1st Question:- Campus Network vs Datacenter Network:-
What is a Campus? What is a Data Center? Are they really different? How are they different?
There is a prevailing misconception that "Campus" Routing & Switching is basically the same as "Data Center" Routing & Switching (and vice versa). They both use Layer 2 & Layer 3 (and above), its all based on Ethernet and TCP/IP, and they both need lots of Ports and Bandwidth... so aren't they the same?
That is almost the same as saying a "Car" and a "Truck" are the same, because they both have an engine, tires, a steering wheel, and a gas and brake pedal. On the surface they are the same... but its the specific job / role that they are designed for, that is different.
The same is true for Campus vs. Data Center routers & switches.
The "Campus" is where USERS (employees) connect to the network, along with all of the devices those employees use (e.g. desktops, laptops, ip phones, mobile phones, video conferencing, printers, etc). These devices are a mix of wired & wireless Ethernet, generally in the 100M to 1G range, some are L2 and some L3, and the types of applications range widely from Email to Web to Video, and so on. These types of applications have a wide range of bandwidth and delay sensitivity requirements.
The "Data Center" is where DEVICES connect to the network, and are mainly rack servers, load balancers, firewalls and other such devices designed to process and exchange "data". These devices are almost completely wired, generally in the 1G to 10G (or higher) range, primarily L2 (within the DC), and the types of applications are primarily database management, virtual machine management, and file transfers. These types of applications have relatively simple bandwidth (albeit large in quantity) and little delay sensitivity.
When considered in this regard, it should be clear that Campus R&S and Data Center R&S are actually very different... and the routers & switches you select should be designed to maximize their potential, based on these very different set of requirements.
2- Question: Catalyst vs Nexus:-
Cisco catalyst switches are mainly designed for distro/core layers in campus network vs the Nexus is mainly for data centers. Nexus series switches can support Ethernet, Fiber Channel and FCOE all in the same chassis but the catalyst don't. The catalyst switches support only Ethernet.
The Nexus offers more bandwidth capacity (although the 6500s have somewhat narrowed the gap with the sup2T) and the Nexus had its FEXs (but 6500s have narrowed this too with the new IAs.)
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