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Routing problems with quick fixes that Every Network Specialist should KNOW! Highlighted

Latest reply: Sep 15, 2021 13:45:33 553 33 20 0 3

Routing problems with quick fixes that Every Network Specialist should KNOW!

 

INTRODUCTION

Routing has same value in Networks as heart in the body, if it stops beating even for few seconds we are in critical condition, Same goes for routing, when it malfunctions, it could be considered as major business disaster (MBD) for business operations.


BRIEF INFORMATION



For avoiding issues /problems occurs due to Routing and/to routing protocols, Every Network engineer should know these FIVE problems with its quick fixes.


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Image Source: BAZTechKnow

 

Troubleshooting the ISSUE

We start with gathering symptoms, questioning end user to isolate the Issue using past knowledge & using the layered models, there are three primary methods for troubleshooting networks:

·        Bottom-up

·        Top-down

·        Divide-and-conquer


Five Common ROUTING problems

Routing issues usually appear when you're first configuring a new piece of network equipment or when anything goes wrong. Routing issues are frequently caused by a configuration or design mistake. Troubleshooting routing issues is difficult since standard tools like ping and traceroute don't always provide the information you need.

 

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Image Source: BAZTechKnow

There are literally hundreds of issues can arise in the world of routing.


Unstable link with Area 0 

 Sometimes OSPF neighbor relationship flapping occurs and routes are not being propagated in OSPF due to link instability of connection with backbone area.

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Image Source: Cisco Website

Reason & Quick Fix

An area is a logical collection of OSPF networks, routers, and links that have the same area identification. All areas in an OSPF autonomous system must be physically connected to the backbone area (area 0). Where not possible, virtual link can be used to connect to the backbone through a non-backbone area.

The link instability may be caused by a faulty optical fiber, faulty optical module, insecurely connected electrical interface, loose cable connection, or link failure.

Redistribution

While redistributing routing sometimes routes do not send properly and causes route loop.

A loop is something else that traceroute will occasionally show you. You'll come across an IP address you've seen before somewhere along the way. That example, a path from router A to B, C, D, C, D. This indicates that router C is passing the packet to router D, which then returns it to router C.

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Quick Fix

To prevent routing loops and route feedback, you must filter the routes appropriately while redistributing routing. The absence of filters is generally a serious issue, but monitoring filters in a complicated and poorly described network is such an administrative load that missing a route here and there is quite frequent.

To avoid this situation, we can tag the route entry and then add a specific tag to the route entry.


BGP is Slow

Normally BGP is fully functional and works as expected so nothing need to worry about, but when we are doing link failover testing and don’t get desired results.

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Image Credit: aptrinhx website 

 


Reason & Quick Fix


BGP has a slow converging time, it will take a few minutes to pick up the change.

BFD can be used to improve link fail detection for making this process little faster.

MAX HOP

When you observe traffic is being dropped for long chain of routers or connectivity and using RIP as IGP (Interior Gateway Protocol) for routing traffic.

 


Reason & Quick Fix

When the hop count is 16, the network is considered unreachable in RIP based configuration.


Hop (networking) - Wikipedia

Mismatch in Parameter

Irregular parameters usually prohibit adjacencies from establishing due to fat fingers, non-standard settings, or incorrect passwords and this applies to almost for all protocols.

OSPF routers must support a common set of parameters in order to create an adjacency. Authentication, area ID, mask, hello interval, router dead interval, and so on are among them.

 

In RIP has two versions, both routers should use the same version as well.

 

Quick Fix

While it's difficult to prevent mistakes. So try to adopt configuration management process religiously.

For RIP configuration, both routers should have the same authentication parameters

 

.. Ending Remarks

Here are some additional tips for enhancing as bonus

     Interface shut: A network on an interface that is in shutdown will not be advertised.

     Passive interface: An interface that has been configured as passive will not send any RIP updates.

    The network command is used to tell RIP what networks to advertise but also where to send RIP routing updates to. Wrong (or missing) network commands will cause issues.

     Route Filtering: Filters might prevent RIP updates from being sent or received.

     Split horizon: Networks that are learned on an interface are not advertised out of the same interface.

     Auto-summarization: Causes issues with discontiguous networks. 

The post is synchronized to: Author groupBAZ's Author Collection

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Sirajs
Created Jul 26, 2021 10:21:20

Great Work... 

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Sirajs
Created Jul 26, 2021 10:22:10

Thanks for sharing
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LuizPuppin
Author Created Jul 26, 2021 10:55:09

Excellent dear BAZ. Good job.
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BAZ
BAZ Created Jul 26, 2021 14:09:13 (0) (0)
Thanks Professor.. Glad you like it  
andersoncf1
MVE Author Created Jul 26, 2021 12:09:15

Well done! Thanks for sharing knowledge dear @BAZ
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Serges_armel
Created Jul 26, 2021 12:30:23

Very good to know. Thank you
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Serges_armel
Serges_armel Created Jul 26, 2021 12:30:46 (0) (0)
 
Saqib123
Created Jul 26, 2021 12:47:32

Routing problems with quick fixes that Every Network Specialist should KNOW!-4051867-1
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EL.BODO
EL.BODO Created Jul 26, 2021 17:50:21 (0) (0)
✌  
Saqib123
Created Jul 26, 2021 12:48:03

Excellent Information !
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Kevin_Thomas
Moderator Created Jul 26, 2021 16:58:20

Nicely done BAZ! Keep up the good work!
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Kevin_Thomas
Kevin_Thomas Created Jul 26, 2021 16:58:28 (0) (0)
 
EL.BODO
EL.BODO Created Jul 26, 2021 17:51:14 (0) (0)
 
bek7
Moderator Created Jul 26, 2021 17:40:30

About route loop, I think it is better if you also include Spanning Tree Protocol (STP)
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BAZ
BAZ Created Jul 28, 2021 08:47:37 (0) (0)
STP is for prevention of Layer 2 loop  
BAZ
BAZ Created Jul 28, 2021 08:49:43 (0) (0)
Thank you dear, will be doing later  
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