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AppleTalk is a local-area network (LAN) system that was designed and developed by Apple Computer, Inc. It can run over Ethernet, Token Ring, and Fiber Data Distributed 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).
This chapter describes how to configure AppleTalk and provides configuration examples. For a complete description of the commands mentioned in this chapter, refer to the "AppleTalk Commands" chapter in the Router Products Command Reference publication. For historical background and a technical overview of AppleTalk, see the Internetworking Technology Overview publication.
Cisco routers support AppleTalk Phase 1 and AppleTalk Phase 2. For AppleTalk Phase 2, Cisco routers support both extended and nonextended networks. Cisco's implementation of AppleTalk can route 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) wide-area networks (WANs).
Cisco routers also support AppleTalk Enhanced IGRP. AppleTalk Enhanced IGRP provides the following features:
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 MIB variables as described in RFC 1243. We provide support for the following AppleTalk protocols: AppleTalk Resolution Protocol (ARP), AppleTalk Port Group, AppleTalk Datagram Delivery Protocol (DDP), AppleTalk Routing Table Maintenance Protocol (RTMP), AppleTalk Zone Information Protocol (ZIP), AppleTalk Name Binding Protocol (NBP), and AppleTalk Echo Group.
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 MAC-address gleaning.
There are two versions, or phases, of AppleTalk. AppleTalk Phase 1 and AppleTalk Phase 2 are implementations of the AppleTalk protocol stack, especially the routing portions of the stack.
AppleTalk Phase 1, the earlier version, supports a single physical network that can have one network number and be in one zone. This network can have up to 254 devices, which can consist of 127 end nodes and 127 servers. AppleTalk Phase 2, the more recent version, supports multiple logical networks on a single physical network. This means that one cable segment can have multiple network numbers. Each logical network in Phase 2 can support up to 253 devices, with no restrictions on the type of devices. Also, in AppleTalk Phase 2 a network can be in more than one zone.
AppleTalk Phase 2 introduced the concepts of extended and nonextended networks. These terms refer to the media-level encapsulation and cable addressing used on a network segment attached to a router interface. While the concepts of extended and nonextended networks do not exist in AppleTalk Phase 1, Phase 1 can be thought of as a nonextended network.
Table 14-1 compares the capabilities of AppleTalk Phase 1 and Phase 2.
Table 14-1 AppleTalk Phase 1 and Phase 2
| Capability | AppleTalk Phase 1 | AppleTalk Phase 2 |
|---|---|---|
| Networks, nodes, and zones | ||
| Media-level encapsulation | ||
| Cable addressing |
| 1The node addresses 0 and 255 are reserved.
2The node addresses 0, 254, and 255 are reserved. 3There is no restriction on the types of devices. There can be a total of 253 end nodes and servers. 4In terms of zones, an AppleTalk Phase 1 network can be thought of as a nonextended AppleTalk Phase 2 network. |
Routers running Software Releases 8.2 and later support AppleTalk Phase 1 and Phase 2.
An AppleTalk address consists of a network number and a node number expressed in decimal in the format network.node.
The network number identifies a network, or cable segment. A network is a single logical cable. Although the logical cable is frequently a single physical cable, bridges can be used to interconnect several physical cables. The network number is a 16-bit decimal number that must be unique throughout the entire AppleTalk internetwork. In AppleTalk Phase 1, networks are identified by a single network number that corresponds to a physical network. In AppleTalk Phase 2, networks are identified by a cable range that corresponds to one or more logical networks. In Phase 2, a single cable can have multiple network numbers. A cable range is either one network number or a contiguous sequence of several network numbers in the format start-end. For example, the cable range 4096-4096 identifies a logical network that has a single network number, and the cable range 10-12 identifies a logical network that spans three network numbers. In both AppleTalk Phase 1 and Phase 2, the network number 0 is reserved.
The node number identifies the node, which is any device connected to the AppleTalk network. The node number is an 8-bit decimal number that must be unique on that network. In AppleTalk Phase 1, node numbers 1 through 127 are for user nodes, node numbers 128 through 254 are for servers, and node numbers 0 and 255 are reserved. In AppleTalk Phase 2, you can use node numbers 1 through 253 for any nodes attached to the network. Node numbers 0, 254, and 255 are reserved.
The following is an example of an AppleTalk network address:
In this example, the network number is 3 and the node number is 45. You enter both numbers in decimal. Our software also displays them in decimal.
