Cisco 10000-2P2-2DC Software Guide - Page 276
Limitations of DHCP-Based Address Assignment, On-Demand Address Pool Manager
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On-Demand Address Pool Manager Chapter 10 Configuring Address Pools Limitations of DHCP-Based Address Assignment DHCP-based address assignment has route summarization problems similar to the problems encountered with RADIUS-based address assignment. Route summarization becomes less efficient as remote users log on and off, and users have limited connectivity while BGP updates all of the PE routers with newly configured routes. For more information, see the "RADIUS-Based Address Assignment" section on page 10-2. On-Demand Address Pool Manager The On-demand Address Pool Manager feature is a mechanism for assigning and managing IP addresses. On-demand address pools (ODAPs) use a central server to manage a block of addresses for each customer. The central server can be a Dynamic Host Configuration Protocol (DHCP) server or a RADIUS server. After the ODAP is configured, the central server populates the ODAP with one or more subnets leased from the central server. The central server divides each address pool into subnets and assigns the subnets to PE routers upon request. Note The Cisco Network Registrar (CNR) DHCP server and the Cisco Access Registrar (CAR) RADIUS server support ODAPs. The customer site connects to a provider edge (PE) router in the provider network. When an ODAP is configured, the pool manager for the PE router initiates a request to the central server for an initial subnet for a specific ODAP. The pool manager then monitors the utilization of the ODAP. If the utilization of the pool exceeds a high-utilization threshold (high-utilization mark), the pool manager requests an additional subnet from the central server and adds it to the ODAP. Similarly, if the utilization of the pool decreases below the low-utilization threshold (low-utilization mark), the pool manager returns one or more subnets to the central server from which it was originally leased. Each time subnets are added to or removed from the ODAP, the summarized routes for each leased subnet must be inserted or removed from the corresponding VRF. The On-demand Address Pool Manager feature is described in the following topics: • Feature History for On-Demand Address Pool Manager, page 10-5 • Address Allocation for PPP Sessions, page 10-5 • Subnet Releasing, page 10-5 • On-Demand Address Pools for MPLS VPNs, page 10-5 • Benefits On-Demand Address Pool Manager, page 10-6 • Prerequisites for On-Demand Address Pool Manager, page 10-6 • Required Configuration Tasks for On-Demand Address Pool Manager, page 10-6 • Optional Configuration Tasks for On-Demand Address Pool Manager, page 10-10 • Verifying On-Demand Address Pool Operation, page 10-12 • Configuration Examples for On-Demand Address Pool Manager, page 10-14 • Monitoring and Maintaining an On-Demand Address Pool, page 10-15 10-4 Cisco 10000 Series Router Software Configuration Guide OL-2226-23
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