FH_2ndOnly - check Fragment Reassembly (2nd fragment only)
Host and Router
FH_2ndOnly.seq [-tooloption ...] -pkt Fragment.def
-tooloption : v6eval tool option
1. Ping to Target (create Neighbor Cache Entries, if not exist) 2. Override Neighbor Cache Entries
Tester Target
| |
|-------------------------->|
| Echo Request (2nd) |
| |
| |
| (<----------------------) |
| No Packet |
| |
| |
v v
1. Send Echo Request (2nd fragment) 2. No Packet from Target
Echo Request Data (original) is:
IPv6 Header
Version = 6
Traffic Class = 0
FlowLabel = 0
PayloadLength = 1032
NextHeader = 58 (ICMP)
SourceAddress = Tester Link Local Address
DestinationAddress = Target Link Local Address
ICMP Echo Request
Type = 128 (Echo Request)
Code = 0
Checksum = (auto)
Identifier = (auto)
SequenceNumber = 0
PayloadData = data repeat{0x1, 512}
data repeat{0x2, 512}
Echo Request Data (2nd fragment) is:
IPv6 Header
Version = 6
Traffic Class = 0
FlowLabel = 0
PayloadLength = 520
NextHeader = 44 (Fragment Header)
SourceAddress = Tester Link Local Address
DestinationAddress = Target Link Local Address
Fragment Header
NextHeader = 58 (ICMP)
FragmentOffset = 65
MFlag = 0
Identification = 32bit (Automatic generation)
Payload
data = 512 octets from the back of ICMP Echo request
PASS: No packet from Target
Sent packet is discarded
RFC2460
4.5 Fragment Header
:
The following error conditions may arise when reassembling fragmented packets:
If insufficient fragments are received to complete reassembly of a
packet within 60 seconds of the reception of the first-arriving
fragment of that packet, reassembly of that packet must be
abandoned and all the fragments that have been received for that
packet must be discarded. If the first fragment (i.e., the one
with a Fragment Offset of zero) has been received, an ICMP Time
Exceeded -- Fragment Reassembly Time Exceeded message should be
sent to the source of that fragment.
perldoc V6evalTool