Difference between revisions of "VLAN"

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{{stub}}
 
 
[[ru:VLAN]]
 
[[ru:VLAN]]
 
[[Category:Networking]]
 
[[Category:Networking]]
Virtual LANs give you the ability to sub-divide a LAN. Linux can accept VLAN tagged traffic and presents each VID as a different network interface (eg: eth0.100 for VID 100)
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Virtual LANs give you the ability to sub-divide a LAN. Linux can accept '''VLAN''' tagged traffic and presents each '''VLAN ID''' as a different network interface (eg: {{ic|eth0.100}} for '''VLAN ID''' {{ic|100}})
 
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{{Article summary start}}
 
{{Article summary start}}
 
{{Article summary text|This article explains how to configure a VLAN using {{Pkg|iproute2}} and [[netcfg]]}}
 
{{Article summary text|This article explains how to configure a VLAN using {{Pkg|iproute2}} and [[netcfg]]}}
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==Configuration==
 
==Configuration==
Previously Arch Linux used [https://aur.archlinux.org/packages/vconfig/ vconfig] to setup VLANs. This had been superseded by the {{ic|ip}} command. Make sure you have {{Pkg|iproute2}} installed.
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Previously Arch Linux used {{AUR|vconfig}} to setup VLANs. This had been superseded by the {{ic|ip}} command. Make sure you have {{Pkg|iproute2}} installed.
  
In the following examples, lets assume the '''interface''' is {{ic|eth0}}, the assigned '''name''' is {{ic|eth0.100}} and the vid is {{ic|100}}.
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In the following examples, lets assume the '''interface''' is {{ic|eth0}}, the assigned '''name''' is {{ic|eth0.100}} and the '''vlan id''' is {{ic|100}}.
 
===Create the VLAN device===
 
===Create the VLAN device===
  
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Using a '''name''' like {{ic|eth0.100}} is just convention and not enforced; you can alternatively use eth0_100 or something descriptive like IPTV
 
Using a '''name''' like {{ic|eth0.100}} is just convention and not enforced; you can alternatively use eth0_100 or something descriptive like IPTV
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 +
To see the VLAN ID on an interface, in case you used an unconventional name:
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{{bc|# ip -d link show eth0.100}}
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The {{ic|-d}} flag shows full details on an inteface.
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===Add an IP===
 
===Add an IP===
 
Now add an IPv4 address to the just created vlan link, and activate the link:
 
Now add an IPv4 address to the just created vlan link, and activate the link:
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===Starting at boot===
 
===Starting at boot===
You can use a [[netcfg]] profile and put '''POST_UP''', '''PRE_DOWN''' command to do above action.
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You can use the following parameters in [[netcfg]] profiles to have VLANs configured automatically:
(Similar thing as done here: [https://bbs.archlinux.org/viewtopic.php?pid=1036395#p1036395])
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For example, a {{ic|eth0}} interface that is both multi-home (DHCP to the modem, and local subnet {{ic|192.168.12.0}}), and VLAN 112 as well.
 
Here is an extract of the configuration:
 
 
{{hc|/etc/network.d/my-network|<nowiki>
 
{{hc|/etc/network.d/my-network|<nowiki>
CONNECTION='ethernet'
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# vlan specific part:
DESCRIPTION='modem cable connection'
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CONNECTION="vlan"
INTERFACE='eth0'
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VLAN_PHYS_DEV="eth0"
IP='dhcp'
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VLAN_ID="100"
POST_UP='ip addr add 192.168.12.1/24 brd 192.168.12.255 dev eth0; ip link add link eth0 name eth0.112 type vlan id 112; ip addr add 192.168.112.1/24 brd 192.168.112.255 dev eth0.112; ip link set dev eth0.112 up'
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INTERFACE="eth0.100"
PRE_DOWN='ip link set dev eth0.112 down; ip link delete eth0.112; ip addr del 192.168.12.1/24 dev eth0'
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# general IP configuration:
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IP="static"
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ADDR="192.168.100.1"
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NETMASK="255.255.255.0"
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GATEWAY="192.168.100.254"
 
</nowiki>}}
 
</nowiki>}}
  
Enable the service:
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Enable the daemon {{ic|netcfg@my-network}}. Read [[Daemons]] for more details.
{{bc|# systemctl enable netcfg@my-network}}
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==Troubleshooting==
 
==Troubleshooting==
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A reboot should mean that VLANs configure correctly with the names assigned to them.
 
