會談邊界控制器(Session Border Controller, SBC),一種NAT穿透的方式。SBC可確保VoIP 安全,又可提供媒體代理伺服器的套件。
SBC架構於IMS網路之上,可作為IMS網路的SIP和RTSP的 Proxy Server,所有的SIP與RTSP訊息都會透過SBC來處理,SBC更具備NAT穿透的功能。目前思科與 Kagoor 對會談邊界控制技術有突破性的發展。
SBCs 會維持整個會議狀態並提供以下功能:
- Malicious 攻擊, 像是分散式阻斷服務攻擊 (DoS) 或是分散式 DoS
- Toll fraud via rogue media streams
- 拓樸隱藏(Topology hiding)
- Malformed packet protection
- 訊號加密 (經由 TLS 以及 IPSec) 以及媒體 (SRTP)
- NAT 穿透
- SIP 正規化 via SIP message and header manipulation
- IPv4 轉 IPv6
- VPN 連結
- 協定轉換, 如 SIP, SIP-I, H.323
- 服务质量 – QoS 的政策是網路狀態的優先取捨問題. 其功能如下:
- Traffic policing
- Resource allocation
- Rate limiting
- Call admission control
- TOS/DSCP bit setting
- Regulatory – many times the SBC is expected to provide support for regulatory requirements such as:
- emergency calls prioritization and
- lawful interception
- Media services – many of the new generation of SBCs also provide built-in digital signal processors (DSPs) to enable them to offer border-based media control and services such as:
- DTMF 中繼與互連
- 媒體轉碼
- Tones 與 announcements
- 數據與內網傳真
- 支援音訊與影訊
- 統計與傳單資訊 – since all sessions that pass through the edge of the network pass through the SBC, it is a natural point to gather statistics and usage based information on these sessions.
- Hautakorpi, J.; Camarillo, G.; Penfield, R.; Hawrylyshen, A.; Bhatia, M.. Requirements from SIP (Session Initiation Protocol) Session Border Control Deployments. IETF. April 2010. RFC 5853.
- Sinnreich, Henry; Johnston, Alan B., Internet Communication Using SIP, Wiley: 180, 2001, ISBN 0-471-77657-2
- Juniper Networks, The Benefits of Router-Integrated Session Border Control (PDF), 2009, (原始内容 (PDF)存档于2012-11-07)
- Sonus Networks WhitePaper — Performance reality of Session Border Controllers
- Acme Packet White Paper (页面存档备份,存于互联网档案馆) — defines the need for session border controllers for interactive IP services
- AudioCodes White Paper — on Enterprise Session Border Controllers.