H3C S9500 Series Operation Manual page 260

Operation Manual – Routing Protocol
H3C S9500 Series Routing Switches
Table 4-19 Set an interval for LSA retransmission between neighboring routers
Configure the interval of LSA retransmission
for the neighboring routers
Restore
interval for the neighboring routers
By default, the interval for neighboring routers to retransmit LSAs is 5 seconds.
The value of interval should be bigger than the roundtrip value of a packet.
Note that you should not set the LSA retransmission interval too small. Otherwise,
unnecessary retransmission will be caused.
4.2.11 Configuring the Network Type of the OSPF Interface
The route calculation of OSPF is based upon the topology of the adjacent network of
the local router. Each router describes the topology of its adjacent network and
transmits it to all the other routers.
OSPF divides networks into four types by link layer protocol:
Broadcast: If Ethernet or FDDI is adopted, OSPF defaults the network type to
broadcast.
Non-Broadcast Multi-access (nbma): If Frame Relay, ATM, HDLC or X.25 is
adopted, OSPF defaults the network type to NBMA.
Point-to-Multipoint (p2mp): OSPF will not default the network type of any link layer
protocol to p2mp. A p2mp network is always changed from another type of
network. The general undertaking is to change a partially connected NBMA
network to p2mp network if the NBMA network is not fully connected.
Point-to-point (p2p): If PPP, LAPB or POS is adopted, OSPF defaults the network
type to p2p.
NBMA means that a network is non-broadcast and multi-accessible. ATM is a typical
example for it. The user can configure the polling interval to specify the interval for
sending polling hello packets before the adjacency of the neighboring routers is formed.
Set the network type to NBMA if routers not supporting multicast addresses exist in a
broadcast network.
Set the interface type to p2mp if not all the routers are directly accessible on an NBMA
network.
Change the interface type to p2p if the router has only one peer on the NBMA network.
The differences between NBMA and p2mp are listed below:
Operation
the default LSA
ospf timer retransmit interval
retransmission
undo ospf timer retransmit
4-18
Chapter 4 OSPF Configuration
Command