At 05:02 PM 3/13/02, PING wrote: >I have follwoing questions: > >Q1: When all the ports are in BLOCKing mode at start on switch, >how the initial broadcasts are then forwarded in a network so that >switches can learn about each other via BPDUs?
A bridge port transitions to listening after expiration of a short timer or receipt of a configuration BPDU on this port or another port. While in the listening state, the port is still not sending any user data or building the bridging table, but it is sending and receiving BPDUs in an effort to build the spanning tree. While in this state, the port may determine that it really isn't a Designated or Root Port and revert to the blocking state. >Q2: When a switch breaks the collision domains, then what is the >point of using Fragment Free method to avoid collisions? Fragment Free does not avoid collisions. It avoids the forwarding of runt (fragment) frames that result from collisions. A collision could occur on any shared LAN that is connected to a switch port. The result of a collision is usually a runt (fragment) frame. The senders notice the collision, stop transmitting, and back off for a random amount of time before resending. The result is a runt. Should a switch forward this runt? Fragment Free means no, it should not. It causes the switch to do a little extra processing and take a little extra time to make sure that it only forwards frames that are 64 bytes or more, that is, non-runts. >/N ________________________ Priscilla Oppenheimer http://www.priscilla.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=38145&t=38137 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
