AppleTalk Configuration on Ripro Server

• Introduction
• How to configure Ripro Server AppleTalk
• Appendix A - How does the Ripro selects AppleTalk address.
• Appendix B - How does a Mac select a AppleTalk address.
• Glossary

Introduction

The Ripro Server can support AppleTalk on a single or multiple network interface (Ethernet and/or FDDI).

• When AppleTalk is configured on a multiple network interface, the Ripro Server acts as a router and publishes Network Numbers (physical cable range) and Zones on the network.
• When only one network interface is configured, the Ripro acts almost like any other AppleTalk device (i.e. Mac, LaserWriter, etc...). However, the Ripro does not fully support dynamic AppleTalk address configuration????.

Throughout this document, AppleTalk refers only to AppleTalk Phase 2.
Whenever Sub Network is mentioned, it refers to the third layer (of the seven layered communication stack) Sub Network. This Sub Network can be segmented by a Switching Hub or Bridge (layer two network segmentation).

For example:
When a server is connected with FDDI to a switching hub with 16 ethernet ports, all the 16 ethernet segments and the FDDI are considered one Sub Network.

The AppleTalk address contains three numbers Net#.Node#.Socket#. Net Number can range from 1 to 65534, Node and Socket numbers may take on a value from 1 to 253 (see the glossary for more details).

On the Ripro Server, the AppleTalk Network Numbers (cable range) and the Zones, need to be configured. This procedure is described below.

How to configure Ripro Server AppleTalk
(using the netconf util on the server)

A Site with No AppleTalk Router

The Ripro acts as an AppleTalk device (no routing activity). The interface that runs the AppleTalk should be configured like the FDDI in the following example:

The meaning of this setup is:

• The Ripro is connected to the network without a router
• The Ripro can talk directly (not via a router) to any other AppleTalk node on any network number (1-65534)
• There are no zones on this network ( on the MAC the chooser has only two windows)
• The Ripro will try to register itself as Network No. 1 and Node No. 140 (1.140). See the appendix for more details.

NOTE: Since the Ripro is not a router, the Ripro cannot publish zone names on the network. Configuring zone names in this case is illegal and will cause problems on the network.

A Site where the Ripro is an AppleTalk Router

The Ripro acts as an AppleTalk router when more than one network interface is configured to run AppleTalk.

The netconf screen should be, for example, as follows:

The meaning of this setup is:

• The Ripro is an AppleTalk router
• There are at least two AppleTalk Sub Networks at this site (more are possible is there is an external router connected to one of the Ripro interfaces- In this case see ÒA Site with an External AppleTalk RouterÓ for information how to configure the interface that is connected to the external router )
• The Macs (or any other AppleTalk device) connected to ent0 (the first ethernet board on the server) are in Sub Network 12-14 and on zone A. If additional zones are configured on et0 they can choose also one of the additional zones. The Macs (or any other AppleTalk device) connected to fi0 (the first FDDI board on the Server) are in Sub Network 25 and on zone ZoneB. If additional Zones are configured on fi0 they can choose also one of the additional Zones.
  It is possible to configure the same zone name on more then one interface, in this case AppleTalk devices on different Sub Networks can share the same Zone name.
• Any AppleTalk device on Net 12-14 that talks to an AppleTalk device on Net 25 (or vice versa) sends the data (packets) to the Ripro and the Ripro forwards it to the other Device (routing).
• The Ripro is publishing himself (AppleShare Server and Printer Spoolers) on the first configure Interface and Zone, in this example the Ripro will be on ZoneA.

NOTE: It is not allowed to connect two interfaces of a Router to the devices that bridge them. For example: configuring AppleTalk on two Ripro interfaces that are connected to the same switching Hub is not allowed and will cause severe problems on the network (i.e. devices jumping from one zone to the other, losing connections, etc.).

A Site with an External AppleTalk Router

If the Ripro is connected to a network with an external router, the Ripro should be configured according to the configuration of the external router.

For example, an external router has 2 interfaces and the Ripro is connected to interface 1 of the router. The external router was configured to publish the following network information on interface 1:

The Ripro configuration should then look as follows (assuming that the Ripro is connected via FDDI):

This meaning of this set up is:

• The Ripro is connected to a network with an external router.
• The Ripro can talk directly (not via the router) to any other AppleTalk node that is on the same Sub Network (4-5).
• The Ripro can communicate with AppleTalk devices that are connected to other interfaces of the router via the router. The Ripro will send the data (packets) to the router and the router will forward it to the appropriate interface (and vice versa).
• The Ripro will try to register itself with Network number 4 , Node no. 140 (4.140).
• The Ripro will publish itself on zone Nirvana.

