CHAPTER II: THE PALESTINIAN BUSINESS CONTEXT
2.3. Demographic and social considerations in Palestine
This section provides information required to troubleshoot OM channel faults. The information includes fault descriptions, background information, possible causes, fault handling method and procedure, and typical cases.
Troubleshooting Guide 11 Troubleshooting Application Layer Faults
11.1 Definitions of Application Layer Faults
Application layer faults include unavailability and intermittent disconnection of Stream Control Transmission Protocol (SCTP) links, Internet Protocol (IP) paths, and operation and
maintenance (OM) channels.
11.2 Background Information
The Stream Control Transmission Protocol (SCTP) is a transmission protocol that works on the IP layer. The function of SCTP is similar to that of the Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) that work on the same layer as the SCTP. The latest standard to which the SCTP conforms is Request for Comments (RFC) 2960 released in October 2000.
Compared with the TCP, the SCTP is improved for specific applications. In addition, multiple features are added to the SCTP. The SCTP is now widely used in radio communications, multimedia, and QoS.
The operation and maintenance (OM) channel is used for remote maintenance of eNodeBs. An OM channel is set up using TCP handshakes.
11.3 Troubleshooting Method
This section describes the method and procedure for troubleshooting IP transport and application layer faults.
Troubleshooting Guide 11 Troubleshooting Application Layer Faults
Troubleshooting flowchart for IP transport and application layer faults
Figure 11-1 Troubleshooting flowchart for IP transport and application layer faults
Troubleshooting Procedure
1. Check whether an alarm indicating a Stream Control Transmission Protocol (SCTP) link fault is reported or whether the SCTP link status is abnormal.
Yes: Troubleshoot the SCTP link fault.
No: Go to 2.
2. Check whether an alarm indicating an Internet Protocol (IP) path fault is reported or whether the IP path status is abnormal.
Yes: Troubleshoot the IP path fault.
No: Go to 3.
3. Check whether an alarm indicating an operation and maintenance (OM) channel fault is reported or whether the OM channel status is abnormal.
Yes: Troubleshoot the OM channel fault.
No: Go to 4.
4. Contact Huawei technical support.
Troubleshooting Guide 11 Troubleshooting Application Layer Faults
11.4 Troubleshooting SCTP Link Faults
This section provides information required to troubleshoot SCTP link faults. The information includes fault descriptions, background information, possible causes, fault handling method and procedure, and typical cases.
Fault Description
l Either of the following alarms is reported:
– ALM-25888 SCTP Link Fault – ALM-25889 SCTP Link Congestion
l The Stream Control Transmission Protocol (SCTP) link is unavailable or available only in one direction.
After sending data to the peer device, the sender does not receive a response from the peer device. In addition, the sender does not receive data from the peer device.
l The SCTP link is abnormal.
The SCTP link is faulty or intermittently disconnected.
Related Information
To rectify SCTP link faults, you need to trace SCTP messages.
SCTP message blocks include 13 types of messages such as INIT, INIT ACK, DATA, SACK, ABORT, SHUTDOWN, ERROR, COOKIEECHO, and HEARTBEAT.
Parameters such as the first peer IP address, the second peer IP address (used in SCTP dual homing), and peer port number configured on the eNodeB must be consistent with those configured on the mobility management entity (MME). Run the LST SCTPLNK command. In the command output, the parameters in red rectangles are eNodeB parameters and the parameters in the blue rectangles are evolved packet core (EPC) parameters. Ensure that the MME parameters configured on the eNodeB are consistent with the SCTP parameters of the MME and that eNodeB parameters configured on the EPC are consistent with the SCTP parameters of the eNodeB.
Troubleshooting Guide 11 Troubleshooting Application Layer Faults
Figure 11-2 SCTP link configuration information
On the MME, check whether the peer port number configured on the MME is the same as the local port number configured on the eNodeB and whether a correct network segment is configured.
