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..

IS-IS and Summarization

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 ..

Currently Recommended Layer 3 Queuing Mechanisms

Each of the previously described Layer 3 queuing tools had serious shortcomings in handling the traffic mix required by converged networks. Either they handled data fairly well or could prioritize real-time applications, such as voice. But none of these tools was capable of handling both types of traffic efficiently. Therefore, enhanced algorithms were developed to leverage the strengths of each type of legacy algorithm and, at the same time, to minimize their weaknesses. Th..

Port Duplex Mode

You also can assign a specific link mode to Ethernet-based switch ports. Therefore, the port operates in half-duplex, full-duplex, or autonegotiated mode. Autonegotiation is allowed only on UTP Fast Ethernet and Gigabit Ethernet ports. In this mode, the port participates in a negotiation by attempting full-duplex operation first and then halfduplex operation if full duplex is not successful. The autonegotiation process repeats whenever the link status changes. Be sure to set..

Filtering Based on DSCP and TOS

You can filter packets based on the contents of the Differentiated Services Control Point (DSCP) field by using the dscp keyword: Router1#configure terminalEnter configuration commands, one per line.  End with CNTL/Z.Router1(config)#access-list 162 permit ip any any dscp af11Router1(config)#end   Similarly, to filter based on TOS, you can use the tos keyword: Router1#configure terminalEnter configuration commands, one per line.  End with CNTL/Z.Router1(confi..