A zone is a logical group of networks. The networks in a zone can be contiguous or noncontiguous. A zone is identified by a zone name, which can be up to 32 characters long and can include standard characters as well as AppleTalk special characters. To include a special character, type a colon followed by two hexadecimal characters that represent the special character in the Macintosh character set. In AppleTalk Phase 2, an extended network can have up to 255 zones, and a nonextended network can have only one zone. An AppleTalk Phase 1 network can have only one zone.
AppleTalk Phase 1 and AppleTalk Phase 2 networks are incompatible and cannot run simultaneously on the same internetwork. As a result, all routers in an internetwork must support AppleTalk Phase 2 before the network can use Phase 2 routing. If your internetwork has a combination of AppleTalk Phase 1 and Phase 2 routers, you must observe the compatibility rules described in this section. Note, however, that you do not need to upgrade all end nodes in order to use the features provided by our AppleTalk enhancements.
Follow these guidelines when configuring an extended AppleTalk network on our router if any router in your AppleTalk internetwork supports only nonextended AppleTalk (that is, if any routers are Phase 1 routers). If you do not follow these guidelines, unpredictable behavior might result.
When using Cisco routers with other vendors' implementations of AppleTalk, follow these guidelines:
To configure AppleTalk routing, complete the tasks in the following sections. At a minimum, you must enable AppleTalk routing. The remaining tasks are optional.
See the end of this chapter for configuration examples.
To enable AppleTalk routing, first enable it on the router, then configure each interface for AppleTalk. These are the only two tasks you must perform when configuring AppleTalk routing.
To configure an interface for AppleTalk, assign an AppleTalk address or cable range to the interface and then assign one or more zone names to the interface. You can perform these tasks either manually or dynamically.
You also can enable our routers to perform transition mode routing from nonextended to extended AppleTalk.
To enable AppleTalk routing on the router, perform the following task in global configuration mode:
For an example of how to enable AppleTalk routing, see the section "Configuring an Extended AppleTalk Network Example" later in this chapter.
You can manually configure an interface for nonextended or extended AppleTalk routing.
To manually configure an interface for nonextended AppleTalk routing, perform the following tasks in interface configuration mode:
| Task | Command |
|---|---|
| Step 1. Assign an AppleTalk address to the interface. | |
| Step 2. Assign a zone name to the interface. |
For an example of how to configure an interface for nonextended AppleTalk routing, see the section "Configuring a Nonextended AppleTalk Network Example" later in this chapter.
After you assign the address and zone name, the interface will attempt to verify them with another operational router on the connected network. If there are any discrepancies, the interface will not become operational. If there are no neighboring operational routers, the router will assume the interface's configuration is correct, and the interface will become operational.
To manually configure an interface for extended AppleTalk routing, perform the following tasks in interface configuration mode:
| Task | Command |
|---|---|
| Step 1. Assign a cable range to an interface. | |
| Step 2. Assign a zone name to the interface. |
You can assign more than one zone name to a cable range. If you do so, the first name you assign is considered to be the default zone.
You can define up to 255 zones.
After you assign the address and zone names, the interface will attempt to verify them with another operational router on the connected network. If there are any discrepancies, the interface will not become operational. If there are no neighboring operational routers, the router will assume the interface's configuration is correct, and the interface will become operational.
If a nonextended or an extended interface is connected to a network that has at least one other operational AppleTalk router, you can dynamically configure the interface using discovery mode. In discovery mode, an interface acquires information about the attached network from an operational router and then uses this information to configure itself.
Using discovery mode to configure interfaces saves time if the network numbers, cable ranges, or zone names change. If this happens, you need to make the changes only on one operational router.
Discovery mode is useful when you are changing a network configuration or when you are adding a router to an existing network.
Note that discovery mode does not run over serial lines.
If there is no operational router on the attached network, you must manually configure the interface as described in the previous sections. Also, if a discovery mode interface is restarted, another operational router must be present before the interface will become operational.
A nondiscovery-mode interface (also called a seed router) starts up as follows. The seed router acquires its configuration from memory. (If the stored configuration is not completely specified when you assign an AppleTalk address to an interface or which you assign a cable range and a zone name to an interface, the interface will not start up. If the stored configuration is completely specified, the interface will attempt to verify the stored configuration with another router on the attached network.). If there is any discrepancy, the interface will not start up. If there are no neighboring operational routers, the router will assume the interface's stored configuration is correct, and the interface will become operational.
