Table Of Contents
Single-router APS for the Cisco 12000 Series Router
Prerequisites for Single-router APS for the Cisco 12000 Series Router
Restrictions for Single-router APS for the Cisco 12000 Series Router
Information About Single-router APS for the Cisco 12000 Series Router
SR-APS Alarms, Statistics, and SNMP Trap Support
High Availability Support for Single-router APS for the Cisco 12000 Series Router
How to Configure Single-router APS for the Cisco 12000 Series Router
Configuring Slot and Port Redundancy
Configuring Primary and Secondary Slot Pairs
Configuring Working and Protection Ports
Performing SR-APS Manual Protection Switching
Configuring Bit Error Rate Thresholds
Configuration Examples for Single-router APS for the Cisco 12000 Series Router
Single-router APS Show Command Examples
Single-router APS for the Cisco 12000 Series Router
This feature provides 1+1 Single-router automatic protection switching (SR-APS) for the Cisco 12000 series ISE ATM line cards (Engine 3) installed in Cisco 12816 or 12810 routers. By installing two identical line cards in physically adjacent slots and bridging traffic across both line cards, the Cisco 12000 Series router SR-APS implementation provides SONET line, ATM interface, and line card redundancy within a single router. This feature supports High Availability and is intended for routers deployed at the service provider multiservice edge.
Feature History for Single-router APS for the Cisco 12000 Series Router
12.0(31)S
This feature was introduced for the Cisco 12810 and Cisco 12816 routers.
Finding Support Information for Platforms and Cisco IOS Software Images
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Contents
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Prerequisites for Single-router APS for the Cisco 12000 Series Router
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Prerequisites for Single-router APS for the Cisco 12000 Series Router
The following hardware is required for operation of SR-APS:
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PN: 12816-CSC-B or 12810-CSC-B=SR-APS supports the following line cards:
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PN: 4OC12X/ATM-MM-SC•
PN: 4OC12X/ATM-IR-SC•
PN: 4OC3X/ATM-MM-SC•
PN: 4OC3X/ATM-IR-SCRestrictions for Single-router APS for the Cisco 12000 Series Router
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ATM interfaces most often connect to an ATM switch or ADM, while PoS interfaces connect to a router. The reflector channel is useful only when connected to a router.
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Information About Single-router APS for the Cisco 12000 Series Router
To implement multirouter APS, you should understand the following concepts:
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Single-router APS Overview
Automatic Protection Switching
This feature allows switchover of ATM circuits in the event of circuit failure due to a line card, interface (port) or SONET line failures. APS refers to the mechanism of configuring a "protection" interface as the backup for a "working" interface. When the working interface fails, the protection interface quickly assumes its traffic load. Single-router APS for the Cisco 12000 Series Router provides one for one (1+1) automatic protection switching for line cards, interfaces and SONET line circuits installed within a single Cisco 12816 or Cisco 12810 router.
1+1 Protection Switching
With 1+1 protection switching, a protect interface (circuit) is paired with each working interface. On a Cisco 12000 Series Router, the protection and working interfaces are connected to an ATM switch or a SONET ADM (Add/Drop Multiplexer) and the working and protection circuits terminate in different line cards in the same router. 1+1 protection switching is described in the Bellcore publication TR-TSY-000253, SONET Transport Systems; Common Generic Criteria, Section 5.3.
On the protection circuit, the K1K2 bytes from the line overhead (LOH) of the SONET frame indicate the current status of the APS connection and convey any requests for action. This signalling channel is used by the two ends of the connection to maintain synchronization.
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Bidirectional, Unidirectional, Revertive, and Non-revertive
The 1+1 protection switching may be bidirectional or unidirectional, and revertive or non-revertive. In bidirectional mode, the receive and transmit channels are switched as a pair. In unidirectional mode, the transmit and receive channels are switched independently. For example, in bidirectional mode, if the receive channel on the working interface has a loss of channel signal, both the receive and transmit channels are switched. In unidirectional mode, only the failed transmit channel is switched to the protection circuit. The revertive option causes the switched channel to switch back to the original working circuit when the line fault is removed. The default attributes for SR-APS are non-revertive and unidirectional. working and protection circuits can also be switched manually (forced) with the command line interface.
Single-router APS for the Cisco 12000 Series Router
Single-router APS for the Cisco 12000 Series Router implements APS by installing two identical line cards in physically adjacent slots in the same router and bridging traffic across both line cards. One line card is designated primary, the other secondary. A port on the primary line card is configured as the working interface, and the port with same port number on the secondary line card as the protection port. The ports form a single virtual interface, configured with the atm-redundancy interface configuration CLI. Ports on the secondary line card cannot be configured with services, they can only be configured as protection ports for the corresponding ports on the primary line card.
