By 1985, the ARPANET was heavily utilized and burdened with congestion. In response, the National Science Foundation initiated phase 1 development of the NSFNET. The NSFNET was composed of multiple regional networks and peer networks (such as the NASA Science Network) connected to a major backbone that constituted the core of the overall NSFNET. In its earliest form, in 1986, the NSFNET created a more distributed, three-tiered network architecture. This architecture connected..
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..
WAN Edge QoS Design Considerations
QoS policies required on WAN aggregators include queuing, shaping, selective dropping, and link-efficiency policies in the outbound direction of the WAN link. Traffic is assumed to be correctly classified and marked (at Layer 3) before WAN aggregator ingress. Remember, Layer 3 markings (preferably DSCP) are media independent and traverse the WAN media, whereas Layer 2 CoS is lost when the media switches from Ethernet to WAN media. Several factors must be kept in mind when de..
One of the motivations for the introduction of the Catalyst 5500 series products was the customer need for system redundancy. The legacy Catalyst 5000 series contains one Supervisor module, which, if it fails, disables the entire unit. The Catalyst 5500/6000 family, on the other hand, enables you to put two Supervisor modules into the chassis at the same time. On power up, one of the modules becomes the active Supervisor engine, and the other becomes the standby Supervisor en..
Authenticating Login IDs from a Central System
When you configure AAA authentication on a router, it starts to ignore the locally configured passwords in favor of those provided by the TACACS+ server. In this example, we have configured the router to consult TACACS+ for both the login and enable passwords. This is a great labor saver because it means that you don't have to reconfigure all of your routers just because you want to change passwords. Instead, because the passwords are stored on a central server, you can chang..
