Catalyst 6000 Layer 3 Switching

Catalyst 6000 Layer 3 Switching

The Catalyst 6000 family of switches build on the existing technologies introduced by Cisco. From a Layer 3 switching perspective, two options are available:

  • The Multilayer Switch Module (MSM)
  • MLS using the Multilayer Switch Feature Card (MSFC)

Note
In a Catalyst 6000, the NFFC functionality is technically handled by an additional card known as the Policy Feature Card (PFC). However, because current implementations require an MSFC to allow a PFC to perform Layer 3 switching (alone, the PFC can provide QoS and access list features), this text will simply refer to the MSFC.

The MSM was the initial Layer 3 offering for the Catalyst 6000s. Based on the 8510 SRP, this card offers approximately 5 million pps for IP and IPX routing. From a configuration standpoint, it uses four Gigabit Ethernet connections to the backplane. Each of these ports can be used in a separate VLAN. Or, by enabling Gigabit EtherChannel on these ports, it can be used as a single interface supporting any number of VLANs. As with the router-on-a-stick approach discussed earlier, each VLAN can then be configured on a separate subinterface.

The second phase of Layer 3 switching for the Catalyst 6000s introduced the MSFC. This brings NFFC II functionality to the Catalyst 6000s, allowing full MLS support at 15 million pps for both IP and IPX. This also provides software-based routing services via technology derived from the 7200 router NPEs. By doing so, it completely eliminates the need for also having an MSM in the same chassis. The on-board router uses software routing to handle the first packet of every IP or IPX flow.

The remaining packets are then handled in hardware by MLS. Finally, the on-board router can also be used to provide full software-based multiprotocol routing for protocols such as AppleTalk, DECnet, and VINEs at approximately 100,000 pps (Fast-Switched speeds).

One of the most interesting features of the MSFC, is that its configuration and management characteristics can be completely changed by using one of two different software images. Under the first option, the software-based router uses a traditional IOS image while the Supervisor uses the traditional XDI/CatOS image. This results in a user-interface and configuration process that is virtually identical to that discussed in the “MLS” section earlier in the chapter.

This is referred to as the MSFC “Hybrid Mode.” In the second option, the MSFC “Native IOS Mode” both the software-based router and the Supervisor run full IOS images. This creates an extremely integrated user interface. In short, by simply modifying the software on your Catalyst you can convert a very switch-like device into a full-blown router! For more information, see Chapter 18, “Layer 3 Switching and the Catalyst 6000/6500s.”

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