A multihomed transit AS has more than one connection to the outside world and can still be used for transit traffic by other ASs (see Figure 4-6). Transit traffic (relative to the multihomed AS) is any traffic that has an origin or destination that does not belong to the local AS. Figure 4-6. Multihomed Transit AS Using BGP Internally and Externally Although BGP-4 is an exterior gateway protocol, it can still be used inside an AS as a pipe to exchange BGP updates. BGP ..
Besides smurf and fraggle attacks, other attacks involve the use of what can be generally termed inappropriate IP addresses, both for the source IP address and destination IP address. By using inappropriate IP addresses, the attacker can remain hidden and elicit cooperation of other hosts to create a distributed denial-of-service (DDoS) attack. One of the Layer 3 security best practices is to use ACLs to filter packets whose IP addresses are not appropriate—for instance, th..
Monitoring and Verifying Frame Relay Switching Enhancements on a Cisco Router
This section discusses the IOS show c ommands for monitoring and verifying the Frame Relay Switching Enhancements information on a Cisco router. To facilitate the discussion on how Frame Relay switching enhancements work, traffic flow is generated on the network to help simulate actual users' traffic. Refer to the network depicted in Figure 6-3. Two servers are set up, one at each end of the Frame Relay network for the purpose of generating users' traffic into the Frame Relay..
A Common Issue Encountered in Frame Relay Networks
This section looks at a common issue encountered during the implementation of Frame Relay networks. The discussion covers the problems introduced by split horizon on Frame Relay networks and how Cisco uses subinterfaces to resolve this problem. Split Horizon The split horizon rule states that a router should not advertise a route out of an interface where the route was learned. For example, when RIP is the designated routing protocol on the network, the split horizon rule m..
Table 1-1 summarizes the common Frame Relay terminology you will continue to see throughout this book. Table 1-1. Common Frame Relay Terminology Term Definition Description CIR Committed Information Rate Rate in bps at which the network commits to transfer user data under normal conditions, averaged over a minimum time interval, Tc. EIR Excess Information Rate The maximum rate in bps in excess of the ..
