def METHOD_NAME(self, netstat_output):
    """
    Return a mapping of network metrics by interface. For example:
        { interface:
            {'bytes_sent': 0,
              'bytes_rcvd': 0,
              'bytes_rcvd': 0,
              ...
            }
        }
    """
    # Here's an example of the netstat output:
    #
    # link:0:net0:brdcstrcv   527336
    # link:0:net0:brdcstxmt   1595
    # link:0:net0:class       net
    # link:0:net0:collisions  0
    # link:0:net0:crtime      16359935.2637943
    # link:0:net0:ierrors     0
    # link:0:net0:ifspeed     10000000000
    # link:0:net0:ipackets    682834
    # link:0:net0:ipackets64  682834
    # link:0:net0:link_duplex 0
    # link:0:net0:link_state  1
    # link:0:net0:multircv    0
    # link:0:net0:multixmt    1595
    # link:0:net0:norcvbuf    0
    # link:0:net0:noxmtbuf    0
    # link:0:net0:obytes      12820668
    # link:0:net0:obytes64    12820668
    # link:0:net0:oerrors     0
    # link:0:net0:opackets    105445
    # link:0:net0:opackets64  105445
    # link:0:net0:rbytes      113983614
    # link:0:net0:rbytes64    113983614
    # link:0:net0:snaptime    16834735.1607669
    # link:0:net0:unknowns    0
    # link:0:net0:zonename    53aa9b7e-48ba-4152-a52b-a6368c3d9e7c
    # link:0:net1:brdcstrcv   4947620
    # link:0:net1:brdcstxmt   1594
    # link:0:net1:class       net
    # link:0:net1:collisions  0
    # link:0:net1:crtime      16359935.2839167
    # link:0:net1:ierrors     0
    # link:0:net1:ifspeed     10000000000
    # link:0:net1:ipackets    4947620
    # link:0:net1:ipackets64  4947620
    # link:0:net1:link_duplex 0
    # link:0:net1:link_state  1
    # link:0:net1:multircv    0
    # link:0:net1:multixmt    1594
    # link:0:net1:norcvbuf    0
    # link:0:net1:noxmtbuf    0
    # link:0:net1:obytes      73324
    # link:0:net1:obytes64    73324
    # link:0:net1:oerrors     0
    # link:0:net1:opackets    1594
    # link:0:net1:opackets64  1594
    # link:0:net1:rbytes      304384894
    # link:0:net1:rbytes64    304384894
    # link:0:net1:snaptime    16834735.1613302
    # link:0:net1:unknowns    0
    # link:0:net1:zonename    53aa9b7e-48ba-4152-a52b-a6368c3d9e7c
    # A mapping of solaris names -> datadog names
    metric_by_solaris_name = {
        'rbytes64': 'bytes_rcvd',
        'obytes64': 'bytes_sent',
        'ipackets64': 'packets_in.count',
        'ierrors': 'packets_in.error',
        'opackets64': 'packets_out.count',
        'oerrors': 'packets_out.error',
    }
    lines = [l for l in netstat_output.splitlines() if len(l) > 0]
    metrics_by_interface = {}
    for l in lines:
        # Parse the metric & interface.
        cols = l.split()
        link, n, iface, name = cols[0].split(":")
        assert link == "link"
        # Get the datadog metric name.
        ddname = metric_by_solaris_name.get(name, None)
        if ddname is None:
            continue
        # Add it to this interface's list of metrics.
        metrics = metrics_by_interface.get(iface, {})
        metrics[ddname] = self.parse_long(cols[1])
        metrics_by_interface[iface] = metrics
    return metrics_by_interface