When you have only one chassis (not recommended!), 2 * supervisors can bring some resiliency (Maintenance, High Availability,etc..) to your environment, there are 2 modes:RPR and SSO (and Nonstop Forwarding (NSF) with SSO)
Operation
Route Process Redundancy (RPR)
- redudant supervisor pauses on system initialization, and become active if active supervisor fails (physical ports restart)
- works in active/standby
Stateful Switchover (SSO)
- is an enhancement of RPR, a fully-initialized state
- works in active/hot-standby
- synchronize the state of interfaces
- it offers zero interruption to Layer 2 sessions
On both modes you have:replication of configuration startup/private, config-register, bootvar, vlan database
Note:SSO is supported in Cisco IOS Release 12.2(20)EWA and later releases
For my tests i used 2 * Supervisors V in a 4510-R chassis, both were using an old code 12.2(18)
Plan
1. Configure RPR using 12.2(18)
2. Upgrade supervisors to 15.0(2)SG9
3. Migrate RPR to SSO
RPR Configuration
redundancy mode rpr main-cpu auto-sync standard
Checking the Redundancy state (active/standby)
Sw-4510R#show redundancy states my state = 13 ACTIVE peer state = 4 STANDBY COLD Mode = Duplex Unit = Primary Unit ID = 2 Redundancy Mode (Operational) = RPR Redundancy Mode (Configured) = RPR Redundancy State = RPR Maintenance Mode = Disabled Manual Swact = enabled Communications = Up (omitted)
The commands on 15.x code changed slightly
Sw-4510R#show redundancy domain default Redundant System Information : ------------------------------ Available system uptime = 1 week, 4 days, 18 hours, 25 minutes Switchovers system experienced = 0 Standby failures = 0 Last switchover reason = none Hardware Mode = Duplex Configured Redundancy Mode = RPR Operating Redundancy Mode = RPR Maintenance Mode = Disabled Communications = Up Current Processor Information : ------------------------------- Active Location = slot 2 Current Software state = ACTIVE Uptime in current state = 1 week, 4 days, 18 hours, 25 minutes Image Version = Cisco IOS Software, Catalyst 4500 L3 Switch Software (cat4500-IPBASE-M), Version 15.0(2)SG9, RELEASE SOFTWARE (fc2) Technical Support: http://www.cisco.com/techsupport Copyright (c) 1986-2014 by Cisco Systems, Inc. Compiled Thu 25-Sep-14 05:01 by prod_rel_team BOOT = bootflash:cat4500-ipbase-mz.150-2.SG9.bin,1; Configuration register = 0x2101 Peer Processor Information : ---------------------------- Standby Location = slot 1 Current Software state = STANDBY COLD Uptime in current state = 1 week, 4 days, 17 hours, 39 minutes Image Version = Cisco IOS Software, Catalyst 4500 L3 Switch Software (cat4500-IPBASE-M), Version 15.0(2)SG9, RELEASE SOFTWARE (fc2) Technical Support: http://www.cisco.com/techsupport Copyright (c) 1986-2014 by Cisco Systems, Inc. Compiled Thu 25-Sep-14 05:01 by prod_rel BOOT = bootflash:cat4500-ipbase-mz.150-2.SG9.bin,1; Configuration register = 0x2101
Upgrading
After copy IOS 15.x to both supervisors, i redeem the free space in bootflash (took around 10 minutes for both supervisors)
***** The system will autoboot in 5 seconds *****
Type control-C to prevent autobooting.
. .
Autoboot cancelled......... please wait!!!
rommon 1 > [interrupt]
rommon 7 >dir bootflash:
File size Checksum File name
--------------------------------------------------
17130956 bytes (0x10565cc) 0x219ae893 cat4500-ipbase-mz.150-2.SG9.bin
12486676 bytes (0xbe8814) 0xb1588783 cat4000-i5s-mz.122-25.EWA3.bin(deleted)
13478072 bytes (0xcda8b8) 0xc06beffc cat4500-entservicesk9-mz.122-31.SG.bin(deleted)
966656 bytes (0xec000) 0x93180cd0 cat4500e-entservices-mz.122-46.SG.bin(invalid)
Total space = 59244544 bytes, Available = 15181672 bytes
Sw-4510R#dir bootflash:
Directory of bootflash:/
4 -rwx 17130956 Mar 12 2013 15:50:50 +01:00 cat4500-ipbase-mz.150-2.SG9.bin
Sw-4510R#squeeze bootflash:
All deleted files will be removed. Continue? [confirm]
Squeeze operation may take a while. Continue? [confirm]
Sw-4510R#squeeze slavebootflash:
All deleted files will be removed. Continue? [confirm]
Squeeze operation may take a while. Continue? [confirm]
Convert RPR to SSO mode, this will force a reboot on standby supervisor
Sw-4510R(config-red)#>redundancy Sw-4510R(config-red)#mode sso Changing to sso mode will reset the standby. Do you want to continue?[confirm] Sw-4510R(config-red)# Jul 1 2015 22:00:03.833: %C4K_REDUNDANCY-3-COMMUNICATION: Communication with the peer Supervisor has been lost Jul 1 2015 22:00:03.865: %C4K_REDUNDANCY-3-SIMPLEX_MODE: The peer Supervisor has been lost
This is how a console on standby supervisor looks like, but you are not able to execute any command
*********************************** * STANDBY SUPERVISOR * * REDUNDANCY mode is SSO * * Continue bootup * *********************************** (...) Sw-4510R-standby#show ? Standby console disabled. Valid commands are: exit, logout
Forcing a switchover and get SSO kickedin without interruption
Sw-4510R#redundancy force-switchover This will reload the active unit and force switchover to standby[confirm] Preparing for switchover..