Re: [pcp] WG Call for Adoption: Optimizing NAT and Firewall Keepalives Using Port Control Protocol (PCP)

[<[e-mail]>]

Hi,

[e-mail] wrote:
> 
> I have one comment for the authors: consider adding some text to highlight
> PCP benefits to reduce keepalive messages when deployed in managed
> networks (i.e., both the underlying network and the service are managed by
> the same administrative entity). A typical example is SIP-based deployments:
> optimize the load on access service nodes (SBC, SBE, P-CSCF, etc.) because
> the lifetime of the mapping is known to the SIP UA and as such there is no
> need to issue frequent register messages to maintain the mapping alive, etc.
> 

Thanks for the comment. 

I have a question, though: If the same entity operates the network and the service such as SIP, do they need an explicit protocol like PCP to control or learn about the mapping lifetimes, or can they just configure them? I mean, since the service provider is able to configure the NAT/FW mapping lifetimes in the way they like, can't they just set the keep-alives in their SIP clients accordingly? As an example, the Firewall in a mobile network can be configured to set the lifetime for TCP connections destined to the SIP proxy (SBC, P-CSCF) to 1 hour, and via Device Management the operator could also turn off or set the IMS client keep-alives to match that. PCP would not be needed for that particular case.

It would seem to me that PCP would have more utility in "unmanaged" or "unrelated" cases where the client app basically has no a priori knowledge about the network, and neither does the application service provider. Or similarly, the NATs or Firewalls would have no idea what the TCP connections would be used for. 

Markus