After a lack of updates, its’ time for a new blog post – this post is about linux networking particularly using active-backup bond interfaces for wired and wireless LAN interfaces, which is part of creating my updated virtual network lab environment.
Unetlab which was pretty much an alternative to GNS3 has now evolved into eve-ng which is quite a nice system. Amongst other things is it has a custom linux kernel that doesn’t block L2 Slow protocols like LACP. One of the things I specifically like about Eve besides having the facility to use html5 sessions to handle telnet/VNC consoles (as well as native tools) is that there are some SROS specific modifications that support the distributed VSR models as well as passing SMBIOS parameters etc.
I did a bare metal install pretty much following the process described in http://www.eve-ng.net/index.php/documentation/installation/bare-install but did a few more things.
I installed xcfe4 so I can have a graphical desktop with firefox so I can use eve locally, not just remoting into it.
I also did a few changes to the base install network configuration to allow the use of the copper ethernet as the primary interface but falling back to wireless.
Normally you cannot add a wireless interface into a bridge (normally eve binds eth0 into bridge pnet0 but simply adding wlan0 didn’t work)
Fortunately you can add a bond into a bridge, and the bond is less picky about who joins.
These are the items I added to /etc/network/interfaces
#Bond0 Config
auto bond0
iface bond0 inet manual
bond-slaves eth0 wlan0
bond-mode 1
bond-miimon 100- bond-slaves are the link members of the bond (eth0 and wlan0 are my copper and wireless lan interfaces respectively)
- bond-mode 1 is active-backup – Only one interface at a time will be operational, with the preference to the interface that is configured as bind-primary
- bond-miimon 100 means that every 100ms the link state is checked
# Wireless interface
allow-hotplug wlan0
iface wlan0 inet manual
wpa-ssid ReplaceThisWithYourSSID
wpa-psk ReplaceThisWithYourPresharedKey
bond-master bond0I’m not sure if its mandatory but allow-hotplug wlan0 seems to help and bond-master seemed to be required.
The eth0 section was modified to the following
# The primary network interface
allow-hotplug eth0
iface eth0 inet manual
bond-master bond0
bond-primary eth0- Here allow-hotplug eth0 seems to wake the system to the fact a cable has been connected
- bond-master bond0 as with wlan0, this appears to be needed
- bond-primary eth0 means that when both eth0 and wlan0 are up, eth0 should be the one used.
And finally pnet0 was modified to use bond0 instead of eth0
auto pnet0
iface pnet0 inet dhcp
bridge_ports bond0
bridge_stp offSo after issuing a “service networking restart”, here’s our verifcation that the bond interface is up:
root@m4600:~# cat /proc/net/bonding/bond0
Ethernet Channel Bonding Driver: v3.7.1 (April 27, 2011)
Bonding Mode: fault-tolerance (active-backup)
Primary Slave: eth0 (primary_reselect always)
Currently Active Slave: eth0
MII Status: up
MII Polling Interval (ms): 100
Up Delay (ms): 0
Down Delay (ms): 0
Slave Interface: eth0
MII Status: up
Speed: 1000 Mbps
Duplex: full
Link Failure Count: 0
Permanent HW addr: d0:67:e5:57:12:9e
Slave queue ID: 0
Slave Interface: wlan0
MII Status: up
Speed: Unknown
Duplex: Unknown
Link Failure Count: 0
Permanent HW addr: 24:77:03:b1:9f:78
Slave queue ID: 0root@m4600:~# brctl show pnet0 bridge name bridge id STP enabled interfaces pnet0 8000.d067e557129e no bond0
root@m4600:~# ip -4 addr show pnet0
4: pnet0: mtu 1500 qdisc noqueue state UP group default qlen 1000
inet 192.168.1.31/24 brd 192.168.1.255 scope global pnet0
valid_lft forever preferred_lft forever Quick Network Verification:
root@m4600:~# ping 8.8.8.8 -c 3 PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data. 64 bytes from 8.8.8.8: icmp_seq=1 ttl=55 time=30.1 ms 64 bytes from 8.8.8.8: icmp_seq=2 ttl=55 time=24.9 ms 64 bytes from 8.8.8.8: icmp_seq=3 ttl=55 time=28.3 ms --- 8.8.8.8 ping statistics --- 3 packets transmitted, 3 received, 0% packet loss, time 2002ms rtt min/avg/max/mdev = 24.924/27.798/30.131/2.164 ms
Summarise the bond status:
root@m4600:~# grep -A 1 "Interface\|Primary" /proc/net/bonding/bond0 Primary Slave: eth0 (primary_reselect always) Currently Active Slave: wlan0 -- Slave Interface: eth0 MII Status: down -- Slave Interface: wlan0 MII Status: up
Now Pull out the Ethernet cable
root@m4600:~# ping 8.8.8.8 -c 3 PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data. 64 bytes from 8.8.8.8: icmp_seq=1 ttl=55 time=28.0 ms 64 bytes from 8.8.8.8: icmp_seq=2 ttl=55 time=35.6 ms 64 bytes from 8.8.8.8: icmp_seq=3 ttl=55 time=27.9 ms --- 8.8.8.8 ping statistics --- 3 packets transmitted, 3 received, 0% packet loss, time 2003ms rtt min/avg/max/mdev = 27.910/30.537/35.614/3.593 ms
Verify the bond interface is using wlan0
root@m4600:~# grep -A 1 "Interface\|Primary" /proc/net/bonding/bond0 Primary Slave: eth0 (primary_reselect always) Currently Active Slave: wlan0 -- Slave Interface: eth0 MII Status: down -- Slave Interface: wlan0 MII Status: up
Re Insert the Ethernet cable
root@m4600:~# ping 8.8.8.8 -c 3 PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data. 64 bytes from 8.8.8.8: icmp_seq=1 ttl=55 time=23.3 ms 64 bytes from 8.8.8.8: icmp_seq=2 ttl=55 time=21.9 ms 64 bytes from 8.8.8.8: icmp_seq=3 ttl=55 time=23.1 ms --- 8.8.8.8 ping statistics --- 3 packets transmitted, 3 received, 0% packet loss, time 2002ms rtt min/avg/max/mdev = 21.968/22.822/23.397/0.628 ms root@m4600:~# grep -A 1 "Interface\|Primary" /proc/net/bonding/bond0 Primary Slave: eth0 (primary_reselect always) Currently Active Slave: eth0 -- Slave Interface: eth0 MII Status: up -- Slave Interface: wlan0 MII Status: up
So this is all good. (Actually during this testing, I was SSHed into the laptop and the session didn’t break)
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