Figure 1 shows a basic SR-APS configuration where the working and protection circuits terminate on different line cards installed in physically adjacent slots of the same router.
Figure 1 Single-router APS Configuration
SR-APS Alarms, Statistics, and SNMP Trap Support
Statistics are maintained for the following APS alarms, and are for bidirectional APS operation only. There are no specific APS alarms for unidirectional APS.
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When a node receives an invalid K1 byte from the remote node, it reports a PSBF condition. An alarm is generated when the condition persists for 2.5 seconds (plus or minus 0.5 seconds). When the PSBF condition is cleared for 10 seconds (plus or minus 0.5 seconds), the alarm is cleared.
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A channel mismatch is when a node receives a channel number in the K2 byte that is different than its transmitted channel number. An alarm is generated when the channel mismatch condition persists for 2.5 seconds (plus or minus 0.5 seconds). When the channel mismatch is cleared for 10 seconds (plus or minus 0.5 seconds), the alarm is cleared.
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If the protection switching class of the local node is configured for 1+1 APS and the remote node is configured for 1:n APS, this alarm would be generated. If the received APS architecture differs from the local APS architecture, it would result in mode mismatch alarm. If the mode mismatch persists for 2.5(+- 0.5)seconds, this alarm will be generated. The alarm is cleared, once the mode mismatch is absent for 10(+- 0.5)seconds.
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The Far End Protection Line Failure alarm is generated when a node receives three consecutive K1 bytes that indicate signal failure (SF) on the protection line.
SNMP Trap Support
The following traps are defined for Single-router APS for the Cisco 12000 Series Router:
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High Availability Support for Single-router APS for the Cisco 12000 Series Router
The Route Processor card (RP) provides support for RPR, RPR+ or SSO modes of Route Processor redundancy. The APS redundancy infrastructure supports each of these RP redundancy modes.
How to Configure Single-router APS for the Cisco 12000 Series Router
This section contains the following procedures for implementing SR-APS with the Cisco 12000 Series ISE ATM line cards:
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Configuring Slot and Port Redundancy
To configure Single-router APS for the Cisco 12000 Series Router you must perform the following sequence of procedures:
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Reserving Adjacent Slots
Single-router APS for the Cisco 12000 Series Router works with identical line cards installed in physically adjacent slots. To detect and manage line card mismatches, OIR insertions, removals, and system reloads, the hw-module slot slot type type [reserve] [preconfig] global configuration command is introduced.
The type keyword lists the supported line cards for the specified slot.
The reserve keyword reserves the slot for only that line card specified with the type keyword. If any other line card is inserted into the reserved slot, that line card is put into a mismatch state, no services are brought up on the line card, and an error message is generated.
The preconfig keyword permits a slot to be preconfigured for the specified line card type, even if the slot is empty or currently occupied by a different line card type. When the specified line card is inserted, it acquires the configuration.
Configuring Primary and Secondary Slot Pairs
Single-router APS for the Cisco 12000 Series Router provides 1+1 line card redundancy, where two slots are configured as the members of a slot-pair. Only identical line cards in physically adjacent slots can be slot-paired. One slot is designated as primary and the other as secondary. The configuration of the line card in the primary slot is applied to the secondary slot. Any configuration for the secondary slot is automatically removed. All traffic to the primary slot is automatically bridged to the secondary slot with the Cisco 12000 fabric mirroring feature.
If a slot is not reserved for a card type that supports slot pairing, it cannot be configured as a slot-pair member. Make line cards slot reservations with the hw-module slot slot type type [reserve] [preconfig] global configuration command.
Create the slot pair with the slot-pair identifier redundancy configuration command. Designate which slot is primary and which is secondary with the member slot slot/port {primary | secondary} redundancy pair configuration command.
Configuring Working and Protection Ports
To configure SR-APS working and protection interfaces, create a port-group, then designate a working interface and a protection interface as members. The working interface is on the primary line card, the protection interface is on the secondary line card. Use the port-group portgroupID aps redundancy configuration command to create a port-group, then the member port slot/port redundancy port pair configuration command to designate the working and protection interfaces.
The working and protection pair combine into a single virtual interface. The configuration of the working physical interface is assumed by the virtual interface, and the configuration of the protection interface configuration is removed. Configure the virtual interface with the interface atm-redundancy slot/port global configuration command. The slot and port number of the virtual interface is the same as the working interface. The configuration of a virtual interface is applied to both of its physical interfaces. Only the protection interface carries the APS control signals.
In a port-group, the working and protection interfaces must have the same port numbers. For example, a 4-port line card in slot one when slot-paired with a line card in slot 2 could have only the following port-group working/protection pairs—1/0 and 2/0, 1/1 and 2/1, 1/2 and 2/2, and 1/3 and 2/3.
The state of the virtual interface is a combined state of both of its physical interfaces, as shown in Table 1.
