show controllers cable-modem mac
Troubleshooting Tips for the Cisco uBR904 Cable Modem 43
Burst Descriptor:
Interval Usage Code
A compound type/length/value (TLV) encoding that defines, for each type of
upstream usage interval, the physical-layer characteristics that are to be used during
that interval. Each burst descriptor is given an identifying number.
Each upstream transmit burst belongs to a class which is given a number called the
IUC (interval usage code). Bandwidth maps messages (MAP) are used by IUC codes
to allocate upstream time slots. The following types are currently defined:
1. Request: bandwidth request slot
2. Request/Data: bandwidth request or data slot
3. Initial Maintenance: initial link registration contention slot
4. Station Maintenance: link keep-alive slot
5. Short Data Grant: short data burst slot
6. Long Data Grant: long data burst slot
Modulation Type
Upstream modulation format. (1 = QPSK; 2 = 16QAM)
Differential Encoding
Indicates whether or not differential encoding is used. (1 = yes; 2 = no)
Preamble Length
Length of the preamble in bits. The value must be an integral number of symbols—a
multiple of 2 for QPSK; a multiple of 4 for 16QAM.
FEC Error Correction
Length of the forward error correction in bytes. The range is 0-10 bytes; a value of 0
implies no forward error correction.
FEC Codeword Info Bytes
Number of information bytes in the FEC codeword.
Scrambler Seed
15-bit seed value loaded at the beginning of each burst after the register has been
cleared. Not used if scrambler is off.
Maximum Burst Size
Maximum number of mini-slots that can be transmitted during this burst type. When
the interval type is Short Data Grant, this value must be greater than 0. If this value is
0, the burst size is limited elsewhere.
Guard Time Size
Amount of time in symbols between the center of the last symbol of one burst and
the center of the first symbol of the preamble of an immediately following burst in an
upstream transmission from the cable modem to the CMTS.
Last Codeword Length
Indicates whether or not the length of the last codeword is fixed or shortened.
(1 = fixed; 2 = shortened)
Scrambler on/off
Indicates whether or not a scrambler is enabled in the upstream modulator.
(1 = on; 2 = off)
Network Access
Indicates whether or not the cable modem has access to the HFC network.
Vendor ID
Unique identifier specifying the cable modem manufacturer.
Auth. Wait Timeout
The number of seconds the cable modem waits for a reply after sending the
Authorization Request message to the CMTS.
Reauth. Wait Timeout
The number of seconds the cable modem waits for a reply after it has sent an
Authorization Request message to the CMTS in response to a reauthorization request
or an Authorization Invalid message from the CMTS.
Auth. Grace Time
The number of seconds before the current authorization is set to expire that the grace
timer begins, signaling the cable modem to begin the reauthorization process.
Op. Wait Timeout
The number of seconds the TEK state machine waits for a reply from the CMTS
after sending its initial Key Request for its SID’s keying material.
Retry Wait Timeout
The number of seconds the TEK state machine waits for a replacement key for this
SID after the TEK grace timer has expired and the request for a replacement key has
been made.
Table 8
Show Controllers Cable-Modem MAC State Field Descriptions (Continued)
Field
Description