This document applies to AIX Versions 4.1 and later.
One of the most important things to consider when planning your SLIP connection is the addressing. You should examine which address class you wish to use and then develop the actual numerical values. See the section "Information on network address types (classes)" for possible class types.
Please verify that your SLIP addresses do not conflict with any existing (network) addresses on your system. For simplicity, these addresses are used in the following instructions:
184.108.40.206 for local system "A" 220.127.116.11 for remote system "B"
This SLIP example starts SLIP from the command line. The following instructions add a tty via SMIT and then configure and start SLIP from the command line. It is good to first configure from the command line, as in these instructions, because command line options are easier to correct. After you get SLIP working correctly from the command line, bring it down, detach it to start cleanly, and reconfigure it through SMIT. Configuring it through SMIT will make the configuration permanent and allow SLIP to start automatically at each system reboot.
Add a tty for a serial port on both machines A and B.
To add a tty to the system, log on as root or use the su command to become the root user. Then enter smit or smitty on the command line. Select the following order of options from each menu.
Remember to set on the tty, the special settings found under "Special Notes" in the preceding section, when you enter the port number.
Configure SLIP lines for both systems A and B using selected addresses. Here, 18.104.22.168 is the address for A and 22.214.171.124 is the address for B.
NOTE: sl# should match the tty# being used; that is, if tty1 is being used, sl# should be sl1.
On system A, enter:
ifconfig sl# 126.96.36.199 188.8.131.52 up# equals the same number of the tty you made, for example, tty7 would be sl7.
On system B, enter:
ifconfig sl# 184.108.40.206 220.127.116.11 up# equals the same number of the tty you made, for example, tty7 would be sl7.
Check the status on both machines with the following command line entry:
Output should be similar to the following:
sl0: flags=6000031<UP,POINTOPOINT,NOTRAILERS,GROUPRT,64BIT> inet 18.104.22.168 --> 22.214.171.124 netmask 0xff000000
On the remote system to be dialed into, enter:
Use the following command line option to dial out of the local system. Replace # with your tty number.
slattach tty# 9600 ' "" AT OK ATDT555-3346 CONNECT "" '
In informal terms, the preceding string is interpreted as "Use tty# at 9600 baud, send AT and I should get back an OK, dial 555-3346 and I should get a CONNECT back."
Test the SLIP connection between system A and system B by using the ping command. On system A, enter:
The system should display packets being sent to and received from that address.
Kill these processes WITHOUT the -9 option. The proper way to kill a slattach is with the commandkill <slip pid number>. If SLIP has been defined via SMIT, severe problems could occur if you use kill -9. Problems can affect your system and may cause a crash with LED 888.
Should your system crash with LED 888, a reboot will not correct the problem. Use SMIT to remove the SLIP interface and associated tty. Use SMIT again to reconfigure tty and SLIP.
ifconfig sl# detach
For this reason, experimenting with SLIP on the command line first is recommended. Then, once the configuration is understood, add it through SMIT.
On a SLIP direct connect, no baud rate or dial string is needed. A direct connect is where a serial cable is run directly between two systems. Modems are not involved.
A common reason SLIP connects but does not allow ping or other network commands is one or more modems or ttys involved are not using RTS appropriately.
Test the connection with ATE or cu by dialing the other system and seeing if you are able to log in. This would be a first test but does not eliminate the chance of port or modem problems. Use IBM cabling or a cable that has adequate shielding.
Issue the command netstat -i to examine them.
Network address classes fall into the following ranges:
Class A: 0 to 128 Class B: 128 to 191 Class C: 192 to 255
######.#####.####.### | |____|____|______ Host Address |_______________________ Network Name
A Class A address consists of an 8-bit network address and a 24-bit local or host address. The first bit in the network address is dedicated to indicating the network class, leaving 7 bits for the actual network address. Since the highest number that 7 bits can represent in binary is 128, there are 128 possible Class A network addresses. Of the 128 possible network addresses, two are reserved for special cases: the network address 127 is reserved for local loopback addresses, and a network address consisting of ones (1s) indicates a broadcast address.
######.#####.####.### | | |____|_______ Host Address |_____|_________________ Network Name
A Class B address consists of a 16-bit network address and a 16-bit local or host address. The first two bits in the network address are dedicated to indicating the network class, leaving 14 bits for the actual network address. Therefore, there are 16,384 possible network addresses and 65,536 local host addresses.
######.#####.####.### | | | |_______ Host Address |_____|____|____________ Network Name
A Class C address consists of a 24-bit network address and an 8-bit local host address. The first two bits in the network address are dedicated to indicating the network class, leaving 22 bits for the actual network address. Therefore, there are 2,097,152 possible network addresses and 256 possible local host addresses.
NOTE: Other systems may support Class D addresses, which are
multicast addresses with the highest order bits set to 1-1-1. TCP/IP does not
support Class D addresses.
[ Doc Ref: 90605222314632 Publish Date: Apr. 06, 2001 4FAX Ref: 8256 ]