Default Gateway for a system v/s Default gateway per Interface

[Ratan Gupta]

Hi All,

Currently, OpenBMC stack allows a single default gateway for the system. 
Latest kernel allows to configure multiple default gateways.

Eg: In a system with two interfaces eth0 and eth1,

eth0 configured with static address and having gateway(192.168.2.1)
eth1 configured with DHCP and gets Gateway from DHCP server (10.10.10.1)
~~~~~~~~~~~~~
Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt 
Iface
0.0.0.0         19.168.2.1      0.0.0.0         UG        0 0          0 
eth0
0.0.0.0         10.10.10.1      0.0.0.0         UG        0 0          0 
eth1
~~~~~~~~~~~~~~

Kernel will first try using the default gateway having higher metric 
value and then fall back to the lower.

More references: 
https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/networking_guide/sec-configuring_the_default_gateway

I'm proposing to make this change in the openBMC D-bus interfaces to tie 
the gateway property with the Ethernet interface schema instead of 
System configuration.

Ethernet Interface Schema =>

https://github.com/openbmc/phosphor-dbus-interfaces/blob/master/xyz/openbmc_project/Network/EthernetInterface.interface.yaml

System Configuration Schema =>

https://github.com/openbmc/phosphor-dbus-interfaces/blob/master/xyz/openbmc_project/Network/SystemConfiguration.interface.yaml


Please let me know your suggestions.

Regards
Ratan Gupta