Notes: bandwidth command under interface

Speed command explanation is actual much more simplest than bandwidth. Some interface (hardware dependent) allow you to set the speed. Speed command is also important, as it has to be the same on both ends of the connection.
speed {10 | 100 | 1000 [negotiate] | auto [speed-list]}

Bandwidth command under interface may have following functions:
bandwidth kilobits

1. Higher-level protocols use bandwidth information to make operating decisions.
2. TCP adjusts initial retransmission parameters on the basis of the apparent bandwidth of the outgoing interface.
3. Load calculations is based upon the perceived bandwidth.
4. QoS calculations (e.g. bandwith percent in top level policy map) will be affected by this.

http://www.gossamer-threads.com/lists/cisco/nsp/133406
https://learningnetwork.cisco.com/thread/4572
http://www.firstdigest.com/2010/08/cisco-speed-vs-bandwidth-interface-command/
http://www.cisco.com/en/US/docs/ios/12_2/interface/configuration/guide/icfgenrl.html#wp1102606

Notes