Table of Contents

Networking Protocol Configurations

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. For more information about the Cisco IOS commands used in this chapter, refer to the Cisco IOS command references. This chapter includes the following sections:

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

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 configuration detail for each protocol. For detailed information, refer to any of the protocol configuration guides in the public domain.

IP routing is enabled by default on the switch router. For IP routing, make the following configurations for the interface:

• a network address
  
  
• a subnetwork address
  
  
• an IP subnet mask
  
  

The following global configurations are also required:

• 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.
  
  

Supported Routing Protocols

Layer 3 switching supports the routing protocols listed and described below.

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.

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.

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.)

Configuring IP Routing Protocols

Table 6-1 shows an example of the Cisco IOS commands used to configure routing protocols to run on a Fast Ethernet interface.

Verifying IP Operation

Once IP routing is configured, you can monitor and troubleshoot the protocol operation using the commands in Table 6-2.

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

Protcol 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

Table 6-3 shows an example of how to configure IP multicast routing.

Verifying IP Multicast Operation

Once IP multicast routing is configured, you can monitor and troubleshoot its operation using the commands in Table 6-4.

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
  
  

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 Identifies 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

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. The switch router supports up to two parallel paths, with a default of one.

Interface Configuration Parameters

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).

Configuring Novell IPX Routing

Table 6-5 shows an example of how to enable Novell IPX routing, and configure an interface.

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 commands in Table 6-6.

Refer to "Comprehensive Configuration Examples," for switch router 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 support 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.

For more detailed instructions on AppleTalk configuration, see the Cisco IOS Command Reference.

To enable AppleTalk routing, use the procedure in Table 6-7.

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 "Bridging Configurations."