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Overview of the Catalyst 8510 Campus Switch Router

Overview of the Catalyst 8510 Campus Switch Router

The Catalyst 8510 campus switch router is a modular Layer 3 switch router that provides wire-speed Ethernet routing and switching services. The system has a five-slot chassis that supports up to 32 ports of 10/100/1000 Fast Ethernet connectivity, or four ports of Gigabit Ethernet uplink capacity. The system can be deployed as a high-speed switch router for campus or enterprise backbones.

The key features of the Catalyst 8510 campus switch router include wire-speed Layer 3 IP, IP multicast, and IPX routing and forwarding across Ethernet and Fast Ethernet Channel (FEC) interfaces. The switch router also provides high quality of service (QoS) capabilities, including support for four queues per port and flow classification based on IP precedence bits.

How the Campus Switch Router Fits Into the Network


Figure 1-1: Typical Network Configuration for the Catalyst 8510

Introduction to Catalyst 8510 Features

The Catalyst 8500 series of campus switch routers provides a complete and resilient backbone switch that offers a complete suite of sophisticated features. This system offers several key components of the enterprise campus network architecture, delivering high-speed performance and quality of service within the network backbone. By incorporating the Cisco IOS technology, the Catalyst 8510 provides seamless integration with the Catalyst 5000 series (including the Route Switch Module and NetFlow feature card), as well as the Cisco 7500 class of routers.

Integration with the Catalyst 5500

The ability to use Catalyst 8510 Ethernet line modules in a Catalyst 5500 chassis provides an easy migration to wire-speed Layer-3 networking. The Catalyst 5500 switch provides full integration of the Catalyst 8510 line modules by utilizing the passive backplane fabric in the Catalyst 5500 lower five slots (9 through 12). The Catalyst 8510 switch route processor (SRP) resides in slot 13 in the Catalyst 5500 chassis. For information on configuring the SRP, see the chapter "Configuring the Catalyst 8510 Switch Route Processor."

Fast EtherChannel

Fast EtherChannel (FEC) establishes a high-bandwidth connection between two Catalyst switch devices. You can utilize up to four Fast Ethernet connections as one Layer-3 forwarding path, which can provide up to 800 Mbps aggregate capacity. If link detection determines a failure of any one link, the packets are switched on the remaining active links in the FEC.

The Catalyst 8510 places no dependencies on which ports are configured in the channel. The ports can exist on the same or on different line modules in the chassis.

Fast EtherChannel uses a source-destination IP address load-balancing scheme. In the Catalyst 8510, you can configure up to four ports in a channel group. Each channel group has its own IP address.When a packet is queued to exit out of the port channel interface, the last two bits of the IP source and destination address determine which interface in the channel the packet takes.

Distributed Hardware Forwarding

The Catalyst 8510 campus switch router employs a distributed architecture in which the control path and data path are relatively independent. The control path code, such as routing protocols, runs on the switch route processor, whereas most of the data packets are forwarded by the Ethernet line module and the switching fabric.

Each line module includes a micro-coded processor that handles all packet forwarding. The main functions of the control layer between the routing protocol and the firmware datapath microcode include:

QoS-Based Forwarding

Quality of Service (QoS) comprises several technologies, such as the Resource Reservation Protocol (RSVP) and Weighted Fair Queuing (WFQ), which help control bandwidth, network delay, jitter, and packet loss in networks that become congested. In the switch router, QoS-based forwarding sorts traffic into a small number of classes and marks the packets accordingly. The QoS identifier provides specific treatment to traffic in different classes, so that different quality of service is provided to each class.

On any Catalyst 8510 system in the network, the frame and packet scheduling and discarding policies are determined by the class to which the frames and packets belong. For example, the overall service given to frames and packets in the premium class will be better than that given to the standard class; the premium class is expected to experience lower loss rate or delay.

The switch router supports QoS-based forwarding for IP traffic only (for the initial release). The implementation of QoS forwarding is based on local administrative policy and IP precedence. The mapping between the IP precedence field and the QoS field determines the delay priority of the packet. Refer to the chapter "Catalyst 8510 Quality of Service Feature Summary" for detailed information about QoS mechanisms on the Catalyst 8510 and the QoS configuration commands that allow you to fine tune your QoS configuration.

Network Class Redundancy

The Catalyst 8510 chassis features hot-swappable, redundant power supply modules, as well as hot-swappable Ethernet line modules. The redundancy of Cisco IOS software allows for key network features, such as Hot Standby Router Protocol (HSRP), routing protocol convergence with Routing Information Protocol (RIP), Open Shortest Path First (OSPF), or Enhanced Interior Gateway Routing Protocol (EIGRP), Fast EtherChannel, and load sharing across equal cost Layer 3 paths and spanning tree (for Layer 2 based networks).

