Provide host unique DVR mac for L3 routing

[er1cthe0ne]

The Alcor Distributed Router setup in the compute host requires a host unique DVR mac to function. It needs to use this DVR mac address as the source mac for packet going from the router to the wire. While the current implementation is still working using a fixed mac address with "fe:16:11:" prefix. Using same source mac for packets send out from different location breaking networking rule. This may also break when we add more features into the OVS dataplane, e.g. mac learning.

Request

We can use an algorithm to transform a host IP address to host dvr mac, using the last three part of the IPv4 address:

#define HOST_DVR_MAC_PREFIX "fe:16:11:" 10.213.43.157 -> fe:16:11:213:43:157 -> fe:16:11:D5:2B:9D

We considered having PM to apply the above algorthm. But I am not sure how PM can send down ONE router info with mulitple host DVR macs based on different host. Looks like DPM would be a good place to apply the algorithm before sending down the router info to a particular host.