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Asked: 2011-05-21 05:00:37 +0800 CST

load balancing using dhcpd

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i'm just wondering if it's possible. i don't want to hear about other solutions, since i know them. I just want to know if ISC dhcpd (or any other open source dhcp server) implement it.

Imagine that i have a subnet configured in my dhcpd and as part of this subnet i have two ip ranges/pools (A and B) with the same allocation policy. Is that true, that in this scenario, the dhcpd will do a round-robin for the address allocation?

Another question is: is that possible to assing to an ip pool two routers with different metrics?

My idea is: to have two ip pools, in the same subnet, allocating ip in a round-robing fashion from those pools and with two gateways using different metrics.

so for a subnet 192.168.100.0/24:

i will have two pools. Pool A (192.168.100.10-119) and Pool B (192.168.100.120-254). For the pool A i want to give router 192.168.100.1 metric 10 and 192.168.100.2 metric 20 and for ips from the pool B, router 192.168.100.2 metric 10 and 192.168.100.1 metric 20.

is that possible?

linux networking load-balancing dhcp

2 Answers

  1. AFAIK, you can definitely have multiple pools per subnet, with different options per pool. However, the ISC dhcp server will use these pools in order of declaration, and will probably first exhaust the first pool before using the next one, unless further conditions are attached (e.g. matching to some kind of vendor identifier or MAC address or similar) which would allow the server to determine which pool to use. In other words, no round-robin.

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  2. I remember that there is an execute evaluation command in isc hdcpd that can be used to make the decision on wich class to use for giving out pools of addresses. So you could have a simple bash script that then assigns these clients to random classes.

    http://linux.die.net/man/5/dhcp-eval

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