Chapter 22 Advanced DHCP Server Properties

Defining Advanced Server Parameters

Table 22-1 DHCP Advanced Parameters

Advanced Parameter

Action

Description

max-dhcp-requests

set/

Controls the number of buffers that the DHCP server allocates for

 

unset

receiving packets from DHCP clients and failover partners. If this

 

 

setting is too large, a burst of DHCP activity can clog the server with

 

 

requests that become stale before being processed. This results in an

 

 

increasing processing load that can severely degrade performance as

 

 

clients try to obtain a new lease, and affects the ability to handle

 

 

bursts. A low buffer setting throttles requests and could affect server

 

 

throughput. If the server runs out of buffers, packets are dropped.

 

 

A good rule or thumb is to increase the buffers if you expect a high

 

 

load (in a steady state or when experiencing frequent stress times)

 

 

or you have a fast multiprocessor system.

 

 

In a nonfailover deployment, the default setting (500) is sufficient.

 

 

In a failover deployment, you can increase it to 1000 if the DHCP

 

 

logs indicate a consistently high number of request buffers. You

 

 

should then also modify the number of DHCP responses (see the

 

 

max-dhcp-responsesparameter) to four times the request buffers.

 

 

When using LDAP client lookups, buffers should not exceed the

 

 

LDAP lookup queue size defined by the total number of LDAP

 

 

connections and the maximum number of requests allowed for each

 

 

connection. Set the LDAP queue size to match the LDAP server’s

 

 

capacity to service client lookups.

 

 

Some log messages that might trigger a change in this value are:

 

 

4493 DHCP ERROR "DHCP has used xx of its yy request

 

 

buffers: the server is dropping a request."

 

 

4494 DHCP WARNING "DHCP has used xx of yy request packets.

 

 

Requests will be ignored if no packet buffers are

 

 

available."

 

 

5270 DHCP WARNING "DHCP has used xx of its yy request

 

 

buffers: the server is congested -- will not keep the

 

 

client last-transaction-time to within value but will keep

 

 

it to within value seconds."

 

 

Required. The default is 500.

 

 

 

Cisco CNS Network Registrar User’s Guide

22-4

OL-6240-02

 

 

Page 3 Page 5
Page 4
Image 4
Cisco Systems OL-6240-02 manual Advanced Parameter Action Description, 22-4
Page 3 Page 5

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.
Top Page Image Contents