ZyXEL Communications 2002 Series 5.3.2.4 Symmetric NAT

Prestige 2002 Series User’s Guide

Figure 18 Port Restricted Cone NAT

5.3.2.4 Symmetric NAT

Symmetric NAT is different from the cone NAT types in that a specific NAT mapping of a private IP address and port to a public IP address and port depends on the packet’s destination IP address. In the following figure, if A sends a packet from IP address 10.0.0.3 and port 80 to B, it may be mapped as IP address a.b.c.d and port 45678, but if A sends from the same IP address and port to a different IP address, it is mapped differently (IP address a.b.c.d and port 12345).

Figure 19 Symmetric NAT

Computer B can only respond to its mapping (IP address a.b.c.d and port 45678) and computer C can only respond to its mapping (IP address a.b.c.d and port 12345). If either computer B or C tries to send to the other’s mapped IP address and port, the NAT router will drop the packets. Like restricted cone NAT, a host on the Internet can only send a packet to the private IP address and port if the private IP address and port has previously sent a packet to that host.

Chapter 5 Introduction to VoIP

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Contents

User’s Guide Page Copyright Disclaimer Trademarks Federal Communications Commission (FCC) Interference Statement Notice Certifications ZyXEL Limited Warranty Note Safety Warnings Customer Support Table of Contents Introduction to VoIP Phone Phone Book Maintenance Troubleshooting Appendix A Hardware Specifications Appendix B Appendix C List of Figures Page List of Tables Page Preface About This User's Guide Related Documentation User Guide Feedback Syntax Conventions Graphics Icons Key Introducing the Prestige 1.1 Prestige 2002 VoIP Analog Telephone Adaptor Overview 1.2Prestige 2002L VoIP Analog Telephone Adaptor with Lifeline 1.3 Features 10/100Mbps Auto-negotiatingFast Ethernet Interfaces PSTN Lifeline REN Dynamic Jitter Buffer Standards Compliance Multiple SIP Accounts 1.4 Applications 1.4.2 Make Calls via IP-PBX Page Page Introducing the Web Configurator 2.1 Web Configurator Overview 2.2Accessing the Prestige Web Configurator Apply Ignore MAIN MENU 2.3 Resetting the Prestige 2.4Navigating the Prestige Web Configurator Page 2.5 Common Screen Command Buttons Page System Screens 3.1 System Overview 3.2 General Setup 3.3 General Setup Configuration 3.4 Configuring Password 3.5 Pre-definedNTP Time Servers List 3.6 Configuring Time Setting Page Page Ethernet Screens 4.1 ETHERNET Overview 4.2 Configuring Ethernet Figure 10 ETHERNET Table 7 ETHERNET 4.3 Configuring the Ethernet Management Port Introduction to VoIP 5.1 Introduction to VoIP 5.2 Introduction to SIP 5.2.1.1 SIP Number 5.2.1.2 SIP Service Domain 5.2.3.1 SIP User Agent Server 5.2.3.2 SIP Proxy Server 5.2.3.3 SIP Redirect Server 5.2.3.4 SIP Register Server 5.3 STUN 5.3.2.1 Full Cone NAT 5.3.2.2 Restricted Cone NAT 5.3.2.3 Port Restricted Cone NAT 5.3.2.4 Symmetric NAT 5.4 SIP ALG 5.5 Pulse Code Modulation 5.6 Voice Coding 5.7 PSTN Call Setup Signaling VoIP Screens 6.1 VoIP Introduction 6.2 VoIP Configuration 6.3 Advanced VoIP Settings Configuration Page Page 6.4 Quality of Service (QoS) 6.4.2.1 DSCP and Per-HopBehavior 6.5 QoS Configuration Phone 7.1 Phone Introduction 7.2 Phone Port Configuration Figure 24 Phone Port Phone Book 8.1 Phone Book Introduction 8.1.1.1 Peer-to-PeerCalls 8.2 Speed Dial Configuration Figure 25 Phone Book 8.3 Lifeline Configuration (Prestige 2002L) Page Logs 9.1 Viewing Logs 9.1.1 Log Message Descriptions Table 19 SIP Logs Table 20 RTP Logs Page Maintenance 10.1 Maintenance Overview 10.2 Status Screen 10.3 F/W Upload Screen Firmware Upload in Process 10.4 Configuration Screen 10.4.1Backup Configuration Configuration Upload Error 10.4.3 Back to Factory Defaults Reset 10.5 Restart Screen Page Troubleshooting 11.1 Problems Starting Up the Prestige 11.2 Problems with the LAN or PC LED 11.3 Problems with the LAN Interface 11.4 Problems with Internet Access 11.5 Problems with the Password 11.6 Problems with the Web Configurator 11.7 Problems with Telephone or Telephone Port 11.8 Problems with Voice Service Appendix A Hardware Specifications Ethernet Port Specifications Prestige 2002 Power Adaptor Specifications Prestige 2002L Power Adaptor Specifications Appendix B Setting up Your Computer’s IP Address Windows 95/98/Me Installing Components Add Adapter Protocol Microsoft Configuring Obtain an IP address automatically Specify an IP address Subnet Mask DNS Windows 2000/NT/XP Network Connections Network and Dial-up Connections 3Right-click Local Area Connection and then click Properties Internet Protocol (TCP/IP) General Use the following IP Address IP address Subnet mask Default gateway Advanced Use the following DNS server addresses Preferred DNS server Alternate DNS server 8Click OK to close the Internet Protocol (TCP/IP) Properties window 9Click OK to close the Local Area Connection Properties window Macintosh OS 8/9 Macintosh OS Automatic Location •Select Built-inEthernet from the Show list Using DHCP Apply Now Appendix C IP Subnetting IP Addressing IP Classes Subnet Masks Subnetting Example: Two Subnets Page Example: Four Subnets Example Eight Subnets Subnetting With Class A and Class B Networks Page Appendix D PPPoE PPPoE in Action Benefits of PPPoE Traditional Dial-upScenario How PPPoE Works Prestige as a PPPoE Client Index