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AppleTalk

AppleTalk Protocol Suite

Notes

1. AFP (AppleTalk Filing Protocol)
2. ADSP (AppleTalk Data Stream Protocol)
3. ZIP (Zone Information Protocol)
   • Maintains zone information and works closely with NBP.
   • Maps between zone names and network numbers.
   • All zone information in an AppleTalk network is synchronized, that means that a Cisco router or access server will not advertise an AppleTalk network until the zone information about that network is known.
   • After a router learns about a new route or network from its routing protocol, it uses ZIP to query the advertising router for the zones associated with that route or network.
   • The router uses this information to build a zone information table (ZIT).
   • Forcing routers to wait on zone information before advertising a route or network slows down the propagation of routing information, but it prevents ZIP storms (The flood of broadcast ZIP requests that can result from advertising routes whose network zone associations are not known) from occurring.
4. ASP (AppleTalk Session Protocol)
5. ATP (AppleTalk Transaction Protocol)
6. AEP (AppleTalk Echo Procotol)
7. AURP (AppleTalk Update-based Routing Protocol)
   • Open standard developed in association with the Internet Engineering Task Force (IETF), can interoperate with routers from different vendors.
   • Primary function: To connect two or more noncontiguous AppleTalk internetworks that are separated by a non-AppleTalk network, such as IP. It defines a standard for tunneling AppleTalk through these networks.
   • Supports remapping of remote network numbers to resolve numbering conflicts.
   • Has its own built-in security features such as device hiding and network hiding.
   • Supports for hop-count reduction means that you can use it to create larger internetworks.
   • Designed to be more efficient than RTMP in handling routing update traffic over LAN links.
   • Includes several feature enhancements that are compatible with AppleTalk phase 2.
   • Reduces WAN traffic by sending routing updates rather than entire routing tables.
   • Deployed to contain broadcast traffic in WAN environment.
   • Reduces the volume of routing overhead traffic on an AppleTalk WAN.
   • Support basic security features.
8. NBP (Name Binding Protocol)
   • Maintains node name information by broadcasting.
   • Has 3 components: object name, type, and zone.
   • Each query contains only 2 fields.
   • The query responses are used to fill in the missing field.
   • Handles the conversion from name to network address.
9. RTMP (Routing Table Maintenance Protocol - default)
   • Establishes and maintains routing tables.
   • Periodically broadcast the entire routing table.
   • Provides slower convergence than EIGRP.
   • Generates more overhead than EIGRP.
   • Its routing tables contain an entry for each reachable network.
   • One routing tuple is generated for every cable range.
   • Has a maximum hop count of 15.
   • Sends routing updates at 10-seconds intervals.
   • Each routing packet contains routing tuples
     • Equivalent to routing table entries in RIP
     • Each comprises a cable range and a hop count, no zone name.
   • Uses split-horizon routing to limit the propagation of routing updates.
     • Updates sent out on a given interface will not include any information that was learned from that interface.
     • Broadcasts will not be retransmitted on the receiving interface.
     • Imposes limitations on the connectivity that you can have in some partial-mesh, packet-switched WAN configurations.
   • RTMP filter is configured to block
     • The advertisement of cable ranges or network numbers.
     • The acceptance of cable ranges or network numbers into the routing table.
10. DDP (Datagram Delivery Protocol)
    • Runs on the backbone to connect isolated AppleTalk networks through a foreign backbone such as IP (EIGRP or AURP should be used for routing table updates in the core WAN).
    • Could be tunneled in the backbone using point-to-point topology.
11. AARP (AppleTalk Address Resolution Protocol)
12. RTMP, NBP, ZIP generates most of the broadcast traffic in AppleTalk internetworks.

