Alternatives to the OSPF Network Command
As of Cisco IOS Software Release 12.3(11)T, OSPF configuration can completely omit the network command, instead relying on the ip ospf process-id area area-id interface subcommand. This new command enables OSPF on the interface and selects the area. For instance, on R3 in Example 10-8, the network 10.3.0.0 0.0.255.255 area 3 command could have been deleted and replaced with the ip ospf 1 area 3 command under S0/0.1 and e0/0. The network and ip ospf area commands have some mi..
Calculating Classfully Assumed Network Ranges
A common task in addressing is to take an IP address and to understand the range of addresses that are on the same network. Originally, this was done by reading the first bits of the address to determine a class; this is called classful addressing. The portion of the address consumed by the network prefix was then assumed, based on that class. Table 2-2 shows the first bits of an IP address, the corresponding classes, and the number of bytes assumed to be in the network..
IS-IS is limited because its metric has only six bits. This means that the value of an individual metric can range only from 0 to 63. The total length of a path between two ISs can be 1023 maximum. You should consider the metric in advance. The default value is assigned to be 10, independent of the bandwidth for all types of links and for both level 1 and level 2. The interface metric can be modified for each level independently. Configuration for level 1 metric is as follows..
Preventing Loops with Spanning Tree Protocol
Bridging loops form because parallel switches (or bridges) are unaware of each other. STP was developed to overcome the possibility of bridging loops so that redundant switches and switch paths could be used for their benefits. Basically, the protocol enables switches to become aware of each other so they can negotiate a loop-free path through the network. Note: Because STP is involved in loop detection, many people refer to the catastrophic loops as “spanning-tree lo..
Creating a Default Route in RIP
There are two ways to get RIP to propagate a default route. The preferred method is using the default-information originate command as follows: Router1#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Router1(config)#ip route 0.0.0.0 0.0.0.0 172.25.1.1 Router1(config)#router rip Router1(config-router)#default-information originate Router1(config-router)#end Router1# In simple situations, you can accomplish the same thing by just redistrib..
