network problem between vlans (linux router)

favorit · 11-20-2007, 05:44 PM

I had setup linux router with vlan interfaces and there is a problem copying from windows clients between vlans, i get "the network name is no longer available" in the middle of copying. inter-vlan communication is ok, i can ping and connect to pc from one vlan to another. I think it is linux router related, because there are no problems when pc comunicate in the same vlan (without going throuh linux box)

I have Hp ProCurve 2626 switch with vlans:
VLAN10: connected linux router(Debian Etch), all servers, wan routers
VLAN11: 1 port connected to another unmanaged switch with about 20-30 winxp clients

linux router has interfaces: eth0 (ip: 192.168.0.7), vlan11/eth0.11 (ip: 192.168.11.1)
linux dhcp gives all vlan11 members ip from 192.168.11.x with gw 192.168.11.1

traffic between vlans routed with:
echo 1 > /proc/sys/net/ipv4/ip_forward
iptables -t nat -A POSTROUTING -o eth0 -s 192.168.11.0/255.255.255.0 -j SNAT --to-source 192.168.0.7

192.168.11.199 (winxp client [VLAN11]) -> switch -> HPProCurve2626 -> 192.168.11.1 (linux gw [VLAN10]) -> HPProCurve2626 -> 192.168.0.250 (win2k3 file server [VLAN10])

backwards is the same instead of if eth0 of linux with ip 192.168.0.7

Could this be because of MTU ? linux/windows has MTU=1500, procurve 2626 switch does not allow changing mtu. Network adapter is Intel server PRO 1000 (driver e1000.ko) it should work with vlan headers as i find out.

Would be very thankfull for any help or suggestions

jschiwal · 11-20-2007, 06:46 PM

Don't you need to run a WINS server if you browse between subnets? A samba server could do that.

The Samba 3 HOWTO & Reference guide has more information.

favorit · 11-21-2007, 01:07 AM

yes, i don't use WINS, but can this really be the issue ? i could see servers from other vlan on client pc, and the problem still exists when accesing by IP address..

jschiwal · 11-22-2007, 04:12 AM

This is from the Samba3-HOWTO.pdf:

Quote:

10.3.1 NetBIOS over TCP/IP
Samba implements NetBIOS, as does MS Windows NT/200x/XP, by encapsulating
it over TCP/IP. NetBIOS-based networking uses broadcast messaging
to effect browse list management. When running NetBIOS over TCP/IP,
this uses UDP-based messaging. UDP messages can be broadcast or unicast.
Normally, only unicast UDP messaging can be forwarded by routers. The
remote announce parameter to smb.conf helps to project browse announcements
to remote network segments via unicast UDP. Similarly, the remote
browse sync parameter of smb.conf implements browse list collation using
unicast UDP.
...
The default Windows network client (or server) network configuration enables
NetBIOS over TCP/IP and b-node configuration. The use of WINS
makes most sense with h-node (hybrid mode) operation so that in the event
of a WINS breakdown or non-availability, the client can use broadcast-based
name resolution.
In those networks where Samba is the only SMB server technology, wherever
possible nmbd should be configured on one machine as the WINS server. This
makes it easy to manage the browsing environment. If each network segment
is configured with its own Samba WINS server, then the only way to get
cross-segment browsing to work is by using the remote announce and the
remote browse sync parameters to your smb.conf file.

If only one WINS server is used for an entire multisegment network, then the
use of the remote announce and the remote browse sync parameters should
not be necessary.

I think that the reason it works on the LAN but not across the vlan is because network broadcasts are being used by the clients but they aren't forwarded.

I didn't notice the masquerading before. A work we use different subnets for each site. The other sites have network appliances (adtec equipment) instead of windows hosts. That is why I thought of WINS, because if you are browsing across different subnets you want to use WINS.

I don't think that the MTU has anything to do with it. 1500 is standard for ethernet devices.

If the error you saw was the linux host, look in the log files for clues. Also look in /var/log/messages. You may see either an entry from samba or the netfilter.

favorit · 11-26-2007, 02:51 PM

I have installed WINS on my DC, updated DHCP to assign it for all clients, now clients on different vlan has configured WINS pointing to DC. I checked with nblookup.exe and it seems to be working, but it didn't solve the problem.

I also changed DC registry to IsMasterBrowser=TRUE, disabled Oplock - nothing..

In winxp client event log i see "The redirector failed to determine the connection type" after unsuccesfull copying, googled for this error, but it says about asking loopback adapter for connection speed, other related problems was master browser issue which i think must be solved with all seting i've done above.