Using discovery mode does not affect an interface's ability to respond to configuration queries from other routers on the connected network once the interface becomes operational.
When activating discovery mode, you do not need to assign a zone name. The interface will acquire the zone name from another interface.
 | Caution Do not enable discovery mode on all routers on a network. If you do and all routers restart simultaneously (for instance, after a power failure), the network will be inaccessible until you manually configure at least one router. |
You can activate discovery mode on a nonextended interface in one of two ways, depending on whether you know the network number of the attached network.
In the first method, you immediately place the interface into discovery mode by specifying an AppleTalk address of 0.0. Use this method when you do not know the network number of the attached network. To use this method, perform the following task in interface configuration mode:
For an example of how to configure discovery mode using this method, see the section "Configuring a Nonextended Network in Discovery Mode Example."
In the second method, you first assign an address to the interface and then explicitly enable discovery mode. Use this method when you know the network number of the attached network. Note, however, that you are not required to use this method when you know the network number. To use this method, perform the following tasks in interface configuration mode:
| Task | Command |
|---|---|
| Step 1. Assign an AppleTalk address to the interface. | |
| Step 2. Place the interface into discovery mode. |
You can activate discovery mode on an extended interface in one of two ways, depending on whether you know the cable range of the attached network.
In the first method, you immediately place the interface into discovery mode by specifying a cable range of 0-0. Use this method when you do not know the network number of the attached network. To use this method, perform the following task in interface configuration mode:
In the second method, you first assign cable ranges and then explicitly enable discovery mode. Use this method when you know the cable range of the attached network. Note, however, that you are not required to use this method if you know the cable range. To use this method, perform the following tasks in interface configuration mode:
| Task | Command |
|---|---|
| Step 1. Assign an AppleTalk address to the interface. | |
| Step 2. Place the interface into discovery mode. |
Our router can route packets between extended and nonextended AppleTalk networks that coexist on the same cable. This type of routing is referred to as transition mode.
To use transition mode, you must have two router ports connected to the same physical cable. One port is configured as a nonextended AppleTalk network, and the other port is configured as an extended AppleTalk network. Each port must have a unique network number, because you are routing between two separate AppleTalk networks: the extended network and the nonextended network.
To configure transition mode, you must have two ports on the same router that are connected to the same physical cable. You configure one port as a nonextended AppleTalk network by performing the following tasks in interface configuration mode:
| Task | Command |
|---|---|
| Step 1. Assign an AppleTalk address to the interface. | |
| Step 2. Assign a zone name to the interface. |
You configure the second port as an extended AppleTalk network by performing the following tasks in interface configuration mode:
| Task | Command |
|---|---|
| Step 1. Assign an AppleTalk cable range to the interface. | |
| Step 2. Assign a zone name to the interface. |
When you enter interface configuration mode, the type of interface must be the same for both ports (for example, both could be Ethernet) and the interface number must be different (for example, 0 and 1).
For an example of how to configure transition mode, see the section "Configuring a Nonextended Network in Discovery Mode Example" later in this chapter.
You can configure the RTMP or Enhanced IGRP routing protocols on any interface. You can also configure the AURP routing protocol on a tunnel interface. To create an AppleTalk routing process, perform the following task in interface configuration mode:
An access list is a list of AppleTalk network numbers or zones that is maintained by the router and used to control access to or from specific zones or networks.
The router supports two general types of AppleTalk access lists:
AppleTalk-style access lists regulate the internetwork using zone names. Zone names are good control points because they are the only network-level abstraction that users can access. You can express zones names either explicitly or by using generalized argument keywords. Thus, using AppleTalk access lists simplifies network management and allows for greater flexibility when adding segments, because reconfiguration requirements are minimal.
The main advantage of AppleTalk-style access lists is that they allow you to define access regardless of the existing network topology or any changes in future topologies—because they are based on zones. A zone access list is effectively a dynamic list of network numbers. The user specifies a zone name, but the effect is as if the user had specified all the network numbers belonging to that zone.
