Tài liệu Networking and Desktop Protocols docx

1 ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○ 7 Networking and Desktop Protocols Terms you’ll need to understand: ✓ Internetwork Packet Exchange (IPX) ✓ Routing Information Protocol (RIP) ✓ NetWare Link State Protocol (NLSP) ✓ Enhanced Interior Gateway Routing Protocol (EIGRP) ✓ AppleTalk ✓ Routing Table Maintenance Protocol (RTMP) ✓ AppleTalk EIGRP ✓ DECnet ✓ OSI ✓ NetBIOS ✓ NetBEUI ✓ Windows Internet Naming Service (WINS) ✓ Dynamic Host Configuration Protocol (DHCP) Techniques you’ll need to master: ✓ Describing how desktop protocols function ✓ Explaining the routing mechanisms for desktop protocols ✓ Managing and configuring desktop support on Cisco routers ✓ Explaining how Windows clients browse a network 2 ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○ Chapter 7 This chapter describes some of the more commonly used desktop protocols, with an emphasis on topics covered in the CCIE Routing and Switching exam. The following CCIE blueprint objectives, as defined by the Cisco Systems CCIE program, are covered: ➤ Internetwork Packet Exchange (IPX)—NetWare Link Services Protocol (NLSP), IPX RIP, IPX Service Advertising Protocol (SAP), IPX EIGRP, Sequenced Packet Exchange (SPX), Network Control Protocol (NCP), IPXWAN, IPX addressing, get nearest server (GNS) requests, Novell Direc- tory Services (routing and mechanisms), access lists ➤ AppleTalk—Routing Table Maintenance Protocol (RTMP), AppleTalk Up- date-Based Routing Protocol (AURP), AppleTalk EIGRP, Datagram Deliv- ery Protocol (DDP), Zone Information Protocol (ZIP), Name Binding Protocol (NBP), addressing (phases 1 and 2), access lists ➤ DECnet/OSI—Addressing, access lists ➤ Windows NT—NetBIOS, browsing, domain controller (such as WINS), ac- cess lists As with other chapters in this book, additional information is provided for complete- ness and in preparation for additional subjects as the CCIE program expands. Internetwork Packet Exchange (IPX) Novell released IPX in 1980. IPX was very popular, but it was primarily designed for local area networks (LANs). The IPX protocol is based on service advertise- ments, called service access point (SAP). When Cisco routers are deployed in IPX networks, they offer increased capabilities that are not usually available. For ex- ample, Cisco routers can forward specific IPX broadcasts that allow serverless IPX LANs to function normally. In this chapter, we will discuss the role of Cisco routers and operation of IPX in greater detail. IPX servers and printers send out SAPs (which are broadcast frames), and Cisco routers listen for the SAPs and install them into a SAP table. For example, when a PC, running IPX attempts to connect to a server, it sends out a request called a get nearest server (GNS) request. If there are any local servers, they respond to the PC’s GNS request. If there are no IPX servers on the local network, the Cisco router responds instead. The client PC then makes a direct connection request to the local or remote server through the Cisco router. Keep in mind that GNS requests are sent as broadcast frames, and excessive broadcasts reduce bandwidth for end users. Later in this chapter, we’ll examine how to manage GNS requests and SAPs. 3 ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○ Networking and Desktop Protocols NetWare Protocol Suite At this point, let’s take a look at the NetWare protocol suite (shown in Figure 7.1) and how Novell’s implementation of a proprietary protocol relates to the OSI model. As you can see in Figure 7.1, the Novell protocol suite provides applica- tion services through NetBIOS, the NetWare shell determines whether the ap- plication requires network services. The routing protocol used by Novell by default is IPX RIP Let’s discuss each layer and associated protocols of the IPX model. Application Layer (NCP) The higher layers of IPX (layers 5 through 7) provide end users with the ability to view files on servers. NetWare Core Protocol (NCP) is used to send and receive files, send print jobs, and provide security. These are just some of NCP’s major functions that are performed by the Application layer of the IPX protocol suite. The service access point application protocol rests on top of IPX and is used to advertise IPX services, such as file servers and printers. SAPs are sent as broad- casts, so if you have a lot of servers and printers, you can significantly increase your broadcast traffic. SAP services are identified in the IPX packet. For ex- ample, the file server SAP has a type code 4, and printers have a type code 7. A complete list of all the SAP codes is available on Novell’s Web site (search for the keyword SAP on www.novell.com). Application Presentation Session Transport Network Data Link Physical IPX Protocol Suite NetBIOS, NetWare shell SPX Routing Protocol, IPX RIP, NLSP EIGRP IPX Ethernet, Token Ring, FDDI, Frame Relay, PPP, and more OSI Model Applications such as Network Control Protocol (NCP) and Service Access Point (SAP) Figure 7.1 NetWare protocol suite. 