Friday, February 19, 2010

System Management: do and don't

Well, I'm working on system management this we, I've suspended blogging about my ospf labs (no time.. sorry), anyway, here are my suggestions about system management:

1) DON'T start the system management labs without reading the "Cisco IOS Configuration Fundamentals Configuration Guide, Release 12.4T" it's full of tricky small commands, easy to forget...

2) DON'T try terminal padding (at least not with my insane testing way ;-))

R4#terminal padding . 255

R4#show terminal
Line 0, Location: "Bl4ckh0l3R4ck", Type: ""
Length: 24 lines, Width: 80 columns
Baud rate (TX/RX) is 9600/9600, no parity, 2 stopbits, 8 databits
Status: PSI Enabled, Ready, Active, Automore On
Capabilities: Notification Set
Modem state: Ready
Group codes: 0
Modem hardware state: CTS* noDSR DTR RTS
Special Chars: Escape Hold Stop Start Disconnect Activation
^^x none - - none
Timeouts: Idle EXEC Idle Session Modem Answer Session Dispatch
never never none not set
Idle Session Disconnect Warning
never
Login-sequence User Response
00:00:30
Autoselect Initial Wait
not set
Modem type is unknown.
Session limit is not set.
Time since activation: 2d06h
Editing is enabled.
History is enabled, history size is 20.
DNS resolution in show commands is enabled
Full user help is disabled
Allowed input transports are none.
Allowed output transports are lat pad telnet rlogin lapb-ta mop v120 ssh.
Preferred transport is lat.
Characters padded with NUL bytes:
Char ASCII count
. 46 255
No special data dispatching characters
R4#

a show run tooks 1 minute, every dot is displayed really slow ... bad idea :-)
"terminal default padding" from privileged mode to remove it

3) DO! setting the escape caracter of a session or of the whole line, useful for terminal servers with asynchronus serials, that doesn't support CTRL+SHIFT+6 ...
(Ascii chars reference table: http://www.cisco.com/en/US/docs/ios/fundamentals/command/reference/cf_ap1.html)

R4#terminal escape-character ?
BREAK Cause escape on BREAK
CHAR or <0-255> Escape character or its ASCII decimal equivalent
DEFAULT Use default escape character
NONE Disable escape entirely
soft Set the soft escape character for this line

R4#terminal escape-character 27 !-- see on ascii table above: 27 = ESC key
"^[" is the escape character
R4#show terminal
Line 0, Location: "Bl4ckh0l3R4ck", Type: ""
Length: 24 lines, Width: 80 columns
Baud rate (TX/RX) is 9600/9600, no parity, 2 stopbits, 8 databits
Status: PSI Enabled, Ready, Active, Automore On
Capabilities: Notification Set
Modem state: Ready
Group codes: 0
Modem hardware state: CTS* noDSR DTR RTS
Special Chars: Escape Hold Stop Start Disconnect Activation
^[x none - - none

Timeouts: Idle EXEC Idle Session Modem Answer Session Dispatch
never never none not set
Idle Session Disconnect Warning
never
Login-sequence User Response
00:00:30
Autoselect Initial Wait
not set
Modem type is unknown.
Session limit is not set.
Time since activation: 2d07h
Editing is enabled.
History is enabled, history size is 20.
DNS resolution in show commands is enabled
Full user help is disabled
Allowed input transports are none.
Allowed output transports are lat pad telnet rlogin lapb-ta mop v120 ssh.
Preferred transport is lat.
No output characters are padded
No special data dispatching characters

R4#ping 10.1.1.1 repeat 100000 !--- after a little while, I hitted the ESC key and...

Type escape sequence to abort.
Sending 100000, 100-byte ICMP Echos to 10.1.1.1, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
R4#

Nice experiment this one, at least for my lab!


4) DON'T use cpu intensive commands when you have configured snmp traps cpu rising ....
eg:
R4#sh snmp mib | inc tcp
tcp.1
tcp.2
tcp.3
tcp.4
tcp.5
tcp.6
tcp.7
tcp.8
tcp.9
tcp.10
tcp.11
tcp.12
tcpConnEntry.1
tcpConnEntry.2
tcpConnEntry.3
tcpConnEntry.4
tcpConnEntry.5
tcp.14
tcp.15

000192: *Feb 19 2010 23:53:38.682 GMT+1: %SYS-1-CPURISINGTHRESHOLD: Threshold:
Total CPU Utilization(Total/Intr): 99%/0%, Top 3 processes(Pid/Util): 3/99%, 2/0%, 97/0%
000193: *Feb 19 2010 23:54:53.646 GMT+1: %SYS-1-CPUFALLINGTHRESHOLD: Threshold:
Total CPU Utilization(Total/Intr) 1%/0%.

Niiice to stall yourself for a minute! :-) Not a snmp related issue, but nice to see your cpu high logged on console.


[[ Well, I will add more system menagement do and don't during this we.. stay tuned! ]]

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