GLBP Operation GLBP prioritizes gateways to elect an active virtual gateway (AVG). Other group members provide backup for the AVG if that AVG becomes unavailable. If multiple gateways have the same priority, the gateway with the highest real IP address becomes the AVG. The group members request a virtual MAC address after they discover the … Read more
VRRP Configuration Configuring basic VRRP is a multistep process. The following are the steps to configure a basic VRRP configuration on the Cisco Nexus 7000 or 9000 Series switch: Step 1. Enable the VRRP feature. Step 2. Configure the VRRP group. Step 3. Configure the virtual IP of the VRRP group. Step 4. Configure the … Read more
VRRP Router Priority and Preemption VRRP router priority determines the role each VRRP router plays (that is, primary or backup) and the order of ascendancy for backup routers to become a primary if the primary fails. The priority of the primary router is 255, and the priorities of the backups are lower. In Figure 3-8, … Read more
Virtual Router Redundancy Protocol Virtual Router Redundancy Protocol (VRRP) allows for a transparent failover at the first-hop IP router by configuring a group of routers (a VRRP group) to share a single virtual IP address. VRRP selects an allowed router in that group to handle all packets for the virtual IP address. The remaining routers … Read more
HSRP Configuration Configuring basic HSRP is a multistep process. The following are the steps to configure a basic HSRP configuration on the Cisco Nexus 7000 or 9000 Series switch: Step 1. Enable the HSRP feature. Step 2. Configure the HSRP version. Step 3. Configure the HSRP group. Step 4. Configure the virtual IP of the … Read more
HSRP Object Tracking HSRP object tracking allows you to modify the priority of an HSRP interface based on the operational state of another interface. The tracking process periodically polls the tracked objects and notes any value change. The value change triggers HSRP to recalculate the priority. The HSRP interface with the higher priority becomes the … Read more
Optimal Path Determination Routing protocols use a metric to evaluate the best path to the destination. A metric is a standard of measurement, such as a path bandwidth, that routing algorithms use to determine the optimal path to a destination. To aid path determination, routing algorithms initialize and maintain routing tables that contain route information … Read more
Routing Metrics Routing algorithms use many different metrics to determine the best route. Sophisticated routing algorithms can base route selection on multiple metrics. Path Length The path length is the most common routing metric. Some routing protocols allow you to assign arbitrary costs to each network link. In this case, the path length is the … Read more
Routing Algorithms Routing algorithms determine how a router gathers and reports reachability information, how it deals with topology changes, and how it determines the optimal route to a destination. Various types of routing algorithms exist, and each algorithm has a different impact on network and router resources. Routing algorithms use a variety of metrics that … Read more
Autonomous Systems An autonomous system (AS) is a portion of an internetwork under common administrative authority that is regulated by a particular set of administrative guidelines. Autonomous systems divide global external networks into individual routing domains, where local routing policies are applied. This organization simplifies routing domain administration and simplifies consistent policy configuration. Each autonomous … Read more