Configuring the Catalyst 8500 Software

This chapter describes how to configure the Catalyst 8500 campus switch router and provides enough information to get the switch router up and running. For detailed information about Cisco IOS commands, refer to the Cisco IOS command references.

Overview of Router Configuration Tasks

Before configuring your switch router, you should have the following information available:

• A map of your network topology
  
  
• The network protocols you are supporting: IP or Novell IPX (or both)
  
  
• The routing protocol you will use for each network protocol
  
  
• The IP or IPX addresses and the IP subnet masks for each network interface
  
  
• The IP addressing plan for each network protocol
  
  

A switch router initially refers to entries about networks or subnetworks that are directly connected. Each interface must be configured with an IP address and IP subnet mask, which the network administrator enters into a configuration file.

The high-level router configuration tasks are as follows:

Step 1   Set up the hardware as described in the Catalyst 8510 Chassis Installation Guide or the Catalyst 8540 Chassis Installation Guide.

Step 2   Initially configure the software as described later in this chapter.

Step 3   Configure any interface or interface management tasks as described in this chapter.

Step 4   Configure protocol-specific features on your switch router as described in the appropriate chapters of the other Cisco IOS software configuration guides.

Step 5   If desired, perform system management tasks to monitor and fine-tune the performance of your switch router in the network.

Entering Configuration Mode

You can configure the switch router from the command-line interface (CLI) that runs on the Catalyst 8500 campus switch router console or terminal. You can also configure Cisco routers using remote access. The Cisco IOS command interpreter, called the EXEC, interprets the commands you type and executes the requested operations.

To use the CLI, your terminal must be connected to the switch router through the console port or one of the TTY lines. By default, the terminal is configured to a basic configuration, which should work for most terminal sessions. However, you may want to alter the terminal settings.

For security purposes, the EXEC has two levels of access to commands: user mode and privileged mode. You can view information about the switch router in user mode, but you cannot modify anything. Privileged mode supports access to the configuration modes, manipulation of the configuration files, detailed examination of the switch router, as well as debugging and testing commands.

Step 1   Connect a console terminal to the Catalyst 8500 campus switch router, then power up the system.

For instructions, see the Catalyst 8510 Campus Switch Router Processor and Line Module Installation Guide or the Catalyst 8540 Campus Switch Router Processor and Line Module Installation Guide.

Step 2   When you are prompted to enter the initial dialog, answer no to enter configuration mode:

Would you like to enter the initial dialog? [yes]: no

The following user EXEC prompt appears: Router>

Step 3   To access privileged EXEC mode, enter the enable command.

Router> enable

The prompt changes to the privileged EXEC (enable) prompt:

Router#

Step 4   To access configuration mode, enter the configure terminal command:

Router# configure terminal

You can now enter any changes you want to the factory-default configuration file. To exit configuration mode, press Ctrl-Z.

Displaying the Operating Configuration

To see the current operating configuration, enter the show running-config command at the enable prompt:

Router# show running-config

To see the configuration in NVRAM, enter the show startup-config command:

Router# show startup-config

If you have made changes to the configuration, but have not yet written them to NVRAM, the results of the show running-config and show startup-config commands will differ. See the section "Saving Configuration Changes to NVRAM" in this chapter.

Overview of Interface Configuration

These general instructions apply to all interface configuration processes. Two types of interfaces are supported: physical and virtual interfaces. The types of physical interfaces on a device depend on its interface processors or port adapters.

The virtual interfaces that Cisco campus switch routers support include subinterfaces and IP tunnels. Configuring multiple virtual interfaces, or subinterfaces, on a single physical interface allows greater flexibility and connectivity on the network. A subinterface is a mechanism that allows a single physical interface to support multiple logical interfaces or networks. That is, several logical interfaces or networks can be associated with a single hardware interface.

To configure an interface, follow these steps:

Step 1   Begin interface configuration in global configuration mode.

Step 2   Enter the configure command at the privileged EXEC prompt to enter global configuration mode.

Step 3   Once in the global configuration mode, start configuring the interface by entering the interface command.

Step 4   Identify the interface type followed by the slot number of the line module, the number 0, and the port number.