Possible Causes
l The transmission network is faulty.
l The SCTP parameters are incorrectly configured on the eNodeB or MME.
l The NE has internal faults.
Fault Handling
None
Fault Handling Procedure
l Typical Scenario
To find the cause for an SCTP fault, perform the following steps:
1. Check configurations.
Check whether SCTP parameters are correctly configured on the MME and the eNodeB.
2. Check the transmission.
Ping the MME IP address. If the MME IP address cannot be pinged, check the route and transmission network. If VLANs are configured for the eNodeB, set the
differentiated services code point (DSCP) value in the ping command to the one configured for the VLAN for user data.
Troubleshooting Guide 11 Troubleshooting Application Layer Faults
3. Start SCTP message tracing.
Start SCTP message tracing and compare the tracing result with normal SCTP message exchange.
4. Start a tracing task using WireShark.
Run the STR PORTREDIRECT command on the eNodeB to start port redirection.
If no desired data is traced, it is possible that the transmitting port did not send the data. If desired data is traced, the transmission network and EPC are normal.
5. If the fault persists, contact Huawei technical support.
l Intermittent SCTP Link Disconnection
If an SCTP link is intermittently interrupted, the eNodeB cannot receive a response from the peer device and then the SCTP link is down. After several seconds, the eNodeB initiates SCTP link reestablishment and the SCTP link recovers.
1. Check transmission alarms.
2. Check the Quality of Service (QoS) of signaling data.
If VLANs are configured for the eNodeB, check whether the VLAN for signaling data is correctly configured on the eNodeB. If VLANs are differentiated by next-hop IP address, the check is not required. If VLANs are differentiated by service type, the check is required.
If no VLAN is configured for the eNodeB, check whether the DSCP value for signaling data is the same as that for the transmission network. Run the LST DIFPRI command to query the DSCP value for signaling data. Check whether the DSCP value is 46 in the QoS configuration for the transmission network. Ensure that data with a DSCP value of 46 can be properly transmitted in the transmission network.
If the transport network bandwidth is limited and the DSCP value for SCTP services is less than that for other types of services, the SCTP link will be intermittently interrupted. Therefore, check whether SCTP services has a high DSCP-indicated priority in the transmission network with the customer.
3. Start SCTP message tracing.
Start SCTP message tracing and analyze the messages to find the cause for the link failure.
4. Check the network packet loss rate.
If the SCTP message tracing shows that packets are lost, check whether the port attribute of the gigabit Ethernet (GE) or fast Ethernet (FE) port is consistent with that on the peer device. If it is consistent, ping the peer device to check the packet loss rate on the transmission network.
5. Start a WireShark tracing task.
Run the STR PORTREDIRECT command on the eNodeB to start port redirection.
If no desired data is traced, it is possible that the transmitting port did not send the data. If desired data is traced, the transmission network and EPC are normal.
6. Take preventive measures.
If configurations are correct and the peer device can be pinged, run the MOD SCTPLNK command or remove the SCTP link information and reconfigure the SCTP parameters so that the eNodeB and the peer device negotiate about the SCTP link again.
7. If the fault persists, contact Huawei technical support.
Troubleshooting Guide 11 Troubleshooting Application Layer Faults
Typical Cases
None
11.5 Troubleshooting IP Path Faults
This section provides information required to troubleshoot IP path faults. The information includes fault descriptions, background information, possible causes, fault handling method and procedure, and typical cases.
Fault Description
l The S1 interface is normal and cells are successfully activated, but UEs cannot attach to the network.
l UEs can attach to the network but cannot set up bearers of some QoS class identifiers (QCIs). QoS is short for quality of service.
Related Information
The related alarm is as follows:
ALM-25886 IP Path Fault
Possible Causes
l The Internet Protocol (IP) route is incorrectly configured.
l The IP path parameters are incorrectly configured.
