MLS Requirements

MLS Requirements
Some Cisco Catalyst switches require additional hardware to make use of the packet header
information. While the 3550 series and the 4000 series with the Supervisor IV card have onboard
processing, Catalyst 6000 series switches use the
Multilayer Switch Feature Card (MSFC)
and the
Policy Feature Card (PFC)
to gather and cache header information. (You may remember
that the old Catalyst 5000 switches used the
NetFlow Feature Card (NFFC)
to gather this
information and cache it.) A detailed process, which will be discussed later in this chapter,
enables switches to establish flows.
MLS requires three components to function in any network (we have already briefly discussed
two of them):

Multilayer Switching Route Processor (MLS-RP)
is a directly attached router. This can be
an MLS-capable external router or an RSM installed in the switch.

Multilayer Switching Switch Engine (MLS-SE)
is an MLS-capable switch (a 6000 with an
MSFC and PFC).

Multilayer Switching Protocol (MLSP)
is a protocol that runs on the router and enables it
to communicate to the MLS-SE regarding topology or security changes.
Now that you have a basic understanding of what MLS does and what is required for MLS
to function in a network, let’s get into the nitty-gritty of how it works. Throughout the rest of
the chapter, you will see the preceding abbreviations many times.