For example, to configure the Fast Ethernet port on slot 1, port 2, you enter this command:

Router# interface fa 1/0/2

See the next section, "Configuring the Catalyst 8500 Interfaces," for more information on the physical interface addresses.

These numbers are assigned at the factory at the time of installation or when line modules are added to a system and can be displayed with the show interfaces command. A report is provided for each interface that the switch router supports, as seen in the following partial sample display:

     Router# show interfaces 
     Ethernet 0/0/0 is up, line protocol is up 
     Hardware is Sonict, address is 172.68.16.0/24
     MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec, rely 255/255, load 1/255 
     Encapsulation ARPA, loopback not set, keepalive set (10 sec) 

To see a list of the system software and hardware, use the show hardware command.

Step 5   Follow each interface command with the interface configuration commands your particular interface requires.

The commands you enter define the protocols and applications that will run on the interface. The commands are collected and applied to the interface command until you enter another interface command, a command that is not an interface configuration command, or you enter Ctrl-Z to get out of configuration mode and return to privileged EXEC mode.

Step 6   Once an interface is configured, you can check its status by entering the show commands provided at the end of each configuration section.

Configuring the Catalyst 8500 Interfaces

This section explains what port addresses and physical interface addresses are and provides procedures to configure interfaces for communication over a LAN.

To configure the interface parameters, you need your interface network addresses and subnet mask information. Consult your network administrator for this information.

Port Addresses

Each interface (or port) in the Catalyst 8500 is designated by several different types of addresses. The physical interface address is the actual physical location (slot/line module/port) of the interface connector within the chassis. The system software uses the physical addresses to control activity within the switch router and to display status information. These physical slot/card/port addresses are not used by other devices in the network; they are specific to the individual router and its internal components and software.

A second type of address is the Media Access Control (MAC) address or hardware address, which is a standard data link layer address required for every port or device that connects to a network. Other devices in the network use these addresses to locate specific ports in the network and to create and update routing tables and data structures.

Physical Interface Addresses

Physical port addresses specify the actual physical location of each module port on the rear of the switch router. The address is composed of a three-part number in the following format:

slot number/0/port number

The first number identifies the slot in which the line module is installed. Module slots are numbered 0 to 12, from top to bottom.

The second number indicates the line module. When the module consists of a single card—as in the case of the Catalyst 8500 campus switch router—this number is always 0.

The third number identifies the physical port number on the line module. The port numbers always begin at 0 and, when facing the rear of the switch router, are numbered from the left port to the right port. The number of additional ports depends on the number of ports available on the line module.

The interface ports on the Ethernet modules maintain the same address regardless of whether other modules are installed or removed. However, when you move a line module to a different slot, the first number in the address changes to reflect the new slot number.

You can identify module ports by physically checking the slot/0/port location on the back of the switch router. You can also use Cisco IOS commands to display information about a specific interface, or all the interfaces, in the switch router.

Catalyst 8510 Line Module Ports

Figure 4-1 and Figure 4-2 illustrate the ports on the Catalyst 8510 line modules.

Catalyst 8540 Line Module Ports

Figure 4-3 and Figure 4-4 illustrate the ports on the Catalyst 8540 line modules

Figure 4-3: Ports on the UTP FastEthernet Line Module

The 10/100BaseT Ethernet line module has 16 ports. This module is used for 10-Mbps or 100-Mbps Layer 2 or Layer 3 unshielded twisted pair (UTP) connections. It supports half-duplex and full-duplex connections and Fast EtherChannel operation.

Figure 4-4: Ports on the FX Fiber-Optic FastEthernet Module

The 100BaseFX multimode fiber Ethernet line module provides 16 multimode fiber ports with MTRJ connectors. You can use this module for 100-Mbps Layer 2 or Layer 3 fiber-optic connections. This module supports ull-duplex connections as well as Fast EtherChannel operation.

Configuring the Ethernet Interfaces

Perform the following tasks to configure features on an Ethernet, Fast Ethernet, or Gigabit Ethernet interface. The first task is required; the remaining tasks are optional.

