We encounterred with SIP signaling commands lost issues recently in different terminals, environments, and scenarios. And we were using UDP as our prior transport type. The potential cause could be: 1. There were SIP commands which could larger than MTU size. 2. The send/recv queue buffer size of the socket […]
SIP
As you may know, to be a robust meeting entity, we must take good care of compatibility requirements for different facilities from different manufacturers. In H.323 protocol, we can use fields like Vendor ID, Product ID, Version ID in the signaling commands. But how to do this when you are using SIP protocol? Definitions in RFC 3261 20.35 Server The Server header field contains information about the software used by the UAS to handle the request. Revealing the specific software version of the server might allow the server to become more vulnerable to attacks against software that is known to contain security holes. Implementers SHOULD make the Server header field a configurable option. Example: Server: HomeServer v2 20.41 User-Agent The User-Agent header field contains information about the UAC originating the request. The semantics of this header field are defined in [H14.43]. Revealing the specific software version of the user agent might allow the user agent to become more vulnerable to attacks against software that is known to contain security holes. Implementers SHOULD make the User-Agent header field a configurable option. Example: User-Agent: Softphone Beta1.5 [H14.43] User-Agent definition in RFC2616 14.43 User-Agent The User-Agent request-header field contains information about the user agent originating the request. This is for statistical purposes, the tracing of protocol violations, and automated recognition of user agents for the sake of tailoring responses to avoid particular user agent limitations. User agents SHOULD include this field with requests. The field can contain multiple product tokens (section 3.8) and comments identifying the agent and any subproducts which form a significant part of the user agent. By convention, the product tokens are listed in order of their significance for identifying the application. User-Agent = “User-Agent” “:” 1*( product | comment ) Example: User-Agent: CERN-LineMode/2.15 libwww/2.17b3 How TANDBERG and Polycom implemented? TANDBERG: POLYCOM: So, jump to the conclusion: As UAC, identify yourself in User-Agent field. As UAS, identify yourself in Server field. Comparing with TANDBERG and POLYCOM’s implementation, TANDBERG format is more proper.
Vendor ID, Product ID information in SIP
This question was origined from an experience of conferencing with different meeting terminals, including Polycom, Cisco, Tandburg, Huawei, etc. In our current implementation of SIP conference, we are using a stream_id tag in the Video Fast Update command to tell the peer we are requesting an Intra frame for a […]
Media Control(Video Picture Fast Update) mechanism for SIP
Facing a new task of standardizing SIP protocols for the Kedacom conference Endpoints. So I digged into some RFC document recently. Here are some key notes for RFC3264: An OfferAnswer Model with the Session Description Protocol (SDP) 1. Capatibility comparison – Direction —————————————– If “a=sendrecv” attribute does not exist, or […]
Some key notes for RFC3264
I’m participating in a project which was targeted to dual stream control together with MTs of Polycom and Huawei, by using BFCP protocol while a SIPProxy is invloved. Working environment: A. Several MTs working behind different NAT. B. A Polycom SIP Proxy Server in internet. MT: Polycom MT model: POLYCOM […]