Configuring The Network Type On The Ospf Interface - Huawei Quidway S3500 Series Operation Manual

Operation Manual - Routing Protocol
Quidway S3500 Series Ethernet Switches

4.2.5 Configuring the Network Type on 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. 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 of
sending polling hello packets before the adjacency of the neighboring routers is formed.
Configure the interface type to nonbroadcast on a broadcast network without
multi-access capability.
Configure 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:
In OSPF, NBMA refers to the networks that are fully connected, non-broadcast and
multi-accessible. However, p2mp network is not required to be fully connected.
DR and BDR are required on a NBMA network but not on p2mp network.
NBMA is the default network type. For example, if ATM is adopted as the link layer
protocol, OSPF defaults the network type on the interface to NBMA, regardless of
whether the network is fully connected. P2mp is not the default network type. No
link layer protocols will be regarded as p2mp. You must change the network type
to p2mp by force. The commonest undertaking is to change a partially connected
NBMA network to a p2mp network.
NBMA forwards packets by unicast and requires to configure neighbors manually.
P2mp forward packets by multicast.
Perform the following configuration in Interface view:
Huawei Technologies Proprietary
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Chapter 4 OSPF Configuration