Changing the Router from Level 1-2
By default, routers support both Level 1 and Level 2 routing. Routing at both levels means twice as many hellos and advertisements, twice as much memory consumed, and twice as much processing. However, routing at both levels makes configuration easier. One easy way to optimize IS-IS is to reduce the unnecessary duplication of routing at both levels. IS-IS level is set under the IS-IS process using the is-type level-1 or is-type level-2 commands. Once applied, all interfaces c..
Level 1 router summarization is done only for external routes (redistributed routes from other protocols) because the level 1 router does not receive any routes from the level 2 routers. As such, there is no need to summarize routes from level 2 routers—you can summarize both level 1 and external routes in level 2. External routes can be summarized only at the redistributing router. After the LSP is originated, it cannot be summarized. Summarizing of external ..
There are several useful commands for checking the status of multicast configuration and protocols. You can see what multicast routes pass through a router with the EXEC command: Router#show ip mroute There are two useful variants of this command. The first reports on forwarding statistics for each multicast group: Router#show ip mroute count And the second reports only on the groups that are currently active: Router#show ip mroute active You can look at statistics on ..
You can configure HSRP so that both routers are always in use if they are available. This allows you to use your network resources more efficiently, but it is slightly more complicated to configure. Configure the first router as follows, with two HSRP groups: Router1#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Router1(config)#interface FastEthernet0/1 Router1(config-if)#ip address 172.22.1.3 255.255.255.0 Router1(config-if)#st..
DHCP-Secured IP Address Assignment
To enable secured IP address assignment, use the update arp command:Router1#configure terminal Enter configuration commands, one per line. End with CNTL/Z.Router1(config)#ip dhcp pool OREILLYRouter1(dhcp-config)#update arpRouter1(dhcp-config)#endRouter1#Beginning with IOS Version 12.2(15)T, Cisco introduced the concept of DHCP secured IP address assignment. This feature synchronizes the ARP entry to the DHCP binding to ensure that IP addresses assign via DHCP can'..
