DHCP QUESTION 2

[maczen]

I am curious as to the best approach for DHCP configuration on my LAN. (This is a prelude/practice to/for a school project so not looking for anything but theory here)


DTE DCE/DCE DTE/DCE DTE/DCE DTE
R1-----R2---------R3---------R4-----R5-----Cat1--Cat2--Cat3
RipV2 | OSPF | OSPF
FR Switch OSPF

R1 has a group of hosts in the 172.16.x.x /22 range as does the VLAN behind R5..

I have read the Cisco DHCP documentation as well as a couple of other articles online.. (Three of the top four results from a google for "configuring DHCP Cisco" and am unclear on one point...

The Question: If I configure R1 as the DHCP server and include multiple default-router statements... (Namely for the 500 hosts on R1 and 700 on the VLANS) will these hosts automatically be given the correct default gateway? I know that I can provide up to 8 ip addresses for default routers but not sure what this does exactly and can not seem to locate any info there..

Another option (I believe) would be to set up two separate DHCP servers... Namely R1 and R5 and just exclude the address ranges.. IE. Exclude the 700+ from the VLANS from R1 and exclude the 500 sitting behind R1 from R5. Ok.. Sorry for that... LoL

I am thinking that there is a way to merely use one router as the DHCP server (R1) and provide addresses ETC. to everyone but am perplexed somewhat due to the fact that I will have 172.16.x.x /22 in separate locations on this network and I foresee hosts receiving the wrong default gateway info.. OK.. That's my problem... LoL Thanks guys!!!

 

[burtsbees]

You can specify one gateway per network---

network 10.10.10.0 255.255.255.0
default-router 10.10.10.1
network 20.20.20.0 255.255.255.0
default-router 20.20.20.1

If that doesn't work (not tested...lol...taking a guess), then make a dhcp pool for each network, specifying different gateways via default-router command. Bam! Who's yer daddy?lol

Burt

 

[CiscoGuy33]

maczen,

I know we did this in a classroom with 1 Miscrosoft DHCP server (not the router) and 6 different subnets/VLANs. I had to use the helper command to forward the DHCP broadcasts between the different routers handling the 6 VLANs (did not have a Fast Ethernet router and the IOS did not support router-on-a-stick for 2611 at that time).

You will need the helper command to get the router/routers to forward the DHCP broadcasts - since routers normally DO NOT forward broadcasts !

Hope this helps!


E.A. Broda
CCNA, CCDA, CCAI, Network +

 

[maczen]

Thanks guys.. The Cisco project only requires one DHCP server be set up for ONE LAN but It just made me wonder if I have two separate LANs here and both are 172.16.x.x /16 or above.. How do you go about setting up DHCP for both... Both of those answers answered that... I will play with them...

Thanks a billion!!!