SIP In Depth

Why this SIP course?

Session Initiation Protocol (SIP) is the signalling protocol that forms the basis of future Voice over IP (VoIP) and converged networks, both fixed and mobile. This three day advanced SIP course enables attendees to:

• Gain an understanding of the architecture, components and functions of the SIP suite.
• Learn SIP and its operation in detail.
• Understand SIP’s strengths, reliability, performance, separation, extensibility, modularity and simplicity.
• Understand the role of SIP within the wider context of signalling, content and communications protocols and in Fixed and Mobile Convergence (FMC).

The course takes a modular approach to covering the Planning, Structure and Operation of Session Initiation Protocol (SIP). The course also covers the integration of SIP with other network technologies such as mobile and SS7.

SIP Training Course Objectives

On completing this course, you will be able to:

• Understand the principles of Ethernet operation and essential IP dependencies
• Understand the principles of IPv4 addressing
• Describe the principles of IPv4 operation and routing
• Describe the differences between UDP and TCP, and explain how each is used in VoIP communications
• Describe the main principles of VoIP, including:
  • o QoS in both IP and the underlying Ethernet
  • o GoS
  • o PESQ
  • o RTP/RTCP
  • o Common Codec techniques
  • Describe the structure of SIP
• State the purpose of each of the SIP header fields
• Describe the operation of the SIP Methods and Responses
• Monitor and diagnose problems with SIP operation
• State the operation and structure of Session Description Protocol (SDP)
• Monitor and diagnose problems with SIP and SDP
• State the role of the SIP Registrar
• Describe the operation of the SIP Registration Server
• Compare the different types of SIP Proxy
• Describe the way in which SIP proxies are used to route SIP messages
• State the role of DNS, and how NAPTR, SVR and A records are used to support SIP
• Identify the SIP header fields and their values that are used to facilitate SIP routing
• Monitor and diagnose problems with SIP and SIP routing
• Explain the role of SIP Redirect and Location servers
• Describe the operation of the SIP 3xx Redirect responses
• Monitor and diagnose problems with SIP redirection
• Describe SIP Forking
• Describe the operation of Presence features in SIP
• Capture and analyse SIP signalling traffic using a network protocol analyser
• Identify common problems when using SIP with NAT firewalls
• Compare the methods of SIP NAT traversal:
  • o STUN
  • o TURN
  • o ICE
  • o Application Layer Gateway and SIP re-write
• Understand the roles of Session Border Controllers (SBCs)
• Identify common threats to SIP
• State the commonly used methods for securing SIP
• Describe the functionality of the SIP PBX
• Configure a SIP PBX
• Discuss the role of MPLS with respect to VoIP and SIP
• Implement SIP across an MPLS backbone
• Identify common security threats to SIP and state some commonly used countermeasures

Who should attend this SIP course

• People responsible for evaluating, planning, installing, configuring, administrating or supporting SIP products and services.
• Level 2, 3 and 4 support staff responsible for diagnosing and troubleshooting issues with SIP servers, PBXs, media gateways and Session Border Controllers.
• Personnel wanting to move into the field of modern SIP-based voice communications or media streaming systems.

SIP Course Pre-requisites

Course participants should have a good understanding of IP, DNS, TCP/UDP, voice telephony and VoIP principlesprior to atending the course.

Hands-on Practicals

This SIP training course features extensive hands-on practical working with:

• SIP Servers
• SIP Clients
• Hard SIP IP phones
• SIP softphones
• SIP-enabled PBXs
• SIP protocol capture and decoding using Wireshark
• SIP Troubleshooting

and more.

Lifetime Post-Course Support

After completing this SIP training course, delegates receive lifetime post-training support from LEVER Technology Group, to help them apply the technologies and skills they have learned with us, to provide career-long support, and to ensure they are better equipped for their future roles in IT and networking.

SIP Training Course Content

IP Networking Essentials

• Brief recap of the ISO 7 Layer Model, and where Ethernet, IP, and VoIP are positioned within the model
• Understanding Ethernet, VLANs and Ethernet QoS
  • Ethernet MAC addresses
  • Ethernet operation
  • Ethernet switches
  • VLAN and QoS Ethernet header
• Understanding IPv4
  • IPv4 addresses, subnets, subnet masks and “/” notation
  • IPv4 operation
  • The IPv4 header and where QoS is implemented.
  • Overview of MPLS
• Transport protocols
  • TCP versus UDP for VoIP
• Domain Name Service (DNS)
  • Overview of DNS operation
  • DNS record types used with SIP

