Fragmentation statistics

Fragmentation statistics can be cleared using the clear nat map frag-stats command. The following fragmentation statistics are available:

• Rx Resolved Frags

  This counter shows fragments that were resolved and never buffered; for example:

  • first fragments (MF=1, FO=0), which are always resolved by definition

  • non-first fragments with matching flow records

• Rx Unresolved Frags

  This counter shows the number of packets that were queued in the system since the last clear command was invoked. For example, packets with out-of-order fragments without a matching flow record (missing 1st fragment) can be eventually resolved and forwarded, or discarded (for example, because of timeout).

• Tx Frags

  This counter shows the fragments that were transmitted (Rx Resolved and Rx Unresolved that were eventually resolved) out of fragmentation logic within the VSR. There is no guarantee that the fragments are transmitted out of the system as they may be dropped on egress because of congestion or restrictions imposed by the configured filter.

• Dropped Frags

  This counter represents the fragments that are dropped because of fragmentation issues such as timeout, buffer full, and so on.

• Buffers in Use

  This counter represents the amount of buffered fragments expressed as a percentage of the maximum buffer space that can be used for fragmentation.

• Max Buffers

  This is a non-cumulative counter that represents the maximum number of buffers allocated since the last clear command. The counter captures the highest value of the buffers-in-use counter since the last clear command. The unit of this counter is the percentage of the total buffer space that can be used by fragmentation.

• Created Flows

  This is a cumulative counter that represents the total number of flow records since the last clear command was invoked. It only counts the first fragment. It represents the number of fragmented packets that were processed by the system since the last clear command. This counter does not indicate the number of flows (packets whose fragments were transmitted fully) that were actually transmitted.

• Flows in Use

  The counter gives an approximation of the number of flow records currently in use and the number of fragmented packets being processed at the time the counter was invoked, as a percentage.

• Max Flows

  A non-cumulative counter that represents the maximum number of flow records reached since the last clear command. The counter shows the highest value of the flows-in-use counter since the last clear command, as a percentage.

• Flow Collisions

  This counter represents the number of overlapping first fragments. For example, in the case where a flow record already exists and another first fragment for the flow is received.

• Exceeded Max Timeouts

  This counter shows the number of fragments that have timed out since the last clear command. The represented fragments are:

  • Rx unresolved (buffered) fragments that have timed out because of a missing first fragment

  • deleted flow-records because they have not received all fragments within the timeout period

• Exceeded Max Flows

  This counter represents the number of times that the flows in the system has exceeded the maximum supported value.

• Exceeded Max Buffers

  This counter represents the number of times that the buffers in the system has exceeded the maximum supported value.

• Exceeded Max Buffers Per Flow

  This counter represents the number of times that the fragment counter per flow has exceeded its limit.