Troubleshooting guide

B-14
Cisco PGW 2200 Softswitch Release 9.8 Operations, Maintenance, and Troubleshooting Guide
OL-0800-14
Appendix B Troubleshooting Cisco ITP-L Signaling
Troubleshooting Cisco ITP-L to Cisco PGW 2200 Softswitch Communications
Step 3 Test router ports and hardware by conducting a loop test of the signal link, excluding connectivity to the
distant-end SS7 node.
Step 4 If the test does not discover an MTP2 (link alignment) problem, the problem likely resides within the
distant end STP node.
If you discover a problem with the Cisco ITP-L, replace the unit.
Troubleshooting Cisco ITP-L to Cisco PGW 2200 Softswitch
Communications
Cisco ITP-Ls communicate with a Cisco PGW 2200 Softswitch through a Cisco Catalyst MSR, which
serves as a LAN switch. Under normal conditions, all Cisco ITP-Ls actively process SS7 message traffic
from the STPs. However, only one of the two Cisco PGW 2200 Softswitches actively processes traffic
at a time. One Cisco PGW 2200 Softswitch always stays in a hot-standby mode while the other actively
processes message traffic.
Routing, call control, network management, and all other SS7 application data is framed within SS7
protocol layers MTP3 and higher. The Cisco ITP-Ls, which terminate the MTP1 and MTP2 layers, pass
MTP3 and higher-layer SS7 protocol data between the Cisco PGW 2200 Softswitches and STP mated
pairs.
Cisco ITP-L to Cisco PGW 2200 Softswitch communication comprises multiple Cisco ITP-Ls, which
pass SS7 message traffic on to the Cisco PGW 2200 Softswitches through the LAN switches. Each STP
linkset coming into a Cisco ITP-L normally has links that are connected to at least two Cisco ITP-Ls to
ensure sustained network operation.
The Reliable User Datagram Protocol (RUDP), that is proprietary to Cisco, is used for Cisco ITP-L to
Cisco PGW 2200 Softswitch communication. In a fault-tolerant configuration, for example, Ethernet
10BASE-T links connect each Cisco ITP-L to two LAN switches. Ethernet 100BASE-T links connect
each LAN switch to both the active Cisco PGW 2200 Softswitch and the standby Cisco PGW 2200
Softswitch.
The following sections describe troubleshooting Cisco PGW 2200 Softswitch and Cisco ITP-L
communications:
• Identifying MTP3 and Higher Layer Problems, page B-14
• Identifying Ethernet Connectivity Problems, page B-15
• Identifying IP Communication Problems, page B-16
• Identifying RUDP Communications Problems, page B-16
Identifying MTP3 and Higher Layer Problems
Although the Cisco ITP-Ls normally pass MTP3 and higher-layer data directly to the Cisco PGW 2200
Softswitches, Cisco ITP-L hardware can also be the cause of MTP3 and higher layer SS7 communication
problems. Cisco ITP-L-originated MTP3 or higher layer SS7 problems can affect message traffic over a
certain link, or just the links that transceive through a certain Cisco ITP-L.