HP MSR2000 series Configuration Manual page 76

Figure 26 Hello packet format
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Version
Major fields of the hello packet are as follows:
Network mask—Network mask associated with the router's sending interface. If two routers have
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different network masks, they cannot become neighbors.
HelloInterval—Interval for sending hello packets. If two routers have different intervals, they cannot
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become neighbors.
Rtr Pri—Router priority. A value of 0 means the router cannot become the DR or BDR.
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RouterDeadInterval—Time before declaring a silent router down. If two routers have different dead
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intervals, they cannot become neighbors.
• Designated router—IP address of the DR.
Backup designated router—IP address of the BDR.
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Neighbor—Router ID of the neighbor router.
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DD packet
Two routers exchange database description (DD) packets, describing their LSDBs for database
synchronization. A DD packet contains only the headers of LSAs to reduce traffic.
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1
Checksum
Network mask
HelloInterval
RouterDeadInterval
Designated router
Backup designated router
15
Packet length
Router ID
Area ID
Authentication
Authentication
Options
Neighbor
Neighbor
63
AuType
Rtr Pri
31