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An error message '%Cannot communicate boot variable to slave' appears when issuing the write memory command on a Cisco 7500 series router due to a communication issue with the slave RSP


Core Issue

This issue occurs on a Cisco 7500 series router with two Route Switch Processors (RSPs). This may be due to the slave RSP being in a halted state, a communication issue between the master and slave RSP on the Inter-Process Communication (IPC) bus, or a hardware issue.


If the error message appears after issuing the write memory or copy running-config startup-config commands, perform these steps:

  1. Check if the slave RSP is halted by issuing the show versioncommand. Look toward the end of the output for the line regarding the slave, as shown in this example:
    Router#show version
     Cisco Internetwork Operating System Software
     IOS (tm) RSP Software (RSP-JSV-M), Version 12.2(13)T,  RELEASE SOFTWARE (fc1)
     TAC Support:
     Copyright (c) 1986-2002 by cisco Systems, Inc.
     Compiled Sat 16-Nov-02 02:29 by ccai
     Image text-base: 0x60010948, data-base: 0x61F00000
     ROM: System Bootstrap, Version 12.0(20011126:200409)
     [mssunil-RSP16_BENGAL_120S 251], DEVELOPMENT  SOFTWARE
     BOOTLDR: RSP Software (RSP-BOOT-M), Experimental Version 12.1(20020118:012025)
     [mssunil-RSP16_IOS_121E 205]
     Router uptime is 7 hours, 22 minutes
     System returned to ROM by reload at 11:26:00 UTC Fri Feb 21 2003
     System image file is "disk0:rsp-jsv-mz.122-13.t.bin"
     cisco RSP16 (R7000A) processor with 131072K/8216K bytes of memory.
     R7000 CPU at 400Mhz, Implementation 39, Rev 3.3, 256KB L2, 2048KB L3 Cache
     Last reset from power-on
     G.703/E1 software, Version 1.0.
     G.703/JT2 software, Version 1.0.
     X.25 software, Version 3.0.0.
     SuperLAT software (copyright 1990 by Meridian Technology Corp).
     Bridging software.
     TN3270 Emulation software.
     Chassis Interface.
     5 VIP2 R5K controllers (7 FastEthernet)(8 Ethernet)(32 Serial).
     8 Ethernet/IEEE 802.3 interface(s)
     7 FastEthernet/IEEE 802.3 interface(s)
     32 Serial network interface(s)
     2043K bytes of non-volatile configuration memory.
     47040K bytes of ATA PCMCIA card at slot 0 (Sector size 512 bytes).
     16384K bytes of Flash internal SIMM (Sector size 256K).
     Slave in slot 2 is halted.
     Configuration register is 0x2102

     2. If the slave is halted, issue the slave reload global configuration command, as shown in this example:

     router(config)#slave reload

     3. After the slave reload is complete, issue the write memory or copy running-config startup-config command to check if the error message reoccurs.

Note: Even if the slave does not appear to be halted, issuing the slave reloadcommand may resolve the problem. This is because the issue might not be a halted slave, but a communication problem across the bus between the master and slave RSPs.

  • If after issuing the slave reload command, the error message still appears, physically remove and reinstall the slave RSP.
  • If after reseating the slave RSP, the error continues, the slave RSP may be defective and needs to be replaced.