Bridging (Layer 2) Features

The following table summarizes the features that the Catalyst 8510 campus switch router supports on the bridging layer (Layer 2).


Table 1-1: Catalyst 8510 Layer 1 and Layer 2 Features
Layer 1 Features

100BaseFX full and half duplex

10/100BaseTX full and half duplex with auto-negotiation

Layer 2 Bridging Features

Layer 2 transparent bridging

Layer 2 MAC learning, aging, and switching by hardware

Spanning tree protocol (IEEE 802.1d) support per bridge group

Support for a maximum of 64 active bridge groups

Integrated Routing and Bridging (IRB) mode support

Virtual LAN (VLAN) Features

Inter-Switch Link (ISL)-based VLAN trunking support on Ethernet ports

Fast EtherChannel (FEC) Features

Bundling of up to 4 Fast Ethernet ports

Load sharing based on source and destination IP addresses of unicast packets

Load sharing for bridge traffic based on MAC address

Inter-Switch Link (ISL) support on the Fast EtherChannel

This section describes the notable Layer 2 features supported by the Catalyst 8510 campus switch router.

Inter-Switch Link

To support a virtual LAN (VLAN) between switches, the Catalyst 8510 identifies frames from end stations as belonging to a particular VLAN. The system does this using a trunking protocol called Inter-Switch Link (ISL) that runs over Ethernet. The ISL technology uses a scheme known as packet tagging. Packet tagging allows the Catalyst 8500 series (as well as the Catalyst 3000 and 5000 series) to multiplex VLANs across a single physical link, maintaining strict adherence to the individual VLAN domains.

The ISL frame is a standard Ethernet or IEEE 802.3 frame, tagged with a VLAN ID. The system sends the ISL frame as a multicast, but it is meaningful only to ISL devices. Since it is a standard frame, repeater hubs and transparent bridges forward it as they would any other frame. Any 100  Mbps Ethernet link can support this protocol. The link can run at either half duplex or full duplex.

Virtual LANs

A VLAN facilitates the configuration of switches and routers according to logical rather than physical topologies. Using VLANs, a network administrator can combine any collection of LAN segments within an internetwork into an autonomous user group, which appears as a single LAN. VLANs logically segment the network into different broadcast domains so that packets are switched only between ports within the VLAN. Typically, a VLAN corresponds to a particular subnet, although not necessarily.

The Catalyst 8510 supports up to 255 VLANs per system. Because routing will take place, each VLAN is assumed to terminate at the Catalyst 8510. This may not necessarily be the case, so the switch router also supports integrated routing and bridging (IRB). The Catalyst 8510 supports VLAN trunking through Cisco ISL technology.

Configuring VLANs for the Catalyst 8510 is similar to VLAN configuration for other Cisco routers. You define a subinterface at the interface and then define a bridge group. Then map a VLAN to the subinterface. For details, see the section, "Specifying Virtual LANs," in the chapter "Configuring the Catalyst 8510 Software."

Cisco Discovery Protocol

CDP is a device-discovery protocol that is both media and protocol independent. CDP is available on all Cisco products, including routers, switches, bridges, and access servers. Using CDP, a device can advertise its existence to other devices and receive information about other devices on the same LAN. CDP enables Cisco products to exchange information with each other regarding their Media Access Control (MAC) addresses, IP addresses, and outgoing interfaces. CDP runs over the data link layer only, thereby allowing two systems that support different network-layer protocols to learn about each other.

Each device configured for CDP sends periodic messages to a multicast address. Each device advertises at least one address at which it can receive Simple Network Management Protocol (SNMP) messages.

Network Layer (Layer 3) Features

The following table summarizes the features that the Catalyst 8510 campus switch router supports at the network layer (Layer 3).

