Hello
2020-12-03T18:05:46.456106+00:00 ashmainkama51 kamailio[22147]: a=candidate:2274611867 1 tcp 1518283007 2001:8a0:78fc:7000:e1d7:e93:3c50:ee71 9 typ host tcptype active generation 0 network-id 2 network-cost 10
is a local candidate sent in the offer from the client
ICE=force just says rtpengine: "when you will resend this offer to the receiver, remove all candidates sent by sender and put yourself as the only candidate"
But rtpengine still has to follow the ICE check for the received candidates as in that case rtpengine is the receiver and it can't just not check local candidates. That is why you facing this behaviour from the rtpengine, which is totally correct.
In other terms
Sender -----------> rtpengine : rtpengine must follow ice procedure and check availability of these local candidates to establish connection between Sender and rtpengine
rtpengine ---------> Receiver: rtpengine pretends to be a Sender for the ICE agent of the receiver. but in this term, RTPengine will be the only candidate for this part of the call, so this part is establishing a connection between rtpengine and Receiver
On 03/12/2020 13.39, Andrew Chen wrote:
> Hi all,
>
> I was wondering if someone can help me understand how the ICE
> parameter works in the rtpengine module works.
>
> So basically our client does an ICE candidate lookup and grabs a list
> of them and applies it to the INVITE that gets sent to the Kamailio.
> The list looks like this:
>
> 2020-12-03T18:05:46.456030+00:00 ashmainkama51 kamailio[22147]:
> a=candidate:3373280875 1 udp 2122262783
> 2001:8a0:78fc:7000:e1d7:e93:3c50:ee71 59827 typ host generation 0
> network-id 2 network-cost 10
> 2020-12-03T18:05:46.456057+00:00 ashmainkama51 kamailio[22147]:
> a=candidate:3040609428 1 udp 2122197247
> 2001:8a0:78fc:7000:d979:bf75:dbc0:69f 59828 typ host generation 0
> network-id 3 network-cost 10
> 2020-12-03T18:05:46.456081+00:00 ashmainkama51 kamailio[22147]:
> a=candidate:1681997092 1 udp 2122129151 192.168.1.66 59829 typ host
> generation 0 network-id 1 network-cost 10
> 2020-12-03T18:05:46.456106+00:00 ashmainkama51 kamailio[22147]:
> a=candidate:2274611867 1 tcp 1518283007
> 2001:8a0:78fc:7000:e1d7:e93:3c50:ee71 9 typ host tcptype active
> generation 0 network-id 2 network-cost 10
> 2020-12-03T18:05:46.456131+00:00 ashmainkama51 kamailio[22147]:
> a=candidate:4223662180 1 tcp 1518217471
> 2001:8a0:78fc:7000:d979:bf75:dbc0:69f 9 typ host tcptype active
> generation 0 network-id 3 network-cost 10
> 2020-12-03T18:05:46.456155+00:00 ashmainkama51 kamailio[22147]:
> a=candidate:717406676 1 tcp 1518149375 192.168.1.66 9 typ host tcptype
> active generation 0 network-id 1 network-cost 10
> 2020-12-03T18:05:46.456180+00:00 ashmainkama51 kamailio[22147]:
> a=candidate:2130547417 1 udp 8199935 206.81.191.27 61165 typ relay
> raddr 85.247.0.121 rport 53091 generation 0 network-id 1 network-cost 10
>
>
> In the rtpengine_offer, I have this:
>
> rtpengine_offer("ICE=force DTLS=passive replace-session-connection
> replace-origin external internal");
>
> What i am trying to do is to tell the freeswitch endpoint to use
> rtpengine as ICE candidate and I see in the SDP this is happening:
>
> a=candidate:6296910676 1 udp 659136 206.81.191.52 52766 typ host
> generation 0
>
> Btw..206.81.191.52 is a separate AWS instance running rtpengine binary.
>
> On the rtpengine_answer, I tell the remote client side the same
> thing..use rtpengine as your ICE candidate:
>
> rtpengine_answer("ICE=force DTLS=passive replace-session-connection
> replace-origin internal external");
>
> and this is snippet from 200 OK:
>
> a=candidate:6296910676 1 udp 659136 206.81.191.52 52766 typ host
> generation 0
>
> Question:
>
> Why does the rtpengine logs still show that it's trying to use
> 2001:8a0:78fc:7000:e1d7:e93:3c50:ee71 as RTP candidate in this scenario?
>
> Dec 3 18:05:47 ashmainrtpe42 rtpengine[8505]: DEBUG:
> [ep1sbnkk9tikhg4kpmot]: Forward to sink endpoint:
> 2001:8a0:78fc:7000:e1d7:e93:3c50:ee71:59827 (RTP seq 25423 TS 0)
>
> I thought ICE=force will handle such adjustments so that all rtp is
> handled by the rtpengine to our client and bypass the STUN server?
>
Isn't that what's happening? Rtpengine receives media from one peer and
forwards it to one of the ICE candidates (presumably the primary one
that was negotiated) of the other peer. Or am I misunderstanding what
you posted?
Cheers
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