Chapter 22 Advanced DHCP Server Properties

Configuring Virtual Private Networks and Subnet Allocation

•Adjust the mcd-blobs-per-bulk-readattribute value to tune DHCP start and reload times. Generally, a higher mcd-blobs-per-bulk-readattribute value results in faster server start and reload times, at the cost of using more memory. Values can be set to any number between 1 and 2500 using the mcd-blobs-per-bulk-readDHCP server attribute. The current default is 256 blobs.

•Consider setting client caching (see the “Setting Client Caching Parameters” section on page 23-12).

•Check the server statistics to aid in monitoring server performance (see the “Displaying Statistics” section on page 6-8).

•Consider setting the scope allocation priority (see the “Configuring Multiple Scopes Using Allocation Priority” section on page 19-7).

•If pinging hosts before offering addresses, consider adjusting the ping timeout period (see the “Pinging Hosts Before Offering Address” section on page 21-5).

•To boost performance, consider limiting the number of scope-selection tags.

•If using Lightweight Directory Access Protocol (LDAP) servers, consider the performance issues described in the “Configuring Network Registrar to Use LDAP” section on page 23-17.

•If using DHCP failover, consider using the load balancing feature (see the “Setting Load Balancing” section on page 26-17).

Tip Be sure to follow any DHCP server attribute changes with a server reload.

Configuring Virtual Private Networks and Subnet Allocation

This section describes how to configure the Cisco CNS Network Registrar DHCP server to support virtual private networks (VPNs) and subnet allocation for on-demand address pools.

Configuring VPNs involves an adjustment to the usual DHCP host IP address designation. VPNs use private address spaces that might not be unique across the Internet. Because of this, Network Registrar supports IP addresses that are distinguished by a VPN identifier. Relay agents on routers must support this capability as well. The VPN identifier selects the VPN to which the client belongs. VPN for DHCP is currently only supported by Cisco IOS software, the newest versions of which can include VPN IDs in the relayed DHCP messages.

Subnet allocation is a way of leasing subnets to clients (usually routers or edge devices) so that they can, in turn, provide DHCP services. This can occur along with or instead of managing individual client addresses. Subnet allocation can vastly improve IP address provisioning, aggregation, characterization, and distribution by relying on the DHCP infrastructure to dynamically manage subnets. Subnet allocation through DHCP is currently only supported by Cisco IOS software, the newest versions of which incorporate the on-demand address pools feature.

Configuring Virtual Private Networks Using DHCP

VPNs that you create provide a filtering mechanism for:

•Viewing the unified address space (see the “Viewing Unified Address Space” section on page 8-2).

•Listing address blocks (see the “Adding Address Blocks” section on page 8-5).

•Listing subnets (see the “Address Blocks and Subnets” section on page 8-4).

 

Cisco CNS Network Registrar User’s Guide

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OL-6240-02

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Cisco Systems OL-6240-02 manual Configuring Virtual Private Networks Using Dhcp, 22-12
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OL-6240-02 specifications

Cisco Systems OL-6240-02 is a highly regarded certification exam that delves into the realm of enterprise networking, particularly focusing on the Cisco Certified Network Professional (CCNP) Routing and Switching track. This particular exam serves as a critical test for network professionals aiming to validate their skills and knowledge in advanced routing technologies and network design.

One of the main features of OL-6240-02 is its emphasis on in-depth understanding of IP routing principles. Candidates are expected to demonstrate proficiency in configuring, maintaining, and troubleshooting complex routing protocols like OSPF (Open Shortest Path First), EIGRP (Enhanced Interior Gateway Routing Protocol), and BGP (Border Gateway Protocol). This includes comprehending routing algorithms, path selection, and the implementation of route redistribution, which are essential for optimizing network performance.

The exam also covers the characteristics of network security and infrastructure, where candidates must exhibit knowledge of implementing security protocols and best practices to safeguard network communications. This includes configuring virtual private networks (VPNs), utilizing access control lists (ACLs), and applying encryption techniques to secure data in transit.

Another crucial technology tested in OL-6240-02 is Quality of Service (QoS). Professionals must be adept at configuring QoS mechanisms to prioritize traffic, ensuring that critical applications receive the necessary bandwidth and latency requirements. This is increasingly important as businesses rely on a multitude of applications that have varying performance needs.

Cisco's emphasis on network automation and programmability is also a focal point of this certification. Candidates are expected to be familiar with using Cisco's software-defined networking (SDN) solutions and automation tools, which are essential for modern network management. This involves understanding how to leverage APIs and modeling tools to streamline network operations and enhance efficiency.

To succeed in OL-6240-02, candidates should possess a solid foundation in network fundamentals and have hands-on experience with Cisco devices. The certification not only validates expertise but also prepares professionals for real-world challenges in designing, implementing, and troubleshooting enterprise networks. Overall, OL-6240-02 is a stepping stone for network professionals seeking higher-level certifications and career advancements in the ever-evolving field of networking.
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