Table 1-2: Catalyst 8510 Layer 3 Features
Layer 3 Routing, Switching, and Forwarding Features

IP, IPX, and IP multicast switching between Ethernet ports

Support for up to 128 IP multicast groups

QoS-based forwarding based on IP precedence queuing

Load balancing among equal cost paths based on source and destination IP and IPX addresses

Supported Routing Protocols

IGRP (Interior Gateway Routing Protocol)

EIGRP (Enhanced Interior Gateway Routing Protocol)

OSPF (Open Shortest Path First)

RIP (Routing Information Protocol) and RIP II

Static routes

PIM (Protocol Independent Multicast): Sparse and Dense modes

DVMRP (Distance Vector Multicast Routing Protocol) tunneling

IPX (Internet Packet Exchange) RIP and EIGRP

Route filtering

Classless interdomain routing (CIDR)

Secondary addressing

Additional Protocols Supported

BOOTP (Bootstrap Protocol)

CGMP (Cisco Group Management Protocol) server support

CDP (Cisco Discovery Protocol) support on Ethernet ports

DHCP (Dynamic Host Configuration Protocol) Relay

HSRP (Hot Standby Routing Protocol)

ICMP (Internet Control Message Protocol)

IGMP (Internet Group Management Protocol)

IPX SAP (Internet Packet Exchange Service Advertisement Protocol) and SAP filtering

IRB (Integrated Routing and Bridging) routing mode support

This section describes the notable Layer 3 features supported by the Catalyst 8510.

Hot Standby Router Protocol

The Hot Standby Router Protocol (HSRP) provides high network availability by routing IP traffic from hosts on Ethernet networks without relying on the availability of any single router. This feature is particularly useful for hosts that do not support a router discovery protocol (such as the Intermediate System-to-Intermediate System Interdomain Routing Protocol) and do not have the functionality to switch to a new router when their selected router reloads or loses power.

Devices that are running the HSRP detect a failure by sending and receiving multicast User Datagram Protocol (UDP)based "hello" packets. When HSRP detects that the designated active router has failed, the selected backup router assumes control of the HSRP group's MAC and IP addresses. (You can also select a new standby router at that time.)

The chosen MAC address and IP addresses are unique and will not conflict with any others on the same network segment. The MAC address is selected from a pool of Cisco MAC addresses. Configure the last byte of the MAC address by configuring the HSRP group number. You also configure the unique virtual IP address. The IP address must be specified on a single router within the same group. When HSRP is running, it selects an active router and instructs its device layer to listen on an additional (dummy) MAC address.

Cisco IOS Routing Protocols

The Catalyst 8510 campus switch router provides a comprehensive suite of routing protocols based on the Cisco IOS software. The Catalyst 8510 supports RIP and RIP version 2, OSPF, IGRP and EIGRP routing for IP networks. For IPX networks, the Catalyst 8510 supports RIP, RIP-2, and EIGRP. Many of the Cisco IOS routing protocol features, such as route redistribution and load balancing over equal cost paths (for OSPF and EIGRP) are supported. Configuration of these routing protocols is identical to the configuration methods currently employed on all of the Cisco router products.

Cisco Express Forwarding

The Catalyst 8510 features Cisco Express Forwarding (CEF). CEF is advanced Layer 3 IP switching technology. CEF optimizes network performance and scalability for networks with large and dynamic traffic patterns, such as the Internet, on networks characterized by intensive Web-based applications, or interactive sessions. Although you can use CEF in any part of a network, it is designed for high-performance, highly resilient Layer 3 IP backbone switching.

CEF manages route distribution and forwarding by distributing routing information from the switch route processor (SRP) to the individual Ethernet line modules. This technology, utilized within the Internet, provides scalability in large campus core networks. CEF provides Layer 3 forwarding based on a topology map of the entire network, resulting in high-speed routing table lookups and forwarding.

One of the key benefits of CEF in the Catalyst 8510 is its routing convergence. Since the forwarding information base (FIB) is distributed to all line modules, whenever a route goes away or is added, the FIB updates that information and provides it to the line modules. Thus, SRP interrupts are minimized. The line modules receive the new topology very quickly and reconverge around a failed link based on the routing protocol being used.

Load Balancing

Load balancing is the ability of a router to distribute traffic over all its network ports that are the same destination from the destination address. Load balancing increases the utilization of network segments, thus increasing effective network bandwidth.

The Cisco IOS software has two load balancing schemes for IP traffic: per-packet load balancing and per-destination load balancing.

Per-packet load balancing allows the router to send data packets over equal-cost paths without regard to the individual end-host or user session. Though packets are evenly distributed in this scheme, they can also get out of order because per-packet load balancing uses a round-robin paradigm.

Per-destination load balancing allows a router to achieve load sharing using equal-cost paths by ensuring that packets for a given destination always take the same path. Note that the path utilization of this scheme might not be as efficient as per-packet load balancing, but the packets cannot be received out of order.

One of the shortcomings of per-destination load balancing, then, is that it does not take into account the source of the packet. If multiple sources (servers) send the IP packets to the same destination, the packets use the same route---even if there are multiple equal-cost paths available.

