Two Final Tiebreaker Steps in the BGP Decision Process
It is possible for BGP to fail to determine a best path to an NLRI using Steps 0 through 8, so BGP includes the following tiebreakers. These values would not typically be manipulated in a routing policy to impact the decision process. 9. Smallest advertising eBGP RID, or iBGP RID, with an exception—If some routes are eBGP routes, the router prefers the route that was advertised by the eBGP router with the lowest RID. If only iBGP routes exist, the same logic is used but fo..
Configuring Bandwidth over an NBMA Cloud
EIGRP works well over all WANs, including point-to-point and NBMA environments such as Frame Relay or ATM. The NBMA topology can include either point-to-point subinterfaces or multipoint interfaces. Cisco identifies three rules that you should follow when configuring EIGRP over an NBMA cloud: • EIGRP traffic should not exceed the committed information rate (CIR) capacity of the virtual circuit (VC). • EIGRP aggregated traffic over all the VCs should..
Enhanced IGRP and Passive Interface
If you do not want to enable Enhanced IGRP on an interface, you must set it in passive mode. This prevents Enhanced IGRP from sending multicast hellos to an interface. The question then becomes: When would you want to set a passive interface? There are situations in which you should set Enhanced IGRP in passive mode. First, you would use the passive mode when a router is connected to a large number of customer sites and you do not want to run Enhanced IGRP on th..
Types of Internetworking Devices
Cisco devices fall into three main categories: bridges and switches, routers, and access servers. We discuss bridges and switches first. Bridges and Switches A bridge is a network device that operates at the data link layer. A bridge connects multiple data link layer network segments into a single logical network segment. There are many different types of bridges: • Transparent or learning • Encapsulation • Translational • Source-route •&n..
Recall that, by definition, a switch must forward broadcast frames out all available ports in the broadcast domain because broadcasts are destined everywhere there is a listener. Unless forwarded by more intelligent means, multicast frames follow the same pattern. In addition, frames destined for an address that the switch has not yet learned or has forgotten (theMAC address has aged out of the address table) must be forwarded out all ports in an attempt to find the destinati..
