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laggdiskless [2011/09/11 12:08]
peterjeremy created
laggdiskless [2011/09/12 00:37]
peterjeremy Finish article
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 ====== Using lagg(4) with diskless booting ====== ====== Using lagg(4) with diskless booting ======
  
-The lagg interface enables transparent failover between (eg) wired & wifi interfaces - making it trivial to combine the flexibility of walking around the house without any cables with the throughput of a wired interface.+The lagg interface enables transparent failover between (eg) wired & wifi interfaces - making it trivial to combine the flexibility of walking around the house without any cables with the throughput of a wired interface by simply connecting and disconnecting the LAN cable.
  
 For a normal boot environment, this is as simple as placing something like the following in ''/etc/rc.conf'': For a normal boot environment, this is as simple as placing something like the following in ''/etc/rc.conf'':
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   ifconfig_lagg0="SYNCDHCP laggproto failover laggport re0 laggport wlan0"   ifconfig_lagg0="SYNCDHCP laggproto failover laggport re0 laggport wlan0"
  
 +If you have multiple boxes available, supporting diskless booting provides a convenient way to install, upgrade or recover systems.  It can also provide a convenient way to test a planned upgrade without installing the upgrade onto the target host.  One downside of diskless booting is that the root filesystem is NFS mounted via the boot interface and it's not possible to PXE boot from a WiFi or lagg interface.  Whilst you would typically want the performance of a wired interface for installing/upgrading/recovering, lagg support is important for regression testing and can make installing/upgrading/recovering more convenient.  Following some experimentation, I came up with the following configuration:
 +
 +Host configuration for ISC dhcpd 3.1:
 +  host client_host {                               # Client name
 +    hardware ethernet 00:1e:68:aa:bb:cc;           # Wired NIC MAC address
 +    fixed-address client.f.q.d.n;                  # FQDN or IP address of diskless client
 +    filename "/tftpboot/pxeboot";
 +    next-server 10.11.12.13;                       # Boot/root server IP
 +    vendor-option-space FreeBSD
 +    option root-path "10.11.12.13:/client/root";   # NFS path to client root filesystem
 +    option host-name "client.f.q.d.n";
 +  }
 +
 +Client ''/etc/rc.conf'' (or ''10.11.12.13:/client/root/etc/conf''):
 +  ifconfig_ath0="ether 00:1e:68:aa:bb:cc"  # Set WiFi MAC address to match wired MAC address
 +  wlans_ath0="wlan0"
 +  ifconfig_wlan0="WPA"
 +  cloned_interfaces="lagg0"
 +  ifconfig_lagg0="laggport wlan0"
 +
 +The magic is an additional script {{lagg.txt|''/etc/rc.d/lagg''}} which flips the IP address from the boot interface to a lagg interface comprising the boot interface.  As a result, whilst it's necessary to boot with a LAN cable attached, once the system has booted to multi-user (or at least to the point where ''wpa_supplicant'' has started and authenticated), you can disconnect the LAN cable and run wireless.
laggdiskless.txt ยท Last modified: 2011/09/12 00:37 by peterjeremy
 
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