show ip fragmentation | show ipv6 fragmentation | show ipv4-in-ipv6 fragmentation | show ipv6-in-ipv4 fragmentation

Description                                                    Show statistics for IP fragmentation.

Syntax                                                                  show {ip | ipv6 | ipv4-in-ipv6 | ipv6-in-ipv4}
fragmentation statistics

Mode                                                                   All

Example                                                            Example output for this command:

ACOS(config)#show ip fragmentation statistics

IP Fragmentation Statistics

---------------------------

Session Inserted                         0

Session Expired                          0

ICMP Received                            0

ICMPv6 Received                          0

UDP Received                             0

TCP Received                             0

IP-in-IP Received                        0

IPv6-in-IP Received                      0

Other Received                           0

ICMP Dropped                             0

ICMPv6 Dropped                           0

UDP Dropped                              0

TCP Dropped                              0

IP-in-IP Dropped                         0

IPv6-in-IP Dropped                       0

Other Dropped                            0

Overlapping Fragment Drop                0

Bad IP Length                            0

Fragment Too Small Drop                  0

First TCP Fragment Too Small Drop        0

First L4 Fragment Too Small Drop         0

Total Sessions Exceeded Drop             0

Out of Session Memory                    0

Fragmentation Fast Aging Set             0

Fragmentation Fast Aging Unset           0

Fragment Queue Success                   0

Payload Length Unaligned                 0

Payload Length Out of Bounds             0

Duplicate First Fragment                 0

Duplicate Last Fragment                  0

Total Queued Fragments Exceeded          0

Fragment Queue Failure                   0

Fragment Reassembly Success              0

Fragment Max Data Length Exceeded        0

Fragment Reassembly Failure              0

MTU Exceeded Policy Drop                 0

Fragment Processing Drop                 0

Too Many Packets Per Reassembly Drop     0

Session Max Packets Exceeded             0

 

The following table describes the fields in the command output.

Field

Description

Session Inserted

Number of times the ACOS device received a new fragment that did not match any existing session (based on source IP, destination ID, and fragment ID).

A fragment session represents multiple fragments that should be reassembled together into a single logical packet.

Session Expired

Number of times a fragment session timed out before all the fragments for the packet were received.

ICMP Received

Number of ICMP fragments received.

ICMPv6 Received

Number of ICMPv6 fragments received.

UDP Received

Number of UDP fragments received.

TCP Received

Number of TCP fragments received.

IP-in-IP Received

Number of IP-in-IP fragments received.

IPv6-in-IP Received

Number of IPv6-in-IP fragments received.

Other Received

Number of other types of fragments received.

ICMP Dropped

Number of ICMP fragments that were dropped. This counter and the other “Dropped” counters below are incremented when a fragment is dropped for any of the following reasons:

  Invalid length

  Overlap with other fragments

  Exceeded fragmentation session threshold

ICMPv6 Dropped

Number of ICMPv6 fragments that were dropped.

UDP Dropped

Number of UDP fragments that were dropped.

TCP Dropped

Number of TCP fragments that were dropped.

IP-in-IP Dropped

Number of IP-in-IP fragments that were dropped.

IPv6-in-IP Dropped

Number of IPv6-in-IP fragments that were dropped.

Other Dropped

Number of other types of fragments that were dropped.

Overlapping Fragment Drop

Number of fragments dropped because the data in the fragment overlapped with data in another fragment already received by the ACOS device.

Bad IP Length

This counter includes both of the following:

  Number of IPv4 packets for which the total length was invalid.

  Number of IPv6 packets for which the payload length was invalid.

Fragment Too Small Drop

Number of fragments in which the length of the data was too short. IP frag­mentation requires at least 8 bytes of data in all except the last fragment.

First TCP Fragment Too Small Drop

Number of fragmented TCP packets that did not contain the entire Layer 4 header in the first fragment.

First L4 Fragment Too Small Drop

Number of fragmented packets other than TCP packets that did not contain the entire Layer 4 header in the first fragment.

Total Sessions Exceeded Drop

Number of times a fragment was dropped because the maximum number of concurrent fragment sessions were already in use.

Out of Session Memory

Number of times the ACOS device ran out of memory for fragment sessions.

Fragmentation Fast Aging Set

Number of times the ACOS device sped up aging of existing fragment sessions in order to accommodate new sessions.

Fragmentation Fast Aging Unset

Number of times the ACOS device returned to normal aging for fragment ses­sions.

Fragment Queue Success

Number of times a new fragment session was created, or a new fragment was added to an existing session.

Payload Length Unaligned

Number of fragments whose length did not consist of a multiple of 8 bytes.

Note: This counter does not apply to the final fragments of fragmented pack­ets. The final fragment of a packet is not required to have a length that is a mul­tiple of 8.

Payload Length Out of Bounds

Number of times a fragmented packet’s data length exceeded what should have been the end of the reassembled packet.

Duplicate First Fragment

Number of times a duplicate first fragment was received for the same packet.

Duplicate Last Fragment

Number of times a duplicate last fragment was received for the same packet.

Total Queued Fragments Exceeded

Number of times the maximum number of concurrent fragmented packets supported by the ACOS device was exceeded.

Fragment Queue Failure

Total number of times a fragmented packet could not be queued to a session, due to any of the errors listed separately by the following counters:

  Duplicate First Fragment

  Duplicate Last Fragment

  Payload Length Out of Bounds

  Payload Length Unaligned

Fragment Reassembly Success

Number of times all fragments for a packet were reassembled successfully.

Fragment Max Data Length Exceeded

Number of times the total length of all reassembled fragments for a packet exceeded 65535. This type of error can indicate an attack such as a ping-of-death attack.

Fragment Reassembly Failure

Total number of fragment reassembly errors, including errors due to unlikely causes such as memory corruption.

MTU Exceeded Policy Drop

Number of packets dropped due to an MTU exceeded policy.

Fragment Processing Drop

Number of packets dropped due to errors during fragment processing.

Too Many Packets Per Reassembly Drop

Number of packets dropped because too many fragments were received for the packet.

Session Max Packets Exceeded

Number of times the limit for fragmented packets has been reached.

IPv4-in-IPv6 Fragmentation Statistics

(Not shown in the example above.)

These are the same as the counters described above, but they apply to packets fragmented into IPv4 fragments before being sent in the IPv6 tunnel. For exam­ple, these counters can apply to fragmented DS-Lite traffic.

These counters are displayed if you use the ipv6 option instead of the ip option.

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