4 ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○ Chapter 7 Transport Layer (SPX) The Transport layer uses the Sequenced Packet Exchange (SPX) protocol in the IPX model. SPX provides reliable services and is connection-orientated. SPX is simi- lar to TCP because of its ability to provide reliable connection-oriented services. Network Layer (IPX) The IPX Network layer provides each device with a unique network layer address used to reach local and remote networks. IPX is connectionless. Like any routable protocol, there must be some form of addressing. IPX addressing is unique in that it provides for almost three times as many possible addresses as IP addressing. An IPX address is made up of 80 bits. The first 32 bits identify the network, and the next 48 bits are taken from the MAC address. Together, these create an IPX address. Having all these SAPs and addresses is a benefit of IPX, however, the next question is how does IPX route all this across the wide area network (WAN)? To populate the IPX routing table so that routers can route IPX traffic across the WAN, Cisco routers can use the following protocols: ➤ IPX RIP—IPX Routing Information Protocol ➤ IPX NLSP—IPX NetWare Link State Protocols ➤ IPX EIGRP—IPX Enhanced Interior Gateway Routing Protocol NLSP is the latest implementation used to address the concerns of IPX RIP, such as poor convergence times and hop count limits. IPX RIP supports a maxi- mum hop count of only 15 hops, whereas IPX NLSP supports up to 127 hops. Therefore, IPX NLSP is more scalable because the increased hop count allows for a greater network diameter. NLSP is a link-state protocol, which means an administrator can take advantage of all the qualities of link-state protocols as opposed to distance-vector protocols. These qualities include faster convergence after a network change and NLSP’s support for hierarchical network design, which allows for networking devices to be grouped into areas and domains. There is no need to use an Address Resolution Protocol (ARP), because the node address is taken from the unique MAC address. Note: The node portion of an IPX address (the last 48 bits) on a serial interface is taken from a LAN interface, because serial interfaces do not have a MAC address. This portion of the IPX address is taken from the first active Ethernet, Token Ring, and then FDDI interfaces. Data Link and Physical Layer The Data Link and Physical layers are designed to provide physical connectivity at an electrical level, that is the Physical layer, and they provide a reliable transit of data across the Physical layer, that is the Data Link layer. IPX can run over 5 ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○ Networking and Desktop Protocols many LAN technologies, such as Ethernet and Token Ring. Further, IPX can run over wide area networks, such as Frame Relay and Point-to-Point Protocol (PPP). Let’s now look at how IPX is routed and configured on a Cisco router using the three available options—IPX RIP, IPX NLSP, and IPX EIGRP. Routing Information Protocol (RIP) The Routing Information Protocol designed for IPX is a distance-vector protocol that uses hop counts and ticks as the metric. Remember, a tick is a measure of delay on an interface. IPX RIP will load balance if the hops and tick count are the same. Let’s examine the configuration tasks on a Cisco router and the available show commands used to monitor and verify proper operation of IPX. By default, Cisco IOS runs IPX RIP unless configured otherwise. To enable IPX RIP routing, you simply type the following command in global mode: ipx routing Like IP, you then configure network addressing on the interface that will run IPX. This is completed with the following IOS command: ipx network <network number> encapsulation <encapsulation type> IPX RIP supports a number of encapsulation types. Table 7.1 shows the options available on Cisco routers. If no encapsulation is entered when you configure a Cisco router interface for IPX, novell-ether for Ethernet and sap for Token Ring are the encapsulation types set by default. The main features of IPX RIP are that it’s a distance-vector protocol, and the metric is based on ticks and hop counts. The maximum hop count is 15. IPX RIP periodically sends out updates every 60 seconds. Do not confuse this