Cisco CCNP / BSCI Exam Tutorial: ISIS Router Types

To pass the BSCI exam and earn your CCNP, you've got to know ISIS inside and out. There are many similarities between ISIS and OSPF, but one major difference is that ISIS has three different types of routers - Level 1 (L1), Level 2 (L2), and L1/L2.

L1 routers are contained in a single area, and are connected to other areas by an L1/L2 router. The L1 uses the L1/L2 router as a default gateway to reach destinations contained in other areas, much like an OSPF stub router uses the ABR as a default gateway.

L1 routers have no specific routing table entries regarding any destination outside their own area; they will use an L1/L2 router as a default gateway to reach any external networks. ISIS L1 routers in the same area must synchronize their databases with each other.

just as we have L1 routers, we also have L2 routers. Anytime we're routing between areas (inter-area routing), an L2 or L1/L2 router must be involved. All L2 routers will have synchronized databases as well.

Both L1 and L2 routers send out their own hellos. As with OSPF, hello packets allow ISIS routers to form adjacencies. The key difference here is that L1 routers send out L1 hellos, and L2 routers send out L2 hellos. If you have an L1 router and an L2 router on the same link, they will not form an adjacency.

An ISIS router can act as an L1 and an L2 router at the same time; these routers are L1/L2 routers. An L1/L2 router can have neighbors in separate ISIS areas. The L1/L2 router will have two separate databases, though - one for L1 routes and another for L2 routes. L1/L2 is the default setting for Cisco routers running ISIS. The L1/L2 router is the router that makes it possible for an L1 router to send data to another area.

In the next part of my ISIS tutorial, we'll take a more detailed look at those ISIS hellos!

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Golf Swing Help - A Guaranteed Way To Improve Your Swing

Getting golf swing help is as simple as booking into your local club for lessons from a private instructor.

Yes, it will cost you money for private tuition but then how serious are you about improving your golf swing?

Too many golfers try to take shortcuts with many relying on books and DVDs to master the art of the golf swing. this is okay however, the one ingredient missing is you cannot ask questions. You could use as many books and DVDs as you want and you could pick up some handy tips but there's nothing like having the watchful eye of an instructor looking over you.

How Many Lessons Do You Need?

this depends at what level you are at. A private instructor is handy for golf swing swing help for those players who have hacked around the course for awhile and haven't shown too much improvement.

The danger with this is golfers can get into bad habits which can be difficult to overcome. private tuition is the first step in getting your game on track and onto the next level.

How many lessons you need depends on how much golf swing help you require. If it's just to iron out one deficiency then one or two lessons could be sufficient and this is then followed up with plenty of practice.

For outright beginners, a minimum of six lessons at least should be the target. One lesson a week should be enough because in between, you'll have several days to put into practice what you've learnt.

Using an instructor for golf swing help will enable you to maximise your skill development. this is your private time so ask as many questions as you can.

Group Or Individual Coaching

One on one tuition is preferred particularly if you don't respond well in a group situation. The main benefit of course is you'll get individual attention.

It's your call... are you serious about improving your game? Getting golf swing help from a qualified instructor is the most likely way you'll shortcut your learning curve.

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