.. Answers to frequently asked questions...




The Open Transport

This article describes some common questions and answers about the Open Transport.

The Open Transport TCP/IP Control Panel Simplified For Beginners

Apple Open Transport Component Technologies

Open Transport 1.0.8 Network Compatibility


The Open Transport TCP/IP Control Panel Simplified For Beginners

This article provides a simplified explanation of the elements of the Open Transport, TCP/IP control panel settings.

Question:

What does the TCP/IP control panel let me do?

Answer:

The Transmission Control Program/Internet Protocol (TCP/IP) control panel lets your Macintosh speak the protocol or "language" of the Internet. The Mac OS uses AppleTalk, the protocol of Apple Macintosh computers and LaserWriter printers. But the Internet uses the TCP/IP protocol suite, which is the "language" of UNIX systems.

Question:

What is an IP address?

Answer:

Each machine or "host" connected to the Internet must have a unique IP address in order to communicate with other hosts. It is like a telephone number. An IP address is a 32-bit number, usually expressed in dotted decimals, for example: 128.1.1.24

Question:

What is the significance of the dotted decimals in an IP address?

Answer:

Similar to the way a telephone number is divided into area code, exchange, and individual phone number, an IP address is also subdivided into octets (each "octet" is 8 bits, 8 bits X 4 octets = 32 bits) that designate network, subnetwork, and node. The network is like the area code; it describes a certain piece of the Internet where your Macintosh is connected. A subnetwork is similar to an exchange; it further breaks down the network into smaller chunks, and each subnetwork can have its own range of nodes, like the individual phone numbers on that exchange. Note that not all networks use subnetworking to further divide their network.

Question:

What is the subnet mask?

Answer:

This mask is what is used to indicate which bits of your 32-bit IP address designate the "network", and which bits designate the "node". Remember that the dotted decimal format is just an easy way of expressing the 32-bit address. If you were to write out the example address, 128.1.1.24, in binary numbers, it would look like this:

10000000.00000001.00000001.00011000

The subnet mask is also a 32-bit number; when superimposed over the IP address, every bit that matched a "1" would be part of the "network", and every bit that matched a "0" would be part of the node. For example, a subnet mask of 255.255.0.0 would look like this:

11111111.11111111.00000000.00000000

This would indicate that the first two octets of the IP address (128.1) indicated the network. The last two octets (1.24) are the node on the network 128.1.0.0.

There are three main classes of IP addresses and each class has a default subnet mask. The class is determined by the first few bits of the 32-bit IP address, as indicated below. For example, because the first bit of a class A address must be 0, when expressed in decimal numbers, the first octet will be 127 (01111111) or lower, because 128 in binary numbers starts with a "1": 10000000.
ClassIdentified by 1st OctetDefault Subnet Mask
AFirst bit = 0 (0-127)255.0.0.0
BFirst two bits =10 (128-191)255.255.0.0
CFirst three bits = 110 (192-223)255.255.255.0
Each organization can use the bits for their nodes to define subnets at their routers. For example, a class A address has the first 8 bits defining the network. An organization might decide to take the two middle octets - 16 bits - to define subnets, and then the final 8 bits would define a node on the subnet on the network.

This information is used by routers to determine how to route the IP packets to the network you are attached to.

Question:

What are the different ways I can connect to the Internet?

Answer:

If you are connected to a LAN that has access to the Internet, you simply use that LAN connection for your Internet communications. If you are on an Ethernet or Token Ring LAN, you can select either Ethernet or Token Ring, respectively, in the connect via field of the TCP/IP control panel. These types of networks support different protocols, so you can direct AppleTalk and TCP/IP, as well as other protocols such as IPX, over these networks at the same time.

If you are on a LocalTalk LAN, or connecting via Apple Remote Access, then you are limited to using AppleTalk protocols. However, TCP/IP packets can be encapsulated in AppleTalk packets for transmission over these connections. This is referred to as "MacIP". To use MacIP, you need a MacIP server, which sits on both an AppleTalk and a TCP/IP network, and acts as a middleman between you and the Internet. You send your AppleTalk encapsulated IP packet to the MacIP server using AppleTalk protocols; it strips off the AppleTalk encapsulation, and places the IP packet out on the Internet. When packets are destined to you from the Internet, it does the reverse.

