Flux SIP Trapéziodal

Etablissement de session à travers deux proxy

Source : https://tools.ietf.org/html/rfc3665#section-3.2

Alice           Proxy 1          Proxy 2            Bob
     |                |                |                |
     |   INVITE F1    |                |                |
     |--------------->|                |                |
     |     407 F2     |                |                |
     |<---------------|                |                |
     |     ACK F3     |                |                |
     |--------------->|                |                |
     |   INVITE F4    |                |                |
     |--------------->|   INVITE F5    |                |
     |     100  F6    |--------------->|   INVITE F7    |
     |<---------------|     100  F8    |--------------->|
     |                |<---------------|                |
     |                |                |     180 F9     |
     |                |    180 F10     |<---------------|
     |     180 F11    |<---------------|                |
     |<---------------|                |     200 F12    |
     |                |    200 F13     |<---------------|
     |     200 F14    |<---------------|                |
     |<---------------|                |                |
     |     ACK F15    |                |                |
     |--------------->|    ACK F16     |                |
     |                |--------------->|     ACK F17    |
     |                |                |--------------->|
     |                Both Way RTP Media                |
     |<================================================>|
     |                |                |     BYE F18    |
     |                |    BYE F19     |<---------------|
     |     BYE F20    |<---------------|                |
     |<---------------|                |                |
     |     200 F21    |                |                |
     |--------------->|     200 F22    |                |
     |                |--------------->|     200 F23    |
     |                |                |--------------->|
     |                |                |                |

   ```

   In this scenario, Alice completes a call to Bob using two proxies
   Proxy 1 and Proxy 2.  The initial INVITE (F1) contains a pre-loaded
   Route header with the address of Proxy 1 (Proxy 1 is configured as a
   default outbound proxy for Alice).  The request does not contain the
   Authorization credentials Proxy 1 requires, so a 407 Proxy
   Authorization response is sent containing the challenge information.
   A new INVITE (F4) is then sent containing the correct credentials and
   the call proceeds.  The call terminates when Bob disconnects by
   initiating a BYE message.

   Proxy 1 inserts a Record-Route header into the INVITE message to
   ensure that it is present in all subsequent message exchanges.  Proxy
   2 also inserts itself into the Record-Route header.  The ACK (F15)
   and BYE (F18) both have a Route header.

###   Message Details

####   F1 INVITE Alice -> Proxy 1
INVITE sip:bob@biloxi.example.com SIP/2.0 Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bK74b43 Max-Forwards: 70 Route: From: Alice sip:alice@atlanta.example.com;tag=9fxced76sl To: Bob sip:bob@biloxi.example.com Call-ID: 3848276298220188511@atlanta.example.com CSeq: 1 INVITE Contact: sip:alice@client.atlanta.example.com;transport=tcp Content-Type: application/sdp Content-Length: 151

v=0 o=alice 2890844526 2890844526 IN IP4 client.atlanta.example.com s=- c=IN IP4 192.0.2.101 t=0 0 m=audio 49172 RTP/AVP 0 a=rtpmap:0 PCMU/8000

   /* Proxy 1 challenges Alice for authentication */


####   F2 407 Proxy Authorization Required Proxy 1 -> Alice
SIP/2.0 407 Proxy Authorization Required Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bK74b43 ;received=192.0.2.101 From: Alice sip:alice@atlanta.example.com;tag=9fxced76sl To: Bob sip:bob@biloxi.example.com;tag=3flal12sf Call-ID: 3848276298220188511@atlanta.example.com CSeq: 1 INVITE Proxy-Authenticate: Digest realm="atlanta.example.com", qop="auth", nonce="f84f1cec41e6cbe5aea9c8e88d359", opaque="", stale=FALSE, algorithm=MD5 Content-Length: 0
####   F3 ACK Alice -> Proxy 1
ACK sip:bob@biloxi.example.com SIP/2.0 Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bK74b43 Max-Forwards: 70 From: Alice sip:alice@atlanta.example.com;tag=9fxced76sl To: Bob sip:bob@biloxi.example.com;tag=3flal12sf Call-ID: 3848276298220188511@atlanta.example.com CSeq: 1 ACK Content-Length: 0

