User guide

Packet Over SONET Module Installation and User Guide 3-61
Configuring and Monitoring Flow Statistics
Flow records are grouped together into UDP datagrams for export to a flow-collector
device. A NetFlow Version 1 export datagram can contain up to 25 flow records.
Figure 3-9 shows the format of the export datagram; Table 3-13 describes the export
datagram header.
Figure 3-9: Format of NetFlow export datagram
dPkts 4 Number of packets sent in this flow
dOctets 4 Number of octets sent in this flow
First 4 SysUptime when flow record was created
Last 4 SysUptime at most-recent, or last packet of flow
srcport 2 Source port number, valid only for TCP and UDP flows
dstport 2 Destination port number, valid only for TCP and UDP flows
pad 2 Unused field
prot 1 Number identifying the IP protocol; for example, 6=TCP and
17=UDP
tos 1 IP Type-of-Service (TOS) field value from initial packet that
caused this flow record to be created
tcp_flags 1 Cumulative OR of TCP flags field, valid only when prot=6
pad 11 Unused field
Table 3-12: NetFlow Version 1 Record Format (continued)
Field Name Octets Field Description
PoS_023
Header Flow record 1 Flow record 2 . . . Flow record n
octets 5216 52 52