HP 4500G PWR 24-Port, Configuration Manual

Page: 459 / 1968

1-24
z
It is required to use the
nssa
command on all the routers attached to an NSSA area.
z
Using the
default-cost
command only takes effect on the ABR/ASBR of an NSSA area.
Configuring a Virtual Link
Non-backbone areas exchange routing information via the backbone area. Therefore, connectivity
between the backbone and non-backbone areas and within the backbone itself must be maintained.
If necessary physical links are not available for this connectivity maintenance, you can configure virtual
links to solve it.
Follow these steps to configure a virtual link:
To do… Use the command… Remarks
Enter system view
system-view
—
Enter OSPF view
ospf
[
process-id
|
router-id router-id
|
vpn-instance instance-name
] *
—
Enter area view
area area-id
—
Configure a virtual
link
vlink-peer router-id
[
hello seconds
|
retransmit seconds
|
trans-delay
seconds | dead seconds
|
simple
[
plain
|
cipher
]
password
| {
md5
|
hmac-md5
}
key-id
[
plain
|
cipher
]
password
] *
Required
You need to configure this
command on both ends of a
virtual link.
Note that
hello
and
dead
intervals must be identical on
both ends of the virtual link.
Configuring OSPF Network Types
OSPF classifies networks into four types: broadcast, NBMA, P2MP, and P2P, upon the link layer
protocol.
You can change the network type of an interface as needed. For example:
z
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.
z
When some routers in the broadcast network do not support multicast, you can change the network
type to NBMA.
z
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.