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jferello
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DHCP and VRRP

Wed Jul 14, 2004 3:19 am

I have a question about using VRRP and DHCP on the Mikrotik Firewall. By the way I have version 2.8.11 on 2 different machines that are connected in a VRRP group. As far as the VRRP goes everything works fine when I unplug the master router, then the backup takes over.

My real question is how should I have DHCP setup on both the master and the backup so that when the master crashes the backup can hand out IPs and still accept requests from existing IPs already in use on the network?
 
Bill
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Wed Jul 14, 2004 10:45 am

I'm actually more interested in your VRRP setup and all the steps needed to make it work. I've been planning to set this up on my network.

I think if you set the DHCP server on the backup router to hand out the same block of IP addresses, you should be okay. The renewal process should be automatic as soon as the user makes an outbound request. They should be able to continue surfing and shouldn't notice anything.
 
jferello
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Wed Jul 14, 2004 8:12 pm

Well the VRRP was so simple, the example in the documents provided by Mikrotik was excellent in this particular area. Its actually easier if you just follow their example than for me to explain it, I may confuse you :) However if you do run into a problem I will be here to help.

As far as the DHCP goes, I currently have it setup the way you suggest however I noticed that some of my workstations are getting addresses from the Master router and some are getting their addresses from the Backup router, which I guess really isnt a problem.

The only thing about that and the VRRP is that when you make one change on the Master router, you have to make the same exact change on the Backup router, so you have double work. I wish there was like a mirror function or cluster function to go with the VRRP.
 
Bill
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Thu Jul 15, 2004 9:45 am

Thanks. I'm going to try the VRRP soon. I'll post if I run into trouble.

I'm not sure on the DHCP. I assign everything static and only have a DHCP pool of 8 addresses for temporary connections.

The only potential problem I can see is if the Master and Backup router both try to give someone the same IP address. I don't know if VRRP will keep this from happening, or if you need to adjust the two DHCP pools so there is no overlap.
 
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lastguru
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Thu Jul 15, 2004 11:47 am

Before DHCP server gives someone an IP address, it checks if that address exists on the network. It would not give an existing address (well, if that computer is shut down at the time somebody else is requesting its IP address, the new DHCP server would not know of it...).
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