How the DHCP AutoInstall Process Works

AutoInstall using DHCP allows for the configuration of a new Cisco router using Ethernet, Token Ring, and FDDI interfaces (the AutoInstall process using serial line interfaces remains unchanged from previous releases).

Note The term “router” is used in the following process to represent any supported Cisco device (including, for example, Access Servers).

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BGP Dampening

BGP route dampening can be used to reduce the propagation of unstable routes throughout a network. When a prefix flaps it will be assigned a penalty of 1000 and moved into the dampening state “history”. Each flap incurs another penalty (of 1000), which is applied cumulatively. If the penalty reaches the suppress-limit, the route is dampened, meaning it won’t be advertised to any neighbors. The default values for each dampening criteria are stated below:

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Active-active router redundancy using VARP

In most of Leaf-Spine deployments, redundancy in Spine layer is required to achieve high availability and to prevent network service disruption. Modern layer 2 networks adopted loop-free and balanced path networks using Multi Chassis Link Aggregation topologies with LACP port channels, leaving loop control methods (STP) as second protection layer. Spines also supports layer 3 networks, using ECMP in a scalable network topology. For unicast redundancy in layer 3, a common method is use First Hop Router Redundancy (FHRR) to provide a simple and unique gateway for Leaf level. VRRP and HRSP are popular FHRR protocols and supported in most equipments today. Although HSRP and VRRP provide redundancy, they are active-standby FHRR protocols and do not provide a balanced data traffic distribution over Multi Chassis Link Aggregated topologies. The following figure show show data traffic is handled using active-standby FHRR protocol topology.

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