-default-addr-select-01.

> - I have an existing TCP connection with local address bound to
> 	  a deprecated address.  can I send a TCP packet to the peer?

Yes.

> 	- User application issued TCP connection request.  The 
> kernel need to
> 	  establish a new connection.  Can I use a deprecated 
> address as the
> 	  local address?

You avoid using a deprecated address, but in some circumstances you do
choose a deprecated address.

> 	- I got a new TCP connection request from outside, with 
> my deprecated
> 	  address as the destination.  am I allowed to accept 
> this connetion?

Yes.

Rich
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From: Jim Bound <[email-masked]>
Date: Thu, 09 Nov 2000 23:09:46 -0500

Rich,

I can think of mission critical applications where no new send
operations would be permitted at all by an implementation as a choice
when an address has become deprecated.  I believe some customers will
want this behavior.

I think it wise if implementors have knobs to not permit any
communications with a deprecated address except for existing
connections.

I think what addrconf has stated is fine and clear.

/jim