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Troubleshoot#1: Correlation vs Causation

Network problems can be as simple as follows: Ping neighbor. 100% packet loss. Check network interface, it’s down. Change SFP and you are done, problem solved   But they can also be complex; really complex .. In the past few years, I have had the unplanned privilege to see some of the shi**iest networking problems on earth. Not because I am an unlucky bastard but simply because I am in the position that if it reaches me, then it’s fairly complex. Dealing with such scenarios have taught me some good lessons that are not necessarily limited to networking or IT. …

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Before you buy a Console Server

In my post about out of band management networks I mentioned console servers as a mean of providing centralized remote access to network devices collocated in the same site. This post is a complementary post for the previous one if you are planning to use a console server in your out of band management network. Below are 7 questions to ask before you buy a console server: What access methods does this console server support?     ” Dial up, GSM, IP connectivity” How many serial console ports does the console server provide?    “No. of managed devices” How many Ethernet …

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Out of Band Management Networks – Console Servers

Building a robust out of band management network is a critical part of any service provider or large enterprise backbone. Although failures may not occur frequently but believe me if you are not prepared when they happen you will know how OoB management is important and critical. Network failures do happen for reasons ranging from human errors to power or hardware failures. One of your main objectives as a network designer is to keep your network available and achieve the highest possible up-time. There are a lot of things you can do to achieve these objectives in terms of redundancy …

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What you need to know about ADSL (broadband Networks #1)

ADSL !!! I can hear you say “I know everything about ADSL, its a mature technology and I already know it inside out, why is he  writing about ADSL now?” To be honest I am also surprised by writing about ADSL after working with it for about 7 years now and the rest of the world is talking about FTTx technologies.However, I found it a good start for a series of posts about broadband technologies. Although ADSL is a mature technology, it is still growing even after the spread of fiber technologies and I believe it has the potential to …

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Etherchannel load balancing case study

Etherchannel is a very effective feature that provides redundancy and load distribution within your switching network. However failing to choose the right load distribution algorithm my leave you under utilizing your network resources. We are going to analyze how to select the load balancing method based on placement of switch and traffic type that needs to be load distributed. I’ll base the discussion on traffic direction from LAN1 to LAN2 but same rules apply in the opposite direction. Firstly we need to briefly consider how packets are forwarded from LAN1 to LAN2 PC1: in LAN1 is pinging PC3: …

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