How to Configure ATM Permanent Virtual Circuits


About this document
IBM-supported ATM adapters
AIX ATM support
Configuring permanent virtual circuits
Troubleshooting PVCs

About this document

This document covers software requirements and configuration of ATM permanent virtual circuits (PVCs) on AIX Versions 4.1.4, 4.1.5, 4.2.0, 4.2.1, and 4.3.x.

IBM-supported ATM adapters

Current adapters supported by IBM are as follows: MCA Turboways 100 ATM adapter - AIX 4.1.4, 4.2.0 and 4.3.x
MCA Turboways 155 ATM adapter - AIX 4.1.4, 4.2.0 and 4.3.x
MCA Turboways 155 ATM UTP/STP adapter - AIX 4.1.5, 4.2.0, 4.3.x
PCI Turboways 25 ATM UTP/STP adapter - AIX 4.2.1, and 4.3.x
PCI Turboways 155 ATM adapter - AIX 4.2.1, and 4.3.x
PCI Turboways 155 ATM UTP/STP adapter - AIX 4.1.5, 4.2.1, and 4.3.x

AIX ATM support

ATM support at AIX Versions 4.x is installed via the following filesets on the base operating system install media.

MCA Turboways 155 ATM software (4.1.x, 4.2.x, and 4.3.x):
devices.mca.8f67.diag (4.1.5 and 4.2.x)
devices.common.IBM.atm.rt (4.2.x and 4.3.x)

MCA Turboways 155 ATM UTP/STP software (4.1.5, and 4.2.x):

devices.common.IBM.atm.rte (4.2.x)

MCA Turboways 100 ATM software:

devices.mca.8f7f.diag (4.1.5 and 4.2.x)
devices.common.IBM.atm.rte (4.2.x)

PCI Turboways 25 STM UTP/STP software (4.2.1 and 4.3.x):


PCI Turboways 155 ATM software (4.1.5, 4.2.1, and 4.3.x):

devices.common.IBM.atm.rte (4.2.x)
PCI Turboways 155 ATM UTP/STP software (4.1.5, 4.2.1, and 4.3.x):

devices.common.IBM.atm.rte (4.2.x)


ATM is not supported at AIX Versions 4.1.1 through 4.1.3.

At AIX levels AIX 4.1.x, common ATM device driver software is contained in the fileset. This fileset needs to be at the latest level regardless of the ATM adapter (MCA or PCI) you have installed.

At AIX 4.2.x and later, common ATM device driver software is contained in the fileset devices.common.IBM.atm.rte.

Configuring permanent virtual circuits

PVCs can be configured in a back-to-back ATM network between two systems, or as a point-to-point connection to a switch.

It is extremely important in a back-to-back ATM 155 Mbs network that one node provide sonet clocking. This is not an issue in an ATM 100 Mbs network. To provide sonet clocking:

  1. Enter smit chg_atm.
  2. Select the ATM adapter that is being configured in a back-to-back network.
  3. At the bottom of the SMIT screen, set Provide SONET clock to 1.

NOTE: It is only necessary to do this on one node of the back-to-back ATM 155 Mbs network.

If you get a device busy message, make sure all ATM IP interfaces are detached or removed and ATM LAN emulation clients are defined or removed.

The first step is to configure the IP interface for the PVC.

  1. For AIX Version 4.x IP interface configuration (smit mkinetat):
                * INTERNET ADDRESS (dotted decimal)                  (
                  Network MASK (hexadecimal or dotted decimal)       (
                  Network Interface                                  (at0)
                  Connection Type                                     pvc
                  ATM Server Address                                 ()
                  Alternate Device                                   (atm0)
                  Idle Timer                                         ()
                  Best Effort Bit Rate (UBR) in Kbits/sec            ()
                * ACTIVATE the Interface after Creating it?          yes
    After configuring the IP address, the permanent virtual channel connection is made through SMIT using the SMIT fastpath:
                  smit mkatmpvc
    Or, follow this series of screens:
                  smit  smit devices /user applications / TCP/IP / network
                  interfaces / network interface selection / pvcs.
  2. For AIX Version 4.x PVC configuration (smit mkatmpvc):
                 PVC Description (Optional)                            ()
               * VPI:VCI                                         (0:1000)
                 Network Interface                                     (at0)
                 Destination IP Address                                ()
                 Automatically Discover Destination IP Address         yes
                 LLC Encapsulation                                     yes
NOTE: Alternatively, you may change Automatically Discover Destination IP Address to no and set Destination IP Address with the address of the node to which you are connecting in a back-to-back network or the switch PVC.

Troubleshooting PVCs

  1. Verify that you are using the correct VPI:VCI and that the remote host contains the same VPI:VCI ratio. A ping will hang on either host if the two ratios are different. As stated earlier, the VPI value must be set to 0 and the VCI value must be greater than 31.

  2. If this is a PVC to a switch, check to make sure there is a proper connection to the ATM switch. This is usually indicated by a port light on the ATM switch. Look for wire fault errors in the error log with the errpt |grep atm command to identify cable problems. If the SC connectors on your fiber cables are not keyed or connected with a plastic cover, try reversing the connectors on one end of the connection. Many problems occur when the switch is incorrectly configured. If no one can ping on the switch and you have double-checked the configuration on AIX, contact the switch administrator to verify the configuration for a pvc channel.

  3. Check to see if one adapter has the sonet clock turned on. ping will hang in back-to-back configuration if no sonet clock is on. If it is connected to a switch, usually the switch will supply the sonet clock. Contact the switch administrator to verify that it is sending clock.

  4. The UNI version is defined at both the switch and the client. The UNI version can be either 3.0 or 3.1. In addition, the client will set the UNI version to auto-detect by default. Problems have occurred such that the ATM switch does not recognize, or is incompatible with, the auto-detect function. If there is a UNI version mismatch or the switch is not working with the auto-detect, the ping will hang. Check the UNI version of the ATM adapter with lsattr -El atmx or via the SMIT fastpath with smit chg_atm. Try changing it to the fixed value of the ATM switch.

  5. Problems of intermittent communications loss or of the inability to ping on reboot are often caused by defects. Please contact your AIX support center to obtain the latest device driver and common ATM device driver software updates.

[ Doc Ref: 90605195414804     Publish Date: Nov. 14, 2000     4FAX Ref: 7468 ]