pdf_gross.gif3GSM and TCP/IP –
Protocols, Operation & Services

[3-day course, Euro 3,450.- (net) per participant]

backtotop.gif The Internet Protocol (IP)

Course Description

  • Introducing the IP-Protocol Stack
  • IP-Addresses
    • IP-Address Classes
    • Special IP-Address Notations
      - Subnet-Addressing
      - Supernetting and CIDR
      - More Details of Classless Inter-Domain Routing
    • Determination of the Owner of an IP-Address
  • The Process of IP-Address Allocation
    • The Dynamic Host Configuration Protocol (DHCP)
      - Automatic Allocation
      - Dynamic Allocation
      - Manual Allocation
      - Operation of the DHCP in GPRS
    • Private IP-Addresses
      - Mobile Subscribers entering the Internet
      - Private IP-Address Ranges
    • Using Network Address Translation (NAT) for Interconnection
      - Principles of Network Address Translation
    • Liabilities of NAT
      - IPsec in Transport Mode
      - Streaming Applications
      - Push Services
    • Optimized Use of NAT in GPRS
      - Business and Power Users
      - Standard Users
  • The IP-Header
    • Overview
    • Example of an IP-Header
    • The IP-Header / Octet 1 – 4
    • The TOS- Field (Type of Service)
    • The TOS- Field / Differentiated Services
    • Using Differentiated Services for the Intra-PLMN Backbone
      - Principles
      - Implementation
      - Differentiation of Control Information and User Data with Different QoS
    • The IP-Header / Octet 5 – 8
    • Fragmentation Control in IP
    • The IP-Header / Octet 9 – 20
    • The IP-Header / Octet 21 – N (IP-Options)
  • Details of the Internet Control Message Protocol (ICMP)
    • ICMP-Message Format
    • ICMP-Messages
      - Echo Reply
      - Destination Unreachable
      - Source Quench
      - Redirect
      - Echo Request
      - Router Advertisement
      - Router Solicitation
      - Time Exceeded for a Datagram
      - Parameter Problem on a Datagram
      - Timestamp Request
      - Timestamp Reply
      - Information Request
      - Information Reply
      - Address Mask Request
      - Address Mask Reply
  • Using ICMP for Roundtrip Time (RTT) Measurements in GPRS
    • Use Trace Route to Determine the IP-Address of the 1st Router
      - Ping with 32 Octets of Data (no Segmentation)
      - Ping with 544 Octets of Data (still no Segmentation)
      - Ping with 1000 Octets of Data (Segmentation)

backtotop.gif Details of TCP-Operation

  • The Roundtrip Time (RTT) in TCP-Connections
    • Roundtrip Time (RTT) and Retransmission Timeout (RTO)
    • Long Term Behavior of SRTT and RTO
    • Advanced TCP-Features
    • The Nagle Algorithm and Delayed Acknowledgements
    • The Slow Start and Congestion Avoidance Algorithms
      - Introduction
      - Slow Start and Congestion Avoidance in Operation
      - Long Term Characteristics
    • The Ultimate Importance of RTT and CWND for GPRS
      - The formula for calculating SRTT and RTO is tailored for wireline connections
      - In GPRS, the RTT is highly variable and may therefore cause unnecessary retransmissions
      - Slow start memorizes instances when RTT <-> 2 x SRTT
      - RTT variance in GPRS can have many reasons
    • Consequences of the RTT-Variance for the GPRS Performance
      - Example: FTP-Upload at 150 km/h
    • Latency Requirements
    • The Fast Retransmit Algorithm
    • The Fast Recovery Algorithm
  • And what about TCP/IP in GPRS?
    • Some Basic Questions
      - How do the various TCP/IP algorithms impact GPRS operation ?
      - Can GPRS be considered as a typical Dial-Up Service ? (which implicitly requires similar settings)
      - How critical is the high variance of RTT during a GPRS data transfer when it comes to unnecessary retransmissions ?
    • The Bandwidth Delay Product
      - Some Example Calculations for GPRS and Dial-Up
      - Consequences for GPRS
      - Performance Improvement through MSS-Adjustment
      - Setting of the Parameter IPMTU in WINDOWS 98
      - Setting of the Parameter DefaultRcvWindow in WINDOWS 98

backtotop.gifVPN-Operation and IPsec

  • Security Concerns for Internet Traffic
    • Privacy
    • Alteration
    • Spoofing
  • Security Analysis of Typical Network Configurations
    • Subnet <- SECURE BACKBONE -> Central Corporate
    • Subnet <- LEASED LINE -> Central Corporate
    • “Road Warrior” <- DIAL UP / INTERNET -> Central Corporate
    • Other Corporate Networks <- INTERNET -> Central Corporate
  • Alternatives for Network Security
    • Encryption and Authentication on Layer 1 / 2
    • Encryption and Authentication on the Network Layer
    • Encryption and Authentication on higher layers
  • VPN Operation Modes
    • IPsec in Transport Mode
      - Transport Mode and AH
      - Transport Mode and ESP
    • IPsec in Tunnel Mode
      - Tunnel Mode and AH
      - Tunnel Mode and ESP
    • VPN with IPsec in Tunnel Mode and Transport Mode
      - VPN with IPsec in Tunnel Mode
      - VPN with IPsec in Transport Mode
  • The IPsec Authentication Header (AH)
    • Next Header (8 bit)
    • Payload Length (8 bit)
    • Reserved (16 bit)
    • Security Parameters Index (SPI) (32 bit)
    • Sequence Number (32 bit)
    • Authentication Data (n bit)
  • The IPsec Encapsulating Security Payload (ESP)
    • Security Parameters Index (SPI) (32 bit)
    • Sequence Number (32 bit)
    • Payload Data (n bit)
    • Padding (0 – 255 octets)
    • Padding Length (8 bit)
    • Next Header (8 bit)
    • ESP Authentication Data (n bit)
  • The Security Association (SA)
  • Algorithms for IPsec
    • How does a Hash Algorithm Work ?
    • How does Encryption Work with IPsec ?
  • Establishment of an IPsec-Relationship
    • ISAKMP (Internet Security Association and Key Management Protocol)
      - Authentication through Signatures
      - Authentication through Pre-Shared Key
      - Authentication through Public Key Encryption

backtotop.gifThe Point-to-Point Protocol (PPP) and PDP-Context Activation

  • GPRS Dial Up Network Access
    • The Point-to-Point Protocol (PPP) Frame Format
    • Operation of Dial Up Network Access
      - Link Establishment Phase
      - Authentication and Network Layer Setup
      - Link Termination
      - (1) Example for Dial-Up Network Access using the PPP
    • The Mobile Originating PDP-Context Activation Procedure
      - Initial Conditions
      - Applicability of this Procedure
      - Description

backtotop.gifExamples for Application Protocols

  • Important Application Protocols
    • Access to Applications <-> The Domain Name System (DNS)
    • The Hypertext Transfer Protocol (HTTP)
      - The HTTP-Message Format
      - Operation of the Hypertext Transfer Protocol
      - Download of a given Web Page
    • GPRS Performance Measurements with HTTP
      - Definition of Trigger Points
      - Impact of GPRS Specific Delays on HTTP-Performance
      - Example of an HTTP-Transaction <-> The Request
      - Example of an HTTP-Transaction <-> The Response
    • The File Transfer Protocol (FTP)
      - GPRS Performance Measurements with FTP
      - Example: FTP-Upload
      - Example: FTP-Download

v1.6

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