Network services
NTP – Network Time Protocol Manually Setting Cisco Clocks Logs on cisco devices have a time stamp. If the time is not correct, the time log in the logs are wrong as well and you…
Why should I care about CDP and LLDP?
Cisco discovery protocol Using Cisco Discovery Protocol CDP allows you to see directly attached devices. But not just the devices, you see as well some information like which local port they are connected to, you…
Configuring Switch Port Security
With port security you can restrict, what device or how many devices can use this port. Port-Sec Max devices -> I want to limit how many devices (mac addresses are allowed to plug in to…
Understanding Vulnerabilities, Exploits, and Threats
Network security Triangle of CIA, our mission of protecting our environment You can make a house so secure that no one can enter or leave it. But that destroys the whole meaning of a house.…
ACL – access lists
So…Why Are Access Lists Important? An ACL is literally just a list of statements. There are two major types; standard and extended. Standard is just a list of source ip addresses with a permit or…
IPv6, the someday protocol
First of all, all IPv6 adresses is a biiiiig number!! (2128). An example of an IPv6 address is: 1051:2ABC:3500:0004:5ABC:7662:AB79:08A1 So the subnetmask always just represents the network bits in IPv6. So what’s a /64 network…
Advantages of Using Routing Protocols
Adaptability If we have a static route in place, to go to router D go over router B. The router can detect if the interface goes down. The router is smart enough to remove the…
How EtherChannel Increases Bandwidth
If we are talking of a LAG in this chapter, we talk about link aggregation group. It is used between ports connecting the same switches. If you have a LAG with 2x 1Gbit/s connection, there…
The Place of PortFast and BPDU Guard
BPDU guard Every 2 seconds we send a BPDU on very port. BPDU guard does the following “whenever you recieve a BPDU on this port, disable it (put it in an error disabled state)” Turn…
Spanning-tree protocol (STP)
Stops broadcast storms in your network. STP looks for redundant connections in your network and blocks them until they really are needed. Why we need STP? Switches send broadcast traffic everywhere! If clients send a…