If you are not on a LAN that has connections to the Internet, then you can gain access through Internet Service Providers (ISPs). SLIP (Serial Line IP) or PPP (Point-to-Point Protocol) connections give you access to the Internet, using your modem and phone lines.

Question:

Where do I get an IP address and a subnet mask?

Answer:

This information must come from the person who is in charge of the network you are physically connecting to. If you are connected to a LAN that has a connection to the Internet, talk to your network administrator. If you are using a SLIP or PPP connection, talk to your Internet Service Provider (ISP).

The network administrator or ISP will also tell you the manner in which you can obtain your IP address (whether you are assigned one that you have to enter manually, or whether you get one from a server), in addition to the other information you need to configure TCP/IP.

Question:

What are BOOTP, RARP, and DHCP?

Answer:

These terms stand for Bootstrap Protocol, Reverse Address Resolution Protocol, and Dynamic Host Configuration Protocol. These protocols let a computer obtain its IP address (and sometimes other information, such as subnet mask) from a server. In the simplest terms, when a machine needs an IP address (on a Macintosh, this might be when you first attempt to launch an application that uses TCP/IP protocols), it asks the server for an IP address. Depending on the type of server, you are either assigned an address that has been set aside especially for your machine, or you are given one from a pool of available addresses.

These protocols are used to make administration of large networks easier.

Question:

What is a domain name and a domain name server?

Answer:

Because it is difficult for humans to remember a series of somewhat meaningless numbers, we assign names to them. Apple Computer's domain is apple.com; it also has lots of subdomains, such as corp.apple.com, and austin.apple.com. The subdomains simply define smaller areas within the apple domain. A machine called max on the subdomain info.apple.com would have a fully qualified domain name of max.info.apple.com, and its IP address might be 204.16.92.4. A domain name server in each domain is in charge of keeping a table of the machines in its network and their IP addresses. If you want to talk to max you can address it with either its IP Address or with its name. If you use its name, you need to resolve the name by asking a domain name server for that machine's IP address. This is all done behind the scenes.

Question:

How does domain name resolution work? Answer: Your network administrator or ISP should give you the IP addresses of one or more domain name servers. You list these in the field called Name server addr: in the TCP/IP control panel.

Here is an example which shows how a name is resolved. Assume that Sue's TCP/IP control panel is configured with a domain name of drc.corp.apple.com. Her admin domain is apple.com. Also in her search domain names, she has entered info.apple.com.

She has listed three different IP addresses in the Name server addr field.

When Sue attempts to connect to a machine using its domain name, max.austin.apple.com., her Macintosh computer contacts the first domain name server in the list to see if it can resolve the name (if it can give her the machine's actual IP address). If it cannot do so, the other name servers are tried, in the order Sue has listed them.

Note that max.info.apple.com. is a "fully-qualified" domain name; the period at the end indicates this. Using simply max is possible, but because max is not fully qualified (and this is clear because it does not contain a single "."), a domain name must be appended to it before a domain name server can resolve it.

First, Sue's own domain is tried: max.drc.corp.apple.com. If a search on this name fails, other attempts to resolve the name are made by dropping off one subdomain at a time, until she reaches her admin domain. For example, the searches are conducted on the following names, in the order given:

max.drc.corp.apple.com max.corp.apple.com max.apple.com

If the name is not found, it attempts to resolve the name using the domain name in the Search domain names field, in this case:

max.info.apple.com

Question:

What is the host file?

Answer:

A host file is a text file that resides at the root level of your System Folder, and contains a table of domain names and IP addresses. This table can also be used for domain name resolution, but domain name servers are more commonly used, because they are easier to manage and maintain. If your network administrator gives you a host file to use, simply place it within your System Folder.

Apple Open Transport Component Technologies

This article is a series of questions and answers on the component technologies in Apple Open Transport.

Question:

What technologies and components are included in Open Transport?

Answer:

Open Transport consists of new programming interfaces, new implementations of protocol stacks, a new model for integration of networking with the underlying operating system, and new human interface components. Open Transport supports LANs and WANs, and integrates serial communications and modems as well as remote (dial-up) networking in a consistent model for end-users, network managers, and developers.

Question:

What current Mac OS technologies, components, and products will Open Transport replace?

Answer:

Open Transport replaces the current implementations of AppleTalk and MacTCP, including the protocols and the existing Network, MacTCP, and AdminTCP control panels. Open Transport products replace the existing "AppleTalk Connection for Macintosh" and "TCP/IP Connection for Macintosh" software.

Open Transport is also designed to replace the Connection Manager and the Communications Resource Manger of the current Communications ToolBox architecture.

Question:

Does this mean that Apple is migrating serial communications away from the Communications ToolBox (CTB)?

Answer:

Not entirely. The CTB File Transfer and Terminal Managers continue to be supported. They will be taken forward into a future OS release, although on new Open Transport/Serial underpinnings. Over time, the CTB Connection Manager and its tools will be phased out in favor of Open Transport. The transition will include a period of backward compatibility to assure a smooth migration for developers and customers.

Question:

Which protocols will be available for Open Transport?

Answer:

Open Transport version 1.0 includes support for AppleTalk, TCP/IP, and serial communications. Over time, subsequent releases will add support for Point to Point Protocol (PPP), NetWare (NCP/IPX), and X.25. Other protocols are under investigation, or may be available from third parties.

Question:

Are there any changes in AppleTalk or TCP/IP with Open Transport?

Answer:

Yes. The new Open Transport/AppleTalk and Open Transport/TCP protocol implementations both have been implemented as Open Transport STREAMsmodules and as native code on Power Macintosh computers. They support the new XTI APIs and can be dynamically loaded and unloaded as needed.

Both protocols also support dynamic reconfiguration (changed settings without requiring reboot), and feature new configuration applications offering Basic, Advanced, and Administrator tools. Each protocol stack also offers addition protocol-specific feature enhancements.

Question:

What are some of the upgraded features of Open Transport/TCP?

Answer:

With the overwhelming acceptance of TCP/IP protocols in the marketplace, and the tremendous excitement and visibility of the Internet - Apple has made a significant investment in bringing a workstation-class implementation of TCP/IP protocols to the Mac OS. As before with MacTCP, Open Transport/TCP is a full 32-bit stack. But with Open Transport/TCP, we add support for:

Question:

What are some of the upgraded features of Open Transport/AppleTalk?

Answer:

Open Transport/AppleTalk includes new support for statically assigned (manually administered) protocol addresses (statically assigned AppleTalk is not supported in Open Transport 1.0). This allows AppleTalk nodes to be managed using protocol address as a unique and stable identifier. It also reduces some of the network traffic associated with AppleTalk's dynamic address assignment features. Dynamic addressing continues to be available for those customers who prefer the automated address allocation.

Question:

Is this "AppleTalk Phase 3"?

Answer:

No. Open Transport/AppleTalk is a new, modern implementation of the AppleTalk Phase 2 protocol architecture for the Mac OS - from the people who invented AppleTalk.

Question:

What about NCP/IPX? Will Novell deliver an Open Transport-based Macintosh client that uses native IPX protocols as the transport layer?

Answer:

Apple and Novell are jointly and publicly committed to making Macintosh a first-class NetWare client. An Open Transport-ready implementation of NetWare protocols and client services is under investigation. At this time, the companies are not ready to announce product or availability details.

Question:

When will additional protocol stacks be available?

Answer:

Open Transport will gain support for Point to Point Protocol (PPP), supporting both AppleTalk and TCP/IP communications, with the release of the next generation of Apple Remote Access products scheduled for later in 1995. Other protocol support, including AppleTalk Secure Datastream Protocol (ASDSP), X25, DECnet, SNA, SNMP, and ATM LAN-E, is underway at Apple and with third party developers.

