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| 3.2 |  | Characteristics of Physical Layer Optimization Problems |
| 3.2.5 |  | Other data transmission issues |

Short Frames
The most likely cause of a short frame is a faulty card, or an improperly configured or corrupt NIC driver file.

Jabber
Jabber, is often defined as the condition in which a network device continually transmits random, meaningless data onto the network. IEEE 802.3 defines a jabber as a data packet whose length exceeds the standard. These packets are called long frames. Cyclically lock the port out, then check later to see if it is ok. The standard says that after the jabber timer expires (20,000 to 50,000 bit times) then the hub should close the port for awhile before reopening the port to see if the attached device has stopped transmitting. If jabber is again detected the port may be closed for another cycle. This may continue forever.

In general jabbers are not a common occurrence. The most likely causes of jabber are a faulty NIC and/or faulty or corrupt NIC driver files, bad cabling, or grounding problems.

Ghosts
Ghosts are easily created by a variety of causes on coaxial Ethernet. They may also be caused by something as simple as installing a second crossover cable between two hubs on half duplex 10BASE-T. The parallel path sometimes causes very strange symptoms. The hub will do one of the following two things:

- Lock one port out, sometimes requiring a power cycle or SNMP management intervention to reopen the port. This is fortunately the most common result.
- Allow the error to continue uninterrupted. This is not permitted by the standard.

The error level often fluctuates between very little and the available bandwidth for no apparent reason. In addition to ghosts, this second crossover cable fault usually produces collisions, late collisions, and FCS errors.