IP-style access lists control network access based on network numbers. This feature can be useful in defining access lists that control the disposition of networks that overlap, are contained by, or exactly match a specific network number range. One class of problem addressed by the use of IP-style access lists involves the potential assignment of conflicting network numbers to different networks. You can use an access list to restrict the network numbers and zones that a department can advertise, thereby limiting advertisement to an authorized set of networks. In general, AppleTalk-style access lists are insufficient for this application.
In general, however, using IP-style access lists is not recommended because the controls are not optimal: they ignore the logical mapping provided by AppleTalk zones. One problem with IP-style access lists is that when you add networks to a zone, you must reconfigure each secure router. Another problem is that because anyone can add network segments (for example, if one group of users gets a LaserWriter and installs a Cayman GatorBox, this creates a new network segment), the potential for confusion and misconfiguration is significant.
You can combine zone and network entries in a single access list. Network filtering is performed first, then zone filtering is applied to the result. However, for optimal performance, access lists should not include both zones (AppleTalk-style) and numeric network(IP-style) entries.
You can filter the following types of AppleTalk packets:
Note The three types of filters are completely independent of each other. This means that if, for example, you apply a data packet filter to an interface, that filter has no effect on incoming routing table updates or GZL requests that pass through that interface. The exception to this is that outgoing routing update filters can affect GZL updates.
AppleTalk network access control differs from that of other protocols in that the order of the entries in an access list is not important. However, keep the following constraints in mind when defining access lists:
To explicitly specify how you want these packets or routing updates to be handled, use the access-list other-access global configuration command when defining access conditions for networks and cable ranges, and use the access-list additional-zones global configuration command when defining access conditions for zones. If you use one of these commands, it does not matter where in the list you place it: The router software automatically places the access-list other-access or access-list additional-zones command at the end of the access list. (With other protocols, you must type the equivalent commands last.)
If you do not explicitly specify how to handle packets or routing updates that do not satisfy any of the access control statements in the access list, the packets or routing updates are automatically denied access and, in the case of data packets, are discarded.
You perform the following tasks to control access to AppleTalk networks. These tasks are described in the sections that follow.
Step 2 Create filters.
An access list defines the conditions used to filter packets sent in to or out of the interface. Each access list is identified by a number. All access-list commands that specify the same access-list number create a single access list.
A single access list can contain any number and any combination of access-list commands. You can include network and cable range access-list commands and zone access-list commands in the same access list. However, you can specify only one each of the commands that specify default actions to take if none of the access conditions are matched. For example, a single access list can include only one access-list other-access command to handle networks and cable ranges that do not match the access conditions and only one access-list additional-zones command to handle zones that do not match the access conditions.
To create access lists that define access conditions for networks and cable ranges (IP-style access lists), perform one or more of the following tasks in global configuration mode:
To create access lists that define access conditions for zones (AppleTalk-style access lists), perform one or more of the following tasks in global configuration mode:
A filter examines specific packets that pass through an interface and permits or denies them based on the conditions defined in the access lists that have been applied to that interface.
You can filter the following types of AppleTalk packets:
You can apply one of each type of filter to each interface, for a total of three filters per interface. Each filter can use the same access list or different access lists.
Data packet filters and incoming routing table update filters use access lists that define conditions for networks and cable ranges only. Outgoing routing update filters use access lists that define conditions for networks, cable ranges, and zones. GZL filters use access lists that define conditions for zones only.
The following sections explain the tasks for creating AppleTalk filters.
A data packet filter checks data packets being sent out an interface. If the packets' source network or cable range has access denied, these packets are not transmitted but rather, are discarded.
Data packet filters use access lists that define conditions for networks and cable ranges only. They ignore any zone information that might be in the access list.
When you apply a data packet filter to an interface, you should ensure that all networks or cable ranges within a zone are governed by the same filters.
To create a data packet filter, perform the following tasks:
Step 2 Apply a data packet filter to an interface.
To create a network-only access list, perform one or more of the following tasks in global configuration mode:
To apply the data packet filter to an interface, perform the following task in interface configuration mode:
| Task | Command |
|---|---|
For an example of how to create data packet filters, see the section "AppleTalk Access List Examples" later in this chapter.
Routing table update filters control which updates the local routing table accepts and which routes the local router advertises in its routing updates. You create distribution lists to control the filtering of routing updates.
Filters for incoming routing updates use access lists that define conditions for networks and cable ranges only. Filters for outgoing routing updates use access lists that define conditions for networks and cable ranges, and for zones.