The implementation of load balancing on the Catalyst 8510 employs a source  +  destination-based load balancing scheme, which is an enhanced version of the Cisco IOS software per-destination load balancing method. Essentially, this method takes certain bits from the source and destination IP addresses and maps this addressing information into a path. There are two benefits of using this method:

This release of the Catalyst 8510 campus switch router supports load balancing for two equal-cost paths. The switch router does not support per-packet load balancing.

Integrated Routing and Bridging

Integrated Routing and Bridging (IRB) provides a means to route a given protocol between routed interfaces and various bridge groups or between bridge groups within a single router. This allows multiple ports in the Catalyst 8510 to reside in one bridge group with one IP address and be routed to other Catalyst 8510 interfaces with different IP addresses.

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.

The Catalyst 8510 supports IRB for IP and IPX only.

Some examples of when to use IRB follow:

For example, when you are migrating a bridged network to a routed network, or when the remote site does not have routing capabilities, you can use the switch router to interconnect the bridged and routed networks.

Cisco IOS Software Basics

This section provides you with some basic information about Cisco IOS software. It describes the Cisco IOS modes of operation and how to get context-sensitive Help.

Cisco IOS Modes of Operation

Cisco IOS software provides access to several different command modes. Each command mode provides a different group of related commands.

The command interpreter is called the EXEC. You must log into the switch router or switch before you can enter an EXEC command. For security purposes, Cisco IOS software provides two levels of access to commands: user and privileged. The user mode is called user EXEC mode. The privileged mode is called privileged EXEC mode and requires a password.

Table 1-3 describes some of the most commonly used modes, how to enter the modes, and the resulting prompts. The prompt helps you identify which mode you are in and, therefore, which commands are available to you.


Table 1-3: Cisco IOS Command Modes
Command Mode Usage How to Enter the Mode Prompt Display

User EXEC

Allows you to connect to remote devices, change terminal settings on a temporary basis, perform basic tests, and display system information. The EXEC commands available at the user level are a subset of those available at the privileged level.

Log in.

Router>

Privileged EXEC

Sets operating parameters. The privileged command set includes the commands in user EXEC mode, as well as the configure command. Use this command to access the other command modes. Privileged EXEC mode also includes high-level testing commands, such as debug.

From the user EXEC mode, enter the enable command.

Router#

Global configuration

Apply to features that affect the system as a whole.

From the privileged EXEC mode, enter the configure terminal command.

Router(config)#

Interface configuration

Many features are enabled for a particular interface. Interface commands modify the operation of an Ethernet port. You initiate interface configuration with the interface command, which defines the interface type.

You can configure several virtual interfaces on a single physical serial interface. These virtual interfaces are logical constructs called subinterfaces.

From global configuration mode, enter the interface type number command.

For example, enter interface fa0/0/0
to configure the Fast Ethernet 0/0/0 interface.

Router(config-if)#

Console configuration

From the directly connected console or the virtual terminal used with Telnet, use this configuration mode to configure the console port.

From global configuration mode, enter the line console 0 command.

Router(config-line)#

When you type exit, the switch router backs out one level. In general, typing exit from one of the specific configuration modes returns you to global configuration mode. To exit configuration mode completely and return to privileged EXEC mode, press <Ctrl-Z>.

You can also abbreviate commands and keywords by entering just enough characters to make the command unique from other commands. For example, you can abbreviate the show command to sh.

Getting a List of Available IOS Commands

In any command mode, you can get a list of available commands by entering a question mark (?).

Router>  ?

To obtain a list of commands that begin with a particular character sequence, type in those characters followed immediately by the question mark (  ?  ). Do not include a space. This form of help is called word help, because it completes a word for you.

Router# co?
configure connect copy

To list keywords or arguments, enter a question mark in place of a keyword or argument. Include a space before the question mark. This form of help is called command syntax help, because it reminds you which keywords or arguments are applicable based on the command, keywords, and arguments you have already entered.

Router# configure  ?
memory Configure from NV memory
network Configure from a TFTP network host
terminal Configure from the terminal

To redisplay a command you previously entered, press the up-arrow key. You can continue to press the up-arrow to see more previously issued commands.

TimeSaver Each command mode restricts you to a subset of commands. If you are having trouble entering a command, check the prompt, and enter the question mark (  ?  ) for a list of available commands. You might be in the wrong command mode or using incorrect syntax.

You can press <Ctrl-Z>in any mode to immediately return to Privileged EXEC (enable) mode (8510#), instead of entering exit, which returns you to the previous mode.


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