vlan issues with 7.0-RC3

Christopher Cowart ccowart at rescomp.berkeley.edu
Mon Feb 25 09:17:12 UTC 2008


Hello,

I have a mac mini running 7.0-RC3, which I'm trying to turn it into a
router. I have a Linksys SRW2008 "fully managed" (via an IE only web
interface, ick) switch. 

Switch:
  Port 1 - Trunk vlans 10,60,98 - FreeBSD Box
  Port 7 - Access vlan 98 - Existing LAN (192.168.1.0/24)

OpenWRT (192.168.1.1):
  WRT54G box on the Existing LAN

FreeBSD Box:
  ifconfig msk0 up
  ifconfig vlan98 create vlan 98 vlandev msk0 inet 192.168.1.67/24

With this configuration, I can ping hosts on the other lan segment (Port
7). Arp and icmp seem to be quite happy. Unfortunately, I'm not having
any luck with tcp and udp. Any attempt to ssh to OpenWRT or dig
@OpenWRT hangs indefinitely. If I do a tcpdump, I see the SYN or A?
leaving and absolutely no response returning. If I run a tcpdump on
OpenWRT, I see no incoming traffic.

When I try to connect *to* the FreeBSD box from the other lan segment, I
continue to have problems. tcpdump shows the SYNs arriving via vlan98
and the FreeBSD box responding with SYN-ACK. OpenWRT receives the SYNACK.

I disabled ipfw just to be sure (sysctl -w net.inet.ip.fw.enable=0), but
it had no effect on the problem. If I connect the FreeBSD box to a vlan
98 access port and assign the address to msk0, my connectivity problems
go away. This leads me to believe that the firewall on OpenWRT is not
the problem and the problem is related to vlans.

Thinking it was a problem with the not-so-cheap Linksys POS (bitterness
about the IE web interface again), I plugged my MacBook (running
Leopard, not FreeBSD) into the trunk port. Running the ifconfig commands
above (s/msk0/en0/), I got up and running without any problems. This
causes me to suspect the FreeBSD box.

Does anyone have any idea what's going on here? Any suggestions for
further troubleshooting?

Thanks,

-- 
Chris Cowart
Network Technical Lead
Network & Infrastructure Services, RSSP-IT
UC Berkeley
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