interval with the IP RIP update interval, which is 30 seconds. Table 7.1 Cisco encapsulation options. Media Cisco Name Novell Name Ethernet novell-ether Ethernet_802.3 sap Ethernet_802.2 arpa Ethernet_II snap Ethernet_Snap Token Ring sap Token-Ring snap Token-Ring_Snap 6 ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○ Chapter 7 IPX RIP Configuration Task List Now, let’s examine the configuration of a simple IPX network using IPX RIP. Later in this chapter, we’ll use the same network to demonstrate using NLSP and EIGRP to route IPX. As you can see in Figure 7.2, there are two routers—R1 and R2. Both routers have a local IPX segment. In this section, you’ll apply the default encapsulation on all segments to novell-ether (which means that no additional configuration is required because novell-ether is the default). Listing 7.1 displays the configura- tion required on both routers. Listing 7.1 IPX configuration on routers R1 and R2. hostname R1 ipx routing 0000.0c75.d97e interface Ethernet0 ipx network 1 interface Serial0 ipx network BAD hostname R2 ipx routing 0000.0c8e.774b interface Ethernet0 ipx network 2 interface Serial0 ipx network BAD Note: In Listing 7.1, notice that the IPX network number on the serial link is the same. If the network numbers were different, the two routers would not share IPX routing information. Listing 7.2 shows the IPX routing table on router R1 by using the command show ipx route. IPX Network 1 E0 IPX Network 2 S0 E0 S0 IPX Network BAD R1 R2 Figure 7.2 A simple IPX network configuration task. 7 ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○ Networking and Desktop Protocols Listing 7.2 The show ipx route command on the R1. R1#sh ipx route Codes: C - Connected primary network,c-Connected secondary network S - Static, F - Floating static, L - Local (internal), R - RIP, E - EIGRP, N - NLSP, X - External, A - Aggregate s - seconds, u - uses 3 Total IPX routes. Up to 1 parallel paths and 16 hops allowed. C 1 (NOVELL-ETHER), Et0 C BAD (HDLC), Se2 R 2 [07/01] via BAD.0000.0c8e.774b, 4s, Se0 As you can see in Listing 7.2, the IPX routing table is very similar to an IP routing table. The table displays, which IPX networks, are reachable locally (C) and remotely (R). The network highlighted in Listing 7.2 has been discovered dynamically using the IPX RIP (indicated by the letter R) protocol. The delay and hop count is described in square brackets [07/01], where 07 is the delay, 01 is the hop count. The next hop address is indicated as BAD.0000.0c8e.774b via Serial 0 (Se0). On R1 in Listing 7.2, you can see that the remote IPX network number 2 is reachable via the serial 0 interface. Notice also that the network was sourced by the IPX RIP protocol, because this network is designated with the R on the left side. Let’s look at some useful show commands that describe the state of IPX. Listing 7.3 displays the configuration parameters on an interface by using the show ipx interface <interface number> command. Listing 7.3 The show ipx interface command. R1# show ipx interface Ethernet 0 Ethernet0 is up, line protocol is up IPX address is 1.0000.0c75.d97e, NOVELL-ETHER [up] Delay of this IPX network, in ticks is 1 throughput 0 link delay 0 IPXWAN processing not enabled on this interface. IPX SAP update interval is 1 minute(s) IPX type 20 propagation packet forwarding is disabled Incoming access list is not set Outgoing access list is not set IPX helper access list is not set SAP GNS processing enabled,delay 0ms,output filter list is not set SAP Input filter list is not set SAP Output filter list is not set SAP Router filter list is not set Input filter list is not set Output filter list is not set Router filter list is not set NetBIOS Input host access list is not set NetBIOS Input bytes access list is not set 8 ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○ Chapter 7 NetBIOS Output host access list is not set NetBIOS Output bytes access list is not set Updates each 60 seconds, aging multiples RIP: 3 SAP: 3 SAP interpacket delay is 55 ms, maximum size is 480 bytes RIP interpacket delay is 55 ms, maximum size is 432 bytes IPX accounting is disabled IPX fast switching is configured (enabled) RIP packets received 14415, RIP packets sent 42177 SAP packets received 0, SAP packets sent 7 The output shown in Listing 7.3 displays a wealth of information. From this display, you can see that the encapsulation is Novell-Ether and the network number is 1. You can also see that IPX is sending updates every 60 seconds. Now, let’s use the show ipx server command to see which SAPs are available on the Cisco router named R1, as shown in Listing 7.4. Listing 7.4 The show ipx server command. R1#show