Other Applications of Policy Routing

One practical application of policy routing is its use with firewalls. Firewalls are devices that apply security requirements to traffic. Firewall implementations include packet filtering, authentication, and encryption. Depending on the network setup, administrators might want to direct some or all incoming (or outgoing) traffic toward a firewall device, as shown in Figure 8-9. Figure 8-9. Incoming or Outgoing Traffic Can Be Routed to a Firewall   An applicable situati..

Defining and Limiting CBWFQ Bandwidth

Cisco IOS checks a CBWFQ policy map to ensure that it does not allocate too much bandwidth. IOS performs the check when the service-policy output command is added; if the policy map defines too much bandwidth for that interface, the service-policy command is rejected. IOS defines the allowed bandwidth based on two interface subcommands: the bandwidth command,and the reserved bandwidth implied by the max-reserved-bandwidth command (abbreviated hereafter as int-bw and max-res, ..

Enhanced IGRP and Bandwidth Control

Before continuing with Enhanced IGRP and bandwidth-related commands, you should understand bandwidth control. By default, Enhanced IGRP limits itself to 50 percent of the configured bandwidth. A benefit of controlling Enhanced IGRP usage is that it limits the Enhanced IGRP traffic in case of failure. This makes the rest of the bandwidth available for data traffic. Another advantage is that you avoid losing Enhanced IGRP packets, which could occur when Enhanced IGRP generates ..

Limiting MIB Access

You can use the following commands to restrict SNMP access to portions of the MIB tree. This example shows the legacy configuration method: Router#configure terminal Enter configuration commands, one per line.  End with CNTL/Z. Router(config)#access-list 99 permit 172.25.1.0 0.0.0.255 Router(config)#access-list 99 deny any log Router(config)#snmp-server view ORAVIEW mib-2 included Router(config)#snmp-server view ORAVIEW at excluded Router(config)#snmp-server view ORAVIE..

VTP Advertisements

Each Cisco switch participating in VTP advertises VLANs (only VLANs 1 to 1005), revision numbers, and VLAN parameters on its trunk ports to notify other switches in the management domain. VTP advertisements are sent as multicast frames. The switch intercepts frames sent to the VTP multicast address and processes them with its supervisory processor. VTP frames are forwarded out trunk links as a special case.Because all switches in a management domain learn of new VLAN configur..