You should know where the router is
located in the hierarchy and what the key needs are for a given
layer so that the router can be configured to meet the specific
needs of the layer. Although some needs are common to all layers,
other needs are unique, or more critical to certain layers, as in
the following example: Core routers must be reliable because they
carry information about all the routers in an internetwork. If one of
these routers goes down, it affects routing on a larger scale than
when an access router goes down.
- Distribution routers need to be able to select the best path
to different locations in order to make efficient use of
bandwidth.
- Access routers are typically where you provide security and
filtering. Access routers reduce the amount of overhead by
keeping unnecessary traffic out of the core of the network.
- Examples of Cisco routers that can be used at each layer of
the hierarchy follow:
- Core --- Cisco 7000 and 12000 series routers
- Distribution --- Cisco 3000 and 4000 series routers
- Access --- Cisco 1700 and 2600 series routers
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