isc-dhcp-server上的共享networking中存在多个池的奇怪行为

我有一个奇怪的行为,在我的dhcp服务器,我使用负载平衡configuration,并在共享networking内使用多个池,我有这样的configuration:

shared-network "my-shared-network" { subnet 186.88.128.0 netmask 255.255.224.0 { option subnet-mask 255.255.224.0; option routers 186.88.128.1; pool { range 186.88.128.2 186.88.159.254; failover peer "my-failover"; } } subnet 186.90.0.0 netmask 255.255.224.0 { option subnet-mask 255.255.224.0; option routers 186.90.0.1; pool { range 186.90.0.2 186.90.31.254; failover peer "my-failover"; } } } 

适用于子网186.88.128.0,但是当我从子网186.90.0.0接收包时,我的服务器提供来自子网186.88.128.0的IP,我在日志中看到:

 Oct 26 18:22:09 my-server dhcpd: DHCPDISCOVER from 60:e7:01:4d:f9:3f via 186.90.0.1 Oct 26 18:22:09 my-server dhcpd: DHCPOFFER on 186.88.139.127 to 60:e7:01:4d:f9:3f via 186.90.0.1 Oct 26 18:22:09 my-server dhcpd: DHCPRELEASE of 186.88.139.127 from 60:e7:01:4d:f9:3f via 186.90.0.1 (found) 

我的configuration有什么问题?

PD:所有DHCPDISCOVER来自同一个IP,例如:172.16.25.40

提前致谢