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Incor User's Guide Ethernet Media Access Controller TMS320C645x DSP

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Appendix A
Jumbo Packets — Jumbo frames are defined as those packets whose length exceeds the standard
Ethernet MTU, which is 1500 kbytes. For the C64x+ devices, it is recommended not to use packets
exceeding 35K in length. The PHY that you use can place additional limits on to the length of the
packets that you can transfer in a system.
Link — The transmission path between any two instances of generic cabling.
Multicast MAC Address — A class of MAC address that sends a packet to potentially more than one
recipient. A group address is specified by setting the LSB of the first MAC address byte. Thus,
01h-02h-03h-04h-05h-06h is a valid multicast address. Typically, an Ethernet MAC looks for only
certain multicast addresses on a network to reduce traffic load. The multicast address list of
acceptable packets is specified by the application.
Physical Layer and Media Notation — To identify different Ethernet technologies, a simple, three-field,
type notation is used. The Physical Layer type used by the Ethernet is specified by these fields:
<data rate in Mb/s><medium type><maximum segment length ( × 100m)>
The definitions for the technologies mentioned in this guide are as follows:
Table A-1. Physical Layer Definitions
Term Definition
10Base-T IEEE 802.3 Physical Layer specification for a 10 Mb/s CSMA/CD local area network over two
pairs of twisted-pair telephone wire.
100Base-T IEEE 802.3 Physical Layer specification for a 100 Mb/s CSMA/CD local area network over two
pairs of Category 5 unshielded twisted-pair (UTP) or shielded twisted-pair (STP) wire.
1000Base-T IEEE 802.3 Physical Layer specification for a 1000 Mb/s CSMA/CD LAN using four pairs of
Category 5 balanced copper cabling.
Twisted pair A cable element that consists of two insulated conductors twisted together in a regular fashion to
form a balanced transmission line.
Port — Ethernet device.
Promiscuous Mode — EMAC receives frames that do not match its address.
146 Glossary SPRU975B – August 2006
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