A reboot should mean that VLANs configure correctly with the names assigned to them.
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==See also==
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* [https://bbs.archlinux.org/viewtopic.php?pid=1036395#p1036395 Post about using POST_UP and PRE_DOWN]

Revision as of 04:31, 6 May 2013

Virtual LANs give you the ability to sub-divide a LAN. Linux can accept VLAN tagged traffic and presents each VLAN ID as a different network interface (eg: eth0.100 for VLAN ID 100)

Summary help replacing me
This article explains how to configure a VLAN using iproute2 and netcfg
Related
Network
Netcfg

Configuration

Previously Arch Linux used vconfigAUR to setup VLANs. This had been superseded by the ip command. Make sure you have iproute2 installed.

In the following examples, lets assume the interface is eth0, the assigned name is eth0.100 and the vlan id is 100.

Create the VLAN device

Add the VLAN with the following command:

# ip link add link eth0 name eth0.100 type vlan id 100

Run ip link to confirm that it has been created.

This interface behaves like a normal interface. All traffic routed to it will go through the master interface (in this example, eth0) but with a VLAN tag. Only VLAN aware devices can accept them if configured correctly else the traffic is dropped.

Using a name like eth0.100 is just convention and not enforced; you can alternatively use eth0_100 or something descriptive like IPTV

To see the VLAN ID on an interface, in case you used an unconventional name:

# ip -d link show eth0.100

The -d flag shows full details on an inteface.

Add an IP

Now add an IPv4 address to the just created vlan link, and activate the link:

# ip addr add 192.168.100.1/24 brd 192.168.100.255 dev eth0.100
# ip link set dev eth0.100 up

Turning down the device

To cleanly shutdown the setting before you remove the link, you can do:

# ip link set dev eth0.100 down

Removing the device

Removing a VLAN interface is significantly less convoluted

# ip link delete eth0.100

Starting at boot

You can use the following parameters in netcfg profiles to have VLANs configured automatically:

/etc/network.d/my-network
# vlan specific part:
CONNECTION="vlan"
VLAN_PHYS_DEV="eth0"
VLAN_ID="100"
INTERFACE="eth0.100"

# general IP configuration:
IP="static"
ADDR="192.168.100.1"
NETMASK="255.255.255.0"
GATEWAY="192.168.100.254"

Enable the daemon netcfg@my-network. Read Daemons for more details.

Troubleshooting

udev renames the virtual devices

An annoyance is that udev may try to rename virtual devices as they are added, thus ignoring the name configured for them (in this case eth0.100).

For instance, if the following commands are issued:

# ip link add link eth0 name eth0.100 type vlan id 100
# ip link show 

This could generate the following output:

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP qlen 1000
    link/ether aa:bb:cc:dd:ee:ff brd ff:ff:ff:ff:ff:ff
3: rename1@eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state DOWN 
    link/ether aa:bb:cc:dd:ee:ff brd ff:ff:ff:ff:ff:ff

udev has ignored the configured virtual interface name eth0.100 and autonamed it rename1.

The solution is to edit /etc/udev/rules.d/network_persistent.rules and append DRIVERS=="?*" to the end of the physical interface's configuration line.

For example, for the interface aa:bb:cc:dd:ee:ff (eth0):

/etc/udev/rules.d/network_persistent.rules
SUBSYSTEM=="net", ATTR{address}=="aa:bb:cc:dd:ee:ff", NAME="eth0", DRIVERS=="?*"

A reboot should mean that VLANs configure correctly with the names assigned to them.

See also