Table 1 States of SR-APS Interfaces
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Up
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Up
When a line card is inserted into a a secondary slot while the primary slot is operational, all interfaces on the secondary line card are brought up with the corresponding virtual interface configurations applied to each physical interface.
Use the show interfaces atm-redundancy slot/port privileged exec command to display the redundancy states of each line card.
Restrictions
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For example, in a Cisco 12816 router, slot 1 and slot 2 are adjacent, slot 6 and slot 7 are not.•
For example, atm1/0 and atm2/0 can be an SR-APS pair, but atm1/0 and atm2/1 cannot.SUMMARY STEPS
Reserving Two Adjacent Redundant Slots for the Same Line Card Types
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Adding Slot Redundancy
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Adding Interface (Port) Redundancy
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Configuring Options—Activation Delay, Direction, Revertiveness and Signalling.
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Enabling and Verifying Configuration of SR-APS
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DETAILED STEPS
Troubleshooting Tips
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Performing SR-APS Manual Protection Switching
The following commands are used to perform the various switch requests. These commands are again available only on the protection router because that is where the K1K2 processing takes place.
Manual Protection Switching
In SR-APS, you can manually switch working channels and protection channels, or you can lock out a switchover altogether while performing system maintenance. A switchover from the working path to protection path is useful when upgrading or maintaining the system, or in cases where a signal failure caused a switchover. When the SR-APS circuit is configured for non-revertive operation, the system does not automatically revert to the original working circuit when the fault has been corrected. The switchover to the formerly failed interface must be requested through the CLI. The interface originally configured as the working path might be preferred because of its link loss characteristics.
There are three types of manual switchover requests:
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The priority order for switchover are a follows (from higher to lower priority):
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If a request or condition of a higher priority is in effect, a lower priority request is rejected.
Use the clear option to remove all manual switching requests. For manual and force, requests, clear only eliminates the precedence effect of these commands and does not cause another switchover.
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Examples
This example manually switches traffic from the working interface to the Protect interface.
Router# redundancy port-group 10 manual 1This example manually switches traffic from the Protect interface to the working interface.
Router# redundancy port-group 10 manual 0The following two commands are used to force switch the traffic.
Router# redundancy port-group 10 force 1Router# redundancy port-group 10 force 0This example prevents a manual switching from a working to a protection interface.
Router# redundancy port-group 10 lockoutThis example clears all existing switch requests.
Router# redundancy port-group 10 clearConfiguring Bit Error Rate Thresholds
The following commands permit the configuration of threshold values for raising SONET alarms. Exceeding the bit error rate (BER) thresholds will result in a signal degrade (SD) request or a signal failure (SF) request.
SUMMARY STEPS
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DETAILED STEPS
Examples
In the following example, the working router's (router1) atm interface is set to BER values other than the default values. The protection router (router2) is set with the same values.
Router1> enableRouter1# configure terminalRouter1(config)# interface atm 1/0Router1(config-if)# sonet-threshold sd-ber 7Router1(config-if)# sonet-threshold sf-ber 5Router1(config-if)# endRouter1#Router1> enableRouter2# configure terminalRouter2(config)# interface atm 1/0Router2(config-if)# sonet-threshold sd-ber 7Router2(config-if)# sonet-threshold sf-ber 5Router2(config-if)# endRouter2#Configuration Examples for Single-router APS for the Cisco 12000 Series Router
The following show commands are provided to monitor and verify Single-router APS configurations:
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Single-router APS Show Command Examples
router# show running-config. . .redundancymode rprslot-pair 7port-group 1 apsdirection unidirectionalactivation-delay 10. . .router# show aps group 1ATM1/0 APS Group 1: protect channel 0 (inactive)Working channel 1 at 127.255.0.0 (Enabled)unidirectional, non-revertivePGP timers (default): hello time=1; hold time=3SONET framing; SONET APS signalling by defaultReceived K1K2: 0x00 0x04No Request (Null)Transmitted K1K2: 0x00 0x04No Request (Null)Remote APS configuration: (null)ATM2/0 APS Group 1: working channel 1 (active)Protect at 127.255.0.0PGP timers (from protect): hello time=1; hold time=3SONET framingRemote APS configuration: (null)router# show interfaces Atm-redundancy 1/0Atm-redundancy1/0 is up, line protocol is upHardware is Atm-redundancy, address is 0000.0000.0000 (bia 0005.dd34.4dfe)MTU 4470 bytes, sub MTU 4470, BW 622000 Kbit, DLY 80 usec, rely 255/255, load 1/255Encapsulation ATM, loopback not setCarrier delay is 0 msecEncapsulation(s): AAL5, PVC mode4095 maximum active VCs, 0 current VCCsMax vpi bits: 8VC idle disconnect time: 300 secondsLast input never, output never, output hang neverLast clearing of "show interface" counters neverQueueing strategy: fifoOutput queue 0/40, 0 drops; input queue 0/75, 0 dropsAvailable Bandwidth 622000 kilobits/sec5 minute input rate 0 bits/sec, 0 packets/sec5 minute output rate 0 bits/sec, 0 packets/sec0 packets input, 0 bytes, 0 no bufferReceived 0 broadcasts, 0 runts, 0 giants, 0 throttles0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort0 packets output, 0 bytes, 0 underruns0 output errors, 0 collisions, 1 interface resets0 output buffer failures, 0 output buffers swapped outAdditional References
The following sections provide references related to Single-router APS for the Cisco 12000 Series Router:
Related Documents
Multirouter APS Configuration Information
APS and SONET commands: complete command syntax, command mode, defaults, usage guidelines, and examples
APS for Packet-over-SONET on the Cisco 7500 and Cisco 12000 series routers
Automatic Protection Switching of Packet-over-SONET Circuits feature document, Release 11.2
Standards
Bellcore SONET linear 1+1 architecture
TR-TSY-000253, SONET Transport Systems; Common Generic Criteria, Section 5.3.