Configuring Ethernet 10BaseT and 100BaseT

Assign an IP address to the Ethernet 10BaseT or 100BaseT interface of your switch router so that it can be recognized as a device on the Ethernet LAN. The Fast Ethernet interface supports 10-Mbps and 100-Mbps speeds with Cisco 10BaseT and 100BaseT routers, hubs, switches, and switch routers.

When autonegotiation is enabled on an Ethernet interface, the Catalyst 8500 automatically detects the port speed (10 Mbps or 100 Mbps) of the partner port. By default, autonegotiation is disabled. To enable autonegotiation on a specific FastEthernet port, issue the following command:

(config-if)# speed auto

When this command is disabled, the saved values for port speed are restored. The speed auto command is unique to the Catalyst 8500 family of switch routers.

Verifying 10/100BaseT Operation

Once you have configured Ethernet 10/100 BaseT operation, you can monitor the settings using the following commands:

Configuring the Gigabit Ethernet Interface

To configure the gigabit Ethernet interface, follow these steps:

Specifying Virtual LANs

A virtual LAN (VLAN) is an emulation of a standard LAN that allows data transfer and communication to occur without the traditional restraints placed on the network. It can also be considered a broadcast domain set up within a switch. With VLANs, switches can support more than one subnet (VLAN) on each switch, and give routers and switches the opportunity to support multiple subnets on a single physical link. A group of devices on a LAN are configured so that they communicate as if they were attached to the same wire, when they are actually located on different LAN segments. The Catalyst 8500 supports up to 255 VLANs per system.

VLANs enable efficient traffic separation and provide excellent bandwidth utilization. VLANs also alleviate scaling issues by logically segmenting the physical LAN structure into different subnetworks so that packets are switched only between ports within the same VLAN. This can be very useful for security, broadcast containment, and accounting.

The Catalyst 8500 supports a port-based VLAN on a trunk port, which is a port that carries the traffic of multiple VLANs. Each frame transmitted on a trunk link is tagged as belonging to only one VLAN.

The Catalyst 8500 supports VLAN frame encapsulation via the Inter-Switch Link (ISL) protocol and the 802.1q standard.

ISL is a Cisco protocol for interconnecting multiple switches and maintaining VLAN information as traffic travels between switches. For more information, see "Configuring Encapsulation Over EtherChannel" in the section "Configuring the EtherChannel."

The VLAN configuration example below assumes the following, as shown in Figure 4-5:

• Fast Ethernet ports 1/0/0 and 1/0/1 and subinterface 1/0/2.1 on the switch router are in bridge group 1, and they are part of VLAN 50.
  
  
• Fast Ethernet ports 3/0/0 and 3/0/1 and subinterface1/0/2.2 are in bridge group 2, and they are part of VLAN 100.
  
  
• Fast Ethernet port 1/0/2 is configured as an ISL trunk.
  
  

Figure 4-5: Example of a VLAN Configuration in a Catalyst 8500 Environment

To configure VLANs on the Catalyst 8500 campus switch router as shown in this example, follow these steps:

When configuring ISL or 802.1q with IP, you cannot configure IP addresses on a subinterface unless the VLANs are already configured (that is, you have already entered the encapsulation isl or encapsulation dot1q command). That is not the case with IPX, however—you can configure IPX networks on a subinterface even when the VLANs have not been configured.

The maximum VLAN/bridge group values obtainable are as follows:

• Maximum number of bridge groups: 64
  
  
• Maximum number of interfaces per bridge group: 32
  
  
• Maximum number of subinterfaces per system: 255
  
  

Verifying VLAN Operation

Once the VLANS are configured on the switch router, you can monitor their operation using the following commands:

Configuring the IP Routing Protocols

This section briefly describes how to configure the switch router for each of the IP routing protocols that the switch router supports. It is intended to provide enough information for any network administrator to get the protocols up and running. However, note that this configuration section is not intended to provide in-depth configuration for each protocol. For such information, please refer to any of the protocol configuration guides in the public domain.

IP routing is enabled by default on the switch router. The selection of IP as a routing protocol requires that you set both global and interface parameters.

