Troubleshooting guide

11-13
Cisco Broadband Local Integrated Services Solution Troubleshooting Guide
OL-5169-01
Chapter 11 Element Management and MIBs
Cisco uBR7246vxr MIBs
cdxQosIfRateLimitShpMaxDelay The maximum shaping delay in milliseconds. That is, the
maximum amount time of buffering the CMTS will allow for
any rate exceeded flow. If the max buffering delay is large,
the grants/packets of the flow will be buffered for a longer
period of time even though the flow is rate exceeded. This
means fewer chances of drops for such rate exceeded flow.
However, too large a max shaping delay can result in quick
drainage of packet buffers at the CMTS, since several packets
will be in the shaping (delay) queue waiting for their proper
transmission time. Also note that delaying a flows packets
(especially TCP flows) for extended periods of time is
useless, since the higher protocol layers may assume a packet
loss after a certain amount of time.
The maximum shaping delay is only applied to rate limit
algorithm: Token bucket algorithm with shaping. If the rate
limit algorithm is not Token bucket algorithm with shaping,
the value is always na(1) which is not applicable.
If the token count is less than the size of request/packet,
CMTS computes the shaping delay time after which the
deficit number of tokens would be available. If the shaping
delay time is greater than the maximum shaping delay, the
request/packet will be dropped.
The enumerations for maximum shaping delay are:
• na(1): maximum shaping delay is not applied to the
current rate limit algorithm
• msec128(2): maximum shaping delay is 128
milliseconds
• msec256(3): maximum shaping delay is 256
milliseconds
• msec512(4): maximum shaping delay is 512
milliseconds
• msec1024(5): maximum shaping delay is 1024
milliseconds
The downstream maximum shaping delay is configurable and
the default value is msec128(2). Whenever the downstream
rate limit algorithm is changed to Token bucket algorithm
with shaping from other rate limit algorithm, the value will
be reset to the default value.
The upstream maximum shaping delay is not configurable
and it is read-only value.
Table 11-2 CISCO-DOCS-EXT-MIB.my Objects (continued)
Object Description