Tag: cisco

CLOS Topology

Edson Erwin invented this highly scalable and optimized way of connecting network nodes in the 1930s and Charles Clos made the telephone nodes interconnection design using that solution. It was even before we had IP networks. He invented it in order to optimize the architecture of telephony network systems back then.

It was not used in IP based network for last few decades but it experienced a big comeback with new datacenter design in the last few years. It was first invented only for scalability requirements that it solved beautifully. In new datacenter design, CLOS topology of interconnecting network devices scalability is also the first requirement that gets solved, but it also greatly helps with improving resiliency and performance.

In today’s datacenters, CLOS topology is used to create Leaf’n’Spine system of interconnecting Leaf switches (datacenter access switches or ToR switches) together through Spine switches. It is created in a way that each Leaf switch is redundantly connected to all Spine switches directly.

As it is shown in the picture below, in this way, using CLOS topology, we are interconnecting Leaf switches in a way that they always have only two hops between each other and this done redundantly as two hops through each Spine switch. Spines are not directly connected and Leafs are also not directly connected.

CLOS

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Cisco Champion for 2019

Again I made it to the list of Cisco Champions, making this the second year in a row!

Cisco Champion 2019

I am so glad that my effort to give back to the community and to all my networking fellows out there paid off again in the shape of this recognition from Cisco. This badge is only a small thing, relating to all the community connections and sharing that my involvement with networking community via social media and this blog, made possible. It only pushes me to get even more done in the future.

In 2018 I was involved in a few very challenging new projects, working with Cisco ACI and VMware NSX, and basically studying and researching continuously in order to get to know the products as much as it was possible, it resulted in not being so active on my blog or twitter this year.

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I Became Cisco Champion for 2018

I just received an e-mail from Cisco with the notice that I was elected Cisco Champion for 2018.

As Cisco says:

Cisco Champions are a group of highly influential technical experts who generously enjoy sharing their knowledge, expertise, and thoughts on the social web and with Cisco. The Cisco Champion program encompasses a diverse set of areas such as Data Center, Internet of Things, Enterprise Networks, Collaboration, and Security. Cisco Champions are located all over the world.”

I must say that last 7 years of writing this blog was the primary reason why one should pick me for this flattering badge.

I’m following some of the most active Cisco Champions on Twitter for years.

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Source-Specific Multicast Configuration

In SSM, Source-Specific Multicast, things are done differently from standard multicast forwarding. SSM is specifying a group of hosts that are receiving same multicast stream using group IP address and additionally using stream unicast source IP.

In this article it is shown how to configure Source Specific Multicast on Cisco and Juniper equipment.

In standard multicast, forwarding is done using group IP address which is an IP from multicast dedicated range 224.0.0.0/4 (224.0.0.0 – 239.255.255.255) or FF00::/8 in IPv6. Each multicast group IP address is a single address which specifies all hosts receiving a specific stream, streamed towards that group IP address from multicast source. In standard multicast everybody can start to stream with some IP multicast group IP, becoming in that way, the multicast source.

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When they throw a Cisco guy to do something with HP networking gear

…There’s a nice little pdf to get you through

UPDATE on 13 Nov 2015:
It was a real pleasure to have Jeff Carell joining in with a comment about an updated version of “HP Networking and Cisco CLI Reference Guide”. Jeff is the author of “Guide to TCP/IP 4th Ed”, a great network fellow and IPv6 enthusiast whose work on informing the community about networking technology is greatly appreciated by the author of this blog. Link is added to the end of the post. Thanks Jeff.

HP is aware that most of networking engineers start their learning process in Cisco Networking Academy. Is is a normal course of events if you want to learn networking. Cisco has the very best study materials and best, carefully developed syllabus that is both high quality and most detailed in the world of networking. Not to mention the high reputation that engineers get with Cisco certificates standing by their names.

Cisco CLI

On the other hand, when you take an average mid-size business customer today you will probably see that he is mostly concerned about the price and not so much about the feature-set and robustness of IT equipment. And there you have your situation in which customer decides to go with HP rather than Cisco gear in their communication closet.

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