Avaya Configuring Interface and Router Redundancy Bedienungsanleitung PDF herunterladen (Seite 23)

Router Redundancy Overview

308626-14.00 Rev 00

2-3

Receives Hello PDU from Router B and

stores its contents in the redundancy

group database.

Checks to see if Router B is a better

primary router; if so, Router A does not

plan to change roles.

Hello PDU

Role = Secondary

<----------------

Starts sending Hello PDUs at periodic

intervals; these PDUs are Router B’s bids for

the primary role.

After the bidding period times out, the

software determines that Router A is the

best primary router.

Router A sends the SOS New Primary

PDU, and then changes role to become

the primary router.

SOS New

Primary PDU

Role = Secondary

---------------->

After the bidding period times out, the

software determines that another member of

the router redundancy group is the best

primary router.

Router B remains in a secondary role and

continues to monitor the redundancy group

status.

Receives the periodic Hello PDU and

updates the redundancy group database,

including each member’s interface status

information.

Hello PDU

Role = Secondary

<----------------

Continues sending periodic Hello PDUs with

local interface status information.

Continues sending periodic Primary

Hello PDUs with local interface status

information.

The Primary Hello PDUs from the

primary router have additional meaning

to other members of the redundancy

group.

Hello PDU

Role = Primary

---------------->

Receives the periodic Primary Hello PDUs

and updates the redundancy group

database, including each member’s interface

status information.

Restarts the Primary OK Timer.

Time Passes

Primary router fails.

Router A is in an unknown state; may not

have received this PDU.

SOS New

Primary PDU

Role = Secondary

<----------------

Primary OK Timer expires for

n

times.

Router B determines that the primary router

has failed.

Based on information in the redundancy

group database, the software determines

that Router B is the best secondary router to

become the new primary router.

Router B sends an SOS New Primary PDU,

which prevents any other secondary router in

the group from becoming the primary router.

Router B becomes the new primary router.

Router A remains in an unknown state;

may not have received this PDU.

Hello PDU

Role = Primary

<----------------

As the new primary router, Router B

periodically sends Primary Hello PDUs with

local interface status information.

Table 2-1. Redundancy Protocol PDU Flow Diagram for Role Bidding

(continued)

Router A PDU Router B

1 2 ... 18 19 20 21 22 23 24 25 26 27 28 ... 89 90

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