Tuesday, January 1, 2013

Multiple VLANs on a Synology NAS

Synology, like other SOHO/SMB NAS vendors, touts VLAN functionality with their current DSM 4.1 software. However, the web interface just lets you specify one VLAN tag to use over each eth interface (or bond interface).

Manual approach

In the busybox environment that you can ssh into as root (after enabling ssh through the webinterface), there's all the tools you need to use multiple VLANs over one link (eth or bond), however:
First you insert the 802.1q module into the Linux kernel:
 /sbin/lsmod | /bin/grep -q 8021q || /sbin/insmod /lib/modules/8021q.ko
Then you add each VLAN you need to every interface (bond0 in this example)
 /sbin/vconfig add bond0 4
And finally you can configure IP addresses on every interface.vlan combination (bond0.4 in this example)
 /sbin/ifconfig bond0.4 192.168.4.1 broadcast 192.168.4.255 netmask 255.255.255.0
The same type of script would work on a QNAP NAS too, by the way. They offer 8021q.ko and vconfig in their commandline environment as well.
Packets from the bond0 interface leave the device untagged, packets from the bond0.4 interface leave with a tag specifying VLAN 4.
Be aware that these settings only last until the next reboot.

Synology approach (future?)

Synology has its own set of utilities that are used by the webinterface to manage devices. The network interface settings are managed by /usr/syno/sbin/synonet. This utility sets up bonded interfaces, IP addresses, and VLAN entries. However, the utility has the same limitations as the web interface (for unknown reasons): creating a VLAN unconfigures the untagged interface you're working on, and you can't add a second VLAN on the same interface.
It would be nice if synonet could get multi-VLAN support, as all the necessary options seem to be there already. Feature request, Synology?

6 comments:

bert said...

An additional note: if you want to present iSCSI targets on manually created VLAN interfaces, you have to add a line to the corresponding /etc/sysconfig/network-scripts/ifcfg-IF.VLAN file (e.g. ifcfg-bond0.15) specifying the IP address IPADDR=192.168.15.2 . If you don't do this, nothing will be listening on port 3260 on this interface

Nick Welsh said...

I have tried this but get "/lib/modules/8021q.ko: Permission denied" although I am log in as admin. the other question I have will this code be resident after reboot or upgrade?

Brandon Neill said...

Admin doesn't have privileges from the command line. Log in as root with the same password as admin.

Unknown said...
This comment has been removed by the author.
Aaron Von Gauss said...

I definitely can't take credit for it as I found it on another blog, but another way is to configure the bonding interface with two or more ports, assign a default VLAN ID such as 1 for 802.1q tagging. Once this is done, SSH in to the box and make clones of the /etc/sysconfig/network-scripts/ifcfg-bond0.1 file for each additional VLAN you want to support (changing the filename, DEVICE and VLAN_ID as appropriate). By assigning a 802.1Q tag to the default channel, DSM will automatically manage kernel modules.

Using this method, DSM should bring up the VLAN interfaces automatically and even (at least in 4.3) exposes them via the GUI albeit with limitations. You can manage the IP addresses / MTU from the GUI for the additional VLAN interfaces as well and it will survive a reboot. I haven't tested with all other services, but I can say basic file sharing, NFS and iSCSI will also automatically start up on the cloned VLAN interfaces.

Bert de Bruijn said...

This article has another approach (and links back here): http://www.ucguerrilla.com/2013/10/provisioning-synology-nas-to-support.html