State

The communication state for two adjacent routers:

 

 

 

 

 

Down:

This is the initial state of a neighbor conversation. It Indicates

 

 

 

 

that there has been no recent information received from the

 

 

 

 

neighbor.

 

 

 

Attempt:

This state is only valid for neighbors attached to

 

 

 

 

non-broadcast networks. It indicates that no recent

 

 

 

 

Information has been received from the neighbor, but that the

 

 

 

 

router is attempting to contact the neighbor by sending Hello

 

 

 

 

packets.

 

 

 

Init:

A Hello packet has recently been seen from the neighbor.

 

 

 

 

However, bidirectional communication has not yet been

 

 

 

 

established with the neighbor.

 

 

 

2-Way:

Communication between the two routers has been

 

 

 

 

established. This is the most advanced state short of

 

 

 

 

beginning adjacency establishment. Note that both the

 

 

 

 

Designated Router and Backup Designated Router are

 

 

 

 

selected from the set of neighbors in state 2-Way or greater.

 

 

 

ExStart:

This is the first step in creating an adjacency between the two

 

 

 

 

neighboring routers. The goal of this step is to decide which

 

 

 

 

router is the master, and to decide upon the initial sequence

 

 

 

 

number. Neighbor conversations in this state or greater are

 

 

 

 

called adjacencies.

 

 

 

Exchange:

The router is describing its entire link state database by

 

 

 

 

sending database description packets to the neighbor. (Each

 

 

 

 

database description packet has a sequence number, and is

 

 

 

 

explicitly acknowledged.) All adjacencies in Exchange state or

 

 

 

 

greater are used by the flooding procedure. In fact, these

 

 

 

 

adjacencies are fully capable of transmitting and receiving all

 

 

 

 

types of OSPF routing protocol packets.

 

 

 

Loading:

Link State Request packets are sent to the neighbor asking

 

 

 

 

for more recent advertisements that have been discovered

 

 

 

 

(but not yet received) in the exchange state.

 

 

 

Full:

The neighboring routers are fully adjacent. These adjacencies

 

 

 

 

will now appear in router links and network links

 

 

 

 

advertisements.

 

 

 

 

 

 

 

Events

The number of events encountered that cause a neighbor state change

 

 

 

since boot up.

 

 

 

 

 

 

Note:

To scroll through the table, use the <Next Page> and <Prev Page> buttons. To display a specific page, set the page number in the Page field and select <Apply>.

Displaying the Virtual Neighbor Table

Virtual links can be used to link an area isolated from the backbone, to create a redundant link between any area and the backbone to help prevent partitioning, or to connect two existing backbone areas into a common backbone. Note that the processes of establishing a active link between virtual neighbors is similar to that used for

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Image 102
LevelOne GSW-2600TXM manual Displaying the Virtual Neighbor Table