Subject: [pcp] [PCP] Using PCP to reduce keepalive traffic of IM application

From: GangChen <[email-masked]>
Date: Mon, 17 Jan 2011 23:12:33 +0800

Hello Dan,

For draft-ietf-pcp-base-02 section 7.7, I find a drawback when PCP is
applied to IM applications. The IM original keepalives (sent from IM
client to IM server) have two purposes. One is to keep NAT state
alive. The other is to make IM server aware of IM client state (alive
or dead).  When it changes to PCP, PCP messages are sent between PCP
client and PCP server.  IM server will regard TCP connection
interrupted, since it can't receive keepalive message for specific
lifetime duration.

Should we consider this problem?

BRs

Gang

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From: "Dan Wing" <[email-masked]>
Date: Tue, 18 Jan 2011 13:36:54 -0800

> Should we consider this problem?

I added the following to my work-in-progress copy of -03, which I
believe goes to your question:

            Note: For reasons beyond NAT, an application may find
            it useful to perform application-level keepalives, such as
            to detect a broken path between the client and server,
            detect a crashed server, or detect a powered-down
            client. These keepalives are not related to maintaining
            middlebox state, and PCP cannot do anything useful to
            reduce those keepalives.

-d