When filtering incoming routing updates, each network number and cable range in the update is checked against the access list. If you have not applied an access list to the interface, all network numbers and cable ranges in the routing update are added to the routing table. If an access list has been applied to the interface, only network numbers and cable ranges that are not explicitly or implicitly denied are added to the routing table:
The following conditions are also applied when filtering routing updates generated by the local router:
To create a filter for routing table updates received on an interface, perform the following tasks:
Step 2 Apply a routing table update filter to an interface.
To create an access list, perform one or more of the following tasks in global configuration mode:
 | Caution Ensure that access lists used to filter incoming routing updates do not contain any zone entries. If they do, these entries might cause undefined behavior. |
To apply the filter to incoming routing updates on an interface, perform the following task in interface configuration mode:
For an example of how to create a filter for incoming routing table updates, see the section "AppleTalk Access List Examples."
To create a filter for routing table updates sent out on an interface, perform the following tasks:
Step 2 Apply a routing table update filter to an interface.
To create an access list, perform one or more of the following tasks in global configuration mode:
To apply a filter to routing updates sent out on an interface, perform the following task in interface configuration mode:
The Macintosh Chooser uses ZIP GZL requests to compile a list of zones from which the user can select services. Any router on the same network as the Macintosh can respond to these requests with a GZL reply. You can create a GZL filter on the router to control which zones the router mentions in its GZL replies. This has the effect of controlling the list of zones that are displayed by the Chooser.
When defining GZL filters, you should ensure that all routers on the same network filter GZL replies identically. Otherwise, the Chooser will list different zones depending upon which router responded to the request. Also, inconsistent filters can result in zones appearing and disappearing every few seconds when the user remains in the Chooser. Because of these inconsistencies, you should normally apply GZL filters only when all routers in the internetwork are our routers, unless the other vendors' routers have a similar feature.
When a ZIP GZL reply is generated, only zones that satisfy the following conditions are included:
Replies to GZL requests also are filtered by any outgoing routing update filter that has been applied to the same interface. You need to apply a GZL filter only if you want additional filtering to be applied to GZL replies. This filter is rarely needed except to eliminate zones that do not contain user services.
Using a GZL filter is not a complete replacement for anonymous network numbers. In order to prevent users from seeing a zone, all routers must implement the GZL filter. If there are any routers on the network from other vendors, the GZL filter will not have a consistent effect.
To create a GZL filter, perform the following tasks:
Step 2 Apply a GZL filter to an interface.
To create an access list, perform one or more of the following tasks in global configuration mode:
To apply the GZL filter to an interface, perform the following task in interface configuration mode:
ZIP reply filters limit the visibility of zones from routers in unprivileged regions throughout the internetwork. These filters filter the zone list for each network provided by a router to neighboring routers to remove restricted zones.
ZIP reply filters apply to downstream routers, not to end stations on networks attached to the local router. With ZIP reply filters, when downstream routers request the names of zones in a network, the local router replies with the names of visible zones only. It does not reply with the names of zones that have been hidden with a ZIP reply filter. To filter zones from end stations, use GZL filters.
To create a ZIP reply filter, perform the following tasks:
Step 2 Apply a ZIP reply filter to an interface.
To create an access list, perform one or both of the following tasks in global configuration mode:
To apply the ZIP reply filter to an interface, perform the following task in interface configuration mode:
If access to any network in a zone is denied, access to that zone is also denied by default. However, if you enable partial zones, access to other networks in that zone is no longer denied.
The permitting of partial zones provides IP-style access control. If enabled, the access control list behavior associated with prior software releases is restored. In addition, NBP cannot ensure consistency and uniqueness of name bindings.
If you permit partial zones, AppleTalk cannot maintain consistency for the nodes in the affected zones, and the results are undefined. With this option enabled, an inconsistency is created for the zone, and several assumptions made by some AppleTalk protocols are no longer valid.
To enable partial zone filters, perform the following task in global configuration mode:
| Task | Command |
|---|---|
Permit access to networks in a zone in which access to another network in that zone is denied. |
Permitting partial zones affects the outgoing routing update and GZL filters.
The AppleTalk Name Binding Protocol (NBP) associates AppleTalk network entity names (that is, AppleTalk network-addressable services) with network addresses. NBP allows you to specify descriptive or symbolic names for entities instead of their numerical addresses. When you specify the name of an AppleTalk device, NBP translates the device's entity name into the device's network address. The name binding process includes name registration, name confirmation, name deletion, and name lookup.
