External View of the IP SSO and NSF
This section describes the IP control-plane SSO and IP NSF operation from the perspective of neighboring nodes. The following description should be useful to better understand interactions between NSF-capable and NSF-incapable neighbors in the ensuing chapters: The IP control-plane SSO capability of a router is not visible to neighbors because it does not involve any protocol message exchange before or after the switchover. In that sense, the IP control-plane SSO capability ..
Input Events and Local Computation
An EIGRP router needs to react when an input event occurs. The obvious input events are when a router learns of new prefixes via newly received routing updates, when an interface fails, or when a neighbor fails. Because EIGRP sends updates only as a result of changed or new topology information, a router must consider the update and decide if any of its routes have changed. When an input event implies that a route has failed, the router performs local computation, a fancy te..
Unlike IGRP, EIGRP is an advanced distance vector protocol that carries the subnet mask information when an update is sent out. Therefore, EIGRP supports discontiguous network and variable-length subnet masking (VLSM). For more explanation about discontiguous networks and VLSM, "Understanding Routing Information Protocol (RIP)." Figure 6-8 shows the network diagram that illustrates EIGRP's support for discontiguous networks. Figure 6-8. Example of EIGRP Support for Discontig..
RSVP is a per-flow protocol that requests a bandwidth reservation from every node in the path of the flow. In its simplest form, RSVP is a unidirectional protocol, so if a bidirectional reservation is required for a flow, both endpoints must initiate a request for a reservation. Basic RSVP protocol operation is shown in Figure 8-1 and its configuration in Example 8-1. The endpoints, or other network devices on behalf of the endpoints, send unicast signaling messages to estab..
Port-based authentication can be handled by one or more external Remote Authentication Dial-In User Service (RADIUS) servers. Although many Cisco switch platforms allow other authentication methods to be configured, only RADIUS is supported for 802.1x. The actual RADIUS authentication method must be configured first, followed by 802.1x, as shown in the following steps: Step 1. Enable AAA on the switch. By default, AAA is disabled. You can enable AAA for port-based aut..
