01-11-2019 12:01 AM
I have a Cisco 3845 router having with monitoring tool reporting high processor utilization. From what I know, RAM specs should also reflect in show memory. However I am observing that RAM indicated at the show version 256MB is different from the one seen in show memory 87MB. Based from the used Total and Used processor memory it yields 95% utilization with only 4MB free space. Can anyone help me further understand this situation.
sh platf | i dim
Size of dimm = 256 Megabytes
sh ver | i memory
Cisco 3845 (revision 1.0) with 211968K/50176K bytes of memory.
sh mem
Head Total(b) Used(b) Free(b) Lowest(b) Largest(b)
Processor 67BF8B80 87061632 82986848 4074784 2820800 2532336
I/O 2CF00000 51379712 22521732 28857980 28782640 28788604
Cisco IOS Software, 3800 Software (C3845-ADVIPSERVICESK9-M), Version 12.4(24)T5, RELEASE SOFTWARE (fc3)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2011 by Cisco Systems, Inc.
Compiled Fri 04-Mar-11 06:12 by prod_rel_team
ROM: System Bootstrap, Version 12.4(13r)T11, RELEASE SOFTWARE (fc1)
WGDCA3845RTR1 uptime is 7 years, 24 weeks, 4 hours, 44 minutes
System returned to ROM by power-on
System restarted at 21:29:40 EDT Thu Jul 28 2011
System image file is "flash:c3845-advipservicesk9-mz.124-24.T5.bin"
This product contains cryptographic features and is subject to United
States and local country laws governing import, export, transfer and
use. Delivery of Cisco cryptographic products does not imply
third-party authority to import, export, distribute or use encryption.
Importers, exporters, distributors and users are responsible for
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agree to comply with applicable laws and regulations. If you are unable
to comply with U.S. and local laws, return this product immediately.
A summary of U.S. laws governing Cisco cryptographic products may be found at:
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If you require further assistance please contact us by sending email to
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Cisco 3845 (revision 1.0) with 211968K/50176K bytes of memory.
Processor board ID FTX1331AHU5
1 FastEthernet interface
3 Gigabit Ethernet interfaces
1 Serial interface
1 Virtual Private Network (VPN) Module
1 Subrate T3/E3 port
DRAM configuration is 64 bits wide with parity enabled.
479K bytes of NVRAM.
62720K bytes of ATA System CompactFlash (Read/Write)
Configuration register is 0x2102
NAME: "3845 chassis", DESCR: "3845 chassis"
PID: CISCO3845 , VID: V03 , SN: FTX1331AHU5
NAME: "c3845 Motherboard with Gigabit Ethernet on Slot 0", DESCR: "c3845 Motherboard with Gigabit Ethernet"
PID: CISCO3845-MB , VID: V07 , SN: FOC132862Q1
NAME: "One-Port Fast Ethernet High Speed WAN Interface Card on Slot 0 SubSlot 0", DESCR: "One-Port Fast Ethernet High Speed WAN Interface Card"
PID: HWIC-1FE , VID: V01 , SN: FOC14494U8C
NAME: "PVDMII DSP SIMM with four DSPs on Slot 0 SubSlot 4", DESCR: "PVDMII DSP SIMM with four DSPs"
PID: PVDM2-64 , VID: V01 , SN: FOC13353RKP
NAME: "PVDMII DSP SIMM with four DSPs on Slot 0 SubSlot 5", DESCR: "PVDMII DSP SIMM with four DSPs"
PID: PVDM2-64 , VID: V01 , SN: FOC13353RN1
NAME: "PVDMII DSP SIMM with four DSPs on Slot 0 SubSlot 6", DESCR: "PVDMII DSP SIMM with four DSPs"
PID: PVDM2-64 , VID: V01 , SN: FOC13353RMP
NAME: "PVDMII DSP SIMM with four DSPs on Slot 0 SubSlot 7", DESCR: "PVDMII DSP SIMM with four DSPs"
PID: PVDM2-64 , VID: V01 , SN: FOC13311D22
NAME: "Clear/Subrate T3/E3 WAN on Slot 1", DESCR: "Clear/Subrate T3/E3 WAN"
PID: NM-1T3/E3= , VID: V01 , SN: FOC13316VKD
NAME: "Gigabit Ethernet Controller on Slot 2", DESCR: "Gigabit Ethernet Controller"
PID: NM-1GE , VID: V01 , SN: FOC13301F49
NAME: "High Density Voice2 Network module with no board interface on Slot 4", DESCR: "High Density Voice2 Network module with no board interface "
PID: NM-HDV2 , VID: V02 , SN: FOC133061TW
01-13-2019 04:14 AM
Hello Carlson,
Indeed, your show memory output suggests that the processor memory is around 83 MiB (MiB = 1024 KiB = 1024 * 1024 B), and if we add it together with the memory set aside for the I/O packet buffers, the total memory apparently available to the system is around 132 MiB. The rest of your 256 MiB RAM module is occupied by the unpacked IOS image itself, and obviously, this part of RAM is not available for any other purposes since writing data there would overwrite the IOS code.
It would appear that your router would truly benefit from more RAM. However, if extending the RAM in the router is not an option, then looking at your I/O memory utilization, it looks like we could try allocating less memory to the I/O region, leaving more memory for the processor usage.
You are currently allocating 49 MiB out of 256 MiB for I/O which is around 20% (somewhat less). We can try changing this percentage to 15% (around 38,4 MiB) to give your processor memory some more breathing space. To do this, you would need to configure this command in the global configuration mode:
memory-size iomem 15
then save the configuration and reload the router.
Please feel welcome to ask further!
Best regards,
Peter
01-13-2019 05:36 AM
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