3. Plan de Negocios
3.3 Estudio Técnico
3.3.1 Ubicación
The multihop BFD sessions may not be established if there are problems in BFD service, configuration, or network connectivity.
7.2.2 Symptoms
The multihop BFD sessions are not established or sessions do not reach UP state.7.2.3 Recovery procedures
1 Check the BFD service.
To check the BFD service, follow these steps:
a) Verify the state of the FSBFDServer recovery unit in the node where BFD is configured. Enter the following command: show has state managed- object /<node>/FSBFDserver
The following output is displayed:
root@CFPU-0 [RNC-89] > show has state managed-object /CFPU-
0/FSBFDserverOBJECT ADMINISTRATIVE OPERATIONAL USAGE ROLE PROCEDURAL DYNAMIC/CFPU-0/FSBFDServer UNLOCKED ENABLED ACTIVE ACTIVE - -
If the recovery unit is locked, unlock it using the following command: set has unlock managed-object /<node>/FSBFDServer
2 Check BFD alarms.
Verify that there are active alarms for BFD (specific problem 70348). Enter the following command: show alarm active filter-by specific-problem 70348
If the active BFD alarms are found, verify BFD configuration (see step 4) and network connectivity (see step 5).
3 Check the BFD runtime information.
Verify that the BFD sessions are found in the runtime environment and that the session state is correct. Enter the following command:
show networking instance <instance-name> bfd runtime node /<node- name>
The Init state means that the remote system is communicating and the local system brings the session up, but the remote system does not realize it. If the sessions are not found, verify the BFD service state provided by HAS. If the session state is down, verify the basic IP connectivity.
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Diagnostic field shows a diagnostic code specifying the reason for change in session state. 4 Check BFD configuration. To check the BFD configuration, follow these steps: a) Verify that BFD is enabled on the correct node with correct parameters. Enter the following commands:show networking monitoring bfd config all
If the BFD is not enable on the correct node with correct parameter, see the section, Configuring IP Connection for Multicontroller RNC for more information. b) Verify that local IP address for BFD session is found from the node and is
assigned to the correct VRF instance. Enter the following command: show networking address
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BFD sessions can be configured before IP address is added to the interface. However, the BFD session control packet are sent only after the IP address is added. If the local IP address for the BFD session is not found and assigned to the correct VRF instance, see the section, Configuring the BFD multihop session section for more information. c) Verify that there are no ACL rules that block BFD packets. Enter the following command:show networking aclrule
If required add rule for allowing BFD packets in both the directions, see the section, Configuring IP Connection for Multicontroller RNCfor more information.
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Multihop BFD control packets are transmitted in UDP with destination port 4784.5 Check the IP connectivity between routers.
To check the IP connectivity between routers, follow these steps:
a) Verify basic IP connectivity between network devices using ping command. Ping from the correct VRF in node you have configured BFD session. If there is no response to ping verify the interface state. To execute the ping command from the SCLI, start the bash shell (in full mode) and then use ssh to connect to the correct node. Enter the following commands:
shell bash full ssh <node-name> ping -V <vrf-id> <ip- address> or ping <ip-address> exit
If you want to make sure that the node where BFD is configured, accepts ICMP (protocol 1) packets in input and output chain, enter the following command: show networking aclrule owner /<nodename> If the node does not accept ICMP (protocol 1) packets, then add accept rules by entering the following commands: add networking aclrule /<nodename> index 20000 chain\ input protocol 1 accept add networking aclrule /<nodename> index 20001 chain\ output protocol 1 accept
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The neighboring router may be configured to dropping requests and may cause ping not to respond.b) Verify that the state for the interface where BFD session is configured has admin state up and has running flag set. Enter the following command:
show networking interface runtime
If running flag is not present, verify that cable is properly connected to the interface. If the admin state is not up, see Configuring IP Connection for
Multicontroller RNCfor more information.
c) Verify that the BFD control packets are sent and received on the interface where BFD session is configured. To execute this command from SCLI, start the bash shell (in full mode) and then use ssh to connect to the correct node. Enter the following commands:
shell bash full ssh <node-name> tcpdump -i <iface-name> port 4784 exit
This command does not require root access.
If only outgoing BFD packets are seen, verify the configuration at the remote endpoint.
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NOTICE: Nokia advises that only advanced users, deeply familiar with the behavior ofthe network element, must use commands of the full bash in general and the tcpdump command in particular. Even if the root account or dedicated non root account access is used, the commands from the full bash shell can be easily exploited, For example, to change security-relevant configuration. Also the tcpdump command in particular when accidentally or on-purpose misused can cause significant performance penalties (a drop of 0-100%) in networking (throughput and latencies), disk I/O or processing capacity. In the worst case this might, for example, cause automatic recovery actions. Also some parts of the tcpdump command might not work as expected due to the peculiarities of the network element architecture.