Table of Contents
Advertisement
COPY_lND_LLC—Copy All Individual LLC Frames
This bit does not affect how the MAC sets the A and C control indicators.
0 = The MAC copies individually addressed LLC frames if the DA is matched (subject
to the COPY_OWN bit). The MAC chip ignores this bit when
COPY_ALL = 11 or 10.
1 = In addition to the frames it is already copying, the MAC copies all LLC,
implementor, and reserved frames whose DA field indicates a 48-bit individual
address. The MAC will not copy LLC frames it sent unless COPY_OWN = 1.
COPY_lND_LLC is primarily used for promiscuous bridges.
COPY_GRP_LLC—Copy All Multicast LLC Frames
This bit does not affect how the MAC sets the A and C control indicators.
0 = The MAC copies multicast LLC frames if the DA is matched (subject to
COPY_OWN) in the CAM. The MAC chip ignores this bit when the
COPY_ALL = 11 or 10.
1 = In addition to the frames it is already copying, the MAC copies all LLC,
implementor, and reserved frames whose DA field indicates a 48-bit group
address. The MAC will not copy group LLC frames it sent unless
COPY_OWN = 1.
COPY_GRP_LLC is primarily used for promiscuous bridges.
DSABL_BRDCST—Disable Broadcast
0 = The MAC treats broadcast frames normally (as described in the FDDI standard).
This bit does not affect the behavior of SMT frames—i.e., SMT broadcast frames
are always recognized and copied. Unlike many register bits, this bit still has an
effect when COPY_ALL = 11 or 10. Specifically, this bit affects the 0D field of an
END_DATA transfer for received broadcast frames.
1 = The MAC treats a MAC, LLC, implementor, or reserved broadcast frame (i.e., DA
is all ones) exactly as if it were another multicast frame of the same frame type.
Hence, an LLC broadcast frame is recognized and copied only if the broadcast
address is found in the CAM or COPY_GROUP_LLC = 1 (subject to
COPY_OWN). The A_FLAG and C_FLAG are only set if the broadcast address is
found in the CAM since COPY_GROUP_LLC has no effect on these indicators.
RUN_BIST—Run Built-In Self-Test
0 = The MAC operates normally.
1 = The MAC runs its internal BIST. To run BIST properly, the MAC_ON and
RUN_BIST bits must both be cleared for at least five BYTCLK cycles, and then
both bits must be set simultaneously. During BIST, the MACINT line is only
asserted when the BIST has finished (after 65535 BYTCLK cycles), at which time
the BIST signature register is frozen. The actual signature depends on the values
of each of the writable or clearable registers, except the interrupt mask and
interrupt event registers. ln addition, the signature also depends upon the value of
the MATCH and RABORT pins (usually negated during BIST). MTESTx should
be 00. Also, the TXPARITY_ON bit should be 0; otherwise, the parity of the nine
MOTOROLA
MC68838 USER'S MANUAL
3-7
Advertisement
Table of Contents
