Changing the Aggregate's Attributes
In some situations, changing the aggregate's attributes is required. The example in this section shows one scenario in which this could be useful. As you have already seen, the aggregate can carry information about its individual elements if configured with the AS_SET option. If one or more of the routes forming the AS_SET aggregate are configured with no-export community attribute, the aggregate itself will carry the same attribute. This will prevent the aggregate from bein..
Application Authentication and Privacy
Many of the application layer protocols mentioned in this chapter have built-in authentication through the use of a basic password mechanism. However, many of these protocols—for instance, Telnet, FTP, and TFTP—send the usernames and passwords in clear text. Some of the more recently defined or updated protocols provide stronger security. For example, Secure Shell (SSH) provides an alternative to Telnet but with strong authentication and privacy. SSH was originally inten..
PPP Layer 2 Payload Compression
Cisco IOS software supplies three different payload compression options for PPP, namely Lempel-Ziv Stacker (LZS), Microsoft Point-to-Point Compression (MPPC), and Predictor. Stacker and MPPC both use the same underlying Lempel-Ziv (LZ) compression algorithm, with Predictor using an algorithm called Predictor. LZ uses more CPU and less memory in comparison to Predictor, and it typically results in a better compression ratio. Table 17-7 summarizes some of the key points regar..
IP networks are susceptible to unsecured intruders using a variety of different methods to gain entry. Through the campus, by dialup, and through the Internet, an intruder can view IP data and attack vulnerable network devices. IP networks must provide network security for the following reasons: • Inherent technology weaknesses All network devices and operating systems have inherent vulnerabilities. • Configuration weaknesses Common c..
Providing a Backup to Frame Relay Virtual Circuits
Using secondary connections to back up the main Frame Relay virtual circuits allows organizations to continue their business operations by ensuring network connectivity in the event of failures to the primary connections. Provisioning a secondary backup connection to the primary Frame Relay virtual circuit can prevent a single point of failure in the network. Some Frame Relay carriers offer network redundancy services by provisioning a secondary virtual circuit as a backup t..