``` /* Alice responds be re-sending the INVITE with authentication credentials in it. */

F4 INVITE Alice -> Proxy 1

   INVITE sip:bob@biloxi.example.com SIP/2.0
   Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bK74bf9
   Max-Forwards: 70
   Route: <sip:ss1.atlanta.example.com;lr>
   From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
   To: Bob <sip:bob@biloxi.example.com>
   Call-ID: 3848276298220188511@atlanta.example.com
   CSeq: 2 INVITE
   Contact: <sip:alice@client.atlanta.example.com;transport=tcp>
   Proxy-Authorization: Digest username="alice",
    realm="atlanta.example.com",
    nonce="wf84f1ceczx41ae6cbe5aea9c8e88d359", opaque="",
    uri="sip:bob@biloxi.example.com",
    response="42ce3cef44b22f50c6a6071bc8"
   Content-Type: application/sdp
   Content-Length: 151

   v=0
   o=alice 2890844526 2890844526 IN IP4 client.atlanta.example.com
   s=-
   c=IN IP4 192.0.2.101
   t=0 0
   m=audio 49172 RTP/AVP 0
   a=rtpmap:0 PCMU/8000

/* Proxy 1 accepts the credentials and forwards the INVITE to Proxy 2. Client for Alice prepares to receive data on port 49172 from the network. */

F5 INVITE Proxy 1 -> Proxy 2

   INVITE sip:bob@biloxi.example.com SIP/2.0
   Via: SIP/2.0/TCP ss1.atlanta.example.com:5060;branch=z9hG4bK2d4790.1
   Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bK74bf9
    ;received=192.0.2.101
   Max-Forwards: 69
   Record-Route: <sip:ss1.atlanta.example.com;lr>
   From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
   To: Bob <sip:bob@biloxi.example.com>
   Call-ID: 3848276298220188511@atlanta.example.com
   CSeq: 2 INVITE
   Contact: <sip:alice@client.atlanta.example.com;transport=tcp>
   Content-Type: application/sdp
   Content-Length: 151

   v=0
   o=alice 2890844526 2890844526 IN IP4 client.atlanta.example.com
   s=-
   c=IN IP4 192.0.2.101
   t=0 0
   m=audio 49172 RTP/AVP 0
   a=rtpmap:0 PCMU/8000

F6 100 Trying Proxy 1 -> Alice

   SIP/2.0 100 Trying
   Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bK74bf9
    ;received=192.0.2.101
   From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
   To: Bob <sip:bob@biloxi.example.com>
   Call-ID: 3848276298220188511@atlanta.example.com
   CSeq: 2 INVITE
   Content-Length: 0

F7 INVITE Proxy 2 -> Bob

   INVITE sip:bob@client.biloxi.example.com SIP/2.0
   Via: SIP/2.0/TCP ss2.biloxi.example.com:5060;branch=z9hG4bK721e4.1
   Via: SIP/2.0/TCP ss1.atlanta.example.com:5060;branch=z9hG4bK2d4790.1
    ;received=192.0.2.111
   Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bK74bf9
    ;received=192.0.2.101
   Max-Forwards: 68
   Record-Route: <sip:ss2.biloxi.example.com;lr>,
    <sip:ss1.atlanta.example.com;lr>
   From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
   To: Bob <sip:bob@biloxi.example.com>
   Call-ID: 3848276298220188511@atlanta.example.com
   CSeq: 2 INVITE
   Contact: <sip:alice@client.atlanta.example.com;transport=tcp>
   Content-Type: application/sdp
   Content-Length: 151

   v=0
   o=alice 2890844526 2890844526 IN IP4 client.atlanta.example.com
   s=-
   c=IN IP4 192.0.2.101
   t=0 0
   m=audio 49172 RTP/AVP 0
   a=rtpmap:0 PCMU/8000

