3Com S7906E - Switch, Configuration Manual

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P2P: When the link layer protocol is PPP, LAPB, HDLC, or POS, OSPF considers the network type
as P2P by default.
You can change the network type of an interface as needed. For example:
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When an NBMA network becomes fully meshed through address mapping, namely, when any two
routers in the network have a direct virtual link in between, you can change the network type to
broadcast, without manually configuring the neighbors.
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When some routers in the broadcast network do not support multicast, you can change the network
type to NBMA.
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An NBMA network is fully meshed, which means any two routers in the NBMA network have a
direct virtual link for communication. If direct connections are not available between some routers,
the type of interfaces associated should be configured as P2MP, or as P2P for interfaces with only
one neighbor.
If two interfaces on a link are both configured as the broadcast, NBMA or P2MP type, they cannot
establish a neighbor relationship unless they are on the same network segment.
Prerequisites
Before configuring OSPF network types, you have configured:
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IP addresses for interfaces, making neighboring nodes accessible with each other at network layer.
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OSPF basic functions.
Configuring the OSPF Network Type for an Interface as Broadcast
Follow these steps to configure the OSPF network type for an interface as broadcast:
To do… Use the command… Remarks
Enter system view system-view
—
Enter interface view
interface interface-type
interface-number
—
Configure the OSPF network
type for the interface as
broadcast
ospf network-type
broadcast
Required
By default, the network type of an
interface depends on the link
layer protocol.
Configure a DR priority for the
interface
ospf dr-priority priority
Optional
The default DR priority is 1.
Configuring the OSPF Network Type for an Interface as NBMA
After configuring the network type of an interface as NBMA, you need to make some special
configurations.
Because NBMA interfaces cannot find neighbors via broadcasting Hello packets, you need to specify
neighbors and neighbor DR priorities. (A DR priority of 0 means the router does not have the DR
election right; a DR priority greater than 0 means the router has the DR election right).