Applications Systems

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

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

First published date

11/29/2018 10:34 PM

Last published date

6/29/2020 5:38 AM

Overview

In the DHCP User Experience Monitor, you can use the DHCP Discovery Request Type field to specify the protocol that SAM uses to detect DHCP servers: Unicast, Broadcast, or Relay Agent.

Product section

Server Application Monitor

Resolution

If 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 server. No special configuration is required for the routers on your network.

If 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, SAM 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 server or on a different subnet.

To monitor DHCP servers on a different subnet than the Orion server, configure routers on the network to allow UDP packets between the Orion 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 server IP	67	DHCP server IP	67	DHCP Request
2	UDP	DHCP server IP	67	Orion server IP	68	DHCP Offer
3	UDP	Orion server IP	67	DHCP server IP	67	Release offered lease

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

If 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 server or on a different subnet.

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

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

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