'Update subnet info the in the IPAM driver.
The only update subnet information the driver needs to be aware of
are allocation pools.'

def update_subnet(self, subnet_request):

    if (not subnet_request.subnet_id):
        raise ipam_exc.InvalidSubnetRequest(reason=_('An    identifier    must    be    specified    when    updating    a    subnet'))
    if (subnet_request.allocation_pools is None):
        LOG.debug('Update    subnet    request    for    subnet    %s    did    not    specify    new    allocation    pools,    there    is    nothing    to    do', subnet_request.subnet_id)
        return
    subnet = NeutronDbSubnet.load(subnet_request.subnet_id, self._context)
    cidr = netaddr.IPNetwork(subnet._cidr)
    subnet.update_allocation_pools(subnet_request.allocation_pools, cidr)
    return subnet
