Using Acceptable MLS Topologies

Using Acceptable MLS Topologies
Few topologies support MLS. Due to the nature of MLS, only certain system topologies allow
candidate and enable packets to transit the router and switch properly. If both candidate and
enable packets cannot be identified, no complete flow cache entry can be made. Acceptable
topologies include the following:
Router on a stick This includes one router (internal RSM/MSFC or external) and one switch.
The router has a single connection to the network, which is the stick (see Figure 18.7).
Multiple switches, one router This is acceptable if only one switch connects to the router and
the switches are connected via an ISL trunk (see Figure 18.8).
The second of the Cisco MLS implementations involves a process called Cisco Express Forwarding
(CEF), which we will discuss in the next section.