How to create a mac access-list and an vlan access-map Last few days at work, we noticed on several access-switches a mac address flapping. I don’t know how to troubleshoot and to fix it for interim arrangement purposes. Figure 1 The syslog error message looks like this. Current situation On SW1 at port fa0/20 and fa0/21, there were a telephone switchboard that operate at vlan
flash-file-system-2970-3550-3560-3750-and-image-handling It’s very useful to know, how a file system on a Catalyst 2970, 3550, 3560, and 3750 Flash file system work. If you loose your password, it’s a easy way with above mentioned hardware to set it to factory default. Step-by-Step Recovery Procedure As a prerequisite, a PC must be attached to the console port to the swi
During my work as a network engineer, i stumble across the switchport nonegotiate command and i never ever care about this command. There were no need for me to know and to configure this command. But last week on doing troubleshooting i decide to get a deeper look into ‘switchport nonegotiate’. Preface Enabling Trunking Trunk links are required to pass VLAN information
Prepare a cisco switch for telnet/ssh access (telnet access line vty 0 15) Everytime i have to prepare a cisco switch for telnet or ssh access i wondering, what i really need to configure proper. It’s a simple thing, but when you need this rarely, i always ‘trial and error’ and this gets me to be aggressive. So i decide to write a short compilation to fresh up my m
All Cisco routers have a 16-bit software register, which is written into NVRAM. By default, the configuration register is set to load the Cisco IOS from flash memory and to look for and load the startup-config file from NVRAM. By changing the configuration register, you can perform cisco password recovery on a Cisco router. If you are locked out of a router because you forgot the pa
The Purpose of the Cisco Configuration Register The configuration register can be used to change router behavior in several ways, such as: The configuration register can be set from configuration mode using the config-register command. From ROMmon, use the confreg command. Issue the show version command to view the current setting of the configuration register: Router#show version C
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