Determining All Subnets of a Network—Binary

Another common question, typically simply a portion of a more challenging question on the CCIE written exam, relates to finding all subnets of a network. The base underlying question might be as follows: Given a particular class A, B, or C network, and a mask/prefix length used on all subnets of that network, what are the actual subnet numbers? The answers can be found using binary or using a simple decimal algorithm. This section first shows how to answer the question using..

Well-Known Multicast Addresses

IANA controls the assignment of IP multicast addresses. To preserve multicast addresses, IANA is reluctant to assign individual IP multicast addresses to new applications without a good technical justification. However, IANA has assigned individual IP multicast addresses to popular network protocols. IANA has assigned several ranges of multicast IP addresses for specific types of reasons. Those types are as follows: ■ Permanent multicast groups, in the range 224.0.0.0–2..

Class-Based Marking (CB Marking) Configuration

As with the other QoS tools whose names begin with the phrase “Class-Based,” you will use MQC commands to configure CB Marking. The following list highlights the key points regarding CB Marking configuration and logic: ■ CB Marking requires CEF (enabled using the ip cef global command). ■ Packets are classified based on the logic in MQC class maps. ■ An MQC policy map refers to one or more class maps using the class class-map-name command; packets classified int..

Using SNMP to Modify a Router's Running Configuration

To upload or download a current copy of your router's configuration file to a TFTP server via SNMP, you have to first configure the router for read-write SNMP access: Router#configure terminal Enter configuration commands, one per line.  End with CNTL/Z. Router(config)#snmp-server community ORARW rw Router(config)#end To download the current configuration file, you will need to create an empty file on your TFTP server. In this case, we assume a Unix server, although TF..

Generating a Report of Interface Information

The netstat.pl script uses SNMP to gather IP subnet information from a list of routers. This ensures that the information is accurate and current. The script gathers all of the pertinent information about each router's IP interfaces and outputs this information as a CSV file. The netstat.pl script requires Perl and NET-SNMP and expects to find both in the /usr/local/bin directory. For more information on Perl or NET-SNMP, please see Appendix A. If you keep these programs in a..