Transcript ppt
Computer Networks Other Network Protocols Autumn 2000 John Kristoff 1 Motivation Even though TCP/IP may have won the protocol wars, you will be able to understand networking and even TCP/IP better if you learn about contrasting solutions and implementations. This may help you to avoid reinventing the wheel or perhaps to borrow from the past's good ideas to solve seemingly new problems. Autumn 2000 John Kristoff 2 Novell IPX/SPX Ñ Novell proprietary Ñ Based on Xerox's XNS protocol system Ñ Runs on top of Ethernet, Token Ring, etc. Ñ Usually used with NetWare OS's Ñ Very popular in corporate environments Ñ Declining usage Autumn 2000 John Kristoff 3 Novell Protocol Stack Illustrated Autumn 2000 John Kristoff 4 Internetwork Packet eXchange (IPX) Ñ 32-bit network, 48-bit node/host address Ñ Network is generally fixed at 32-bits Ñ Node address = IEEE 802 MAC address Ñ Dynamic host address assigment Ñ Many features IP wishes it had! Autumn 2000 John Kristoff 5 IPX Routing Ñ IPX Routing Information Protocol Ñ TTL counts up Ñ NLSP Ñ Similar to OSPF and IS-IS Ñ Never took off Ñ Concept of internal IPX numbers Autumn 2000 John Kristoff 6 Sequenced Packet eXchange (SPX) Ñ Similar to TCP, but with no sliding window! Ñ SPX II addressed the window size problem ÑThough, not really well Ñ Most Novell based apps avoided SPX ÑIt was inefficient and just got in the way ÑSome newer apps used SPX II (e.g. Notes) Autumn 2000 John Kristoff 7 Service Advertisement Protocol (SAP) Ñ Services are advertised periodically ÑThe anti-DNS system Ñe.g. "I'm a Netware printer, here I am!" Ñ Default interval was every 60 seconds ÑVery chatty on large networks ÑDoes not scale Ñ NDS was supposed to help Autumn 2000 John Kristoff 8 NetWare Core Protocol (NCP) Ñ Novell's layer 5, 6 and 7 layers - kinda Ñ File access protocol Ñ Print services Ñ Login/authentication requests Ñ Messaging/management services Ñ Provided "burst mode" for file read/writes Autumn 2000 John Kristoff 9 NetWare Directory Services (NDS) Ñ Hierarchical database of network objects Ñ Based on X.500 and works with LDAP Ñ Logical and physical objects represented ÑLeafs, containers, users, drive mapping, etc. Ñ Naming structure similar to DNS Ñe.g. jdoe.networks.acme_us. Ñ Partitions and replicas stored on servers Autumn 2000 John Kristoff 10 AppleTalk Ñ De Facto standard from Apple for Macs Ñ Very easy for end users Ñ Very chatty - scaling problems Ñ Runs on top of LocalTalk, Ethernet, Token Ring, etc. Ñ TokenTalk and EtherTalk technologies developed to support AppleTalk over IEEE LANs Autumn 2000 John Kristoff 11 This Picture is Wrong! Autumn 2000 John Kristoff 12 AppleTalk Network Layer Addressing Ñ Only 3 bytes for network layer addresses! Ñ2 bytes for network, 1 byte for host/node Ñ Networks can be ranges Ñe.g. 135-141 ÑArbitrary size, unlike IP (x2) Ñ Looks/Requests network address Ñ Chooses host/node address at random! ÑSends an AARP and looks for a reply Autumn 2000 John Kristoff 13 AppleTalk Routing Ñ Routing Table Maintenance Protocol (RTMP) ÑSimilar to RIP Ñ Seed Router Ñ1 router configured with network, others learn Ñ Nodes can optimize best exit router by examining received packets ÑAssociates NET with ROUTER ADDRESS Autumn 2000 John Kristoff 14 AppleShare Ñ Centralized file sharing system Ñ Runs on top of AppleTalk Ñ Also allows for ÑPrinter sharing ÑPeer to peer sharing ÑMail handling ÑSecurity functions (ids and passwords) Autumn 2000 John Kristoff 15 ISO Network Layer Ñ Connectionless Network Layer Protocol (CNLP) Ñ Variable length, 20 bytes max Ñ Address specifies a host rather than an interface Ñ Was considered to replace IPv4 Ñ Provided for autoconfiguration like IPv6 and IPX Autumn 2000 John Kristoff 16 ISO Routing Ñ Intermediate System to Intermediate System (IS-IS) Ñ Link state routing protocol Ñ Very similar to OSPF Ñ Widely used by many ISPs Ñ Runs directly on top of a layer 2 protocol Autumn 2000 John Kristoff 17 ISO Transport Layer Ñ Transport Protocol (TP) Ñ Four classes of transport layer protocols ÑTP0, TP1, TP2, TP3, TP4 ÑEach provide increasing degree of features Ñ TP4 is similar to TCP ÑThree-way handshake ÑSliding window ÑRetransmission timer Autumn 2000 John Kristoff 18 ISO Protocol Stack Illustrated Autumn 2000 John Kristoff 19 DECnet Ñ Most commonly referred to as Phase IV ÑEarlier phases and Phase V also defined Ñ DECnet Phase V was CLNP or IP Ñ Only 2 bytes for addresses in Phase IV! Ñ6 bits for network (area), 10 bits for host/node Ñ Traditionally implemented on Digital Equipment Corp. machines (e.g. VAX) ÑPorted to many other systems Autumn 2000 John Kristoff 20 DECnet Protocol Stack Illustrated Autumn 2000 John Kristoff 21 Systems Network Architecture (SNA) Ñ Proprietary architecture from IBM Ñ There is no true layer 3 function in legacy SNA - no routing! Ñ Historically built for token ring and source routing (that was the layer 3 network) Ñ Central control (dumb terminals) Ñ APPN came later to provide distributed control Autumn 2000 John Kristoff 22 SNA Protocol Stack Illustrated Autumn 2000 John Kristoff 23 SNA Components Ñ Hosts (mainframe) Ñ Communications controller/FEP Ñ Cluster controllers - like a hub Ñ Terminals and printers Ñ Software (VTAM, NCP, emulation) Ñ Physical and logical concepts (PUs/LUs) Autumn 2000 John Kristoff 24 Network Basic Input Output System (NetBIOS) Ñ A simple API for LAN applications Ñ Assigns names for nodes on the network Ñ Very chatty - does not scale Ñ No network layer Ñ Often uses the NetBIOS Extended User Interface (NetBEUI) Ñ Server Message Block (SMB) used to provide file/print sharing (e.g. Samba) Autumn 2000 John Kristoff 25