Table of Contents

Configuring Networking Protocols

This chapter describes networking protocol configurations for your switch router. It provides initial configuration information so you can get your switch router up and running.

Unless otherwise noted, the information in this chapter applies to the Catalyst 8540 CSR, Catalyst 8510 CSR, and Catalyst 8540 MSR with Layer 3 functionality. For further information about the commands used in this chapter, refer to the command reference publications in the Cisco IOS documentation set and to "Command Reference."

This chapter includes the following sections:

• About IP Routing Protocols
  
  
• Configuring IP Routing Protocols
  
  
• About IP Multicast Routing
  
  
• Configuring IP Multicast Routing
  
  
• About Novell IPX Protocol
  
  
• Configuring Novell IPX Routing
  
  
• About AppleTalk
  
  
• Configuring AppleTalk
  
  

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Note   You are at Step 4 in the suggested process for configuring your switch router (see the "Suggested Procedure for Configuring Your Switch Router" section). You should have already completed general interface configurations and now be ready to proceed with configuring networking and routing protocols.

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About IP Routing Protocols

This section briefly describes how to configure the switch router for supported IP routing protocols. It is intended to provide enough information for a network administrator to get the protocols up and running. However, this section does not provide in-depth configurations for each protocol. For detailed information, refer to any of the protocol configuration guides in the public domain and to the Cisco IOS publications for networking protocols.

IP routing is enabled by default on the switch router. For IP routing, you must configure the following values on the interface:

• Network address
  
  
• Subnetwork address
  
  
• IP subnet mask
  
  

You must also do the following global configurations:

• 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.
  
  

Layer 3 switching supports the routing protocols listed and described in the following sections. For more information on these routing protocols, see the Cisco IOS Network Protocols Configuration Guide, Part I and Cisco IOS Network Protocols Configuration Guide, Part II .

Routing Information Protocol

Routing Information Protocol (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.)

Open Shortest Path First

Open Shortest Path First (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 the attached interfaces and their metrics 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 multipath 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.

Interior Gateway Routing Protocol

Interior Gateway Routing Protocol (IGRP) is a distance vector interior-gateway routing 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.

Enhanced Interior Gateway Routing Protocol

Enhanced Interior Gateway Routing Protocol (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.

Border Gateway Protocol

Border Gateway Protocol (BGP) is an Exterior Gateway Protocol (EGP) that allows you to set up an interdomain routing system to automatically guarantee the loop-free exchange of routing information between autonomous systems. In BGP each route consists of a network number, a list of autonomous systems that information has passed through (called the autonomous system path), and a list of other path attributes.

Layer 3 switching supports BGP version 4, including classless interdomain routing (CIDR). CIDR lets you reduce the size of your routing tables by creating aggregate routes resulting in supernets. CIDR eliminates the concept of network classes within BGP and supports the advertising of IP prefixes. CIDR routes can be carried by OSPF, EIGRP, and RIP.

Intermediate System-to-Intermediate System

Intermediate System-to-Intermediate System (IS-IS) is an OSI link-state hierarchical routing protocol that floods the network with link-state information to build a complete, consistent picture of the network topology. To simplify router design and operation, IS-IS distinguishes between Level 1 and Level 2 ISs. Level 1 ISs communicate with other Level 1 ISs in the same area. Level 2 ISs route between Level 1 areas and form an intradomain routing backbone. Hierarchical routing simplifies backbone design because Level 1 ISs only need to know how to get to the nearest Level 2 IS. The backbone routing protocol also can change without impacting the intra-area routing protocol.

Note   Layer 3 switching does not support the Next Hop Resolution Protocol (NHRP).

Configuring IP Routing Protocols

To configure routing protocols to run on a Fast Ethernet interface, perform the following steps, beginning in global configuration mode:

Configuring Load Balancing

Load balancing based on equal-cost paths is supported for all IP routing protocols. To configure load balancing for a routing protocol, perform the following steps, beginning in global configuration mode:

Monitoring IP Operation

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

About 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. IP 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 supports constrained multicast flooding over bridge group virtual interfaces (BVIs), as well as BVIs over Fast EtherChannel. Using constrained multicast flooding, the switch router can dynamically determine group membership of IP multicast groups and flood multicast packets only to those ports where group members reside.

A principle component of IP multicast is the Internet Group Membership Protocol (IGMP). With IGMP, a class D address can 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

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 truncating 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.
  
