Configuring LSQ Interface Redundancy in a Single Router Using Virtual Interfaces
You can configure failure recovery on M Series, MX Series, and T Series routers that have multiple AS or Multiservices PICs and DPCs with lsq- interfaces by specifying a virtual LSQ redundancy (rlsq) interface in which the primary Link Services IQ PIC is active and a secondary PIC is on standby. If the primary PIC fails, the secondary PIC becomes active, and all LSQ processing is transferred to it. To determine which PIC is currently active, issue the show interfaces redundancy command.
 | Note: This configuration does not require the use of SONET APS for failover. Network interfaces that do not support SONET can be used, such as T1 or E1 interfaces. |
The following sections provide more information:
Configuring Redundant Paired LSQ Interfaces
The physical interface type rlsq specifies the pairings between primary and secondary lsq interfaces to enable redundancy. To configure a backup lsq interface, include the redundancy-options statement at the [edit interfaces rlsqnumber] hierarchy level:
For the rlsq interface, number can be from 0 through 1023. If the primary lsq interface fails, traffic processing switches to the secondary interface. The secondary interface remains active even after the primary interface recovers. If the secondary interface fails and the primary interface is active, processing switches to the primary interface.
The hot-standby option is used with one-to-one redundancy configurations, in which one working PIC is supported by one backup PIC. It is supported with MLPPP, CRTP, FRF.15, and FRF.16 configurations for the LSQ interface to achieve an uninterrupted LSQ service. It sets the requirement for the failure detection and recovery time to be less than 5 seconds. The behavior is revertive, but you can manually switch between the primary and secondary PICs by issuing the request interfaces (revert | switchover) rlsqnumber operational mode command. It also provides a switch over time of 5 seconds and less for FRF.15 and a maximum of 10 seconds for FRF.16.
The warm-standby option is used with redundancy configurations in which one backup PIC supports multiple working PICs. Recovery times are not guaranteed, because the configuration must be completely restored on the backup PIC after a failure is detected.
Certain combinations of hot-standby and warm-standby configuration are not permitted and result in a configuration error. The following examples are permitted:
- Interface rlsq0 configured with primary lsq-0/0/0 and warm-standby, in combination with interface rlsq0:0 configured with primary lsq-0/0/0:0
- Interface rlsq0:0 configured with primary lsq-0/0/0:0, in combination with interface rlsq0:1 configured with primary lsq-0/0/0:1
The following example combinations are not permitted:
- Interface rlsq0 configured with primary lsq-0/0/0 and hot-standby, in combination with interface rlsq0:0 configured with primary lsq-0/0/0:0
- Interface rlsq0:0 configured with primary lsq-0/0/0:0, in combination with interface rlsq1:0 configured with primary lsq-0/0/0:0
- Interface rlsq0:0 configured with primary lsq-0/0/0:1, in combination with interface rlsq1:1 configured with primary lsq-0/0/0:1
- Interface rlsq0 configured with primary lsq-0/0/0, in combination with interface rlsq1 configured with primary lsq-0/0/0
In addition, the same physical interface cannot be reused as the primary interface for more than one rlsq interface, nor can any of the associated logical interfaces. For example, primary interface lsq-0/0/0 cannot be reused in another rlsq interface as lsq-0/0/0:0.
Restrictions on Redundant LSQ Interfaces
Link Services IQ PIC failure occurs under the following conditions:
- The primary PIC fails to boot. In this case, the rlsq interface does not come up and manual intervention is necessary to reboot or replace the PIC, or to rename the primary PIC to the secondary one in the rlsq configuration.
- When configuring an rlsq interface, ensure that:
- The unit number allocated to the rlsq interface is less than the number of Multilink Frame Relay user-to-network interface network-to-network interface (UNI-NNI) (FRF.16) bundles allocated on the Link Services PIC.
- Data-link connection identifier (DLCI) is configured for the rlsq interface.
If these conditions are not met, the rlsq interface does not boot. When you issue the show interfaces redundancy command, the state of the rlsq interface is indicated as Waiting for primary MS PIC.
- The primary PIC becomes active and then fails. The secondary PIC automatically takes over processing.
- A failover to the secondary PIC takes place. The secondary PIC then fails. If the primary PIC has been restored to active state, processing switches to it.
- The FPC that contains the Link Services IQ PIC fails.
The following constraints apply to redundant LSQ configurations:
- We recommend that primary and secondary PICs be configured in two different FPCs (in chassis other than M10i routers).
- You cannot configure a Link Services IQ PIC with explicit bundle configurations and as a constituent of an rlsq interface.
- Redundant LSQ configurations provide full GRES support. (You must configure GRES at the [edit chassis] hierarchy level; see the Junos OS System Basics Configuration Guide.
- If you configure the redundancy-options statement with the hot-standby option, the configuration must include one primary interface value and one secondary interface value.
- Since the same interface name is used for hot-standby and warm-standby, if you modify the configuration to change this attribute, it is recommended that you first deactivate the interface, commit the new configuration, and then reactivate the interface.
- You cannot make changes to an active redundancy-options configuration. You must deactivate the rlsqnumber interface configuration, change it, and reactivate it.