Question:

Which datalinks will be supported by Open Transport?

Answer:

Open Transport version 1.0 includes support for LocalTalk and Ethernet LANs, and serial communications ports. Modem and ISDN support will come with the introduction of PPP. Subsequent releases will add support for Token Ring, fast Ethernet, FDDI, and ATM LANs. Other datalinks are under investigation, or may be available from third parties.

Open Transport 1.0.8 Network Compatibility

This article is a series of questions and answers on network compatibility in Apple Open Transport 1.0.8.

Question:

What is this version of Open Transport?

Answer:

Open Transport 1.0.8 is a maintenance release of Open Transport networking software.

Question:

Is Open Transport interoperable with installed AppleTalk and TCP/IP networks? Answer Open Transport 1.0.x is compatible with existing AppleTalk and TCP/IP LocalTalk and ethernet network at the "packets on the wire" level. Organizations can introduce one, a few, or hundreds of new Macintosh systems running Open Transport into their environment without worrying about interoperability with existing networking services.

Question:

Is Open Transport compatible with existing Internet Service Provider offerings?

Answer:

As noted in "Network Interface Options" Open Transport/TCP currently supports dial-up connectivity to TCP/IP networks, including the Internet, through backward compatibility with select third party software modules known as "mdevs". With the appropriate mdev installed, end-nodes can use either SLIP or PPP to connect to Internet Service Providers and other dial-up IP-access points. However, not all versions of all mdevs are supported by Open Transport backward compatibility services. It is important that the recommended versions of software be installed for the greatest level of compatibility. It is also important that TCP/IP addressing and other configuration information be properly configured. As there is a new human interface provided by the Open Transport/TCP configuration utility, there are some changes in the process as compared to the older MacTCP software.

Question:

Is there documentation available to assist with configuring Open Transport/TCP?

Answer:

Yes. Although a full user's guide is planned for release with Open Transport v1.1, configuration tips for Open Transport 1.0.x are already available from various sites on the internet including:

Question:

Does Apple offer a solution for SLIP or PPP dial-up to the Internet?

Answer:

Yes. The Apple Internet Connection Kit is a selection of the most popular Internet applications from third party companies, including the Netscape Navigator and RealAudio Player from Progressive Networks, as well as Claris Emailer Lite. The kit includes MacPPP 2.1.4 along with the Apple Internet Dialer - software designed to make it simpler for Macintosh customers to register with a qualified Internet Service Provider (ISP) and get connected to the Internet. To help users work with their Internet applications, the Apple Internet Connection Kit includes Apple Guide software for online assistance.

Question:

What is MacPPP 2.1.4? Is it available on the Internet?

Answer:

MacPPP 2.1.4 is a derivative of the MacPPP 2.1.x SD versions of Merit's PPP. It includes code contributed by Apple engineering to enhance compatibility with Open Transport/TCP. These Apple updates have also been provided to the authors of FreePPP (the successor to the "SD" releases of MacPPP).

FreePPP 1.0.x also includes these updates, and is available for download on the Internet.

Question:

Does the Apple Internet Connection Kit require Open Transport?

Answer:

The Apple Internet Connection Kit works with either MacTCP, or Open Transport/TCP.

Question:

Which mdevs are currently supported by Open Transport/TCP?

Answer:

Open Transport 1.0.8 supports the following MacTCP Link Access Modules (mdevs):

Apple is continuing to work with developers to provide better support for existing mdevs; contact the third party developer of interest for the most recent information on compatibility.

Question:

Are there known limitations to backward compatibility mdev support?

Answer:

Yes. Due to differences in the underlying architectures (between MacTCP and Open Transport/TCP), and some current (1.0.8) shortcomings in the backward compatibility services, there are some additional limitations to mdev support:

Question:

If a user needs an updated copy of one of these mdevs, how can they get the software?

Answer:

Sources for mdev software will vary, as some of the noted products are commercial and some are shareware or public domain.