Cisco Catalyst 3560-X Software Configuration Manual page 1330

Information About Implementing IPv6 Multicast
Static Mroutes
IPv6 static mroutes behave much in the same way as IPv4 static mroutes used to influence the RPF
check. IPv6 static mroutes share the same database as IPv6 static routes and are implemented by
extending static route support for RPF checks. Static mroutes support equal-cost multipath mroutes, and
they also support unicast-only static routes.
MRIB
The Multicast Routing Information Base (MRIB) is a protocol-independent repository of multicast
routing entries instantiated by multicast routing protocols (routing clients). Its main function is to
provide independence between routing protocols and the Multicast Forwarding Information Base
(MFIB). It also acts as a coordination and communication point among its clients.
Routing clients use the services provided by the MRIB to instantiate routing entries and retrieve changes
made to routing entries by other clients. Besides routing clients, MRIB also has forwarding clients
(MFIB instances) and special clients such as MLD. MFIB retrieves its forwarding entries from MRIB
and notifies the MRIB of any events related to packet reception. These notifications can either be
explicitly requested by routing clients or spontaneously generated by the MFIB.
Another important function of the MRIB is to allow for the coordination of multiple routing clients in
establishing multicast connectivity within the same multicast session. MRIB also allows for the
coordination between MLD and routing protocols.
MFIB
The MFIB is a platform-independent and routing-protocol-independent library for IPv6 software. Its
main purpose is to provide a Cisco IOS platform with an interface with which to read the IPv6 multicast
forwarding table and notifications when the forwarding table changes. The information provided by the
MFIB has clearly defined forwarding semantics and is designed to make it easy for the platform to
translate to its specific hardware or software forwarding mechanisms.
When routing or topology changes occur in the network, the IPv6 routing table is updated, and those
changes are reflected in the MFIB. The MFIB maintains next-hop address information based on the
information in the IPv6 routing table. Because there is a one-to-one correlation between MFIB entries
and routing table entries, the MFIB contains all known routes and eliminates the need for route cache
maintenance that is associated with switching paths such as fast switching and optimum switching.
Distributed MFIB
Distributed MFIB (dMFIB) is used to switch multicast IPv6 packets on distributed platforms. dMFIB
may also contain platform-specific information on replication across line cards. The basic MFIB
routines that implement the core of the forwarding logic are common to all forwarding environments.
dMFIB implements the following functions:
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Catalyst 3750-X and 3560-X Switch Software Configuration Guide
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Distributes a copy of the MFIB to the line cards.
Relays data-driven protocol events generated in the line cards to PIM.
Provides an MFIB platform application program interface (API) to propagate MFIB changes to
platform-specific code responsible for programming the hardware acceleration engine. This API
also includes entry points to switch a packet in software (necessary if the packet is triggering a
data-driven event) and to upload traffic statistics to the software.
Chapter 1 Implementing IPv6 Multicast
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