Summary of Routing Between VLANs
This list that follows summarizes the key points that were discussed in this section.
?– Inter-VLAN routing using a router on a stick utilizes an external router to pass traf?¬?c
between VLANs.
?– A router on a stick is con?¬?gured with a subinterface for each VLAN and 802.1Q trunk
encapsulation.
Securing the Expanded Network
Routers and switches that are internal to an organization often have minimal security
con?¬?gurations, which render them targets for malicious attacks. If an attack is launched at
Layer 2 on an internal campus device, the rest of the network can be quickly compromised,
often without detection.
This section discusses security features that exist to protect switches and Layer 2
operations.
Overview of Switch Security Concerns
Much industry attention surrounds security attacks from outside the walls of an
organization and at the upper Open Systems Interconnection (OSI) layers. Network
security often focuses on edge routing devices and the ?¬?ltering of packets based on Layer 3
and Layer 4 headers, ports, stateful packet inspection, and so on. This focus includes all
issues surrounding Layer 3 and above, as traf?¬?c makes its way into the campus network
from the Internet.
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