Fault Handling
None
Fault Handling Procedure
1. Check whether ALM-25886 IP Path Fault is reported.
Yes: clear the alarm by referring to eNodeB Alarm Reference.
2. Check whether IP path parameters are correctly configured.
Run the LST IPPATH command. In the command output, if Path Type is QOS and DSCP is 0, only default bearers can be set up. In this case, change Path Type to ANY.
3. If the fault persists, contact Huawei technical support.
Typical Cases
None
11.6 Troubleshooting OM Channel Faults
This section provides information required to troubleshoot OM channel faults. The information includes fault descriptions, background information, possible causes, fault handling method and procedure, and typical cases.
Troubleshooting Guide 11 Troubleshooting Application Layer Faults
Fault Description
The ALM-25901 Remote Maintenance Link Failure alarm is reported.
Operation and maintenance (OM) channel faults are classified into two categories:
l OM channel unavailability: The OM channel is faulty.
l OM channel interruption: The OM channel is intermittently interrupted.
Related Information
None
Possible Causes
l The transmission network is faulty.
l The OM channel parameters are incorrectly configured on the eNodeB or mobility management entity (MME).
l Some ports are disabled in the transport network.
Fault Handling
None
Fault Handling Procedure
This section describes how to handle an OM channel fault in various scenarios.
l Typical Scenario
1. Check configurations.
Check whether OM channel parameters are correctly configured on the M2000 client and the eNodeB.
2. Check the transmission.
Ping the IP address of the M2000. If the IP address of the M2000 cannot be pinged, check the route and transport network.
NOTE
If ping operations are prohibited in the operator network, do not ping the M2000 client.
3. (Optional) Trace protocol data.
If allowed, a protocol data tracing tool such as WireShark can be used to analyze packet headers. Add a switch between the transmitting port and the transmission network, configure transmitting port mirroring on the switch, and connect a personal computer (PC) to the mirroring port on the switch to trace packet headers. If no desired packet header is traced, the transmitting port is faulty. If desired packet headers are traced, the transmission network is faulty.
4. If the fault persists, contact Huawei technical support.
l Intermittent OM Channel Interruption 1. Check transmission alarms.
On the M2000 client, check whether a transmission alarm is reported by the eNodeB during the intermittent transmission, for example, whether an Ethernet trunk fault alarm is reported. If a transmission alarm is reported, adjust the transport network. If
Troubleshooting Guide 11 Troubleshooting Application Layer Faults
no transmission alarm is reported, go to the next step. Check whether an alarm indicating intermittent link (such as SCTP link) disconnections is also reported. If such an alarm is reported, rectify the fault too.
2. Check the VLAN configuration.
If VLANs are configured for the eNodeB, check whether the VLAN for OM data is correctly configured on the eNodeB. If VLANs are differentiated by next-hop IP address, the check is not required.
3. Check whether network loopbacks exist.
Check whether loopbacks exist in the network based on the network topology. The causes of loopbacks are twofold. Some loopbacks are caused by oversights in network design, whereas others are temporary loopback links that were built during link tests but were not removed promptly. As a result, loopbacks require careful investigation.
4. (Optional) Trace protocol data.
If allowed, a protocol data tracing tool such as WireShark can be used to analyze packet headers. Add a switch between the transmitting port and the transmission network, configure transmitting port mirroring on the switch, and connect a personal computer (PC) to the mirroring port on the switch to trace packet headers. If no desired packet header is traced, the transmitting port is faulty. If desired packet headers are traced, the transmission network is faulty.
5. If the fault persists, contact Huawei technical support.
Typical Cases
None
Troubleshooting Guide 11 Troubleshooting Application Layer Faults
12 Troubleshooting Transmission Synchronization Faults
About This Chapter
This chapter describes how to troubleshoot transmission synchronization faults. This type of faults include the clcok reference problem, IP clock link fault, system clock unlocked fault, base station synchronization frame number error, or time synchronization failure.