The global tasks include:

• Select a routing protocol, such as the Enhanced Interior Gateway Routing Protocol (EIGRP) or the Routing Information Protocol (RIP).
  
  
• Assign IP network numbers without specifying subnet values.
  
  

To configure the interface, assign network and subnetwork addresses and the appropriate IP subnet mask.

Supported Routing Protocols

The Catalyst 8500 campus switch router supports the following routing protocols:

• IGRP is a distance vector interior-gateway protocol developed by Cisco Systems, Inc. Distance vector routing protocols call for each other to send all or a portion of its routing table in a routing update message at regular intervals to each of its neighboring routers. As routing information proliferates through the network, routers can calculate distance to all the nodes within the internetwork. IGRP uses a combination of metrics: internetwork delay, bandwidth, reliability, and load are all factored into the routing decision.
  
  
• EIGRP is an enhanced version of IGRP that combines the advantages of link-state protocols with distance vector protocols. EIGRP incorporates the Diffusing Update Algorithm (DUAL). EIGRP includes features such as fast convergence, variable-length subnet masks, partial bounded updates, and multiple network-layer support.When a network topology change occurs, EIGRP checks its topology table for a suitable new route to the destination. If such a route exists in the table, EIGRP updates the routing table instantly.You can use the fast convergence and partial updates EIGRP provides to route IPX packets.
  
  

  EIGRP saves bandwidth by sending routing updates only when routing information changes. The updates contain only information about the link that changed, not the entire routing table. EIGRP also takes into consideration the available bandwidth when determining the rate at which it transmits updates.

• OSPF is a standards-based IP routing protocol designed to overcome the limitations of IP RIP. Because OSPF is a link-state routing protocol, it sends link-state advertisements (LSAs) to all other routers within the same hierarchical area. Information on attached interfaces, metrics used, and some other information is used in OSPF LSAs. As routers accumulate link-state information, they use the Shortest Path First (SPF) algorithm to calculate the shortest path to each node. Additional OSPF features include equal-cost multi-path routing and routing based on the upper-layer type of service (ToS) requests.
  
  

  OSPF employs the concept of an area, which is a grouping of contiguous OSPF networks and hosts. OSPF areas are logical subdivisions of OSPF autonomous systems whose internal topology is hidden to routers outside the area. Areas allow an additional level of hierarchy different from that provided by IP network classes, and they can be used to aggregate routing information and mask the details of a network. These features make OSPF particularly scalable to large networks.

• RIP is a distance-vector, intradomain routing protocol. RIP works well in small, homogeneous networks. However, in larger, more complex internetworks it has many limitations, such as a maximum hop count of 15, lack of support for variable-length subnet masks (VLSMs), inefficient use of bandwidth, and slow convergence. (RIP II does support VLSMs.)
  
  

The following table includes the Cisco IOS commands used to configure each of these routing protocols, but you need to configure only those protocols that you run on your network.

Verifying IP Operation

Once IP routing is configured, you can monitor and troubleshoot the protocol operation using the following commands:

Configuring the Novell IPX Protocol

Cisco's implementation of the Novell Internetwork Packet Exchange (IPX) protocol provides all of the functionality of a Novell external bridge (Novell refers to their router functionality as bridging).

IPX is a proprietary protocol. Novell IPX can be described as follows:

• A datagram, connectionless protocol that does not require an acknowledgment for each packet
  
  
• A layer 3 (network) protocol that defines the internetwork and internode addresses
  
  
• A router specification used to identify the Novell NetWare protocol suite
  
  

Novell IPX uses the following protocols and services

• Routing Information Protocol (RIP). Facilitates the exchange of routing information
  
  
• NetWare Core Protocol (NCP). Provides client-to-server connections and applications
  
  
• Sequenced Packet Exchange (SPX). Service for Layer 4 (Transport) connection-oriented services
  
  
• Service Advertising Protocol (SAP). Advertises NetWare services and addresses, which makes service availability dynamic
  
  

An IPX network address consists of a network number and a node number, expressed in the format network.node.

The network number is a 4-byte (32-bit) number that identifies the physical network. The network number is expressed in hexadecimal and must be unique throughout the entire IPX internetwork. When configuring an IPX network number, you can omit the leading zeros.

