DECnet No Phase IV Connectivity over Phase V Backbone

Symptom: Communication between DECnet Phase IV areas separated by an ISO CLNS (Phase V) backbone fails. Phase IV nodes cannot communicate with other Phase IV nodes across a Phase V cloud. However, nodes can communicate with one another within the same Phase IV cloud.

Note For more information about troubleshooting DECnet /OSI internetworks, see Chapter 12, "Troubleshooting ISO CLNS."

Table 11-7 outlines the problems that might cause this symptom and describes solutions to those problems.

Table 11-7 DECnet: No DECnet Phase IV Connectivity over Phase V Backbone

DECnet: No Phase IV Connectivity over Phase V Backbone

Possible Problem

Solution

Misconfigured addresses

Step 1 Use the show interfaces command to confirm that CLNS and DECnet Phase IV are both configured on ISO CLNS backbone routers.

Step 2 Make sure that the decnet conversion global configuration command is configured on backbone routers to allow DECnet Phase IV-to-ISO CLNS conversion.

Step 3 Use the show running-config privileged exec command on backbone routers to verify that DECnet addresses agree with CLNS addresses.

Two kinds of addresses are easily misconfigured: DECnet addresses, which should be specified in decimal, and CLNS Network Service Access Point addresses, which should be specified in hexadecimal.

For more information, refer to the section "DECnet Phase IV and ISO CLNS Addresses" later in this chapter.

Step 4 If the area addresses do not agree, confirm the address specifications and reconfigure the DECnet and CLNS addresses on the router.

For detailed information on configuring DECnet Phase IV, CLNS, and conversion, refer to the Cisco IOS Network Protocol Configuration Guide, Part 2.

ISO CLNS or DECnet not enabled on appropriate interfaces

Step 1

On Phase IV routers bordering the backbone, use the show clns interface and show decnet interface commands to see which interfaces are running which protocols.

Verify that DECnet and ISO CLNS are enabled on backbone router interfaces where conversion will occur.

Step 2

If DECnet is not configured on the correct interfaces, enable it. Make sure you specify the decnet cost interface configuration command to assign a cost to the interface. If ISO CLNS routing is not configured on the correct interfaces, use the clns router interface configuration command. The full syntax for this command is clns routing

Use the no clns routing command to disable CLNS routing: no clns routing

For detailed information on configuring DECnet Phase IV and ISO CLNS, refer to the Cisco IOS Network Protocol Configuration Guide, Part 2.

DECnet Phase IV and ISO CLNS Addresses

Address conversion between DECnet Phase IV and ISO CLNS (Phase V) requires that NSAP addresses be Phase IV compatible. If an address can be converted to a valid Phase IV address, it is Phase IV compatible.

To be compatible, the OSI area number must be between 1 and 63 (when converted to decimal) and the OSI station ID must be in the format AA00.0400.x™r. In addition, the OSI area and the DECnet area (calculated from the OSI station ID) must match. This allows the DECnet Phase IV address to be extracted properly from the NSAP.

Table 11-8 shows addresses and their equivalent DECnet Phase IV addresses, and indicates whether the NSAP address is Phase IV compatible and why.

Table 11-8 OSI NSAP-to-DECnet Phase IV Address Conversion

Are DECnet Address OSI NSAP Address (Hex) a (Decimal) Phase-IV Compatible

49.1111.0012.AA00.0400.0149.20

18

18.257

Yes

49.1111.0009.AA00.0400.BC04.20

9

1.188

No—OSI area does not match the DECnet area

49.1111.0041.AA00.0400.FFFF.20

65

63.1023

No—OSI area is greater than 63

49.1111.000E.AA00.0400.0000.20

14

0.0

No—DECnet address in NSAP station ID is invalid

49.1111.0009.0800.2B05.8297.20 9 — No—NSAP station ID is not in the proper format (AA00.0400.axax)

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