Understanding Supervisor Resilience

The supervisor resilience feature allows you to install a second supervisor engine module in the Catalyst 5500 switch to create a high-speed, fault-tolerant environment that supports mission-critical applications. The second supervisor module takes over if the active supervisor module fails. No software commands are needed to enable this functionality.

Note Supervisor resilience is available only on the 13-slot chassis of the Catalyst 5500 switch. Also, the Catalyst 5500 switch requires Supervisor Engine II in both normal and redundant supervisor configurations.

When you use two supervisor modules in the Catalyst 5500 switch, the first supervisor module to come up is considered the active module; the second supervisor module remains in standby mode. All network management functions, such as Simple Network Management Protocol (SNMP), command-line interface (CLI) console, Telnet, Spanning-Tree Protocol, Cisco Discovery Protocol (CDP), and virtual LAN (VLAN) Trunk Protocol (VTP), take place on the active supervisor module. The Ethernet ports on the standby supervisor module are inactive in the same way that enabled ports on disabled modules are inactive. The console port on the standby supervisor module is also inactive.

The redundant Supervisor Engine II modules must be installed in the first two slots of the 13-slot chassis. The supervisor modules are hot-swappable, and the system continues to operate with the same configuration after switching over to the redundant supervisor. For information on installing redundant supervisor engine modules, refer to the Catalyst 5000 Series Installation Guide.

User Interface Displays

This section shows example displays of the redundant supervisor module.

show module Command

This example shows the display for the second supervisor module when you enter the show module command:

Console> show module
Mod Module-Name          Ports Module-Type           Model    Serial-Num  Status
--- -------------------- ----- -------------------   -------- ----------  ------
 1  Supervisor           2     100BaseTX Supervisor  WS-X5006  001040409  ok
 2  Supervisor           2     100BaseTX Supervisor  WS-X5006  001040410  standby
 5  Management           12    100BaseFX Ethernet    WS-X5111  000023012  ok
 8  Marketing            24    10BaseT Ethernet      WS-X5010  012304930  ok
13  ATM BackBone         1     MM OC-3 ATM           WS-X5155  000459238  ok
Mod MAC-Address(es)                           Hw      Fw     Sw   
--- ----------------------------------------  ------  ------ -------------
 1  00-40-0b-90-00-24 thru 00-40-0b-90-04-23  1.3     1.4    1.1
 2  00-40-0b-90-04-24 thru 00-40-0b-90-08-23  1.3     1.4    1.1
 5  00-40-0b-92-9e-04 thru 00-40-0b-92-9e-0f  1.1     1.1    1.5
 8  00-40-0b-92-9e-fc thru 00-40-0b-92-9f-13  1.0     1.1    1.1
13  00-40-0b-05-01-48                         1.7     2.1    1.8
Console>

show port Command

This example shows the display for the second supervisor module when you enter the show port command. The ports on the standby supervisor indicate a status of standby.

Console> show port
Port Name                 Status   Vlan       Level  Duplex Speed  Type
---- -------------------- -------- ---------- ------ ------ -----  ------------
1/1  Management Port      connect  1000       high     full   100  100 BASE-TX
1/2  InterSwitchLink      connect  trunk      high     full   100  100 BASE-TX
2/1  Management Port      standby  1000       high     full   100  100 BASE-TX
2/2  InterSwitchLink      standby  trunk      high     full   100  100 BASE-TX
...

show test Command

This example shows the display for standby supervisor module when you enter the show test mod_num command. You can see the diagnostic test results for both the standby and active supervisor modules.

Console> (enable) show test 2
Network Management Processor (NMP) Status: (. = Pass, F = Fail, U = Unknown)
  ROM:  .   RAM:  .   DUART: .   Flash-EEPROM: .   Ser-EEPROM: .   NVRAM: .
  FAN:  .   Temperature: .
  PS (3.3V)  .     PS (12V): .   PS (24V): .
 
8051 Diag Status for Module 2(. = Pass, F = Fail, N = N/A)
 CPU         : .    Ext Ram 0: .    Ext Ram 1: .    Ext Ram 2: N
 DPRAM       : .    LTL Ram 0: .    LTL Ram 1: N    LTL Ram 2: N
 BootChecksum: .    CBL Ram 0: .    CBL Ram 1: N    CBL Ram 2: N
 Saints      : .    Pkt Bufs : .    Repeaters: N    Sprom    : .
 SAINT Status :
  Ports 1  2  3
  --------------
        .  .  .
 Packet Buffer Status :
  Ports 1  2  3
  --------------
        .  .  .
System Diagnostic Status : (. = Pass, F = Fail, N = N/A)
 Module 2: MCP
 EARL Status :
        NewLearnTest:         .
        IndexLearnTest:       .
        DontForwardTest:      .
        MonitorTest           .
        DontLearn:            .
        FlushPacket:          .
        ConditionalLearn:     .
        EarlLearnDiscard:     .
 PMD Loopback Status :
  Ports 1  2  3 
  --------------
        .  .  . 
Console> (enable)

reset mod_num Command

In the Catalyst 5500 switch, you can switch over to the standby supervisor module by entering the reset mod_num command, where mod_num is the number of the active supervisor. After entering the reset mod_num command, you see this display:

Console> (enable) reset 1
This command will force a switch-over to the standby supervisor module
and disconnect your telnet session.
Do you want to continue (y/n) [n]? y
Connection closed by foreign host.
host%

You can switch to the standby supervisor module by setting CISCO-STACK-MIB moduleAction to reset(2) on the active supervisor module.When the switch-over occurs, the system sends a standard SNMP warm-start trap to the configured trap receivers.

How Supervisor Resilience Works

The active supervisor module sends information to the standby supervisor module to keep the nonvolatile random-access memory (NVRAM) configuration on the standby supervisor current. If the software images on the active and standby supervisor modules are different, the active supervisor module downloads its image to the standby supervisor module. When the active supervisor module fails, the standby supervisor takes over within a few minutes.

At power-up, both supervisor modules run through initial module level diagnostics. Assuming both modules pass this level of diagnostics, the two modules communicate over the backplane, allowing them to cooperate during switching bus diagnostics. The module in slot 1 then becomes active, and the module in slot 2 enters standby mode. At this point, if the software versions of the two modules are different, the active supervisor automatically downloads its software image to the standby supervisor. If the NVRAM configuration on the two modules is different, the active supervisor automatically downloads its configuration to the standby supervisor.

After completing its initial module-level diagnostics, the just-inserted supervisor communicates with the active supervisor over the backplane. Because the active supervisor is already switching traffic on the backplane, no switching-bus diagnostics are run for the just-inserted supervisor. Running diagnostics would disrupt normal traffic. The just-inserted supervisor goes immediately into standby mode. At this point, the active supervisor downloads software and configuration information to the standby supervisor, if necessary.

If the background diagnostics on the active supervisor detect a major problem or a software crash watchdog timeout occurs, the active supervisor resets. The standby supervisor detects that the active supervisor is no longer running and becomes active. The standby supervisor also can detect if the active supervisor is not functioning and can force it to reset, if necessary. Once the reset supervisor comes up, it behaves as if a hot swap occurred, eventually entering the standby mode.

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