OSPF: DESIGNING OSPF FAILOVER & AVOIDING ASYMMETRIC LOOP


SCENARIO

Our company name: AB 

New company name: CG

CG is planning to get connected to AB through OSPF connectivity.

We have two Locations, A & B in our Company.

In simple terms,  Routers, R1 at Location A  & Router, R2 at Location B.

Company, CG will connect to our Company, AB, through Router R1  &  Router R2 using OSPF.

 

SCENARIO DIAGRAM

DOWNLOAD —–>  overview


 

OBJECTIVES 

1. OSPF Connectivity between Company, CG  &  Our Company, AB

 

2. OSPF Dual Connectivity for Fail over  Purpose

 

3. Asymmetric Loop Avoidance

What is Asymmetric Loop?

 

Example in our scenario

At R1, new subnet from Company, CG will be learned at Company, AB  through two different paths

Path 1: Through Direct connection: CG  ——>   R1

Path 2:  Through Diverted path: CG  —–>  R2  ——>  R1

To avoid this, we utilize OSPF process ID. At R1, we make process ID 100 & 200. By default, Two different Processes cannot exchange subnets.

Point To Note: OSPF  Process ID is locally significant to Router

Reference Link

https://networkproxy.wordpress.com/2014/07/11/ospf-tshoot-understanding-process-id-topology/

 

This is just an Overview …..


 

DESIGN DOCUMENTS

I have picked configuration from Live Environment & prepared explained document for Two Different Location, Location A & location B.

PLAN OF ACTION FOR ” LOCATION A “

DOWNLOAD ——> CG DIAGRAM & CONFIG LOCATION A

 

PLAN OF ACTION FOR ” LOCATION B “

DOWNLOAD ——-> CG DIAGRAM & CONFIG LOCATION B


 

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