Hello packages have been mentioned several times with ISIS, and with good reason. Hello packets are the heartbeat of the OSPF and ISIS if heartbeats are no longer heard by a neighbor, that the proximity is dropped. A major difference between OSPF and ISIS is that OSPF has a kind of packet hi, where ISIS actually has three!
An ES hello (ESH) is at the end of all systems, equipment and everything is listen to this hello. This is how a router (IS) discovers a host (ES).
An IS hello (ISH) announces the presence of an IS. One is by hi Everything is devices and systems for these hear hellos.
An IS-IS hello (IIH) is used by an IS to discover and other adjacencies with ISES to them.
An interesting page NOTE: A router sends a IIH to another Router on the link to the form or maintaining close, but it is still by ISH as well as for the case, there are end-systems on the segment.
ISIS OSPF and both create and maintain adjacencies with the hi packet. Let& 39;s take a look at the rules on ISIS adjacencies and the proximity types.
L1 and L2 Hellos are different messages, so that an L1 router must exchange Hellos L1 with another router to a close, as well as L2 routers form adjacencies with L2 Router. L1 router can only close with a L2 routers, when one of the two parties router is actually a L1/L2 router.
L1 router must be in the same area to a close. The hi timers, as well as the MTU, must match between the interfaces to the form of adjacency.
That & 39; of a quantity of L1, L2, and L1/L2, is not it? Let & 39; s review of adjacencies each router-type form:
L1: Can form near L1 with any L1/L2 in the same area and all the same area.
L2: Can form close with a L2 in each area and a L1/L2 in any area.
L1/L2: Can form with a close L1 in the same area, L1/L2 in every area, and L2 in any area.
Knowing the similarities and differences in terms of ISIS and OSPF is of crucial Importance for the CCNP exam success. Take time to master the basics, and long before the magic letters " CCNP " are behind your name and on your application!
Chris Bryant, CCIE 12933, is the owner of the Bryant Advantage (http://www.thebryantadvantage.com), home of free CCNA, CCNP tutorials, The Ultimate CCNA Study Package, Ultimate CCNP Study Packages, and CCNA CBT Video Training. Pass the CCNA exam, BSCI exam, and BCMSN exam with Chris Bryant, CCIE 12933!
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