Avaya Configuring Interface and Router Redundancy Manuel d'utilisateur télécharger pdf (Page 25)

Router Redundancy Overview

2-3

The primary router periodically checks that it is functioning normally. If the

primary router is not functioning properly, a role change occurs, as follows:

1. The primary router notiﬁes the best secondary router that it intends to change

out of the primary role.

2. The best secondary router informs the other members of the impending role

change, and those members start a timer (using the Bidding Timer value) to

prevent additional role changes by other members.

3. The best secondary router reboots using the primary conﬁguration ﬁle and

assumes primary status.

able 2-2 describes how a primary router changes to a secondary role while the

best secondary router assumes the primary role.

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

times.

Router B determines that the primary

router has failed.

Based on information in the redundancy

group database, it is determined that

Router B is the best secondary router to

become the new primary router.

Router B sends a SOS New Primary

PDU, which prevents other secondary

routers 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 ... 20 21 22 23 24 25 26 27 28 29 30 ... 71 72

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Avaya Configuring Interface and Router Redundancy Manuel d'utilisateur Page 25

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