The node number identifies a node on the network. It is a 48-bit number, represented by dotted triplets of 4-digit hexadecimal numbers. The node number is normally the MAC address of the NetWare node or router interface.

Since both the network number and the host address are needed to deliver traffic to a host, addresses are usually given as network numbers, followed by host addresses, separated with dots, as in the example: 4a.0000.0c00.23fe. In this example, the network number is 4a, and the host address is 0000.0c00.23fe.

The serial interface does not have a MAC address. It uses the default Novell node address, which is the MAC address of the first activated interface.

Configuration Tasks

To configure Novell IPX as a routing protocol, you must configure both global and interface parameters. The global configuration tasks are as follows:

  Load sharing is the division of routing tasks evenly among multiple routers to balance the work and improve network performance. The switch router supports up to two parallel paths, with a default of one.

The interface configuration tasks are:

  You can assign multiple network numbers to an interface, allowing support of different encapsulation types. The IPX network number is the number of the Novell network to which the interface is attached. IPX packets received on an interface that does not have a network number are ignored.

  The default encapsulation type for the switch router is novell-ether (Ethernet_802.3).

This section does not describe IPX configuration in detail. Please refer to the IPX documentation on the Cisco Documentation CD for detailed conceptual and configuration information.

Verifying IPX Operation

The argument number is the number of the Novell network to which that interface is attached. Novell packets received on an interface that does not have a Novell network number are ignored.

Once IPX routing is configured, you can monitor and troubleshoot the protocol operation using the following commands:

Configuring IP Multicast Routing

As networks increase in size, multicast routing becomes critically important as a means to determine which segments require multicast traffic and which do not. Internet Protocol Multicast is a routing technique that allows IP traffic to be propagated from one source to a number of destinations, or from many sources to many destinations. Rather than sending one packet to each destination, one packet is sent to the multicast group identified by a single IP destination group address.

IP multicast routing arose because unicast and broadcast techniques do not effectively handle the requirements of new applications. In addition, multicast addressing supports transmission of a single IP datagram to multiple hosts.

A principle component of IP multicast is the Internet Group Membership Protocol (IGMP). With IGMP, a class D address is used to dynamically register an individual host in a multicast group. Hosts identify their group membership by sending IGMP messages to the switch router. Traffic is sent to all members of a multicast group. A host can be a member of more than one group at a time. Also, a host does not need to be a member of a group to send data to that group. Enabling Protocol Independent Multicast (PIM) on an interface also enables IGMP operation on that interface.

The routing protocols that the switch router uses to discover multicast groups and build routes for each group follow:

• Protocol Independent Multicast (PIM)
  
  
• Distance Vector Multicast Routing Protocol (DVMRP)
  
  
• Constrained Multicast Flooding (CMF)
  
  

  The Catalyst 8500 supports interoperability with routers configured for DVMRP.

About Protocol Independent Multicast

PIM includes two different modes of behavior for dense and sparse traffic environments. These are referred to as dense mode and sparse mode.

PIM dense mode assumes that the downstream networks want to receive the datagrams forwarded to them. The switch router forwards all packets on all outgoing interfaces until pruning and truncation occurs.Thus, interfaces with PIM dense mode enabled receive the multicast data stream until it times out. PIM dense mode is most useful under these conditions:

• Senders and receivers are in close proximity to each other.
  
  
• The internetwork has fewer senders than receivers.
  
  
• The stream of multicast traffic is constant.
  
  

PIM sparse mode assumes that the downstream networks do not want to forward multicast packets for a group unless there is an explicit request for the traffic. PIM sparse mode defines a rendezvous point, which is used as a registration point to facilitate the proper routing of packets.

When a sender wants to send data, it first sends the data to the rendezvous point. When a router is ready to receive data, it registers with the rendezvous point. After the data stream begins to flow from the sender to the rendezvous point and then to the receiver, routers in the data path optimize the path by automatically removing any unnecessary hops, including the rendezvous point.

