Cisco Systems OL-6240-02 manual Using Extensions to Affect Dhcp Server Behavior, 22-8

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Chapter 22 Advanced DHCP Server Properties

Using Extensions to Affect DHCP Server Behavior

When you install the Microsoft BackOffice Resource Kit, the system path is not updated to reflect the location of the SMS data link library (DLL). Use one of these methods to configure this attribute:

a.Set the sms-library-pathattribute to a relative path:

•First, modify the system PATH variable to append the path of the directory where the DLL is installed:

sms-install-directory\diagnose

•Then, set sms-library-pathto the name of the DLL, such as smsrsgen.dll. You can also accept the system default by unsetting the attribute.

b.Set sms-library-pathto an absolute path. If you do not want to change the system path, set this attribute to the absolute path of the DLL location:

"\\Program Files\\Resource Kit\\sms\\diagnose\\smsrsgen.dll"

Step 6 Set the sms-network-discoveryDNS attribute to 1 to turn SMS network discovery on.

If you use the default of 0, you disable SMS network discovery.

Step 7 Set the sms-site-codeDHCP server attribute by entering the SMS site code from Step 3.

The default string is empty, but for data discovery to be successful, you must provide the site code.

Step 8 Set the sms-lease-intervalattribute to the SMS lease interval.

The lease interval is the time between sending addresses to SMS, or how long, in milliseconds, the DHCP server should wait before pushing the next lease to the SMS server when you run

server dhcp updateSms. Early versions of the SMSRsGen.dll file (SMS Version 2.0) did not allow SMS to reliably receive multiple updates within a one-second window (1000 ms); the default value, therefore, was set to 1.1 second (1100 ms). If you install a future version of the Microsoft BackOffice Resource Kit, which might contain an enhanced version of the SMSRsGen.dll file, then reduce this interval or set it to 0 to increase performance.

Step 9 Reload the DHCP server and check the name_dhcp_1_log file for a successful load.

Step 10 In the CLI, use server dhcp updateSms to initiate SMS processing. (This command can take an optional all keyword to send all leased addresses from the DHCP server to SMS. If you omit this keyword, the DHCP server sends only new leases activated since the last time the command ran.) Then, verify that both the DHCP and SMS logs indicate successful completion. Note that a server reload during SMS updating interrupts the process, but the process resumes (or restarts) after the server is back up.

Using Extensions to Affect DHCP Server Behavior

Network Registrar provides the ability to alter and customize the operation of the DHCP server through extensions, programs that you can write in TCL or C/C++. Extensions interact with the server in two ways: by modifying request or response packets, and through environment variables stored in the environment dictionary (see Chapter 28, “Using Extension Points” for details).

For example, you might have an unusual routing hub that uses BOOTP configuration. This device issues a BOOTP request with an Ethernet hardware type (1) and MAC address in the chaddr field. It then sends out another BOOTP request with the same MAC address, but with a hardware type of Token Ring (6). The DHCP server normally distinguishes between a MAC address with hardware type 1 and one with type 6, and considers them to be different devices. In this case, you might want to write an extension that prevents the DHCP server from handing out two different addresses to the same device.

Cisco CNS Network Registrar User’s Guide

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OL-6240-02

 

 

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Contents 22-1 Configuring BootpAbout Bootp Enabling Bootp for Scopes 22-2Moving or Decommissioning Bootp Clients Using Dynamic BootpBootp Relay Setting Advanced Dhcp Server ParametersAdvanced Parameter Action Description 22-422-5 Deferring Lease Extensions 22-6Integrating Windows System Management Servers 22-7Using Extensions to Affect Dhcp Server Behavior 22-8Unix 22-9Tuning the Dhcp Server 22-10Dhcp set activity-summary-interval 22-11Configuring Virtual Private Networks Using Dhcp 22-12Typical Virtual Private Networks 22-13Creating Virtual Private Networks 22-14Then 22-15VPN Usage 22-16Configuring Dhcp Subnet Allocation 22-1722-18 22-19 Setting Dhcp ForwardingVPN and Subnet Allocation Tuning Parameters 22-20

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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