F8 100 Trying Proxy 2 -> Proxy 1

   SIP/2.0 100 Trying
   Via: SIP/2.0/TCP ss1.atlanta.example.com:5060;branch=z9hG4bK2d4790.1
    ;received=192.0.2.111
   Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bK74bf9
    ;received=192.0.2.101
   From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
   To: Bob <sip:bob@biloxi.example.com>
   Call-ID: 3848276298220188511@atlanta.example.com
   CSeq: 2 INVITE
   Content-Length: 0

F9 180 Ringing Bob -> Proxy 2

   SIP/2.0 180 Ringing
   Via: SIP/2.0/TCP ss2.biloxi.example.com:5060;branch=z9hG4bK721e4.1
    ;received=192.0.2.222
   Via: SIP/2.0/TCP ss1.atlanta.example.com:5060;branch=z9hG4bK2d4790.1
    ;received=192.0.2.111
   Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bK74bf9
    ;received=192.0.2.101
   Record-Route: <sip:ss2.biloxi.example.com;lr>,
    <sip:ss1.atlanta.example.com;lr>
   From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
   To: Bob <sip:bob@biloxi.example.com>;tag=314159
   Call-ID: 3848276298220188511@atlanta.example.com
   Contact: <sip:bob@client.biloxi.example.com;transport=tcp>
   CSeq: 2 INVITE
   Content-Length: 0

F10 180 Ringing Proxy 2 -> Proxy 1

   SIP/2.0 180 Ringing
   Via: SIP/2.0/TCP ss1.atlanta.example.com:5060;branch=z9hG4bK2d4790.1
    ;received=192.0.2.111
   Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bK74bf9
    ;received=192.0.2.101
   Record-Route: <sip:ss2.biloxi.example.com;lr>,
    <sip:ss1.atlanta.example.com;lr>
   From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
   To: Bob <sip:bob@biloxi.example.com>;tag=314159
   Call-ID: 3848276298220188511@atlanta.example.com
   Contact: <sip:bob@client.biloxi.example.com;transport=tcp>
   CSeq: 2 INVITE
   Content-Length: 0

F11 180 Ringing Proxy 1 -> Alice

   SIP/2.0 180 Ringing
   Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bK74bf9
    ;received=192.0.2.101
   Record-Route: <sip:ss2.biloxi.example.com;lr>,
    <sip:ss1.atlanta.example.com;lr>
   From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
   To: Bob <sip:bob@biloxi.example.com>;tag=314159
   Call-ID: 3848276298220188511@atlanta.example.com
   Contact: <sip:bob@client.biloxi.example.com;transport=tcp>
   CSeq: 2 INVITE
   Content-Length: 0

F12 200 OK Bob -> Proxy 2

   SIP/2.0 200 OK
   Via: SIP/2.0/TCP ss2.biloxi.example.com:5060;branch=z9hG4bK721e4.1
    ;received=192.0.2.222
   Via: SIP/2.0/TCP ss1.atlanta.example.com:5060;branch=z9hG4bK2d4790.1
    ;received=192.0.2.111
   Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bK74bf9
    ;received=192.0.2.101
   Record-Route: <sip:ss2.biloxi.example.com;lr>,
    <sip:ss1.atlanta.example.com;lr>
   From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
   To: Bob <sip:bob@biloxi.example.com>;tag=314159
   Call-ID: 3848276298220188511@atlanta.example.com
   CSeq: 2 INVITE
   Contact: <sip:bob@client.biloxi.example.com;transport=tcp>
   Content-Type: application/sdp
   Content-Length: 147

   v=0
   o=bob 2890844527 2890844527 IN IP4 client.biloxi.example.com
   s=-
   c=IN IP4 192.0.2.201
   t=0 0
   m=audio 3456 RTP/AVP 0
   a=rtpmap:0 PCMU/8000

