[SR-Users] Websockets Keep-Alive

Peter Dunkley peter.dunkley at crocodilertc.net
Thu Sep 26 16:36:39 CEST 2013

The Kamailio WebSocket stack will only ping on idle connections.  If
nathelper is sending SIP level pings on a shorter interval than the
WebSocket stack is the connection won't be considered idle.  The
load-balancer doesn't understand the TCP traffic so it won't care as long
as there is traffic.

However, it would seem silly to me to use nathelper pings over the
WebSocket transport (unless you already have them enabled for another
transport) as it is more efficient just to let the WebSocket layer take
care of it.  After all, the nathelper pings from Kamailio are something of
work-around that pre-dates RFC 5626.  Under outbound it's quite clear that
if SIP-level keep-alives are needed for a particular transport the UA
should do it, not the server.



On 26 September 2013 14:55, Juha Heinanen <jh at tutpro.com> wrote:

> Peter Dunkley writes:
> > A good example is that if you are using Amazon Elastic Load-Balancer to
> > distribute WebSocket connections, idle connections will be timed-out (by
> > the Load-Balancer) after 60 seconds - so make sure the server sends
> > WebSocket pings more frequently than that.
> peter,
> websocket readme has this:
>   4.1. keepalive_mechanism (integer)
>   The keep-alive mechanism to use for WebSocket connections.
>   Note
>   If nathelper is only being used for WebSocket connections then nathelper
>   NAT pinging is not required. If nathelper is used for WebSocket
>   connections and TCP/TLS aliasing/NAT-traversal then WebSocket
>   keep-alives are not required.
> based on what you write now, is the above readme text still valid, i.e.,
> are nat pings enough to prevent amazon load balancer from timing out
> websocket connections or are native websocket pings needed instead?
> -- juha
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Peter Dunkley
Technical Director
Crocodile RCS Ltd
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