Sunday, April 20, 2014

Default reserved VLAN numbers on Cisco IOS and NX-OS

Fire-like Kapok blossoms in Taipei City, Taiwan

To show the reserved VLAN numbers on both IOS and NX-OS, the common command is:
show vlan internal usage

Saturday, March 8, 2014

Notes of PONG command on Nexus 7000

Mountain view over Devine Trees near Chilan (棲蘭), Yilan County, Taiwan. (棲蘭神木園)

We can use PONG command to measure and and analyze switch port to other switch port latency. Example of using this command can be found on PONG command reference.

Tuesday, March 4, 2014

My notes about Configuration Register on Cisco Routers

This page on Cisco.com defines all details about "Configuration Register" on Cisco routers.
http://www.cisco.com/c/en/us/support/docs/routers/10000-series-routers/50421-config-register-use.html
The Purpose of the Configuration Register
The configuration register can be used to change router behavior in several ways, such as:
  • how the router boots (into ROMmon, NetBoot)
  • options while booting (ignore configuration, disable boot messages)
  • console speed (baud rate for a terminal emulation session)
Configuration registers are indeed DIP switches on most of PC motherboard.

DIP-Switch as part of a PCB from 1976, by Rainglasz.
Captured on Wikipedia.

Wednesday, January 29, 2014

Thursday, January 16, 2014

Fw: NTP Amplification Attacks Using CVE-2013-5211 | US-CERT

Screen capture of this alert page.

If you are running NTP Daemon, remember to upgrade to Version 4.2.7, or just disable “monlist” functionality.

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