195.6.2.3 Trace point ETHSD, ETHRV
Wie bereits am Anfang des Abschnitt auf Seite 2463 angemerkt wurde, müssen die Tracepunkte ETHSD und ETHRV verwendet werden, falls die Protokoll Daten benötigt werden. Die Struktur der Trace Daten entspricht denen von den Tracepunkten ETHSD und ETHRV. Diese Struktur - für TCP Kommunikation - wird in Bild dargestellt und kurz kommentiert. Für nähere Details und andere Protokolle schauen Sie bitte in RFC791(IP), RFC792(ICMP), RFC793(TCP) und RFC826(ARP) nach.
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Destination MAC Address: Ethernet address of destination host
(0xFF FF FF FF FF FF = Broadcast address) Source MAC Address: Ethernet address of source host
Type Field: Ethernet Frame Type
(EtherType_IP = 0x0800, EtherType_ARP = 0x0806) Ver (bit 0 - bit 3): IP Version 4 is the only supported
IHL (bit 4 - bit 7): length of IP header in Dwords (normally = 5)
TypeOfService: unused inside the Atlantic LAN and always 0
Total Length: length of the datagram, measured in octets, including internet header and data
Identification: value assigned by the sender to aid in assembling the fragments of a datagram.
Flags(bit0-2): Bit 0: reserved, must be zero
Fragment Offset: indicates where in the datagram this fragment belongs, it is measured in units of 8 octets
TimeToLive: indicates the maximum time the datagram is allowed to remain in the internet system
Protocol: indicates the next level protocol used in the data portion of datagram (ICMP = 0x0001, TCP = 0x0006, UDP = 0x0011)
Header Checksum: a checksum on the header only
Source/Destination Address: IP addr. of source/destination host
Source/Destination Port: The source/destination port number.
Sequence Number: the sequence number of the first data octet in this segment
Acknowledgment Number: contains the value of the next sequence number the sender of the segment is expecting to receive
Data Offset (bit 0 - 3): length of TCP header in Dwords( = 5)
Reserved (bit 4 - 9): Reserved for future use, must be zero.
Window: number of data octets beginning with the one indicated in the acknowledgment field which the sender of this segment is willing to accept.
Checksum: is the 16 bit one’s complement of the one’s complement sum of all 16 bit words in the header & data
Urgent Pointer: communicates the current value of the urgentpointer as a positive offset from the sequence number in this segment. The urgent pointer points to the sequence number of the octet following the urgent data. This field is only be interpreted in segments with the URG control bit set
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