H3C S7500E Series Ethernet Switches Operation Manual

Operation Manual – IPv4 Routing
H3C S7500E Series Ethernet Switches Chapter 3 OSPF Configuration
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 Note:
MD5 authentication data is added following an OSPF packet rather than contained in
the Authentication field.
II. Hello packet
A router sends hello packets periodically to neighbors to find and maintain neighbor
relationships and to elect the DR/BDR, including information about values of timers, DR,
BDR and neighbors already known. The format is shown below:
Figure 3-10 Hello packet format
Major fields:
z Network Mask: Network mask associated with the router’s sending interface. If two
routers have different network masks, they cannot become neighbors.
z HelloInterval: Interval for sending hello packets. If two routers have different
intervals, they cannot become neighbors.
z Rtr Pri: Router priority. A value of 0 means the router cannot become the DR/BDR.
z RouterDeadInterval: Time before declaring a silent router down. If two routers
have different time values, they cannot become neighbors.
z Designated Router: IP address of the DR interface.
z Backup Designated Router: IP address of the BDR interface
z Neighbor: Router ID of the neighbor router.