How to avoid multiple DHCP request forward to all Servers?

[Sten Carlsen]

Hi

Does it matter that both servers see all messages? Only the one with the
appropriate address pool should answer.

The other solution I can see is to have separate relays, it seems that
the only link between the otherwise completely separate network systems
is the relay.

If this is a larger setup with other connections between the segments,
then you could consider doing failover between the dhcp servers.


On 06/04/2017 14:34, priyankrathi wrote:
> Hi,
> Network_Topology_Multiple_Relay-Server.png
> <http://isc-dhcp-users.2343191.n4.nabble.com/file/n1905/Network_Topology_Multiple_Relay-Server.png>  
>
>                                      _____________
>                                     |                       |
> Client 1 ----[S/W]------- |                       |----------- Server 1
>                                     |   relay agent    |
>                                     |                       |
> Client 2 ---[S/W]-------- |                       |----------- Server 2
>                                     |_____________|
>
> As per the above attached Network Topology, the following are configuration
> done on every machine.
>
> 1. Server1:
> IP address on eth1 is 10.1.1.1/24
> DHCP server IP pool: 192.168.1.100 - 192.168.1.200
> Static Route to 192.168.1.0/24 via 10.1.1.2
>
> 2. Server2:
> IP address on eth1 is 10.1.2.1/24
> DHCP server IP pool: 192.168.2.100 - 192.168.2.200
> Static Route to 192.168.2.0/24 via 10.1.2.2
>
> 3. Relay Agent (R)
> IP address on eth1: 192.168.1.1/24
> IP address on eth2: 192.168.2.1/24
> IP address on eth3: 10.1.1.2/24
> IP address on eth4: 10.1.2.2/24
> Enable IP forwarding for IPv4.
> dhcrelay -i eth1 -i eth3 10.1.1.1 -i eth2 -i eth4 10.1.2.1 -4
>
> 4. Client1:
> eth1 has a DHCP client which is connected to the same network of R:eth1.
>
> 5. Client2:
> eth1 has a DHCP client which is connected to the same network of R:eth2.
>
> After doing this configuration:
> Client1 got the IP from Server1's Pool.
> Client2 got the IP from Server2's Pool.
>
> Problem Statement: 
> While observing the packet capture, I found that the relay agent is
> forwarding the request received from Client1 to both the servers. Similarly,
> the request from Client2 is also forwarded to both the servers.
> How can we achieve the request coming from Client1 should ONLY be forwarded
> to 10.1.1.1 and request from Client2 should be forwarded ONLY to 10.1.2.1?
>
>
>
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-- 
Best regards

Sten Carlsen

No improvements come from shouting:

       "MALE BOVINE MANURE!!!" 

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