Understanding the Prepended Header ! 175
Chapter 6: Packet Mirroring
Figure 11: Prepended Header
01234567890123456789012345678901
Version (4) IHL (5) Type of service (0) Total length
Identification Flags Fragment offset
Time to live (255) Protocol (17) Header checksum
Source address (Analyzer port address)
Destination address (MD-IP-address - VSA 26-60)
Source port (Analyzer-port-number - VSA 26-61) Destination port (Analyzer-port-number - VSA 26-61)
Length Checksum (0)
Mirror identifier
MHV
(0)
Session ID
Mirrored packet header and data
IP header
UDP
header
Mirror
header
g014400
0123
Table 33: Prepended Header Field Descriptions
Field Value Length (Bits)
IP Header
Version 4 4
IHL 5 4
Type of Service 0 8
Total Length Dynamically computed 16
Identification Dynamically computed 16
Flags Dynamically computed 3
Fragment Offset Dynamically computed 13
Time to Live 255 8
Protocol 17 8
Header Checksum Dynamically computed 16
Source Address Analyzer port IP address 32
Destination Address VSA 26-60 32
UDP Header
Source Port VSA 26-61 16
Destination Port VSA 26-61 16
Length Dynamically computed 16
Checksum 0 16