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AppleTalk and Novell IPX Overview

AppleTalk and Novell IPX Overview

The Cisco IOS software supports a variety of routing protocols. The Network Protocols Configuration Guide, Part 2 discusses the following network protocols:

The Network Protocols Configuration Guide, Part 1 discusses the following network protocols:

The Network Protocols Configuration Guide, Part 3 discusses the following network protocols:

This overview chapter provides a high-level description of AppleTalk and Novell IPX. For configuration information, refer to the appropriate chapter in this publication.

AppleTalk

AppleTalk is a LAN system designed and developed by Apple Computer, Inc. It can run over Ethernet, Token Ring, and Fiber Distributed Data Interface (FDDI) networks, and over Apple's proprietary twisted-pair media access system (LocalTalk). AppleTalk specifies a protocol stack comprising several protocols that direct the flow of traffic over the network.

Apple Computer uses the name AppleTalk to refer to the Apple network protocol architecture. Apple Computer refers to the actual transmission media used in an AppleTalk network as LocalTalk, TokenTalk (AppleTalk over Token Ring), EtherTalk (AppleTalk over Ethernet), and FDDITalk (AppleTalk over FDDI).

Cisco IOS software supports AppleTalk Phase 1 and AppleTalk Phase 2. For AppleTalk Phase 2, Cisco devices support both extended and nonextended networks. Cisco's implementation of AppleTalk routes packets over Ethernet, Token Ring, and FDDI LANs, and over X.25, High-Level Data Link Control (HDLC), Frame Relay, and Switched Multimegabit Data Service (SMDS) WANs.

Cisco routers and access servers also support AppleTalk Enhanced Internet Gateway Protocol (Enhanced IGRP). AppleTalk Enhanced IGRP provides the following features:

Standard AppleTalk Services

The Cisco implementation of AppleTalk supports the following standard AppleTalk protocols:

AARP, DDP, and RTMP provide end-to-end connectivity between internetworked nodes. AARP maps AppleTalk node addresses to the addresses of the underlying data link, thus making it possible for AppleTalk to run on several data links. DDP provides socket-to-socket delivery of packets. RTMP establishes and maintains routing tables.

NBP and ZIP maintain node name and zone information. NBP maps network names to AppleTalk addresses. ZIP tracks which networks are in which zones.

AEP is an echo (or ping-type) protocol. It generates packets that test the reachability of network nodes.

ATP is a reliable transport protocol that provides data acknowledgment and retransmission for transaction-based applications, such as file services provided by the AppleTalk Filing Protocol (AFP) and print services provided by the Printer Access Protocol (PAP).

Our software provides support for the AppleTalk Management Information Base (MIB) variables as described in RFC 1243.

Enhancements to Standard AppleTalk

The Cisco AppleTalk implementation includes the following enhancements to standard AppleTalk:

AppleTalk, like many network protocols, makes no provisions for network security. The design of the AppleTalk protocol architecture requires that security measures be implemented at higher application levels. Cisco supports AppleTalk distribution lists, allowing control of routing updates on a per-interface basis. This security feature is similar to those that Cisco provides for other protocols.

Note that Cisco's implementation of AppleTalk does not forward packets with local source and destination network addresses. This behavior does not conform with the definition of AppleTalk in Apple Computer's Inside AppleTalk publication. However, this behavior is designed to prevent any possible corruption of the AARP table in any AppleTalk node that is performing address gleaning through Media Access Control (MAC).

A Cisco router or access server may receive equivalent routes advertised by neighboring routers with one router giving an AppleTalk Phase 1 form of the route (for example, 101), and another giving an AppleTalk Phase 2 form of the route (for example, 101-101). When neighboring routers advertise equivalent overlapping routes to a router, the router always uses the AppleTalk Phase 2 form of the route and discards the AppleTalk Phase 1 route.

Novell IPX

Novell Internet Packet Exchange (IPX) is derived from the Xerox Network Systems (XNS) Internet Datagram Protocol (IDP). IPX and XNS have the following differences:

Cisco's implementation of Novell's IPX protocol is certified to provide full IPX routing functionality.

Cisco supports the IPX MIB (currently, read-only access is supported). The IPX Accounting group represents one of the local Cisco-specific IPX variables we support. This group provides access to the active database that is created and maintained if IPX accounting is enabled on a router or access server.

Cisco IOS software also supports IPX Enhanced IGRP, which provides the following features:

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