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Home > Success Center > Server & Application Monitor (SAM) > Monitor DHCP servers on a different subnet than the Orion APM Server using the Orion APM DHCP User Experience Monitor

Monitor DHCP servers on a different subnet than the Orion APM Server using the Orion APM DHCP User Experience Monitor

Table of contents
Created by Aileen de Lara_ret, last modified by MindTouch on Jun 23, 2016

Views: 64 Votes: 1 Revisions: 9

Overview

In the DHCP User Experience Monitor, there is a field named DHCP Discovery Request Type. Use this field to specify the DHCP discovery request type that Orion APM uses. There are three options: UnicastBroadcast, or Relay Agent.  Refer to the section DHCP User Experience Monitor in the Orion APM Administrator Guide for details.

Environment

APM version 4.0.2 or later

Detail

Broadcast

If you are using the Broadcast option, the broadcast flag is set, the ciaddr (Client IP Address) is set to the local address, and the giaddr (Relay Agent IP Address) is not set. The DHCP client sends a unicast DHCP DISCOVER to the DHCP server IP address and the UDP Request Port (defaults to 67). The DHCP server then sends a broadcast DHCP Offer to theUDP Response Port (defaults to 68).

With this option, you can only monitor DHCP servers on the same subnet as the Orion APM server. No special configuration is required for the routers on your network.

 

Unicast

If you are using the Unicast option, The broadcast flag is not set, the ciaddr (Client IP Address) is set to the local address, and the giaddr (Relay Agent IP Address) is not set. The DHCP client sends a unicast DHCP DISCOVER to the DHCP server IP address and the UDP Request Port (defaults to 67). The DHCP server then sends a unicast DHCP Offer to the ciaddr address and the UDP Response Port (defaults to 68).

With this option, Orion APM uses a unicast message for the DHCP request, and it also expects a unicast response from the DHCP server. This option can be used to monitor DHCP servers on the same subnet as the Orion APM server or on a different subnet.

 

In order to monitor DHCP servers on a different subnet than the Orion APM Server, routers on the network should be configured to allow UDP packets between the Orion APM server and the DHCP server on selected ports, as shown in the following table:

 

No. Protocol Source 
IP
Source
Port
Target 
IP
Target 
Port
Notes
1 UDP Orion APM
server IP
67 DHCP 
server IP
67 DHCP 
Request
2 UDP DHCP server
IP
67 Orion APM
server IP
68 DHCP 
Offer
3 UDP Orion APM
server IP
67 DHCP 
server IP
67 Release 
offered 
lease

Note: The numbers for ports are configurable using the DHCP User Experience Monitor options.

 

Relay Agent

If you are using the Relay Agent option, the broadcast flag is not set, the ciaddr (Client IP Address) is set to the local address, and the giaddr (Relay Agent IP Address) is set to the local address. The DHCP client sends a unicast DHCP DISCOVER to the DHCP server IP address and the UDP Request Port (defaults to 67). The DHCP server then sends a unicast DHCP Offer to the giaddr (Relay Agent IP Address) and the UDP Request Port(defaults to 67).

This option can be used to monitor DHCP servers on the same subnet as the Orion APM server or on a different subnet.

In order to monitor DHCP servers on a different subnet than the Orion APM Server, routers on the network should be configured to allow UDP packets between the Orion APM server and the DHCP server on selected ports, as shown in the following table:

 

No.

Protocol

Source 
IP

Source
Port

Target 
IP

Target 
Port

Notes

1

UDP

Orion APM
server IP

67

DHCP 
server IP

67

DHCP 
Request

2

UDP

DHCP server
IP

67

Orion APM
server IP

67

DHCP 
Offer

3

UDP

Orion APM
server IP

67

DHCP 
server IP

67

Release 
offered 
lease

Note: The numbers for ports are configurable using the DHCP User Experience Monitor options.

 

 

 

 

Last modified
02:57, 23 Jun 2016

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