Subject: [Dots] draft-ietf-dots-call-home: Franck's comment about the heartbeat procedure

From: <[email-masked]>
Date: Thu, 25 Jul 2019 14:04:56 +0000

Hi Franck,

You asked yesterday whether the call home uses the same heartbeat mechanism as in the base signal channel. Below some clarifications:

*         The same heartbeat messages are used

*         Unlike the base spec, it is the DOTS server which must start sending the heartbeats (NAT/FW traversal issues)

*         Unlike the base spec, the server may access to the times used by a NAT/FW. It can therefore adjust the heartbeat-interval accordingly.

*         Unlike the base spec, only the server can resume the connection (the client can't)

*         Unlike the base spec, heartbeats from the server to the client may be dropped because of an outgoing attack

We considered in previous version of the spec to rely as much on the heartbeat mechanism in the base signal channel by calling out the main difference: role reversal. But we found later that this wouldn't work because of the considerations listed above.

Thus, a simplified mechanism is defined for the call-home. Please check: https://tools.ietf.org/html/draft-ietf-dots-signal-call-home-03#section-3.2

Cheers,
Med