mac access-list and vlan access-map behavior
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.
switchport nonegotiate
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’.
- What take effect with the ‘switchport nonegotiate’ command?
- Is it useful to configure it?
- Do i really need an automatism to force the port to be a trunk or access port?
Preface
Layer 3 communication between different vlans
I will show a little tricky thing about Layer 3 communication between different vlans.
Given the following figure.
So it is a very silly thing. On SW1 you have configured vlan30 for port fa0/1 and fa0/2.
On Switch SW2 you have configured Vlan20 for port fa0/3 and fa0/1.
Cisco NTP
Cisco NTP basics
NTP is a protocol designed to synchronize clock with a atomic- or a radio clock.
The NTP Protocol uses the current standard of protocol version 4.
NTP is reserved for the UDP-Port 123.
The timestamp at NTP are 64bit long. 32 bits encode the seconds since the beginning of 1. Januar 1900 00:00:00. The next 32 bits are the fraction of the seconds.
With this manner it is possible to calculate the time in a resolution of 2 -32 seconds.
Cisco Certified
Cisco Certified