PIM sparse mode is optimized for environments in which there are many multipoint data streams and each multicast stream goes to a relatively small number of LANs in the internetwork. PIM sparse mode is most useful under these conditions:

• There are few receivers in the group.
  
  
• Senders and receivers are separated by WAN links.
  
  
• The stream of multicast traffic is intermittent.
  
  

Configuration Tasks

To configure IP multicast routing, follow these steps:

Verifying IP Multicast Operation

Once IP multicast routing is configured, you can monitor and troubleshoot its operation using the following commands:

Configuring Bridging

Cisco IOS software supports transparent bridging for Ethernet. In addition, Cisco supports all the mandatory Management Information Base (MIB) variables specified for transparent bridging in RFC 1286.

Cisco IOS software bridging functionality combines the advantages of a spanning-tree bridge and a full multiprotocol router. This combination provides the speed and protocol transparency of an adaptive spanning-tree bridge, along with the functionality, reliability, and security of a router.

The Catalyst 8500 campus switch router can be configured to serve as both an IP and IPX router and a MAC-level bridge, bridging any traffic that cannot otherwise be routed. For example, a router routing IP traffic can also bridge the Digital local-area transport (LAT) protocol or NetBIOS traffic.

To configure bridging, you must perform the following tasks:

• Global configuration
  
  
• • Select Spanning-Tree Protocol.
    
    
  • Assign a priority to the bridge (optional).
    
    
• Interface configuration
  
  
• • Determine which interfaces that you want to belong to the same bridge group.
    
    

  These interfaces will be part of the same spanning tree. This allows the switch router to bridge all nonrouted traffic among the network interfaces comprising the bridge group. Interfaces not participating in a bridge group cannot forward bridged traffic.

  If the packet's destination address is known in the bridge table, it is forwarded on a single interface in the bridge group. If the packet's destination is unknown in the bridge table, it is flooded on all forwarding interfaces in the bridge group. The bridge places source addresses in the bridge table as it learns them during the process of bridging.

  A separate spanning-tree process runs for each configured bridge group. Each bridge group participates in a separate spanning tree. A bridge group establishes a spanning tree based on the BPDUs it receives on only its member interfaces.

  • Assign a cost to the outgoing interface (optional).
    
    

To set up the switch router for bridging, follow these steps:

For additional transparent bridging configuration tasks, such as configuring bridged VLANs and routing between VLANs, as well as adjusting the Spanning-Tree Protocol, refer to the Cisco IOS documents on those subjects.

Monitoring the Bridging Operation

Once the VLANS are configured on the switch router, you can monitor their operation using the following commands:

Configuring Integrated Routing and Bridging

Your network may require you to bridge local traffic within several segments while having hosts on the bridged segments reach the hosts or routers on routed networks. For example, if you are migrating bridged topologies into routed topologies, you may want to start by connecting some of the bridged segments to the routed networks.

Using the Integrated Routing and Bridging (IRB) feature, you can route a given protocol between routed interfaces and bridge groups within a single switch router. Specifically, local or unroutable traffic will be bridged among the bridged interfaces in the same bridge group, while routable traffic will be routed to other routed interfaces or bridge groups.

Because bridging is in the data-link layer (Layer 2) and routing is in the network layer (Layer 3), they have different protocol configuration models. With IP, for example, bridge group interfaces belong to the same network and have a collective IP network address. In contrast, each routed interface represents a distinct network and has its own IP network address. Integrated routing and bridging uses the concept of a Bridge Group Virtual Interface (BVI) to enable these interfaces to exchange packets for a given protocol.

A BVI is a virtual interface within the switch router that acts like a normal routed interface. A BVI does not support bridging, but it actually represents the corresponding bridge group to routed interfaces within the switch router. The interface number is the link between the BVI and the bridge group.

The Catalyst 8500 campus switch router supports the routing of IP and IPX between routed interfaces and bridged interfaces in the same router, in both fast-switching and process-switching paths.

Configuration Considerations

Consider the following before configuring IRB:

• The default route/bridge behavior in a bridge group when IRB is enabled is to bridge all packets. Make sure you explicitly configure routing on the BVI for protocols that you want routed.
  
