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SRX Services Gateway

dhcp helper - identifying client

‎06-17-2015 05:36 PM

I have an SRX which has two IP addresses associated with a vlan. The vlan services dhcp clients and the SRX uses a bootp helper directive to send dhcp requests to a Windows server. What mechanism does the SRX use to identify to the dhcp server which ip scope the client should receive an address from? For example, if the vlan has addresses 1.1.1.1 and 2.2.2.2 set on the SRX, how would i specify that dhcp clients should be served from the 1.1.1.X scope?

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SRX Services Gateway

Re: dhcp helper - identifying client

‎06-17-2015 09:32 PM

Hi,

 

You need to set the 1.1.1.1 addres then as primary / preffered on your interface. DHCP is a broadcast thingie... Your clients is asking for an IP the router recieves it picks up the request as you have a dhcp-relay configured. Sends the request over to the dhcp server. At the moment the dhcp-relay recieves the packet from the client it does a lookup on which interface it came in and what ip is on that interface. It encapsulates the ip information into the packet en sends it over to the dhcp-server. The server sees a request comming from a client, sees that the scope it needs to be used in the ip information the dhcp-relay added to the packet. Then gets a free IP from the scope and sends it back to the client.

 

 

Marc



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