F13 200 OK Proxy 2 -> Proxy 1

   SIP/2.0 200 OK
   Via: SIP/2.0/TCP ss1.atlanta.example.com:5060;branch=z9hG4bK2d4790.1
    ;received=192.0.2.111
   Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bK74bf9
    ;received=192.0.2.101
   Record-Route: <sip:ss2.biloxi.example.com;lr>,
    <sip:ss1.atlanta.example.com;lr>
   From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
   To: Bob <sip:bob@biloxi.example.com>;tag=314159
   Call-ID: 3848276298220188511@atlanta.example.com
   CSeq: 2 INVITE
   Contact: <sip:bob@client.biloxi.example.com;transport=tcp>
   Content-Type: application/sdp
   Content-Length: 147

   v=0
   o=bob 2890844527 2890844527 IN IP4 client.biloxi.example.com
   s=-
   c=IN IP4 192.0.2.201
   t=0 0
   m=audio 3456 RTP/AVP 0
   a=rtpmap:0 PCMU/8000

F14 200 OK Proxy 1 -> Alice

   SIP/2.0 200 OK
   Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bK74bf9
    ;received=192.0.2.101
   Record-Route: <sip:ss2.biloxi.example.com;lr>,
    <sip:ss1.atlanta.example.com;lr>
   From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
   To: Bob <sip:bob@biloxi.example.com>;tag=314159
   Call-ID: 3848276298220188511@atlanta.example.com
   CSeq: 2 INVITE
   Contact: <sip:bob@client.biloxi.example.com;transport=tcp>
   Content-Type: application/sdp
   Content-Length: 147

   v=0
   o=bob 2890844527 2890844527 IN IP4 client.biloxi.example.com
   s=-
   c=IN IP4 192.0.2.201
   t=0 0
   m=audio 3456 RTP/AVP 0
   a=rtpmap:0 PCMU/8000

F15 ACK Alice -> Proxy 1

   ACK sip:bob@client.biloxi.example.com SIP/2.0
   Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bK74b76
   Max-Forwards: 70
   Route: <sip:ss1.atlanta.example.com;lr>,
    <sip:ss2.biloxi.example.com;lr>
   From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
   To: Bob <sip:bob@biloxi.example.com>;tag=314159
   Call-ID: 3848276298220188511@atlanta.example.com
   CSeq: 2 ACK
   Content-Length: 0

F16 ACK Proxy 1 -> Proxy 2

   ACK sip:bob@client.biloxi.example.com SIP/2.0
   Via: SIP/2.0/TCP ss1.atlanta.example.com:5060;branch=z9hG4bK2d4790.1
   Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bK74b76
    ;received=192.0.2.101
   Max-Forwards: 69
   Route: <sip:ss2.biloxi.example.com;lr>
   From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
   To: Bob <sip:bob@biloxi.example.com>;tag=314159
   Call-ID: 3848276298220188511@atlanta.example.com
   CSeq: 2 ACK
   Content-Length: 0

F17 ACK Proxy 2 -> Bob

   ACK sip:bob@client.biloxi.example.com SIP/2.0
   Via: SIP/2.0/TCP ss2.biloxi.example.com:5060;branch=z9hG4bK721e4.1
   Via: SIP/2.0/TCP ss1.atlanta.example.com:5060;branch=z9hG4bK2d4790.1
    ;received=192.0.2.111
   Via: SIP/2.0/TCP client.atlanta.example.com:5060;branch=z9hG4bK74b76
    ;received=192.0.2.101
   Max-Forwards: 68
   From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
   To: Bob <sip:bob@biloxi.example.com>;tag=314159
   Call-ID: 3848276298220188511@atlanta.example.com
   CSeq: 2 ACK
   Content-Length: 0

/* RTP streams are established between Alice and Bob */

/* Bob Hangs Up with Alice. */

/* Again, note that the CSeq is NOT 3. Alice and Bob maintain their own separate CSeq counts */

