NFFC also provides protocol filtering to allow segmentation by VLANs. It can provide per−port filtering of
data in four different groups:
Internet Protocol (IP)• Internetwork Packet Exchange (IPX)• AppleTalk, DECnet, and Banyan Vines• Other group•
Tip By default, the IP group is on, but it can be turned off for the other groups listed. Remember, the NFFC
and NFFC II do not process Token Ring packets. A port where a server resides and that is configured for
IP can be turned off for other protocols such as IPX and AppleTalk. No broadcasts from these protocols
will reach the server or end−user interface, because the NFFC will filter them.
IGMP snooping is another feature of the NFFC II. Spawned by multicast applications such as video
conferencing, it provides advanced features that help keep multicast traffic from flooding all the ports and
degrading network performance. Using this feature, Catalyst 5500 switches are able to intelligently forward
multicast to the correct destination. IGMP snooping reads IGMP messages from the end−user’s interface and
learns their port location. This process allows the NFFC II card to forward multicast data streams out the port
attached to the destination interface.
Both cards also provide broadcast and unicast traffic filtering based on the port’s membership in the different
protocol groups in addition to the port’s assigned VLAN. The NFFC II also has the ability to become a
multicast forwarder. The ASICs on the NFFC II replicate multicast packets to allow wire−speed multicast
forwarding.
Route Switch Module
The RSM enhances the Catalyst 5000 switch family by letting the switch provide some of the same Layer 3
switching capabilities as a router. As a result, a switch that normally forwards only Layer 2 command
broadcasts and VLAN traffic and that relies on a router to forward traffic to other segments or VLANs can
now route the traffic itself without relying on a router.
The RSM contains a MultiChannel Interface Processor (MIPS) R47000, 32MB Dynamic RAM (DRAM)
expandable to 128MB, a 16MB Flash card expandable to 40MB, 1.5MB high−speed RAM for the backplane
interface, and 8MB of Flash memory. It connects directly into the backplane of the switch. The RSM adds to
the Cisco IOS such features as multiprotocol routing for the Ethernet interfaces, security control, multicast
control, interVLAN routing, and some basic QoS features. The routing protocols supported by the RSM are as
follows:
AppleTalk• Enhanced Interior Gateway Routing Protocol (EIGRP)• Hot Standby Routing Protocol (HSRP)• Interior Gateway Routing Protocol (IGRP)• Internet Protocol (IP)• Internetwork Packet Exchange (IPX)• NetWare Link Services Protocol (NLSP)• Open Shortest Path First (OSPF)• Routing Information Protocol (RIP)• Routing Table Maintenance Protocol (RTMP) for AppleTalk•
A Catalyst 5500 has 13 slots available for additional modules. Slots 1 and 2 are reserved for the Supervisor
Engine and a redundant Supervisor Engine. If there is no redundant Supervisor Engine card, up to seven
RSMs can be installed in the switch in slots 2 through 12.
The RSM interface to the Catalyst 5000 series backplane is through VLAN 0 mapped to channel 0 and VLAN
1 mapped to channel 1. The switch uses VLAN 0 to communicate with the RSM; the user cannot access
VLAN 0. VLAN 1 is the switch default, but this default can be changed and mapped to a specific channel to
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