Add option to specify an interface or an address for routers.

The interface is used on routers to source ping and traceroute.
On software routers, an address is required instead of the interface.

1 files changed, 13 insertions, 0 deletions

diff --git a/docs/configuration.md b/docs/configuration.md
index 8391492..39257da 100644
--- a/docs/configuration.md
+++ b/docs/configuration.md
@@ -107,6 +107,19 @@ $config['routers']['router1']['type'] = 'juniper';
 The router type can be Juniper, Cisco, Quagga or BIRD. You can take a look at
 the specific documentation for your router.
 
+It is also highly recommended to specify a source interface ID to be used by
+the router when it will try to ping or traceroute a destination. This is done
+with:
+
+```php
+$config['routers']['router1']['source-interface-id'] = 'lo0';
+```
+for Cisco and Juniper routers (change lo0 with your interface), and with:
+```php
+$config['routers']['router1']['source-interface-id'] = '192.168.1.1';
+```
+for BIRD and Quagga routers (use your own IP address).
+
 After that you need to set the authentication information for the looking
 glass to be able to log into the router. For this you select a type of
 authentication and then supply the needed information.