Ospf Network Type - Huawei Quidway S5600 Series Operation Manual

Operation Manual – Routing Protocol
Quidway S5600 Series Ethernet Switches-Release 1510
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:
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.
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.
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).
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
packets. Therefore, you must manually specify an IP address for the adjacent router
and whether the adjacent router has the right to vote for a DR.
An NBMA network must be fully connected. That is, any two routers in the network must
be directly reachable to each other through a virtual circuit. If two routers in the network
are not directly reachable to each other, you must configure the corresponding
Area 0 Area 0
Area 8 Area 8
Huawei Technologies Proprietary
Area 12 Area 12
Virtual link Virtual link
RTA RTA
4-4
Chapter 4 OSPF Configuration
19.1.1.0/24 19.1.1.0/24
Area 19 Area 19
19.1.3.0/24 19.1.3.0/24
19.1.2.0/24 19.1.2.0/24