ipx server Codes: S - Static, P - Periodic, E - EIGRP, N - NLSP, H - Holddown, + = detail 2 Total IPX Servers Table ordering is based on routing and server info Type Name Net Address Port Route Hops Itf P 4 server1 2.0000.0000.0001:0451 7/01 2 Se0 P 7 printer1 2.0000.0000.0001:0451 7/01 2 Se0 The SAP table shown in Listing 7.4 lists all the SAPs collected by router R1. Listing 7.4 describes two services available, namely a server called server1 and a printer named printer1. As you can see in the table, the services are reachable through serial 0 with a hop count of 2. Finally, here are a number of commands that you can use to troubleshoot IPX RIP (including the commands mentioned earlier in this section): ➤ debug ipx routing—Displays information about IPX routing packets. ➤ debug ipx sap activity—Provides detailed output of SAP packets, including displays of services in SAP packets. ➤ ipx maximum paths <number>—Defines the maximum allowed paths for load balancing. The default is set to 1, which means there is no load balancing. ➤ show ipx interface—Describes the IPX interface configuration. ➤ show ipx route—Displays the IPX routing table. ➤ show ipx server—Displays the SAPs seen by the router. ➤ show ipx traffic—Displays IPX statistics. 9 ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○ Networking and Desktop Protocols NetWare Link State Protocol (NLSP) Instead of using a distance-vector protocol to route IPX and have all the associ- ated problems (such as convergence time and full routing updates), you can use NLSP to carry network information so that remote networks can be visible to each other by populating an IPX routing table. NLSP provides the ability to propagate IPX networks without the need to send periodic updates. NLSP pro- vides a number of advantages over IPX RIP, including: ➤ No periodic updates are sent. Updates are sent only when a change occurs. The whole link-state database is exchanged at a predefined interval. The de- fault is 2 hours on a Cisco router. ➤ NLSP uses a better metric than hops and ticks; instead, NLSP is based on cost. The cost-based approach provides the administrator with the ability to define preferred links by assigning differing costs. ➤ The maximum NLSP hop count is 127, compared to 15 with IPX RIP. ➤ Like any link-state protocol, convergence is much faster. NetWare Link State Protocol uses hello packets to discover new IPX-speaking routers. Further, NLSP is backward compatible with IPX RIP. Let’s take a look at the tasks involved in configuring NLSP on a Cisco router. Configuring NLSP To configure NLSP on a Cisco router, you need to define an internal network number by using the ipx internal-network network-number IOS command. The internal network number must be unique across the network. After you assign the number, you start NLSP by executing the ipx router nlsp command. Note: As mentioned earlier, Cisco routers use IPX RIP to send updates by default, if IPX routing is configured. Therefore, you must disable all IPX RIP networks that will use NLSP; otherwise, both NLSP and IPX RIP will be used to advertise the network. To start NLSP on an interface, use the ipx nlsp enable command. Let’s revisit the network shown earlier in the chapter in Figure 7.2. In this sec- tion, you’ll change the IPX routing protocol to NLSP and disable IPX RIP. List- ings 7.5 and 7.6 display the configurations required for routers R1 and R2. Listing 7.5 Enabling NLSP and disabling IPX RIP on router R1. hostname R1 ipx routing 0000.0c75.d97e ipx internal-network 10 interface Ethernet0 ip address 10.1.9.1 255.255.255.0 ipx network 1 ipx nlsp enable 10 ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○ Chapter 7 ! This command enables IPX NLSP on E0 interface Serial0 ipx network BAD ipx nlsp enable ! Enable NLSP with the following command. The area command defines ! which networks are in NLSP. A value of 0 indicates to place all ! networks in NLSP ipx router nlsp area-address 0 0 ! ! IPX RIP is disabled with the following command. no ipx router rip . Listing 7.6 Enabling NLSP and disabling IPX RIP on router R2. hostname R2 ipx routing 0000.0c8e.774b ipx internal-network 20 interface Ethernet0 ipx network 2 ipx nlsp enable ! interface Serial0 ipx network BAD ipx nlsp enable ! Enable NLSP with the following command. The area command defines ! which networks are in NLSP. A value of 0 indicates to place all ! network in NLSP. ipx router nlsp area-address 0 0 ! ! IPX RIP is disabled with the following command. no ipx router rip As you can see in Listings 7.5 and 7.6, the no ipx router rip command disables the IPX RIP process. Note: Typically on a WAN interface, IPXWAN is used. IPXWAN is a connection startup protocol that can be used between different router vendors. To enable IPXWAN, you must first remove any ipx network statements and then add ipx ipxwan. NLSP is a link-state protocol, and you have a number of useful IOS commands that you can use to tell you what is happening in a NLSP environment using Cisco routers. To begin, let’s look at the IPX routing table shown in Listing 7.7. [...]