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CCNP Tutorial For The BSCI Exam:

ISIS Hello Packet Types

By Chris Bryant, CCIE #12933

This is just one of several ISIS tutorials I've written to help you beat the July 31, 2010 deadline for the BSCI exam. Links to the other tutorials are right here, and there's more to come - so be sure to visit our BSCI Exam Resource Center daily in March for more tutorials!

ISIS Fundamentals

BSCI Tutorial: ISIS Router Types (L1, L2, L1/L2)

The July 2010 CCNP Changes (And How To Beat Them!)

Now let's get to the tutorial!

With OSPF, one hello packet is pretty much like another. While hello packets serve as keepalives for both ISIS and OSPF, ISIS actually features three different hello types...and you better know them before taking your CCNP BSCI exam! :)

An ES Hello (ESH) is send by all End Systems, and all IS devices listen for this Hello. This is how a router (IS) discovers a host (ES).

End System Hello For BSCI Exam

An IS Hello (ISH) announces the presence of an IS. An IS Hello is sent by all IS devices, and End Systems listen for these hellos.

IS Hello For CCNP Certification

Finally, an IS-to-IS Hello (IIH) is used by an IS to discover other ISes and to form adjacencies with them.

IS-to-IS Hello On A Cisco Router

An interesting side note: A router will send an IIH to another router on the link to form or maintain an adjacency, but it will still send an ISH as well in case there are end systems located on that segment.

IIH and ISH

ISIS takes some getting used to when you first start working with it, since it's unlike any other protocol you're studied. Once you get the fundamentals down, though, you'll be comfortable with in in production networks and in the CCNP exam room!

Earn Your CCNP With The Personal Guarantee Of Chris Bryant, CCIE #12933:

“I GUARANTEE You'll Pass The Current CCNP Exams - BSCI, ONT, ISCW, and BCMSN - Before The July 31, 2010 Cutoff Date With My CCNP Study Packages ...

... And If You Don't Pass FOR ANY REASON Before That Time, I'll Give You a 100% Free CCNP Study Package Download For The New Exam Track!"

You Also Get A FREE CCNA Security Study Package, Valued at $67, With The Purchase Of Any CCNP Study Package!