IOS Device Troubleshooting
I've started a wiki page dedicated to explaining Troubleshooting Commands for IOS Devices in practical terms. The intent is to compile commands relevant to troubleshooting the behavior of a Cisco IOS device itself (CPU, memory, performance, etc.) and to provide an accompanying description of each.
Contributions and suggestions are welcome.
About the Author
Jeremy Stretch is a freelance networking engineer, instructor, and the maintainer of PacketLife.net. He currently lives in Fairfax, Virginia, on the edge of the Washington, DC metro area. Although primarily an R&S guy, he likes to get into everything, and runs a free network training lab out of his basement for fun. You can contact him by email or follow him on Twitter.
Comments
I think not all cisco devices have the option "show environment", the older like 1720 don't have, and 18xx have limited information.
show stacks might be one
@triton: Good idea, I've added show environment.
@J: show stacks might also be a good one to include, I need to dig into it some.
have you'll try the command "test crash", is a undocumented cisco command can use for simulating problem. i only use this for testing in my test router.
THANK YOU!!!
Checking ASIC utilization:
Router# show fabric utilization
or any of the show fabric commands for that matter.
This is an awesome project!
thanks a ton
The "show diag" command gives a fairly detailed output of hardware specs(mainboard info, onboard vpn accelerator, interface card info, etc.). Along the same lines, the "show platform" command has similar output. Benefit of "show platform" is it gives you dimm slot usage(on pre-ISRs the command is "show c", e.g. "show c1700" or "show c2600").
Also, this might not be worth mentioning but comparing numbers from "show version" and the "show memory" commands should show you how much working memory the ios image takes after loading(for whatever that's worth).
Using numbers from your output:
Show Version Cisco 3725 (R7000) processor (revision 0.1) with 124928K/6144K bytes of memory.
"Show Memory" Processor Total = 27130896 | I/O Total = 6291456
Total Installed Memory = 128MB(124928 + 6144 / 1024 = 128)
Second number in "show version" is I/O memory and is equal to the total I/O Mem in the "show memory" command: 6291456 / 1024 = 6144
IOS image should be taking up roughly around 98433K of ram(124928 - 98433 = 26495 * 1024 = 27130880). At least that's how much memory is available after the image loads.
I second the nod for "show diag" on a router.
Another thing I struggle with is understanding the different memory print outs on different devices and understanding how much flash, nvram, etc. a device has.
sh mod
sh logg
"sh ipc status" is a very useful to debug IPC message drops. It shows the number of messages dropped, number of messages still queued up etc.
Another good command is show environment.