Information Technology Reference
In-Depth Information
The Network Edge Layer
The network edge, shown in Figure 9-3, is responsible for all external connectivity. This
includes customer aggregation, transit, and peering connections. The network edge is the
lowest level in the network hierarchy. Typically, an edge router has uplinks to two aggrega-
tion routers. This provides redundancy for the failure of an aggregation router or the uplink
to the aggregation router.
Figure 9-3
Network Edge
Customer Networks
Network Edge
Aggregation Layer
Network Core
Aggregation Layer
Network Edge
Customer Networks
Services and policy are applied at the network edge. The traffic rates on the edge routers are
much lower than at the aggregation and core routers. This improves the scalability of per-
forming processor-intensive functions, because the processing load is distributed across a
larger number of devices.
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