  
• Packets of nonroutable protocols such as local-area transport (LAT) are always bridged. You cannot disable bridging for the nonroutable traffic.
  
  
• When using IRB to bridge and route a given protocol, no protocol attributes should be configured on the bridged interfaces. Bridging attributes cannot be configured on the BVI.
  
  
• Because bridges link several segments into one big and flat network and you want to bridge the packet coming from a routed interface among bridged interfaces, the whole bridge group should be represented by one network-layer segment—in the switch router, an interface.
  
  
• The BVI has default data-link and network-layer encapsulations. These encapsulations are the same as on the Ethernet, except that you can configure the BVI with some encapsulations that are not supported on a normal Ethernet interface.
  
  

Configuration Tasks

Configuring integrated routing and bridging consists of two key tasks:

When you configure the BVI and enable routing on it, packets that come in on a routed interface destined for a host on a segment that is in a bridge group complete the following process:

The packet is routed to the BVI.From the BVI, the packet is forwarded to the bridging engine. From the bridging engine, the packet exits through a bridged interface.

Similarly, packets that come in on a bridged interface but are sent to a host on a routed interface go first to the BVI. Then the BVI forwards the packets to the routing engine before sending them out on the routed interface.

Verifying IRB Operation

Once IRB is configured, you can monitor the IRB operation using the following command:

Configuring the EtherChannel

EtherChannel is a trunking technology that groups together multiple full-duplex 802.3 Ethernet interfaces to provide fault-tolerant high-speed links between switches, routers, and servers. EtherChannel is a logical aggregation of multiple Ethernet interfaces. EtherChannel forms a single higher bandwidth routing or bridging endpoint. EtherChannel is designed primarily for host-to-switch connectivity or Inter-Switch Link (ISL) switch-to-switch connectivity (for example, connectivity to a Catalyst 5500 switch).

In summary, EtherChannel provides the following benefits:

• Logical aggregation of bandwidth
  
  
• Load balancing
  
  
• Fault tolerance
  
  

The EtherChannel interface (consisting of up to four Ethernet interfaces) is treated as a single interface, which is called a port channel. You must configure EtherChannel on the EtherChannel interface rather than on the individual member Ethernet interfaces. You create the EtherChannel interface by using the interface port-channel interface configuration command. The switch router supports up to 64 port channels.

EtherChannel connections are fully compatible with Cisco IOS VLAN and routing technologies. The ISL VLAN trunking protocol can carry multiple VLANs across an EtherChannel, and routers attached to EtherChannel links can provide full multiprotocol routing with support for host standby using Host Standby Router Protocol (HSRP).

The Catalyst 8500 campus switch router supports Fast EtherChannel (FEC) and Gigabit EtherChannel (GEC).

Cisco's Fast EtherChannel technology builds upon standards-based 802.3 full-duplex Fast Ethernet to provide a reliable high-speed solution for the campus network backbone. Fast EtherChannel provides bandwidth scalability within the campus by providing increments of 200 Mbps to 800 Mbps.

Cisco's Gigabit EtherChannel technology provides bandwidth scalability within the campus by providing increments of 2 Gbps to 8 Gbps.

Configuration Tasks

Configuring a Fast EtherChannel or a gigabit EtherChannel consists of the following required steps:

Configuring the EtherChannel Interface

To configure the EtherChannel interface, perform the following tasks beginning in global configuration mode:

For information on other configuration tasks for the EtherChannel, refer to the section "Configure an Ethernet or Fast Ethernet Interface" in the chapter "Configuring Interfaces" of the Configuration Fundamentals Configuration Guide.

Assigning Interfaces to the EtherChannel

You can now assign the Fast Ethernet or gigabit Ethernet interfaces to the EtherChannel.

Caution The EtherChannel interface is the routed interface. Do not enable Layer 3 addresses on the physical Fast Ethernet or gigabit Ethernet interfaces. Do not assign bridge groups on the physical Fast Ethernet or gigabit Ethernet interfaces because doing so creates loops. Finally, you must disable the Spanning-Tree Protocol.

