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..
Decimal Shortcuts to Find the Subnet Number and Valid Range of IP Addresses
Many of the IP addressing and routing related problems on the exam come back to the ability to solve a couple of classic basic problems. One of those problems runs as follows: Given an IP address and mask (or prefix length), determine the subnet number/prefix, broadcast address, and range of valid IP addresses. If you personally can already solve such problems with only a few seconds’ thought, even with tricky masks, then you can skip this section of the chapter. If you c..
ATM adopts a strategy of segmenting all IP packets into small, 53-byte cells carrying a 48-byte data payload. The motivation for small cells is based on minimizing packetization delay, which makes the technology suitable for time-sensitive applications. The motivation for fixed cells is to allow the switching to occur in hardware, because hardware switching of variably sized frames is more complex. The choice of small cell size has been a source of debate. Nevertheless, in lo..
Preventing Unauthorized Configuration Modifications
You can use the snmp-server tftp-server-list configuration command to restrict which TFTP servers the router can use in response to an SNMP trigger to upload or download configuration information: Router#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Router(config)#access-list 92 permit 172.25.1.1 Router(config)#access-list 92 deny any log Router(config)#snmp-server tftp-server-list 92 Router(c..
Displaying Historical CPU Values
To display the router's historical CPU values, use the show processes cpu history command: Router# show processes cpu history Router 03:48:18 PM Monday Apr 17 2006 EDT &n..
