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Cisco CCNP / BSCI Exam Tutorial: ISIS Router Varieties
To pass the BSCI exam and earn your CCNP, you've got to know ISIS inside and out. There are numerous similarities in between ISIS and OSPF, but one main difference is that ISIS has three diverse kinds of routers - Level 1 (L1), Level 2 (L2), and L1/L2. water ionizer .
L1 routers are contained in a single area, and are linked to other regions by an L1/L2 router. The L1 uses the L1/L2 router as a default gateway to reach destinations contained in other locations, a lot like an OSPF stub router utilizes the ABR as a default gateway.
L1 routers have no precise routing table entries concerning any destination outdoors their own area they will use an L1/L2 router as a default gateway to reach any external networks. ISIS L1 routers in the very same place ought to synchronize their databases with each and every other.
Just as we have L1 routers, we also have L2 routers. Anytime we're routing amongst locations (inter-place routing), an L2 or L1/L2 router need to be involved. All L2 routers will have synchronized databases as nicely. worth reading .
Each L1 and L2 routers send out their personal hellos. As with OSPF, hello packets permit ISIS routers to type adjacencies. The important difference right 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 type an adjacency.
An ISIS router can act as an L1 and an L2 router at the very 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, even though - 1 for L1 routes and an additional for L2 routes. L1/L2 is the default setting for Cisco routers operating ISIS. The L1/L2 router is the router that tends to make it feasible for an L1 router to send data to one more region. Lewes SEO Online Reputation Management here .
In the next part of my ISIS tutorial, we'll take a more comprehensive look at these ISIS hellos!