F18 BYE Bob -> Proxy 2

   BYE sip:alice@client.atlanta.example.com SIP/2.0
   Via: SIP/2.0/TCP client.biloxi.example.com:5060;branch=z9hG4bKnashds7
   Max-Forwards: 70
   Route: <sip:ss2.biloxi.example.com;lr>,
    <sip:ss1.atlanta.example.com;lr>
   From: Bob <sip:bob@biloxi.example.com>;tag=314159
   To: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
   Call-ID: 3848276298220188511@atlanta.example.com
   CSeq: 1 BYE
   Content-Length: 0

F19 BYE Proxy 2 -> Proxy 1

   BYE sip:alice@client.atlanta.example.com SIP/2.0
   Via: SIP/2.0/TCP ss2.biloxi.example.com:5060;branch=z9hG4bK721e4.1
   Via: SIP/2.0/TCP client.biloxi.example.com:5060;branch=z9hG4bKnashds7
    ;received=192.0.2.201
   Max-Forwards: 69
   Route: <sip:ss1.atlanta.example.com;lr>
   From: Bob <sip:bob@biloxi.example.com>;tag=314159
   To: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
   Call-ID: 3848276298220188511@atlanta.example.com
   CSeq: 1 BYE
   Content-Length: 0

F20 BYE Proxy 1 -> Alice

   BYE sip:alice@client.atlanta.example.com SIP/2.0
   Via: SIP/2.0/TCP ss1.atlanta.example.com:5060;branch=z9hG4bK2d4790.1
   Via: SIP/2.0/TCP ss2.biloxi.example.com:5060;branch=z9hG4bK721e4.1
    ;received=192.0.2.222
   Via: SIP/2.0/TCP client.biloxi.example.com:5060;branch=z9hG4bKnashds7
    ;received=192.0.2.201
   Max-Forwards: 68
   From: Bob <sip:bob@biloxi.example.com>;tag=314159
   To: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
   Call-ID: 3848276298220188511@atlanta.example.com
   CSeq: 1 BYE
   Content-Length: 0

F21 200 OK Alice -> Proxy 1

   SIP/2.0 200 OK
   Via: SIP/2.0/TCP ss1.atlanta.example.com:5060;branch=z9hG4bK2d4790.1
    ;received=192.0.2.111
   Via: SIP/2.0/TCP ss2.biloxi.example.com:5060;branch=z9hG4bK721e4.1
    ;received=192.0.2.222
   Via: SIP/2.0/TCP client.biloxi.example.com:5060;branch=z9hG4bKnashds7
    ;received=192.0.2.201
   From: Bob <sip:bob@biloxi.example.com>;tag=314159
   To: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
   Call-ID: 3848276298220188511@atlanta.example.com
   CSeq: 1 BYE
   Content-Length: 0

F22 200 OK Proxy 1 -> Proxy 2

   SIP/2.0 200 OK
   Via: SIP/2.0/TCP ss2.biloxi.example.com:5060;branch=z9hG4bK721e4.1
    ;received=192.0.2.222
   Via: SIP/2.0/TCP client.biloxi.example.com:5060;branch=z9hG4bKnashds7
    ;received=192.0.2.101
   From: Bob <sip:bob@biloxi.example.com>;tag=314159
   To: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
   Call-ID: 3848276298220188511@atlanta.example.com
   CSeq: 1 BYE
   Content-Length: 0

F23 200 OK Proxy 2 -> Bob

   SIP/2.0 200 OK
   Via: SIP/2.0/TCP client.biloxi.example.com:5060;branch=z9hG4bKnashds7
    ;received=192.0.2.201
   From: Bob <sip:bob@biloxi.example.com>;tag=314159
   To: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
   Call-ID: 3848276298220188511@atlanta.example.com
   CSeq: 1 BYE
   Content-Length: 0

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