# SPAN port not functioning



## keleathi (May 11, 2011)

I have a perfectly functioning bridge to which I am attempting to add a span port.  I add the span, it shows successfully, but when I run tcpdump on that port I see nothing, and the PC that is plugged into the span port also sees nothing while running tcdump on its attached interface.  I'm not sure what to try next, as the implementation seems as if it should be simple.


```
cat /etc/rc.conf
# Created: Sat Mar 26 10:21:06 2011
# Enable network daemons for user convenience.
# Please make all changes to this file, not to /etc/defaults/rc.conf.
# This file now contains just the overrides from /etc/defaults/rc.conf.
sshd_enable="YES"
hostname="bridgebox.int"
#network
cloned_interfaces="bridge0"
ifconfig_bridge0="ether 02:00:00:00:00:02 addm em0 addm em1 up"
ifconfig_em0="up"
ifconfig_em1="up"

ifconfig bridge0 span em3

ifconfig em3 up

uname -a
FreeBSD sutherland.pm.int 8.2-RELEASE FreeBSD 8.2-RELEASE #0: Thu Feb 17 02:41:51 UTC 2011    
 [email]root@mason.cse.buffalo.edu[/email]:/usr/obj/usr/src/sys/GENERIC  amd64

ifconfig
em0: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> metric 0 mtu 1500
        options=219b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,TSO4,WOL_MAGIC>
        ether 00:90:fb:2d:d9:b4
        media: Ethernet autoselect (1000baseT <full-duplex>)
        status: active
em1: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> metric 0 mtu 1500
        options=219b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,TSO4,WOL_MAGIC>
        ether 00:90:fb:2d:d9:b5
        media: Ethernet autoselect (1000baseT <full-duplex>)
        status: active
em2: flags=8802<BROADCAST,SIMPLEX,MULTICAST> metric 0 mtu 1500
        options=219b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,TSO4,WOL_MAGIC>
        ether 00:90:fb:2d:d9:b6
        media: Ethernet autoselect
        status: no carrier
em3: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
        options=219b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,TSO4,WOL_MAGIC>
        ether 00:90:fb:2d:d9:b7
        media: Ethernet autoselect (1000baseT <full-duplex>)
        status: active
plip0: flags=8810<POINTOPOINT,SIMPLEX,MULTICAST> metric 0 mtu 1500
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> metric 0 mtu 16384
        options=3<RXCSUM,TXCSUM>
        inet6 fe80::1%lo0 prefixlen 64 scopeid 0x6
        inet6 ::1 prefixlen 128
        inet 127.0.0.1 netmask 0xff000000
        nd6 options=3<PERFORMNUD,ACCEPT_RTADV>
bridge0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
        ether 02:00:00:00:00:02
        inet 192.168.0.10 netmask 0xffffff00 broadcast 192.168.0.255
        id 00:00:00:00:00:00 priority 32768 hellotime 2 fwddelay 15
        maxage 20 holdcnt 6 proto rstp maxaddr 100 timeout 1200
        root id 00:00:00:00:00:00 priority 32768 ifcost 0 port 0
        member: em1 flags=143<LEARNING,DISCOVER,AUTOEDGE,AUTOPTP>
                ifmaxaddr 0 port 2 priority 128 path cost 2000000
        member: em0 flags=143<LEARNING,DISCOVER,AUTOEDGE,AUTOPTP>
                ifmaxaddr 0 port 1 priority 128 path cost 2000000
        member: em3 flags=8<SPAN>
                ifmaxaddr 0 port 4 priority 128 path cost 2000000
```

Is there anything I've missed?


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## ecazamir (May 14, 2011)

You could try bringing up the physical interface em3 up before adding it to the bridge. Add 
	
	



```
ifconfig_em3="up"
```
 to /etc/rc.conf. You could also try to enable the span port on the same configuration line:

```
ifconfig_bridge0="ether 02:00:00:00:00:02 addm em0 addm em1 span em3 up"
```

PS: I didn't test this configuration, so I can't assure anyone that this is the proper solution.


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## keleathi (May 14, 2011)

That actually worked for em3, thanks.  It's a shame it doesn't work manually after the fact.

It still doesn't work, however for my tap0 interface, which I was planning on using in addition so that I could monitor two bridges simultaneously using libpcap.


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