- The rlsqnumber configuration becomes active only if the primary interface is active. When the configuration is first activated, the primary interface must be active; if not, the rlsq interface waits until the primary interface comes up.
- You cannot modify the configuration of lsq interfaces after they have been included in an active rlsq interface.
- All the operational mode commands that apply to rsp interfaces also apply to rlsq interfaces. You can issue show commands for the rlsq interface or the primary and secondary lsq interfaces. However, statistics on the link interfaces are not carried over following a Routing Engine switchover.
- The rlsq interfaces also support the lsq-failure-options configuration, discussed in Configuring LSQ Interface Redundancy Across Multiple Routers Using SONET APS. If the primary and secondary Link Services IQ PICs fail and the lsq-failure-options statement is configured, the configuration triggers a SONET APS switchover.
- Redundant LSQ configurations that require MLPPP Multilink Frame Relay (FRF.15 and FRF.16) are supported only with the warm-standby option.
- Redundant LSQ support is extended to ATM network interfaces.
- Channelized interfaces are used with FRF-16 bundles, for example rlsq0:0. The rlsq number and its constituents, the primary and secondary interfaces, must match for the configuration to be valid: either all must be channelized, or none. For an example of an FRF.16 configuration, see Configuring LSQ Interface Redundancy for an FRF.16 Bundle.
| Note: Adaptive Services and Multiservices PICs in layer-2 mode (running Layer 2 services) are not rebooted when a MAC flow-control situation is detected. |
Configuring Link State Replication for Redundant Link PICs
Link state replication, also called interface preservation, is an addition to the SONET Automatic Protection Switching (APS) functionality that helps promote redundancy of the link PICs used in LSQ configurations.
Link state replication provides the ability to add two sets of links, one from the active (working) SONET PIC and the other from the backup (protect) SONET PIC to the same bundle. If the active SONET PIC fails, links from the standby PIC are used without causing a link renegotiation. All the negotiated state is replicated from the active links to the standby links to prevent link renegotiation. For more information about SONET APS configurations, see the Junos® OS Network Interfaces.
To configure link state replication, include the preserve-interface statement at the [edit interfaces interface-name sonet-options aps] hierarchy level on both network interfaces:
The following constraints apply to link PIC redundancy:
- APS functionality must be available on the SONET PICs and the interface configurations must be identical on both ends of the link. Any configuration mismatch causes the commit operation to fail.
- This feature is supported only with LSQ and SONET APS-enabled link PICs, including Channelized OC3, Channelized OC12, and Channelized STM1 intelligent queuing (IQ) PICs.
- Link state replication supports MLPPP and PPP over Frame Relay (frame-relay-ppp) encapsulation, and fully supports GRES.
- Enabling the interface or protocol traceoptions with a
large number of MLPPP links can trigger Link Control Protocol (LCP)
renegotiation during the link switchover time.
Note: This renegotiation is more likely to take place for configurations with back-to-back Juniper Networks routers than in networks in which a Juniper Networks router is connected to an add/drop multiplexer (ADM).
- In general, networks that connect a Juniper Networks router to an ADM allow faster MLPPP link switchover than those with back-to-back Juniper Networks routers. The MLPPP link switchover time difference may be significant, especially for networks with a large number of MLPPP links.
- An aggressive LCP keepalive timeout configuration can
lead to LCP renegotiation during the MLPPP link switchover. By default,
the LCP keepalive timer interval is 10 seconds and the consecutive
link down count is 3. The MLPPP links start LCP negotiation only after
a timeout of 30 seconds. Lowering these configuration values
may trigger one or more of the MLPPP links to renegotiate during the
switchover time.
Note: LCP renegotiation is more likely to take place for configurations with back-to-back Juniper Networks routers than in networks in which a Juniper Networks router is connected to an ADM.
As an example, the following configuration shows the link state replication configuration between the ports coc3-1/0/0 and coc3-2/0/0.
Examples: Configuring Redundant LSQ Interfaces for Failure Recovery
Configuring LSQ Interface Redundancy for MLPPP
The following configuration shows that lsq-1/1/0 and lsq-1/3/0 work as a pair and the redundancy type is hot-standby, which sets the requirement for the failure detection and recovery time to be less than 5 seconds:
The following example shows a related MLPPP configuration:
| Note: MLPPP protocol configuration is required for this configuration. |
The following example shows a related CoS configuration:
The following example shows a complete link state replication configuration for MLPPP. This example uses two bundles, each with four T1 links. The first four T1 links (t1-*:1 through t1-*:4) form the first bundle and the last four T1 links (t1-*:5 through t1-*:8) form the second bundle. To minimize the duplication in the configuration, this example uses the [edit groups] statement; for more information, see the Junos OS System Basics Configuration Guide. This type of configuration is not required; it simplifies the task and minimizes duplication.
Configuring LSQ Interface Redundancy for an FRF.15 Bundle
The following example shows a configuration for an FRF.15 bundle:
Configuring LSQ Interface Redundancy for an FRF.16 Bundle
The following example shows a configuration for an FRF.16 bundle:
