Classful Distance Vector to Classless Distance Vector Protocol RIP to Enhanced IGRP

Migrating from RIP to Enhanced IGRP requires careful planning because there is a possibility of routing loops and because metric conversion must be considered. For example, in the network shown in Figure 12-2, the customer does not want to create hierarchy in the physical topology to accommodate OSPF. However, without hierarchy, OSPF cannot be implemented because of scaling issues. In this case, the only other option is Enhanced IGRP. As with any other routing protocol, Enhanced IGRP has...

Configuring the Areas in OSPF

Recall that OSPF has four types of areas in the Cisco environment, which were defined in the earlier section The OSPF Area Concepts Recall that in a regular area, every link state is flooded. Configuration for regular area is simple network 131.108.0.0 0.0.255.255 area 1 External link states are not flooded in the stub area. All routers in that area need to be defined as stub. If any router within the area is not defined as stub, an adjacency is not formed. The stub area configuration is as...

Building an IBGP Core

In Figure 16-14, USA.Cal.R1 needs full IBGP mesh, so it must maintain peering statements for all the IBGP-speaking routers. However, full IBGP mesh causes difficulty with optimal routing. To accommodate optimal routing and add predictability, Alpha.com is not peering USA.Cal.R1 with Euro.Fra.R2, which accommodates the physical topology. To accommodate optimal routing with IBGP, Alpha.com must break the IBGP model and perform many tricks that complicate the network. Another possible problem...

OSPF Over Different Physical Media

Classically, networks can be divided into three types broadcast (Ethernet, Token Ring, and FDDI), point-to-point (HDLC and PPP), and non-broadcast multiaccess (Frame Relay, SMDS, and X.25). Behavior of OSPF over broadcast and point-to-point networks is uncomplicated, but the behavior of OSPF over non-broadcast multiaccess networks (NBMA) requires further explanation. When configuring OSPF over NBMA networks, you can configure the router to behave in four ways Each of these methods is discussed...

ISIS and Default Routes

The purpose of the default route in any routing protocol is to forward traffic to destinations that are not in the router's routing table. It is not possible for all the routers in a network to have full Internet routes. For this purpose, routers without full routes to all the destinations forward traffic to the default originating router. Level 1 routers never maintain information about any destination that is outside their area, so all level 1 routers merely send packets to the nearest level...

RIP and Discontiguous Networks

Recall that discontiguous networks have subnets of the same major network, separated by a different major network. RIP does not carry a prefix mask, and it summarizes at the natural classful length mask. This raises another issue How can you support discontiguous networks This type of network must communicate exact addresses across the entire network. Referring again to Figure 6-3, when the router must send updates about subnet 140.10.20.0 to router R1, it summarizes the update at the natural...

The Dijkstra Algorithm

Before you continue, you should review the Dijkstra algorithm. Figure 10-3 shows the network setup for which SPF is to be executed. Also, study the following network tables to understand how the router calculates the shortest path to the destination. All the associated costs for the interfaces are listed. Costs for exiting the interface are always considered. Figure 10-3. Network Setup for which SPF Is to Be Executed To begin the process, each router considers three lists When the process is...

Figure 113 Comparison of Dna Iv and the OSI Model

MQP Ettoritt , FQD1 LAPtJ _ IE> ,C ttt LOHon KWT1G DOC Pi P 902.2 LLC H rty FWay Elteire Tofcen R ny FDDI i sciiif v -A 1 Ipfihvare i ls dware Therefore, there is no need for an equivalent of ARP in the DNA IV. The network-layer address is 16 bits, with the first six bits used to identify an area and the remaining 10 bits used as a node address. Addresses are usually written in the form area.node, where area is 1-, and node is 1-1023. This area node distinction enables DNA IV to perform...

Flow Accounting and Traffic Engineering

Distance-dependent charging schemes also exist. As with telephone calls, to determine the cost of each byte, it is necessary to know where each byte originates and its destination. The origin issue seems obvious the traffic enters the network on an interface associated with a particular customer. To determine the destination, you must perform flow accounting this is where Netflow comes in. It is generally recommended that you deploy Netflow as a perimeter technology that is, enable Netflow on...

OSPF Packet Types

Ospf Router Types

As mentioned previously, OSPF has five kinds of routing protocol packets, and each is identified by the Type field in the protocol header. Now, we will discuss those packet types in more detail. OSPF Packet type 1, as shown in Figure 9-2, is the hello packet. Hello packets are sent periodically to all functional OSPF interfaces, and are used to detect neighbors. OSPF packets are sent to the multicast address 224.0.0.5. The basic function of the hello packet is to establish a neighbor...

CCIE Professional Development Large Scale IP Network Solutions

Khalid Raza Mark Turner Publisher Cisco Press First Edition November 09, 1999 ISBN 1 -57870-084-1, 576 pages CCIE Professional Development Large-Scale IP Network Solutions is a core preparation textbook for the CCIE Routing and Switching exam track. In addition to CCIE preparation, this book provides solutions for network engineers as IP networks grow and become more complex. The book discusses all major IP protocols in depth, including RIP, IGRP, EIGRP, OSPF, IS-IS, and BGP. It evaluates the...

Figure 1650 ISPnet BGP Architecture

The generic BGP router configuration for ISPnet includes the large-scale configuration developed in Chapter 11, Border Gateway Protocol, along with a number of peer group definitions. Note that full functionality is not required for all routers, but it is beneficial to maintain a consistent configuration across the network. ISPnet extensively uses communities to color routes. In particular, the following communities are defined Communities used for BGP QoS policy propagation ip community-list...