Archive for the 'Switching' Category

Nov 21 2007

Things to know about VTP

Published byBrad Hedlund under CCIE, Switching

Some notes about VTP (VLAN Trunking Protocol):

Cisco switches running Cisco IOS store VTP and VLAN information in a separate database stored in Flash, in file called vlan.dat.
Cisco switches running CatOS store VTP and VLAN information in the main switch configuration file, stored in NVRAM.
VTP information is only transmitted over trunk ports.
A VTP client does not [...]

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Nov 21 2007

Identifying Ethernet Multicast

Published byBrad Hedlund under CCIE, Switching

Just like there are 3 different Ethernet header types, there are also 3 different types of Ethernet addresses:

Unicast
Broadcast
Multicast

A unicast frame contains the unique MAC address of the destination receiver. A broadcast frame contains all binary 1’s as the destination address (FFFF.FFFF.FFFF). A multicast frame contains the unique multicast MAC address of an application, [...]

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Nov 19 2007

Identifying Ethernet Header Types

Published byBrad Hedlund under CCIE, Switching

There are 3 different Ethernet Header types defined by the IEEE and in use today. So, one question comes to mind: When a Ethernet receiver receives a frame, how does it know what kind of header it is? After all, if a receiver is unable to properly recognize the header type, it will [...]

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