MPLS in the DataCenter? According to Juniper, they say "HECK YEAH!" and I can totally see why. Most data centers have a nicely redundant, fully meshed switching architecture. Most host servers are multi-homed (or connected to two separate switches for redundancy) and the access layer switches are multi-homed to the core to provide a fast spanning tree for all layer two traffic.  And this is great for switching, but move up a layer and more times than not the routing occurs in more spot, at the core on two dedicated routers operating in some sort of failover configuration (HSRP).

Switches have come a long way and even your rack level or IDF closet switches can now route.  However, most still switch frames up to the core router to be routed.  Most facilities have  switches deployed through out the data center that have the ability to route but are just not used.

Wouldn't it be great if the routing decisions could be made right at the edge? Well Juniper has a clever way to wake up your sleeping routers and begin to add more intelligence between your layer 2 switching and your later 3 routing. Best of all you're probably using it on your WAN circuits now.  It's MPLS!!

By using MPLS to overlay on top of your OSPF routing protocol within the DataCenter you greatly increase the intelligence and security of your OSPF routing to better optimize  your interior data center traffic. I personally don't fully understand all of the details in how MPLS integrates with the layer 2 protocol such as Spanning-Tree is or how Juniper provides its ciruit to packet resiliency.  It could be just vendor fluff, but  one thing is for sure, Juniper has been doing provider level services such as mpls and ipv6 for a long time and doing it very well.

I know, I know.. Your saying "Your switches and routers in the data center don't talk MPLS".  Well with Juniper Network's EX 4200 Series Ethernet with Virtual Chassis Technology they can! And they're are listed at a great price point! Between $10-$11K list means you should be able to pick one of these puppy's up for around $5-6K depending on quantity and your relationship with your VAR.

The EX 4200 series switches offers a full suite of layer2 and layer3 switching capability to satisfy a variety of high-performance deployments including branch and data center locations.  This is the same performance that we've come to enjoy in other switches like the  Cisco 3750 line.  But the Juniper EX 4200 goes one step further.

Every switch is PoE. No need to worry about future upgrades for VoIP or wireless AP's that need PoE power. Every switch enjoys the Juniper Networks Virtual Chassis Technology with allows up to 10 EX 4200 series switches to be interconnected over a 128 gigabit backplane (I believe Cisco can only do 64 gig).  Port density will scale from 24 ports on up to 480 10/100/1000 ports.  And every switch has the capability to have either Gigabit Ethernet or 10-Gigabit Ethernet uplink options for high-speed connectivity to your aggregation or core layer switches.

All Juniper EX 4200 switches include HA features for redundant, hot swappable internal power and fan trays. Plus the full gamut of JUNOS routing protocols to allow for any standard dynamic routing configuration you can think of.  But best of all these little babies will run MPLS to totally hyper charge your data center traffic and bridge your layer 2 and layer 3 protocols for optimum data flow.

I got one of these EX 4200's to play with and will be writing more later.  If these are even close to what has been promised I expect to see phenomenal things.

FREAK!!!

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Today I'm going to get back to basics and discuss the 7 layer OSI reference model and how it applies to networking.  Most experienced network engineers know the OSI model all to well and most if not all certifications will expect you to know it. So lets unwrap this 7 layer burrito and see whats inside.

The first thing we need to understand is what is the OSI reference model anyway?  Well,  Wikipedia defines it as - The 'Open Systems Interconnection Basic Reference Model' (OSI Reference Model or OSI Model) is an abstract description for layered communications and computer network protocol design.

Basically it is structure of guide lines for developers and equipment manufacturers to be able to follow when designing new network cards, create new network drivers, new network software, etc and feel confident that the widget will work once it hits the wire.

So the 7 layers of the OSI Model is broken down as follows:  Application, Presentation, Session, Transport, Network, Data Link, and Physical.  Lets look at each one to get a better idea of how each one works and what each layer is responsible for.

Application - This is the layer that is closest to the user. In a web application this would be the browser.

Presentation - This layer would define how the application is presented to the user. Again using the web example. The html of a web page would fall into the presentation layer.

Session - This layer established the communication between computers. From client to server. In our web application the http protocol would fit nicely in the preentations layer.

Transport - This layer provides reliable transport services to the upper layers between users. At this point the TCP session of our web application is functioning here. The TCP syn-synack-ack occurs at the transport layer.

Network - This is the layer that ensures a functional means of having variable data lengths transfer from source to destination between different networks.  Here is where IP is defined and routing occurs.

Data Link - This layer provides a functional means to transfer data between network entities. This is where the MAC address lives and switching and bridging occurs.

Physical - This layers defines the physical and electrical specifications for devices. This is where the rubber meets the road.  Here is where the one's and zero's get put out onto the wire. This is also where cable specs are maintained, network drivers and the transition from physical to electrical occurs.

Now not everyone may agree with my definitions and there has been volumes written about exactly what occurs within the OSI Model. In my example I am merely trying to give a brief overview and understanding of what the OSI reference model is.

In order to help you memorize the OSI model its often helpful to use an analogy.  There are a couple common ones you can use.  One popular one is - All People Seem To Need Data Processing.  Or you can make one up.  Either way the, more you understand the  OSI Model the more it will help you in your networking career.

Until next time

Get your Freak On!

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