Single CPU port vs two ports Archer C7

Installing and Using OpenWrt
1

I'm building a firmware to Archer C7 V5 and noticed it has only one CPU port. My old hardware is Archer C7 V2 came with two CPU ports. I have some doubts regarding MAC address definition and VLAN settings.

This is Archer C7 V2

# ls -l /sys/class/net
lrwxrwxrwx    1 root     root             0 May  8 16:37 br-lan -> ../../devices/virtual/net/br-lan
lrwxrwxrwx    1 root     root             0 Dec 31  1969 eth0 -> ../../devices/platform/ag71xx.0/net/eth0
lrwxrwxrwx    1 root     root             0 Dec 31  1969 eth1 -> ../../devices/platform/ag71xx.1/net/eth1

This is Archer C7 V5

# ls -l /sys/class/net
lrwxrwxrwx    1 root     root             0 Jun 27 12:20 br-lan -> ../../devices/virtual/net/br-lan
lrwxrwxrwx    1 root     root             0 Jan  1  1970 eth0 -> ../../devices/platform/ag71xx.0/net/eth0
lrwxrwxrwx    1 root     root             0 Jun 27 12:20 eth0.1 -> ../../devices/virtual/net/eth0.1
lrwxrwxrwx    1 root     root             0 Jun 27 12:20 eth0.2 -> ../../devices/virtual/net/eth0.2

In V5 one of the MAC address is definided by the UCI system:

/etc/config/network

config device 'wan_dev'
        option name 'eth0.2'
        option macaddr '98:da:c4:30:a6:94'

If I remove this lines both eth0.1 and eth0.2 will assume the same MAC 98:da:c4:30:a6:93. How does Openwrt define the wan_dev MAC address. Does it extract this value from somewhere or is it just CPU MAC + 1. At what point is it defined?

Regarding the VLAN configuration I have the following in V5:

config switch
        option name 'switch0'
        option reset '1'
        option enable_vlan '1'

config switch_vlan
        option device 'switch0'
        option vlan '1'
        option ports '2 3 4 5 0t'

config switch_vlan
        option device 'switch0'
        option vlan '2'
        option ports '1 0t'

What is the 0t in this configuration?

2

This is the CPU.

The latter, to avoid MAC address conflicts.

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3 
openwrt/target/linux/ath79/base-files/etc/board.d/02_network

        tplink,archer-a7-v5|\
        tplink,archer-c7-v4|\
        tplink,archer-c7-v5|\
        tplink,tl-wr1043nd-v4|\
        tplink,tl-wr1043n-v5)
                base_mac=$(mtd_get_mac_binary info 0x8)
                wan_mac=$(macaddr_add "$base_mac" 1)
                ;;
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4

Thanks Trendy!

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5

You can have different MACs on different VLANs on the same CPU eth port. By default they inherit the same MAC unless you explicitly change it.

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6

Hi Jeff, thanks for taking the time to show me how it's done! I'm assuming this is applied when the image is flashed.

7

That kind of code is executed at boot, either configuring the device(s) directly, or writing the config-related files to the overlay.

8

If I remove the lines

config device 'wan_dev'
        option name 'eth0.2'
        option macaddr '98:da:c4:30:a6:94'

they're not rewriten at boot, just confirmed it.

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9

Config files are generally only rewritten if they don't exist at all.

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10

I see. Thanks a lot!