Removing an Interface from the EtherChannel

You might need to remove a Fast Ethernet interface or gigabit Ethernet from an EtherChannel. To perform this task, follow these steps, beginning in global configuration mode:

The Cisco IOS software automatically removes a Fast Ethernet or gigabit Ethernet interface from the EtherChannel if the interface goes down, and the software automatically adds the interface to the EtherChannel when the interface is back up.

Currently, EtherChannel relies on keepalives to detect whether the line protocol is up or down. Keepalives are enabled by default on the Fast Ethernet and gigabit Ethernet interfaces. If the line protocol on the interface goes down because it did not receive a keepalive signal, the EtherChannel detects that the line protocol is down and removes the interface from the EtherChannel.

However, if the line protocol remains up because keepalives are disabled on the Fast Ethernet or gigabit Ethernet interface, the EtherChannel cannot detect this link failure (other than a cable disconnect) and does not remove the interface from the EtherChannel even if the line protocol goes down. This can result in unpredictable behavior.

Configuring Encapsulation Over EtherChannel

When configuring encapsulation over FEC or GEC, be sure to configure the ISL or 802.1q over the EtherChannel (that is, the port-channel interface), not on its member ports. Further, make sure that you do not apply protocol-level configuration (such as an IP address or a bridge group assignment) to the member interfaces. All protocol-level configuration should be on the port-channel or on its subinterface. You must configure ISL or 802.1q encapsulation on the partner system of the EtherChannel as well.

To configure encapsulation over Fast EtherChannel or gigabit EtherChannel, follow these steps:

Monitoring EtherChannel Status

Once Fast EtherChannel or gigabit EtherChannel is configured, you can monitor its operation using the following command:

Saving Configuration Changes to NVRAM

Whenever you make changes to the switch router configuration, you must save the changes; if you do not, the changes will be lost if there is a system reload or power outage. The two types of configuration files are stored in different forms of memory: the running configuration is stored in RAM; the startup configuration is stored in nonvolatile random-access memory (NVRAM).

To save your configuration changes to NVRAM so that they are not lost during a power cycle or power outage, take these steps:

This concludes the procedure for configuring the Catalyst 8500 campus switch router. Refer to the appendix "Comprehensive Configuration Examples" for real-world switch router configuration examples.

Caution The aal5 buffers command lets you adjust the AAL5 buffer pool settings. Because an inappropriate setting can adversely affect system performance, issue the aal5 buffers command only after consulting with technical support personnel.

More Configuration Information

After you have installed the Catalyst 8500 campus switch router hardware, checked all external connections, turned on the system power, allowed the system to boot up, and minimally configured the system, you might need to perform more complete and complex configurations, which are beyond the scope of this text.

The Cisco IOS software running your Catalyst 8500 campus switch router contains extensive features and functionality. The effective use of many of many of these features is easier if you have more information at hand. For additional information on Cisco IOS software and configuring your router, refer to the following documentation resources:

For systems with Cisco IOS Release 10.0 (1) or later, refer to the following publications:

— Cisco IOS Software Command Summary

— Configuration Builder Getting Started Guide

— Cisco Management Information Base (MIB) User Quick Reference

— Debug Command Reference

— Router Products Command Reference

— Router Products Configuration Guide

— System Error Messages

— Troubleshooting Internetworking Systems

For systems with Cisco IOS Release 11.2(1) or later, refer to the following modular configuration and modular command reference publications, as appropriate for your configuration:

— Bridging and IBM Networking Configuration Guide

— Bridging and IBM Networking Command Reference

— Cisco IOS Software Command Summary

— Cisco IOS Solutions for Voice, Video, and Home Applications

— Cisco Management Information Base (MIB) User Quick Reference

— Configuration Builder Getting Started Guide

— Configuration Fundamentals Configuration Guide

— Configuration Fundamentals Command Reference

— Debug Command Reference

— Network Protocols Configuration Guide, Parts 1, 2, and 3

— Network Protocols Command Reference, Parts 1, 2, and 3

— Quality of Service Solutions

— Security Configuration Guide

— Security Command Reference

— System Error Messages

— Troubleshooting Internetworking Systems

— Wide-Area Networking Configuration Guide

— Wide-Area Networking Command Reference