Operation Manual – Routing Protocol
Quidway S3900 Series Ethernet Switches-Release 1510 Chapter 4 OSPF Configuration
Huawei Technologies Proprietary
4-4
For example, in Figure 4-1, there are three intra-area routes in Area 19: 19.1.1.0/24,
19.1.2.0/24, and 19.1.3.0/24. If route summary is configured, the three routes are
aggregated into one route 19.1.0.0/16, and only one corresponding LSA, which
describes the route after summary, is generated on RTA.
Area 12
Area 8
Area 19
Area 0
Virtual link
19.1.1.0/24
19.1.2.0/24
19.1.3.0/24
RTA
Area 12
Area 8
Area 19
Area 0
Virtual link
19.1.1.0/24
19.1.2.0/24
19.1.3.0/24
RTA
Figure 4-1 Area partition and route aggregation
4.1.4 OSPF Network Type
I. Four OSPF network types
OSPF divides networks into four types by link layer protocols:
z Broadcast: If Ethernet or FDDI is adopted, OSFP defaults the network type to
broadcast. In a broadcast network, protocol packets are sent in multicast
(224.0.0.5 and 224.0.0.6) by default.
z Non-broadcast multi-access (NBMA): If Frame Relay, ATM, or X.25 is adopted,
OSPF defaults the network type to NBMA. In an NBMA network, protocol
packets are sent in unicast.
z Point-to-multipoint (P2MP): OSPF will not default the network type of any link
layer protocol to P2MP. A P2MP network must be compulsorily changed from
another network type. The common practice is to change an NBMA network into
a P2MP network. In a P2MP network, protocol packets are sent in multicast
(224.0.0.5).
z Point-to-point (P2P): If PPP or HDLC is adopted, OSPF defaults the network
type to P2P. In a P2P network, protocol packets are sent in multicast (224.0.0.5).
II. Principles for configuring an NBMA network
An NBMA network is a non-broadcast and multi-accessible network. ATM and frame
relay networks are typical NBMA networks.
Some special configurations need to be done on an NBMA network. In an NBMA
network, an OSPF router cannot discover an adjacent router by broadcasting Hello
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