Appendix A - How does the Ripro selects AppleTalk address.

The Network Number is set for each interface that is running AppleTalk according to the netconf configuration. The Ripro tries to use the Network Start number.

The Node number is set as follow (assuming that the Network Numbers are 1-2):
The Ripro will try to use 140 as the node number. If any other station already uses this address, the Ripro will try 141 as the node number and so on, until it finds a free node number on this Sub Network. If all the nodes from 1.140 (Net #.Node #) to 1.253 are in use, the Ripro will try 2.140 and higher (there are almost no chances that this will happen even in a network with a lot of Macs).

Appendix B - How does a Mac select a AppleTalk address.

The Mac configures the network and node numbers dynamically. First, it will try to use the same address it had the last time it was connected to the network. If this address is taken, or the network configuration was changed and the address does not fit the new configuration, the Mac will pick another address (pseudo-dynamically).

Glossary

AppleTalk Router

A Router is a device that moves some kind of network traffic between two or more Sub Networks. It does this by looking at a AppleTalk destination address (layer three adress) in the traffic off of the first network, and copying the traffic to whichever network gets the traffic closer to the network that the address in the traffic indicates is the destination. Depending on the type of Router, the address could be one of many different protocols, such as AppleTalk, IP, or DECnet.

Bridge

A bridge is a device that moves some kind of network traffic between two or more segments. It does this by looking at a physical destination address (layer two address) in the traffic off of the first segment, and copying the traffic to whichever segment gets the traffic closer to the segment that the address in the traffic indicates is the destination. Bridges suppose to compliance to IEEE 802.1d (the IEEE standard that defined how bridges should work)

Network Numbers

Each AppleTalk Sub Network needs a unique 16-bit network number. The Network Number ensures that traffic from one Sub Network can be distinguished from traffic on another Sub Network when the two are connected with a Router. In particular if a network wishes to be on the campus-wide AppleTalk, the numbers must be unique across campus.

A Sub Network can support multiple zones, theoretically up to 255. Two examples of extended networks, and how their numbering works are:

LocalTalk -- All LocalTalk Sub Networks have a single Network Number, which can theoretically support up to 254 nodes. In reality, 254 is way too many nodes for a LocalTalk network.

EtherTalk Phase 2 -- Phase 2 uses a range of Network Numbers, each of which can support up to 253 nodes. EtherTalk Phase 2 is commonly just called EtherTalk.

Node

A number between 1 and 253. It is unique for a device on a physical network. This number is determined by the device at its boot time, and it keeps that number (at least) until it is powered off or restarted. Node numbers 1-127 are "client" numbers (i.e.: regular Macintoshes), and numbers 128 - 253 are "server" numbers (i.e.: printers and AppleShare file servers).

Socket

A socket is a logical entity in a node connected to an AppleTalk network. A socket is owned by software that can send and receive data through the socket. There can be 254 different sockets on a node, and various sockets are reserved for different things.

Switch

Switch can be relate as an high speed multiport bridge. Some switches are fully compliance to the 802,1d standard, others are implementing proprietary mechanism in order to improve performance.

(The LP2500, LS2200 and LP6000 in there default configuration are compliance to the 802.1d standard - When a Switch is being use in SciNet environment it should compliance to the 802.1d standards otherwise it can cause "no communication" problems).

Zone -- Also Zones, or Zone Name

A zone is basically a text name that represents some parts or all of a network. Zones make it easy to find groups of devices in the Chooser. A zone can consist of only one Sub Network, or it can group together several Network Numbers into a single "logical" network. This allows devices on EtherTalk and LocalTalk Sub Networks to be seen together in the Chooser under one zone name. Thus allowing all departmental servers and printers to be found in one place, even if they have more than one Sub Network. It is also possible to have a list of zone names that are all used by a single extended network. Any zones in that list could also be used on other Sub Networks. Here are some examples of the use of zone names on networks:

Any machine on the Sub Network 4608-4608 could choose between zones Ripro1 and SCITEX, while a machine on 4611 would have to be in SCITEX. A machine on 8448-8449 or 8450 would have to be in Ripro1, while a machine on 51456-51456 could choose from Ripro1 or OutPut. Any machine on 51458 would have to be in OutPut. So while only three zones would show up in the chooser, there would actually be 6 networks that were connected and accessible.