ArpTable in contrail_snmp_collector does't support ipNetToPhysicalPhysAddress

[Kevin Chai]

Underlay Overlay Mapping depends on arpTable. But not all switch vendors support MIB ipNetToMediaTable. Instead, they use MIB ipNetToPhysicalTable.

But the contrail is hard code that just only supports ipNetToMediaTable.The code should be friendly to support both tables. Here is the detailed code.

class ArpTable(SnmpTable):
    def __init__(self, session):
        super(ArpTable, self).__init__(session)
        self.arpTable = []

    def py_obj(self):
        return self.arpTable

    def table_names(self):
        return 'ipNetToMediaPhysAddress'

    def ifid(self, x):
        ns = x.split('.')
        ifindex = int(ns[0])
        return ifindex, '.'.join(ns[1:])

    def ipNetToMediaPhysAddress_translator(self, snmp_dict):
        for x in snmp_dict['vars']:
            ifidx, ip = self.ifid(x.iid)
            self.arpTable.append({'localIfIndex': ifidx,
                    'ip': ip, 'mac':self._to_mac(x.val)})