WHY ISIS :
As we all know that ISIS is making a comeback in form of entirely different forwarding technologies like Fabric path(Cisco), SPB(Avaya,Alcatel etc),Qfabric(juniper). Specially in the world of data center in coming few days you would see the necessity to learn ISIS. Considering this even Cisco has introduced ISIS in its CCIE RnS v5 curriculum. So here I would be publishing few of the basic and advanced labs and articles related to ISIS…have fun!!
ISIS has many similarities with ospf as it uses same kind of the forwarding algorithm. So to understand this protocol it would be good if you revise your ospf basics . Below is the small description of ISIS and its attributes:
Brief history :
ISIS was developed by a company named DEC and from there IEEE has taken it for standardization. Once it has become open standard , it has evolved as preferred IGP within ISP networks. Initially ISIS was only designed for OSI addressing that means there was no IP support for the protocol …the protocol has its own mechanism for learning and forwarding and its different than how we do in IP e.g. we don’t use ARP , DHCP etc in ISIS rather ISIS has its own hello mechanism to do the everything. As the time changed and need to IP based networked increased ISIS also changed into integrated ISIS or Dual ISIS which started the support of IP over it. Then many new protocol came in picture with better reliability and more tweaking features like EIGRP,OSPF and people stopped using ISIS. But as ISIS has very flexible characteristics to accommodate new TLVs and that enabled it to make a comeback like a king of IGPs again …this time even in better shape and with better powers as its going to give better L2 network than what we had with STP …yes!! there is no need to learn all port states and roles and convergence etc …!!
For now this should be enough ….you see the image above the post ? That I would be explained in my coming posts with few more tech articles about ISIS and related technologies like SPB and Fabric path….happy learning!!
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