System information

Troubleshooting ISO CLNS 12-279
ISO CLNS: Host Cannot Access Hosts in Different Area
Figure 12-3 Multihomed Area Sample Network
ISO CLNS: Host Cannot Access Hosts in Different Area
Symptom: Host cannot access hosts in a different area. Hosts in the same area are accessible.
Table 12-5 outlines the problems that might cause this symptom and describes solutions to those
problems.
ES host is not running
ES-IS protocol
Step 1 Use the appropriate host commands to verify that an ES-IS process is
running. If necessary, initiate the ES-IS process on the host.
Step 2 Check the adjacency database on the host and verify that it has an entry
for its directly connected router.
Step 3 Use the debug clns packet privileged exec command on the Level 1
router to verify that it sees and forwards packets from the ES.
ES host is not running
ES-IS protocol
Caution: Because debugging output is assigned high priority in the
CPU process, it can render the system unusable. For this reason, use
debug commands only to troubleshoot specific problems or during
troubleshooting sessions with Cisco technical support staff. Moreover,
it is best to use debug commands during periods of lower network
traffic and fewer users. Debugging during these periods decreases the
likelihood that increased debug command processing overhead will
affect system use.
Step 4 If necessary, statically configure the router to recognize the ES by using
the clns es-neighbor interface configuration command. The following
is the syntax for the clns es-neighbor command:
clns es-neighbor nsap snpa
Syntax Description:
• nsap—Specific NSAP to map to a specific MAC address.
• snpa—Data link (MAC) address.
Example:
The following example defines an ES neighbor on Ethernet interface 0:
interface ethernet 0
clns es-neighbor 47.0004.004D.0055.0000.0C00.A45B.00
0000.0C00.A45B
Route redistribution problem Misconfigured route redistribution can cause connectivity problems. For specific
troubleshooting information, see the section “ISO CLNS: Redistribution Causes
Routing Problems” later in this chapter.
Possible Problem Solution
Area 1
Area 1, area 2
Router A
Area 1, area 2
Area 2
Single area with two area addresses
Host 1 Host 2
Router B