Determining All Subnets of a Network—Decimal
You may have noticed the trend in the third octet values in the subnets listed in the previous paragraph. When assuming SLSM, the subnet numbers in decimal do have a regular increment value, which turns out to be the value of the magic number. For example, instead of the binary math in the previous section, you could have thought the following: ■ The interesting octet is the third octet. ■ The magic number is 256 – 224 = 32. ■ 172.31.0.0 is the zero subnet, because..
Network-Based Application Recognition
CB Marking can make use of NBAR’s powerful classification capabilities via the match protocol subcommand. Example 14-5 shows a configuration for CB Marking and NBAR in which the following requirements are met: ■ Any HTTP traffic whose URL contains the string “important” anywhere in the URL is marked with AF21. ■ Any HTTP traffic whose URL contains the string “not-so” anywhere in the URL is marked with DSCP default. ■ All other traffic is marked with AF11. Exa..
This section presents a sample network to summarize the configuration for MPCs and MPSs. Figure 10-9 Sample MPOA Network illustrates the network where two MPCs interconnect through one MPS. Figure 10-9. Sample MPOA Network The MPCs reside inside of Catalysts equipped with MPOA-capable LANE modules. The MPS resides in a 7204 router. Each MPC has one LEC enabled. The MPS has two LECs enabled, one for each of the two ELANs. The LECS and LESs reside in the 7204 rout..
NTP is used for accurate time-keeping and can, for example, reference atomic clocks that are present on the Internet. NTP is capable of synchronizing clocks within milliseconds and is a useful protocol when reporting error logs (for instance, from Cisco routers). NTP is useful for security/incident event correlation across multiple security devices and helps to determine the exact time of the event. For NTP, the defined ports are UDP port 123 and TCP port 123. NTP can ..
Summarizing Outbound Routing Information
By default, BGP will try to summarize routes. This is not always desirable, though, which is why we have explicitly disabled this feature in many of the examples in this chapter. In fact, many engineers prefer to manually summarize their routing tables because they want to control what gets summarized and what doesn't. The first problem with auto-summarization is that it is strictly classful. Your AS may not control all of the subnets in a classful network, and even if you d..
