Layer-2 configuration

You can define one or more layer-2 networks inside every AS. You can do this through three configuration files that describe these layer-2 networks. These configuration files are applied on one or more ASes, according to the AS_config.txt file. In the following, we explain each configuration file and give an example.

The default configuration files depicted below build the following L2 network:

[!NOTE] In case you do not want to have a layer-2 network in your mini-Internet, just make the following configuration files empty.

l2_switches.txt

This file lists the switches in the layer-2 networks included in an AS. The following table shows an example of this configuration file.

C1     C2     C3           C4          C5
------------------------------------------
TCW     S1    LAUS   11:11:11:11:11:11   1
TCS     S2    BELL   22:22:22:22:22:22   2
TCS     S3    N/A    33:33:33:33:33:33   3

Below is the description of each column:

• C1: Name of the layer-2 network the switch belongs to. Here, TCW (resp. TCS) means Train Control West (resp. South).
• C2: Name of the layer-2 switch.
• C3: Router to which the layer-2 switch is connected to (or N/A if the switch is not connected to a router).
• C4: The MAC address to use for a switch which will serve as an ID.
• C5: The bridge ID for the switch which is used for the spanning tree computation.

Note that a router can only be connected to one L2 network, but a layer 2 network can be connected to one or more routers.

[!NOTE] When a switch is connected to a router, it must also be indicated in the third column of the l3_router.txt configuration file, which lists the L3 routers. In the l3_router.txt configuration file, the name of the L2 network must always be preceded by L2-.

l2_hosts.txt

This file lists the hosts that are in the layer 2 network along with their parameters. The following table shows an example of such a configuration file.

C1                   C2         C3    C4      C5     C6      C7     C8
-----------------------------------------------------------------------
A_VAUD   miniinterneteth/host:26 TCW   S1    10mbit   1ms    50ms    10
C_VAUD   miniinterneteth/host:26 TCW   S1    10mbit   1ms    50ms    20
A_GOTT   miniinterneteth/host:26 TCS   S2    10mbit   1ms    50ms    10
C_GOTT   miniinterneteth/host:26 TCS   S2    10mbit   1ms    50ms    20
A_CENE   miniinterneteth/host:26 TCS   S3    10mbit   1ms    50ms    10
C_CENE   miniinterneteth/host:26 TCS   S3    10mbit   1ms    50ms    20

Below is the description of each column:

• C1: Name of the host.
• C2: Docker image to use for this host.
• C3: The name of the L2 network the host belongs to.
• C4: The name of the switch to which the host is connected.
• C5: The throughput of the link between the host and the switch.
• C6: The delay of the link between the host and the switch.
• C7: The maximum time a packet will be buffered before it is dropped.
• C8: The VLAN to which the host belongs to.

l2_links.txt

The last file describes the layer-2 topologies. Each line corresponds to a link between two switches.
The following table shows an example of such a configuration file.

C1    C2    C3   C4     C5     C6      C7
------------------------------------------
TCS   S2   TCS   S3   10mbit   1ms    50ms

Below is the description of each column:

• C1: Name of the L2 network where the first switch of the link is located.
• C2: The name of the first switch of the link.
• C3: Name of the L2 network where the second switch of the link is located.
• C4: The name of the second switch of the link.
• C5: The throughput of the link between the host and the switch.
• C6: The delay of the link between the host and the switch.
• C7: The maximum time a packet will be buffered before it is dropped.

[!NOTE] The names of the layer-2 networks should be identical for the two switches since it is not possible to connect two switches that are in two different L2 networks.