The Open Transport TCP/IP Control Panel Simplified For Beginners
Apple Open Transport Component Technologies
Open Transport 1.0.8 Network Compatibility
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.
Class | Identified by 1st Octet | Default Subnet Mask |
---|---|---|
A | First bit = 0 (0-127) | 255.0.0.0 |
B | First two bits =10 (128-191) | 255.255.0.0 |
C | First three bits = 110 (192-223) | 255.255.255.0 |
This information is used by routers to determine how to route the IP packets to the network you are attached to.
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.
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.
These protocols are used to make administration of large networks easier.
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
Open Transport is also designed to replace the Connection Manager and the Communications Resource Manger of the current Communications ToolBox architecture.
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.
FreePPP 1.0.x also includes these updates, and is available for download on the Internet.
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.