Link-layer protocols that support AppleTalk

1. EtherTalk Link Access Protocol (ELAP)
2. LocalTalk Link Access Protocol (LLAP)
3. TokenTalk Link Access Protocol (TLAP)
4. FDDITalk Link Access Protocol (FLAP)

AppleTalk Version

1. AppleTalk phase 1: Original version designed for local workgroups, nonextended networks (254 nodes limit).
   1. Each node number is unique: Only a single network number and a single zone are allowed per cable plant (LocalTalk).
2. AppleTalk phase 2: Enhanced version, supports larger and more scalable internetworks, allowing multiple network numbers and zone names with improved routing capabilities.
   1. 16-bit network numbers, equivalent to Class B IP network, which means that over 64,000 network numbers are available.
   2. Each LAN can have several network numbers, which is referred as a cable range.
   3. Should have 1 number in the cable range for every 50 AppleTalk device on the LAN (To support 200 devices, use a cable range of four - say 200-203).
   4. The cable range allocated must be unique and cannot overlap.
   5. Floating static routes should be implemented for backup, which have a higher administrative distance than dynamically learned routes, which guarantees that they will be used only as a last resort.
   6. Floating static routes for AppleTalk and IPX first available with release 11.0 of Cisco IOS software.
   7. Distinguishes between nonextended and extended networks.
   8. Each network-number and node-number combination is unique (EtherTalk - 1024 nodes limit, TokenTalk - 260 nodes limit, FDDITalk), allowing a range of network numbers per cable plant (cable range - can have more than 254 devices on a LAN segment).

Cisco supported AppleTalk Version

1. Phase 1
2. Phase 2
3. Networks in transition from phase 1 to phase 2 (complex)

To calculate the amount of routing overhead traffic

• There is a maximum of approximately 200 routing tuples per RTMP packet.
• One routing tuple is generated for every AppleTalk cable range.
• RTMP sends routing updates to each interface at 10-seconds intervals.
• A DDP packet can be up to 600 bytes long with no fragmentation.

AppleTalk software interface

• AppleTalk Chooser allows user to select shared network services. It is particularly broadcast intensive in terms of overall network traffic. With older versions of the MAC OS, the Chooser generates an NBP broadcast every three seconds, provided the Chooser window is open and a zone and device driver are selected. This results in significant network traffic. Release 7.0 of the MAC OS incorporates an exponential timing delay that reduces the frequency of NBP broadcasts.
• When the Chooser is opened, the Apple Macintosh computer sends a GZL request to its router to obtain a list of all (unfiltered) zones on the internetwork.

Communication in an AppleTalk network takes place between Network Visible Entities (VNEs)

1. 16-bit network number
2. 8-bit node number
3. 8-bit socket number identifying an application or process (socket 4 for AppleTalk ping).

AppleTalk allows you to name VNEs with up to 32 characters long consists of 3 fields - object, type, and zone.

With AppleTalk filters, 2 fundamental tasks needed:

1. Create a AppleTalk access list that defines which zones, networks, or names should be identified.
2. Apply the access lists created to an interface.

By using the following types of filter

1. GetZoneList (GZL) filter
   • Filters ZIP information locally between a router and hosts.
   • Could hide specific zones from users on specific networks.
   • An Apple Macintosh default router is selected dynamically. Therefore you must configure the identical GZL filter on each router to implement that filter on the cable segment. This means that a GZL filter is not a scalable solution with a large network with many routers.
   • Allows you to control ZIP GZL requests from the Chooser to the router only.
2. ZIP reply filter
   • Filters zone information exchange between routers.
   • Hide zone information between routers by applying it on the replying routers.
   • Useful to connect AppleTalk administrative domains.
   • Does not prevent hosts from getting lists of network numbers.
3. NBP filter
   • Applies to the incoming traffic only.
   • Can be set up to deny access to a single device or to all devices within a zone.
   • Could control DDR.
   • To implement for AppleTalk VNE, the entity name required.
4. distribute list

An AppleTalk distribute list filter controls RTMP broadcast between routers.

The partial zones feature permits access to the other networks in a zone when access to one of those networks is denied.

Redistribution: A feature that allows internetworks using different routing protocols to exchange routing information.

EIGRP

• Only sends routing updates when changes occur.
• Designed to converge very quickly - within one second of a link failure.
• Convert from RTMP to EIGRP using the formula
  metric = hops * 25652400