  

Configuring IP Multicast Routing

To configure IP multicast routing, perform the following steps:

For complete configurations using PIM and DVMRP, see "Configuration Examples."

IP Unicast and IP Multicast Fragmentation

Your switch router supports IP unicast and IP multicast data packet fragmentation on the POS OC-12c uplink and ATM OC-3c and OC-12c uplink interfaces.

• For IP unicast fragmentation, the packet must ingress on either the POS or ATM uplink interface and egress on any interface.
  
  
• For IP multicast fragmentation, IP multicast data packets greater than 1500 bytes are fragmented to 1500 bytes on the ingress POS or ATM uplink interface before being switched to other members in the multicast group. All the members in the multicast group must have an MTU equal to or greater than 1500 bytes.
  
  

Monitoring IP Multicast Operation

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

About Novell IPX Protocol

The Cisco implementation of 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
  
  

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Note   Layer 3 switching does not support the NetWare Link Services Protocol (NLSP).

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About IPX Network Addresses

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

• network number—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.
  
  
• node number —a node on the network, 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.

About Global and Interface Parameters

To configure Novell IPX as a routing protocol, you must configure both global and interface parameters.

Global Configuration Parameters

To configure global parameters for Novell IPX routing, perform the following steps:

Step 1   Start the IPX routing process.

Step 2   Enable load sharing if appropriate for your network.

Load sharing divides routing tasks evenly among multiple routers to balance the work and improve network performance.Up to two parallel paths (six for the enhanced Gigabit Ethernet interfaces) are supported, with a default of one.

Once you have started IPX routing and enabled load sharing (if needed) on the router, you can configure the interface for Novell IPX routing.

Interface Configuration Parameters

To configure an interface for Novell IPX routing, perform the following steps:

Step 1   Assign unique network numbers to each interface.

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.

Step 2   Set the optional encapsulation type, if it is different from the default.

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

Note   This section does not describe IPX configuration in detail. Refer to the IPX documentation in the Cisco IOS documentation set for detailed conceptual and configuration information.

Configuring Novell IPX Routing

To enable Novell IPX routing and configure an interface, perform the following steps, beginning in global configuration mode:

Monitoring 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:

See "Configuration Examples."

About AppleTalk

AppleTalk refers to the Apple network protocol architecture. Layer 3 switching software supports AppleTalk Phase 1 and AppleTalk Phase 2. For AppleTalk Phase 2, Layer 3 switching software supports both extended and nonextended networks.

AppleTalk Enhanced IGRP provides automatic redistribution. By default, AppleTalk Routing Table Maintenance Protocol (RTMP) routes are automatically redistributed into Enhanced IGRP, and AppleTalk Enhanced IGRP routes are automatically redistributed into RTMP. If desired, you can turn off redistribution. You can also completely turn off AppleTalk Enhanced IGRP and AppleTalk RTMP either on the device or on its individual interfaces.

Interfaces that are configured for AppleTalk can be configured to use either RTMP, Enhanced IGRP, or both. If two neighboring routers are configured to use both RTMP and Enhanced IGRP, the Enhanced IGRP routing information supersedes the RTMP information; however, both routers continue to send RTMP routing updates. This feature allows you to control the excessive bandwidth usage of RTMP.

Apple Update-based Routing Protocol (AURP) can be enabled on a tunnel interface.

The AppleTalk protocol architecture requires that security measures be implemented at higher application levels. Layer 3 switching supports AppleTalk distribution lists, allowing control of routing updates on a per-interface basis.

To prevent any possible corruption of the AARP table in any AppleTalk node that is performing address gleaning through Media Access Control (MAC), Layer 3 switching AppleTalk does not forward packets with local source and destination network addresses.

Configuring AppleTalk

To enable AppleTalk routing, first enable it on the router, and then configure it on each interface. All routers in a network or data link must agree on the cable range, default zone, and zone list. After an address and a zone name are assigned, the interface is enabled for packet processing.

To enable AppleTalk routing, perform the following steps, beginning in global configuration mode:

After you assign the address and zone names, the interface attempts to verify them with another operational router on the connected network. If there are any discrepancies, the interface does not become operational. If there are no neighboring operational routers, the device assumes the interface's configuration is correct, and the interface becomes operational.

Now that you have configured the networking protocols for your switch router, see "Configuring Bridging."