Friday, December 18, 2020

读书笔记 - Session Border Controllers for Dummies

 This 49 pages of SBC for Dummies free ebook is 6th Ribbon special edition. It describes SBC functions, advantages and use cases in RTC (realtime communication) network.

An SBC performs the following functions:

  • Securing the RTC network: An SBC protects and secures RTC from various threats such as spoofing, denial-of-service (DoS) attacks, and toll fraud. 
  • Enabling SIP trunking: An SBC provides you with a demarcation or termination point of the SIP trunk connection into your communications network. 
  • Interconnecting and interworking networks and protocols: An SBC provides a smooth experience in terms of interconnecting and interworking between different networks and the protocols running over them.
  • Acting as session traffic cop: The SBC is the gatekeeper to SIP-based services in an enterprise or service provider network. 
  • Intelligent Routing and Policy Controls 

Some common VoIP attacks include:

  • Service theft and fraud: Attackers accessing a VoIP system to route traffic and use network resources without paying for them
  • Spoofing: Deliberately modifying or disguising an identity (for example, caller ID) on the network
  • DoS/Distributed Denial-of-Service (DDoS) attacks: Flooding a server or SBC with requests to overwhelm its available resources
  • Registration storms: Like a DDoS attack, in which many devices (typically hundreds of thousands to millions) simultaneously attempt to register with a SIP server in a UC network

An SBC employs various techniques to protect enterprises and service providers from cyberattacks against RTC networks, including the following:

  • Media and signaling encryption
  • Dynamic pinholing
  • Topology hiding with B2BUA
  • List monitoring (Whitelists, Blacklists, Greylists)

SBC other features besides security:

  • An SBC must be able to speak all the different dialects of SIP and do on-the-fly translations in both directions.
  • Another one of the SBC’s jobs is to transcode, or change, codecs as media sessions pass through the SBC. 
  • Dealing with NAT Traversal (NAT traversal requires a significant amount of processing power in the SBC because of the large number of devices participating in VoIP and other sessions that are located behind a NAT gateway.)
  • Fax and Tone Detection
  • Video Support
  • Performance, Scalability, Resiliency (CPU utilization, Concurrent calls or sessions supported, Redundancy, Registration rate, QoS policies)
  • The gradual adoption of IPv6 is another reason to use an SBC, because the SBC has intelligence that enables IPv4 and IPv6 network segments to talk to each other.

Some of the benefits of virtualization

  • Efficient resource utilization
  • Reduced operating expenses
  • Low total cost of ownership (TCO)
  • Faster time to market
  • Greater agility 

The contact center is vital to the success of many businesses because in a competitive marketplace, high-quality customer service is essential. The contact center has evolved from simply a call center where customer service agents take voice calls, to a full-fledged contact center where agents handle voice, e-mail, chat, text messages, and video calls. 

  • Call recording
  • Remote agents
  • Internal transfers
  • Enterprise Connectivity
  • Mobile
  • IMS Networks
  • WebRTC

Adding Value to Video with SBCs

  • Session management: The SBC is the ideal element in a complex network to enforce call admission control (CAC) on a session-by-session basis. The SBC can perform CAC for multiple unified communications (UC) and video devices. SBCs can perform QoS prioritization (discussed in Chapter 2) to ensure audio and video traffic passes through the network as efficiently as possible. CAC helps to provide an optimal end-user experience by regulating the number of end-points allowed on the network and making sure there’s enough bandwidth for each video and audio stream. 
  • Endpoint interoperability: Even if all the endpoints in a video call use the same video codec, the SIP protocol implementations used by Cisco, Microsoft, Avaya, Polycom, and others differ enough to require a translation device to make sure the signaling works to connect to all the devices. Protocol normalization allows organizations to keep their hardware and software investments, while making video solutions from different vendors work together so they don’t have to get all their network components from a single vendor.

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