nsim.c

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/*
 * nsim.c - skeleton vpp engine plug-in
 *
 * Copyright (c) <current-year> <your-organization>
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at:
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/**
 * @file
 * @brief Network Delay Simulator
 */
/*? %%clicmd:group_label Network Delay Simulator %% ?*/

#include <vnet/vnet.h>
#include <vnet/plugin/plugin.h>
#include <nsim/nsim.h>

#include <vlibapi/api.h>
#include <vlibmemory/api.h>
#include <vpp/app/version.h>

/* define message IDs */
#include <nsim/nsim_msg_enum.h>

/* define message structures */
#define vl_typedefs
#include <nsim/nsim_all_api_h.h>
#undef vl_typedefs

/* define generated endian-swappers */
#define vl_endianfun
#include <nsim/nsim_all_api_h.h>
#undef vl_endianfun

/* instantiate all the print functions we know about */
#define vl_print(handle, ...) vlib_cli_output (handle, __VA_ARGS__)
#define vl_printfun
#include <nsim/nsim_all_api_h.h>
#undef vl_printfun

/* Get the API version number */
#define vl_api_version(n,v) static u32 api_version=(v);
#include <nsim/nsim_all_api_h.h>
#undef vl_api_version

#define REPLY_MSG_ID_BASE nsm->msg_id_base
#include <vlibapi/api_helper_macros.h>

nsim_main_t nsim_main;

/* List of message types that this plugin understands */

#define foreach_nsim_plugin_api_msg                                     \
_(NSIM_CROSS_CONNECT_ENABLE_DISABLE, nsim_cross_connect_enable_disable) \
_(NSIM_OUTPUT_FEATURE_ENABLE_DISABLE, nsim_output_feature_enable_disable) \
_(NSIM_CONFIGURE, nsim_configure)

/* Action functions shared between message handlers and debug CLI */

int
nsim_cross_connect_enable_disable (nsim_main_t * nsm, u32 sw_if_index0,
                                   u32 sw_if_index1, int enable_disable)
{
  vnet_sw_interface_t *sw;
  vnet_hw_interface_t *hw;
  int rv = 0;

  if (nsm->is_configured == 0)
    return VNET_API_ERROR_CANNOT_ENABLE_DISABLE_FEATURE;

  /* Utterly wrong? */
  if (pool_is_free_index (nsm->vnet_main->interface_main.sw_interfaces,
                          sw_if_index0))
    return VNET_API_ERROR_INVALID_SW_IF_INDEX;

  if (pool_is_free_index (nsm->vnet_main->interface_main.sw_interfaces,
                          sw_if_index1))
    return VNET_API_ERROR_INVALID_SW_IF_INDEX;

  /* Not a physical port? */
  sw = vnet_get_sw_interface (nsm->vnet_main, sw_if_index0);
  if (sw->type != VNET_SW_INTERFACE_TYPE_HARDWARE)
    return VNET_API_ERROR_INVALID_SW_IF_INDEX;

  sw = vnet_get_sw_interface (nsm->vnet_main, sw_if_index1);
  if (sw->type != VNET_SW_INTERFACE_TYPE_HARDWARE)
    return VNET_API_ERROR_INVALID_SW_IF_INDEX;

  /* Add graph arcs for the input / wheel scraper node */
  hw = vnet_get_hw_interface (nsm->vnet_main, sw_if_index0);
  nsm->output_next_index0 =
    vlib_node_add_next (nsm->vlib_main,
                        nsim_input_node.index, hw->output_node_index);

  hw = vnet_get_hw_interface (nsm->vnet_main, sw_if_index1);
  nsm->output_next_index1 =
    vlib_node_add_next (nsm->vlib_main,
                        nsim_input_node.index, hw->output_node_index);

  nsm->sw_if_index0 = sw_if_index0;
  nsm->sw_if_index1 = sw_if_index1;

  vnet_feature_enable_disable ("device-input", "nsim",
                               sw_if_index0, enable_disable, 0, 0);
  vnet_feature_enable_disable ("device-input", "nsim",
                               sw_if_index1, enable_disable, 0, 0);

  return rv;
}

int
nsim_output_feature_enable_disable (nsim_main_t * nsm, u32 sw_if_index,
                                    int enable_disable)
{
  vnet_sw_interface_t *sw;
  vnet_hw_interface_t *hw;
  int rv = 0;

  if (nsm->is_configured == 0)
    return VNET_API_ERROR_CANNOT_ENABLE_DISABLE_FEATURE;

  /* Utterly wrong? */
  if (pool_is_free_index (nsm->vnet_main->interface_main.sw_interfaces,
                          sw_if_index))
    return VNET_API_ERROR_INVALID_SW_IF_INDEX;

  /* Not a physical port? */
  sw = vnet_get_sw_interface (nsm->vnet_main, sw_if_index);
  if (sw->type != VNET_SW_INTERFACE_TYPE_HARDWARE)
    return VNET_API_ERROR_INVALID_SW_IF_INDEX;

