Ipfilter双网关问题！

大家帮我分析一下。不胜感激！

我的网络环境。FB ->三层交换 -> 客户机（200以内）无vlan；
原因是我在三层交换上做了端口镜像;（仅能支持一组的端口镜像）
我的目的是想让一个网卡；em0或是fxp1 绕过端口镜像 也就是不加入span会话（就是想给客户机指定不同的网关；从而实现；因为镜像的源端口仅能指定一个交换机端口）
所有客户机IP这样分配置的。192.168.0.0/23
在FB上这样配置的
em0 192.168.0.1 255.255.254.0
fxp1 192.168.1.1 255.255.254.0

以下是我的出错信息，（只抓取了部分。类似如下的信息一直在狂刷屏）
arp: 192.168.0.100 is on em0 but got reply from 00:03:99:88:4f:4a on fxp1
arp: 192.168.0.100 is on em0 but got reply from 00:03:99:88:4f:4a on fxp1
arp: 192.168.0.100 is on em0 but got reply from 00:03:99:88:4f:4a on fxp1
arp: 192.168.0.100 is on em0 but got reply from 00:03:99:88:4f:4a on fxp1
arp: 192.168.0.100 is on em0 but got reply from 00:03:99:88:4f:4a on fxp1
arp: 192.168.0.100 is on em0 but got reply from 00:03:99:88:4f:4a on fxp1
arp: 192.168.0.100 is on em0 but got reply from 00:03:99:88:4f:4a on fxp1
arp: 192.168.0.100 is on em0 but got reply from 00:03:99:88:4f:4a on fxp1
arp: 192.168.0.36 is on em0 but got reply from 00:50:8d:64:b0:b3 on fxp1
Aug 22 16:25:43 www last message repeated 97 times
Aug 22 16:25:52 www kernel: arp: 192.168.0.36 is on em0 but got reply from 00:50:8d:64:b0:b3 on fxp1
arp: 192.168.0.36 is on em0 but got reply from 00:50:8d:64:b0:b3 on fxp1
arp: 192.168.0.2 is on em0 but got reply from 00:50:8d:63:cf:1c on fxp1
Aug 22 16:25:53 www kernel: arp: 192.168.0.36 is on em0 but got reply from 00:50:8d:64:b0:b3 on fxp1
Aug 22 16:25:58 www kernel: arp: 192.168.0.2 is on em0 but got reply from 00:50:8d:63:cf:1c on fxp1