Introduction IP telephony allows organizations and individuals to lower the costs of existing services such as data and broadcast video, while broadening their means of communication to include modern video conferencing, application sharing, and whiteboarding tools. In the past, organizations have deployed separate networks to handle traditional voice, data and video traffic. IP telephony blends voice, video and data by specifying a common IP-protocol transport. Traditional Telephony IP Telephony Voice, Data, Video Integration Fax PBX or PSTN PBX Public switch Fax Data Communication Fax Corporate LAN, WAN, or Internet Corporate LAN, WAN, or Internet Media Convergence IP Router Server IP Router Video Distribution Fax UHF/VHF Broadcast Server Cable Microwave Figure 1 Voice over IP (VOIP) IP telephony uses open IETF and ITU standards like, the IP protocol and the H.323 standard. The latter standard is a comprehensive International Union (ITU) standard for multimedia communications (voice, data and data) over connectionless networks that do not provide a guaranteed quality of service. H.323 allows multimedia streaming over current packet switched networks. To counter the effects of LAN latency, H323 uses as a transport the Real time Transport Protocol. Quality of Service protocols (QoS) is improving the service of the computernetwork. 1
H.323 Audio Codec G.711 G.723 G.729 Video Codec H.261 H.263 Data Interface T.120 Call Setup Q.931 RAS Gatekeeper Interface Control H.245 System Control Transport RTP Control RTCP TCP/IP Network Figure 2 H.323 architecture H.323 telephony is complicated by the fact that a user s IP address is highly volatile and cannot be counted on to remain unchanged between H.323 sessions. The following user scenario illustrates IP address resolution in accordance with the H.323 standard: 1. John wishes to initiate an H.323 conference with Alice, another user on the LAN. Once Alice s video conferencing application creates an Address object and puts it in listen mode. Alice s IP address is added to the Internet Locator Service (ILS) Dynamic Directory. John 1 Alice Alice registers and refreshes her IP address via LDAP ILS Dynamic Directory Server Figure 4 Alice registers her IP address automatically 2. John s communication software which is based on the H.323 standard queries the ILS Dynamic Directory server for Alice s IP address. 2
John 2 Alice John performs a resource query for Alice's IP address via LDAP ILS Dynamic Directory Server Figure 5 John queries for Alice s IP address 3. With Alice s up-to-date IP address, John initiates an H.323 call to Alice s computer. H.323-standard negotiations and media selection occur between the peer entities on both computers. 1. Objectives 1. Student can build up a LAN which consists of at least two Windows workstations and a Windows NT server. HOST A (Windows 95 or higher) HOST B (Windows 95 or higher) Windows NT server, functioning as: DHCP server DNS server ILS D Dynamic Directory Server IP-address: 10.0.0.3 FQDN: www.roos.test IP network address: 10.0.0.0 netmasker: 255.255.255.0 Figure 6 LAN 2. Student can install and configure DHCP server. 3
3. Student can install and configure DNS server. 4. Student can install ILS Dynamic Directory Server. 5. Student can install and configure Netmeeting so that the ILS server is used. 6. Student can analyze the data traffic between Netmeeting users with a LAN monitor. 2. Requirements hardware number description Operating system 2 host * minimal Pentium 90-processor * minimal 16MB internal RAM memory * network interface card * sound card, speakers, microphone and webcam * VGA- or SVGA-monitor 1 Windows NT server * Pentium 100 MHz or higher * minimal 64 MB internal RAM memory * 1 GB free hard disk space * CD ROM-drive * Network interface card * VGA- or SVGA-monitor * IE 4.01 or higher Windows95 or higher Windows NT 4.0 and Service Pack 3 or higher Software 1 hub --- description URL-number Netmeeting 3.01 http://www.microsoft.com/windows/netmeeting/download/default.asp Internet Locator http://www.microsoft.com/windows/netmeeting/download/ils20x86.asp Server 2.0 Manuals description Netmeeting Resource Kit 3.0 URL-number http://www.microsoft.com/windows/netmeeting/download/default.asp 4
3. Start situation The following preps have already been made, before you start: a) Windows NT server plus the network interface card and driver have been installed. b) The two Windows workstations plus the following devices and drivers have been installed: * network interface plus drivers * webcams plus drivers * microphone plus drivers c) Windows NT server and Windows workstations have been connected to a hub. 4. Exercise 1) Assign an IP address and netmasker to the NIC in the Windows NT 4.0 server, see figure 6. 2) You have to install the Microsoft DHCP Server, Microsoft DNS Server and the Networkmonitor Tools and agent on the Windows NT 4.0 server. Procedure a) Click on: Start Settings Control Panel. b) Click on the Network icon in the Control Panel. c) Click on the Services tab. d) Click on the Add tab, e) Select DHCP Server. f) Click on the Add tab. g) Select de DNS server. 5
Figure 7 Select DNS server h) Select Monitor Tools and Agent. i) Click on Close in the Network menu. j) Restart the computer. 3) Configure the DNS server. Procedure a) Click on: Start Programs Administrative Tools (Common) DNS Manager. b) Create New Server. IP address DNS server, see figure 6. c) Create New Primary Zone. Zone name is: test (see figure 6). d) Create New Domain. Domain name is: roos (see figure 6). e) Add a A Record to the New Domain. Host Name is www and Host IP address is 10.0.0.3 (see figure 6). 6
Figure 8 DNS manager 4) Configure the DHCP server. You have to: a) Click on: Start Programs Administrative Tools (Common) DHCP Manager. b) Create a Scope IP addresses. Figure 9 DHCP manager 7
c) In the Global Scope of the DHCP manager you have to register the IP address of the DNS server. Figure 9 Global Scope 5) Configure the TCP/IP stack of the Windows workstations in such a way, that these workstations are leasing TCP/IP-parameters from the DHCP server. 6) Show the teacher that the DHCP server has send TCP/IP-parameters to the Windows Workstations. For this purpose tools like ipconfig an winipconfig can be used. 7) Show the teacher in which way you can check the TCP/IP connection between a Windows workstation and the Windows NT server, if you use the ping command. 8) Install the Internet Locator Server 2.0 on the Windows NT 4.0 server. 8
9) Install Netmeeting 3.01 on the Windows workstations and the Windows NT server. 10) Netmeeting 3.01 has to make a connection with the Internet Locator Server automatically, when a user starts this program in a Windows workstation. You can find background information in Microsoft Windows Netmeeting 3 Resource Kit. Figure 10 Netmeeting configurations 11) Check in the Find Someone menu, if the information about the Netmeeting users has been registered in the Inter Locator Server. 9
Figure 11 Personal information 12) Analyze the data traffic between a Windows workstation and the Windows NT server. You have to use the Network Monitor on the Windows NT server. Procedure a) Make a Netmeeting-connection between a Windows workstation and the Windows NT server. b) Start the Capture mode of the Network Monitor. c) Send a chat message from a Windows workstation to the Windows NT server. Figure 12 Chat message d) Stop the Capture mode of the Network monitor and display the captured data. 10
e) Look in the trace and find the IP-frame in which the chat message is placed. Figure 13 Trace 13) The following questions are based on the trace. a) What is the MAC address of the Windows NT server? b) How many routers can an IP-frame pass which have been sent by the Windows workstation? c) Netmeeting is connected to a TCP port. Determine the number of this TCP-port in the Windows NT server. 11