MIBs
RFCs
No new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified by this feature.
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Technical Assistance
Command Reference
This section documents new and modified commands only.
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hw-module slot
To reserve line card slots for Single-router APS, use the hw-module slot command in global configuration mode. To release slots from a reservation, use the no form of this command.
hw-module slot slot type {0x71| 0x81} [reserve] [preconfig]
no hw-module slot slot type {0x71| 0x81} [reserve] [preconfig]
Syntax Description
Command Default
None
Command Modes
Global configuration
Command History
12.0(31)S
This command was introduced for the Cisco 12000 Series router Single-router APS.
Usage Guidelines
This command associates a line card type with a specific slot. This association is required for configuring Single-router APS (SR-APS) on the Cisco 12000 Series router where interface, line card, and SONET line redundancy is achieved by installing identical line cards into physically adjacent slots.
The reserve keyword indicates that if a line card of a type other than the reserved type is inserted in the slot, the line card is put into a mismatch state, and cannot be configured.
The preconfig keyword permits line card configuration for the specified line card type even if the slot is empty. When the specified type of line card is inserted, it acquires the preconfiguration.
Examples
The following example reserves slots 2 and 3 for 4-port ISE ATM Over SONET OC-12/STM-4 line cards:
router#config terminalrouter(config)# hw-module slot 2 type 0x71 reserverouter(config)# hw-module slot 3 type 0x71 reserveRelated Commands
interface atm-redundancy
To configure a virtual redundant ATM interface for Single-router APS, use the interface atm-redundancy command in interface configuration mode. To disable the virtual interface, use the no form of this command.
atm-redundancy interface slot/port
no atm-redundancy interface slot/port
Syntax Description
interface
Indicates interface configuration.
slot/port
Specifies the slot and port number of the working interface in the Single-router APS pair.
Command Default
None
Command Modes
Interface configuration
Command History
12.0(31)S
This command was introduced for the Cisco 12000 Series router Single-router APS.
Usage Guidelines
Two ATM interfaces specified in a port group as a working and protection pair for Single-router APS (SR-APS) are configured as a single logical interface with the interface atm-redundancy interface configuration command. The slot and port of the atm-redundancy interface is the slot and port of the working interface in the port group. The protection interface receives the same configuration automatically. Any previous configuration of the protection interface is removed.
Examples
The following example enables an ATM redundant interface and verifies its operation:
cRouter# configure terminalRouter(config)# interface Atm-redundancy2/0Router(config-if)# no shutRouter(config-if)# endRouter# show interfaces atm-redundancy 2/0Related Commands
member port
To add ports as members to a redundancy port group, use the member port command in redundancy port configuration mode. To remove a port as a member, use the no form of this command.
member port slot/port {protection [working-ip-address] | working}
no member port slot/port
Syntax Description
Command Default
No default behavior or values
Command Modes
Redundancy port configuration
Command History
12.0(30)S
This command was introduced for the Cisco 12000 Series router Multirouter APS.
12.0(31)S
This command was extended for the Cisco 12000 Series router Single-router APS.
Usage Guidelines
This command adds ports as members to a port group defined by the port-group redundancy command. For Multirouter or Single-router APS, there are two ports specified per port group, one designated a working interface, the other as a protection interface. Single-router APS does not use the working-ip-address argument. In Multirouter APS, the working IP address is specified only when configuring the port group of the protection interface on the protection router.
Examples
The following example adds port 2/0 on router1 as a member of port group 1:
Router1# configure terminalRouter1(config)# redundancyRouter1(config-red)# port-group 1 aps multi-routerRouter1(config-red-port)# member port 2/0 workingRouter1(config-red-port)# end
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