Node addresses can change frequently because AppleTalk uses dynamic addresses. Therefore, NBP associates numerical node addresses with aliases that continue to reference the correct addresses if the addresses change. These node addresses do not change very frequently because each device keeps track of the last node number it was assigned. Typically, node numbers change only if a device is shut down for an extended period of time or if it is moved to another network segment.
To control the router's name display facility, perform one or both of the following tasks in global configuration mode:
To set up special configurations, perform the tasks in the following sections, as appropriate:
The AppleTalk Update-based Routing Protocol (AURP) is a standard Apple Computer routing protocol that provides enhancements to the AppleTalk routing protocols that are compatible with AppleTalk Phase 2. The primary function of AURP is to connect two or more noncontiguous AppleTalk internets that are separated by a non-AppleTalk network, such as IP. In these configurations, you would want to use AURP instead of RTMP, because AURP broadcasts fewer data packets than RTMP.
You configure AURP on a tunnel interface. Tunneling encapsulates an AppleTalk packet inside an IP packet, which is sent across the backbone to a destination router. The destination router then extracts the AppleTalk packet and, if necessary, routes it to an AppleTalk network. The encapsulated packet benefits from any features normally applied to IP packets, including fragmentation, default routes, and load balancing.
To configure AURP, perform the following tasks:
| Task | Command |
|---|---|
Specify the interface out which the encapsulated packets will be sent. |
|
Specify the IP address of the router at the far end of the tunnel. |
tunnel destination [ip-address | hostname]1 |
tunnel mode aurp1 |
| 1This command is documented in the "Interface Commands" chapter of the Router Products Command Reference publication. |
By default, AURP sends routing updates every 30 seconds. To modify this interval, perform the following task in global configuration mode:
| Task | Command |
|---|---|
To set the AURP last-heard-from timer value, perform the following task in interface configuration mode:
A free-trade zone is a part of an AppleTalk internetwork that is accessible by two other parts of the internetwork, neither of which can access the other. You might want to create a free-trade zone to allow the exchange of information between two organizations that otherwise want to keep their internetworks isolated from each other or that do not have physical connectivity with one another.
To establish a free-trade zone, perform the following task in interface configuration mode:
For an example of how to configure a free-trade zone, see the section "Hiding and Sharing Resources with Access List Examples," which contains the section "Establishing a Free-Trade Zone Example."
The Simple Network Management Protocol (SNMP) normally uses the User Datagram Protocol (UDP), IP's connectionless datagram service, to monitor network entities. Our router software lets you run SNMP using DDP, the AppleTalk datagram service. Use DDP if you have SNMP consoles running on a Macintosh.
You must configure AppleTalk routing globally and on an interface basis before you configure SNMP for the router.
To configure SNMP in AppleTalk networks, perform the following tasks:
| Task | Command |
|---|---|
| Step 1. Enter global configuration mode. | |
| Step 2. Disable SNMP on the router. | |
| Step 3. Enable AppleTalk routing on the router. | |
| Step 4. Enable Appletalk event logging. | |
| Step 5. Enter interface configuration mode. | |
| Step 6. Enable IP routing on the interface. | |
| Step 7. Enable AppleTalk routing on the interface. | |
| Step 8. Set a zone name for the AppleTalk network. | |
| Step 9. Enable SNMP server operations. | snmp-server community string [R] [W]1 |
| 1This command is documented in the "System Management Commands" chapter in the Router Products Command Reference publication.
2This command is documented in the "IP Commands" chapter in the Router Products Command Reference publication. |
For an example of configuring SNMP, see the section "SNMP Example."
For information about configuring SNMP on the router, refer to the "Managing the System" chapter.
When connecting two AppleTalk networks with a non-AppleTalk backbone such as IP, the relatively high bandwidth consumed by the broadcasting of Routing Table Maintenance Protocol (RTMP) data packets can severly hamper the backbone's network performnace. You can solve this problem by tunneling AppleTalk through a foreigh protocol, such as IP. Tunneling encapsulates an AppleTalk packet inside the foreign protocol packet, which is then sent across the backbone to a destination router. The destination router then de-encapsulates the AppleTalk packet and, if necessary, routes the packet to a normal AppleTalk network. Because the encapsulated AppleTalk packet is sent in a directed manner to a remote IP address, bandwidth usage is greatly reduced. Furthermore, the encapsulated packet benefits from any features normally enjoyed by IP packets, including default routes and load balancing.
There are two wasy to tunnel AppleTalk. The first method implements Cayman tunneling as designed by Cayman Systems. This method enables routers to interoperate with Cayman GatorBoxes. The second method is a proprietary tunnel protocol known as generic route encapsulation (GRE).
When you use Cayman tunneling, you can have our routers at either end of the tunnel, or you can have a GatorBox at one end and our router at the other end. When you use GRE tunneling, you must have only our routers at both ends of the tunnel connection.
Multiple tunnels originating from the router are supported.
Logically, tunnels are point-to-point links.This requires that you configure a separate tunnel for each link.
To configure a Cayman tunnel, perform the following tasks:
| Task | Command |
|---|---|
| Step 1. Configure a tunnel interface. | |
| Step 2. Specify the interface out which the encapsulated packets will be sent | tunnel source interface1 |
| Step 3. Specify the IP address of the router at the far end of the tunnel | tunnel destination interface1 |
| Step 4. Enable Cayman tunneling. | tunnel mode cayman1 |
| 1This command is documented in the "Interfaces Commands" chapter in the Router Products Command Reference publication. |
 | Caution Do not configure a Cayman tunnel with an AppleTalk network address. |
To configure a GRE tunnel, perform the following tasks:
| Task | Command |
|---|---|
| Step 1. Configure a tunnel interface. | |
| Step 2. Specify the interface out which the encapsulated packets will be sent | tunnel source interface1 |
| Step 3. Specify the IP address of the router at the far end of the tunnel | tunnel destination interface1 |
| Step 4. Enable Cayman tunneling. | tunnel mode cayman1 |
| 1This command is documented in the "Interfaces Commands" chapter in the Router Products Command Reference publication. |
Our routers implement MacIP, which is a protocol that allows routing of IP datagrams to IP clients using the DDP for low-level encapsulation.
Our routers implement the MacIP address management and routing services described in the draft Internet RFC, A Standard for the Transmission of Internet Packets over AppleTalk Networks. Our implementation of MacIP conforms to the September 1991 draft RFC with the following exceptions:
Some situations require the use of MacIP. For example, if some of your Macintosh users use AppleTalk Remote Access or are connected to the network using LocalTalk or PhoneNet cabling systems, then MacIP is required to provide access to IP network servers for those users.
MacIP services also can be useful when you are managing IP address allocations for a large, dynamic Macintosh population. There are several advantages to using MacIP in this situation:
However, there are several disadvantages in implementing MacIP on our routers:
To configure MacIP on our routers, AppleTalk must be configured as follows:
When setting up MacIP routing, keep the following address range issues in mind:
To configure MacIP, perform the following tasks:
Step 2 Allocate IP addresses for Macintosh users by specifying at least one dynamic or static resource address assignment command for each MacIP server.
To establish a MacIP server for a specific zone, perform the following global configuration task:
| Task | Command |
|---|---|
Note that the MacIP server must reside in the default AppleTalk zone.
You can configure multiple MacIP servers for a router, but you can assign only one MacIP server to a zone, and you can assign only one IP interface to a MacIP server. In general, you must be able to establish an alias between the IP address you assign with the appletalk macip server global configuration command and an existing IP interface. For implementation simplicity, the address you specify in this command should match an existing IP interface address.
A server is not registered by NBP until at least one MacIP resource is configured.
Dynamic clients are those that accept any IP address assignment within the dynamic range specified. Dynamic addresses are for users who do not require a fixed address, but can be assigned addresses from a pool.
To allocate IP addresses for Macintosh users if you are using dynamic addresses, perform the following global configuration task:
For an example of configuring MacIP with dynamic addresses, see the section "MacIP Examples."
Static addresses are for users who require fixed addresses for IP DNS services and for administrators who do not want addresses to change so they always know the IP addresses of the devices on their network.
To allocate IP addresses for Macintosh users if you are using static addresses, perform the following global configuration task:
| Task | Command |
|---|---|
Allocate an IP address to be used by a MacIP client that has reserved a static IP address. |
appletalk macip static ip-address [ip-address] zone server-zone |
For an example of configuring MacIP with static addresses, see the section "MacIP Ex