Overview of VoIP

• Brief mention of SIP versus H.323, H.248/MEGACO and Skinny (for context only)
• What SIP does
• VoIP operation
  • Challenges of transmitting voice signals over IP
  • Quality Of Service, QoS recap
  • Impact of QoS on Grade of Service (GoS)
  • Concept of Connection Admissions Control, CAC/VCAC
  • Codec types and operation
    • G.711 aLaw and µLaw
    • G.722.2 / HD Voice
    • The DTMF problem
  • Real Time Protocol (RTP) and Real Time Control Protocol (RTCP)
    • RTP payload type description as advertised/negotiated in SIP/SDP
  • Voice Quality
    • Mean Opinion Scoring (MOS)
    • Perceptual Evaluated Speech Quality (PESQ)

Lab: Analysis of RTP using Wireshark

An overview of Wireshark operation will be given if necessary.

SIP Protocol Operation

• Key SIP RFCs and standards
• The SIP User Agent client and server
  • SIP Phones
  • SIP ATA
• The SIP URI and URI structure
• SIP protocol structure
• SIP Methods overview
• SIP Responses overview
• The SIP dialog
• The SIP session
• The SIP message line
• Key SIP header fields including:
  • From
  • Call-id  
  • To
  • Via
    • The Via “Branch” parameters
  • Call tags
  • Contact
  • Cseq
  • Max forwards
  • Content fields
  • Allow
  • Options tags
• SIP message exchange
  • SIP Messages involved in setting up a simple SIP call
    • INVITE method
    • 100 Trying
    • 180 Ringing
    • 200 OK
    • ACK
    • BYE method
• SIP INFO Method
• SIP OPTIONS Method

Lab: SIP Calling and SIP in-depth analysis using Wireshark

• Common SIP call Error Messages

Session Description Protocol (SDP)

• SDP description and role
• SDP structure
• SDP fields
  • Owner/Creator
  • Connection Information
  • Time Description
  • Media Description
  • Media Attributes
• RFC 2833

Lab: SDP analysis

• SIP error messages relating to SDP

SIP and Servers

• SIP Registration and Location Servers
  • Role of the SIP Registration Server
  • SIP Registration Method

Lab: Setting up the SIP Registration

SIP Call Routing

• SIP Proxy
  • SIP Stateful Proxy
  • SIP Call Stateful Proxy
  • SIP Stateless Proxy
  • SIP Stateful and Stateless proxies
• SIP and DNS
  • SIP and the NAPTR record
  • SIP and the SVR record
  • SIP and the A record
• Routing with SIP Call Stateless and Call Stateful proxies
  • SIP INVITE and responses header manipulation
    • Multiple VIA header fields
    • The Record-route fields
    • The Route fields
• SIP Back To Back User Agent (B2BUA) versus SIP Proxy
  • SIP header manipulation with B2BUAs
  • Where B2BUAs would be used

Lab/Demo: Routing SIP proxies

• The SIP Redirect Server
• SIP REDIRECT methods
  • 300 series SIP messages

 Lab/Demo: SIP Redirection

• SIP Forking
• SIP and IP Multicasting

SIP and NAT Traversal

• Problems of NAT Traversal
• Simple Traversal of UDP through NATs, STUN
• Traversal using Relay NAT, TURN
• Universal Plug and Play, UPnP
• Application Layer Gateway, ALG
• SIP rewrite
• Session Border Controller (SBC)
  • The roles of the SBC
    • I-SBC
    • A-SBC
    • SIP normalisation
    • NAT Traversal
    • Security

SIP PBX Trunking

• SIP Trunking
• SIP Routing and number plans
• SIP number filtering and manipulation

Lab: Building and Monitoring a SIP Trunked PBX Network

SIP Presence and Other Features

• SIP NOTFIY method
• SIP REFER method
• SIP PUBLISH method

Lab / Demo: Analysis of SIP Presence

SIP Security

• Potential threats to SIP
  • Registration Hijacking
  • Impersonating a server
  • Tampering with message bodies
  • Tearing down sessions
  • Denial of Service and Amplification
• The Securing SIP “Toolbox”
  • Transport and Network Layer Security
  • SIPS URI Scheme
  • HTTP Authentication
  • Registration and Call Security
    • Proxy-Authenticate
    • Proxy-Authorization
    • Authenticate-Info
    • Authorization
    • WWW-Authenticate
  • Peer-to-Peer Requests
  • DoS Protection
  • Encrypting Media Streams
  • Encrypting SIP