... 2 and IPX node address of 0800.4000.1527 All other requests will be forwarded by the access-list 1000 permit –1 command Table 7.2 summarizes the main points about filtering IPX traffic on Cisco routers You should memorize the three main access lists ranges used to manage IPX networks These ranges are list 800 through 899, 900 through 999, and 1000 through1099, respectively Networking and Desktop Protocols. .. IPX ❍ b IPX ❍ c UPX ❍ d SPX The correct answer is d SPX is the protocol used at the Transport layer in the IPX model Answers a and b are incorrect, because EIGRP IPX and IPX are layer 3 protocols Answer c is incorrect, because UPX is an invalid protocol Networking and Desktop Protocols 35 ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ Question 3 What access list range... routing protocol (IPX EIGRP) to reduce broadcasts Another way to conserve bandwidth is to use access lists Access lists can help you manage IPX traffic The access list numbers that are available for use with IPX are: Networking and Desktop Protocols 15 ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ➤ Standard IPX filters—Ranges from decimal 800 through 899 ➤ Extended IPX... 39s, Se0 ○ Client PC Networking and Desktop Protocols 17 ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ As you can see in Listing 7.15, the network filter stops network 2 and allows all others, such as the Network 4 loopback interface via the next hop address BAD.0000.0c8e.774b Extended IPX Filters Extended IPX access list can be applied to both source and destination addresses... unless they are unavailable This saves bandwidth on the serial link between routers R1 and R2, thereby saving bandwidth for end users to use to send data 12 Chapter 7 ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ As with IPX RIP, NLSP has a number of commands that you can use to monitor and troubleshoot NLSP, such as (including the commands mentioned earlier in this section):... a DECnet address, and convert it to binary 3 Swap the first 8 bits with the second 8 bits 4 Convert to hexadecimal, and append to the originating address (AA-00-04-00) To further illustrate, let’s determine the local MAC address that will be used by a DECnet Phase IV device For this example, let’s say that you have a device with the DECnet address of 7.10 Networking and Desktop Protocols 27 ○ ○ ○... The equivalent of using a mask of 63.1023 in DECnet is the keyword any for an IP access list Windows NT and NetBIOS This section briefly covers Windows NT and two networking protocols used by Windows PCs, namely NetBEUI and NetBIOS We’ll begin by briefly covering Windows NT Windows NT allows clients and servers to be grouped into domains or workgroups A domain is typically a large group of devices under... currently using NetBIOS (Network Basic Input/Output Networking and Desktop Protocols 31 ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ System) NetBEUI is not routable and must be bridged in cases where networks are not locally reachable NetBEUI was also designed for earlier versions of Windows, namely Windows 3.1 and MS-DOS based clients NetBIOS is a Session layer protocol... As you can see in Figure 7.7, NetBIOS can operate over three protocols NetBEUI (non-routable), IPX (routable), and TCP/IP (routable) NetBIOS over IPX is called NWLink, and NetBIOS over TCP/IP is called NetBT We’ll now move on and discuss how Windows devices can find network resources by browsing and using Windows name resolution Browsing and Windows Names Resolution Windows NT’s browsing service, called... defined lists WINS allows client PCs to dynamically register and request name resolution by a specific server running the WINS services Instead of sending broadcasts, the client sends unicasts WINS typically runs Networking and Desktop Protocols 33 ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ on a Windows NT server and has an IP address Clients are statically or dynamically . master: ✓ Describing how desktop protocols function ✓ Explaining the routing mechanisms for desktop protocols ✓ Managing and configuring desktop support on Cisco. ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○ 7 Networking and Desktop Protocols Terms you’ll need to understand: ✓ Internetwork Packet Exchange (IPX) ✓ Routing