Next Hop Using DHCP

Answered Question
Jan 4th, 2009

I have a question about using static routes with DHCP.

I understand that a static default route pointing to an interface, as the next hop, will generate superfluous ARP entries for every destination. So, with that in mind, will the static route (A) below, produce the same kind of superfluous ARP messages as the static route (B) below?

A. ip route 0.0.0.0 0.0.0.0 dhcp

B. ip route 0.0.0.0 0.0.0.0 fa 0/4

Correct Answer by Mark Yeates about 8 years 1 month ago

Using DHCP in your static route will not produce the superfluous ARP entries on your router. I would recommend using ip route 0.0.0.0 0.0.0.0 dhcp over ip route 0.0.0.0 0.0.0.0 fa 0/4.


Having a static route to point to specific IP address is better practice than pointing to interface. Specifically for default route learned from DHCP server (in your case is probably the ISP DHCP server).


HTH,

Mark

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Correct Answer
Mark Yeates Sun, 01/04/2009 - 14:45

Using DHCP in your static route will not produce the superfluous ARP entries on your router. I would recommend using ip route 0.0.0.0 0.0.0.0 dhcp over ip route 0.0.0.0 0.0.0.0 fa 0/4.


Having a static route to point to specific IP address is better practice than pointing to interface. Specifically for default route learned from DHCP server (in your case is probably the ISP DHCP server).


HTH,

Mark

Richard Burts Sun, 01/04/2009 - 14:47

Michael


I believe that your A static route will not generate the number of ARP entries that the B static route would. It is my understanding that Cisco added the ability to specify dhcp in a static route to address this very issue. The DHCP information typically includes the address of the gateway router and this configuration allows your router to use this learned address so that it does not need to ARP for the next hop address.


HTH


Rick

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