  /* Add a graph arc for the input / wheel scraper node */
  hw = vnet_get_hw_interface (nsm->vnet_main, sw_if_index);
  vec_validate_init_empty (nsm->output_next_index_by_sw_if_index, sw_if_index,
                           ~0);
  /* Note: use the tx node, this pkt has already visited the output node... */
  nsm->output_next_index_by_sw_if_index[sw_if_index] =
    vlib_node_add_next (nsm->vlib_main, nsim_input_node.index,
                        hw->tx_node_index);

  vnet_feature_enable_disable ("interface-output", "nsim-output-feature",
                               sw_if_index, enable_disable, 0, 0);
  return rv;
}

static int
nsim_configure (nsim_main_t * nsm, f64 bandwidth, f64 delay, f64 packet_size,
                f64 drop_fraction)
{
  u64 total_buffer_size_in_bytes, per_worker_buffer_size;
  u64 wheel_slots_per_worker;
  int i;
  int num_workers = vlib_num_workers ();
  u32 pagesize = getpagesize ();
  vlib_main_t *vm = nsm->vlib_main;

  if (bandwidth == 0.0)
    return VNET_API_ERROR_INVALID_VALUE;

  if (delay == 0.0)
    return VNET_API_ERROR_INVALID_VALUE_2;

  if (packet_size < 64.0 || packet_size > 9000.0)
    return VNET_API_ERROR_INVALID_VALUE_3;

  /* Toss the old wheel(s)... */
  if (nsm->is_configured)
    {
      for (i = 0; i < vec_len (nsm->wheel_by_thread); i++)
        {
          nsim_wheel_t *wp = nsm->wheel_by_thread[i];
          munmap (wp, nsm->mmap_size);
          nsm->wheel_by_thread[i] = 0;
        }
    }

  nsm->delay = delay;
  nsm->drop_fraction = drop_fraction;

  /* delay in seconds, bandwidth in bits/sec */
  total_buffer_size_in_bytes = ((delay * bandwidth) / 8.0) + 0.5;

  /*
   * Work out how much buffering each worker needs, assuming decent
   * RSS behavior.
   */
  if (num_workers)
    per_worker_buffer_size = total_buffer_size_in_bytes / num_workers;
  else
    per_worker_buffer_size = total_buffer_size_in_bytes;

  wheel_slots_per_worker = per_worker_buffer_size / packet_size;
  wheel_slots_per_worker++;

  /* Save these for the show command */
  nsm->bandwidth = bandwidth;
  nsm->packet_size = packet_size;

  vec_validate (nsm->wheel_by_thread, num_workers);

  /* Initialize the output scheduler wheels */
  for (i = num_workers ? 1 : 0; i < num_workers + 1; i++)
    {
      nsim_wheel_t *wp;

      nsm->mmap_size = sizeof (nsim_wheel_t)
        + wheel_slots_per_worker * sizeof (nsim_wheel_entry_t);

      nsm->mmap_size += pagesize - 1;
      nsm->mmap_size &= ~(pagesize - 1);

      wp = clib_mem_vm_alloc (nsm->mmap_size);
      ASSERT (wp != 0);
      wp->wheel_size = wheel_slots_per_worker;
      wp->cursize = 0;
      wp->head = 0;
      wp->tail = 0;
      wp->entries = (void *) (wp + 1);
      nsm->wheel_by_thread[i] = wp;
    }

  vlib_worker_thread_barrier_sync (vm);

  /* turn on the ring scrapers */
  for (i = num_workers ? 1 : 0; i < num_workers + 1; i++)
    {
      vlib_main_t *this_vm = vlib_mains[i];

      vlib_node_set_state (this_vm, nsim_input_node.index,
                           VLIB_NODE_STATE_POLLING);
    }

  vlib_worker_thread_barrier_release (vm);

  nsm->is_configured = 1;
  return 0;
}

/*
 * enable or disable the cross-connect
 */
static clib_error_t *
nsim_cross_connect_enable_disable_command_fn (vlib_main_t * vm,
                                              unformat_input_t * input,
                                              vlib_cli_command_t * cmd)
{
  nsim_main_t *nsm = &nsim_main;
  unformat_input_t _line_input, *line_input = &_line_input;
  u32 sw_if_index0 = ~0;
  u32 sw_if_index1 = ~0;
  int enable_disable = 1;
  u32 tmp;
  int rv;

  /* Get a line of input. */
  if (!unformat_user (input, unformat_line_input, line_input))
    return 0;

  while (unformat_check_input (line_input) != UNFORMAT_END_OF_INPUT)
    {
      if (unformat (line_input, "disable"))
        enable_disable = 0;
      else if (unformat (line_input, "%U", unformat_vnet_sw_interface,
                         nsm->vnet_main, &tmp))
        {
          if (sw_if_index0 == ~0)
            sw_if_index0 = tmp;
          else
            sw_if_index1 = tmp;
        }
      else
        break;
    }

  unformat_free (line_input);

  if (sw_if_index0 == ~0 || sw_if_index1 == ~0)
    return clib_error_return (0, "Please specify two interfaces...");

  rv = nsim_cross_connect_enable_disable (nsm, sw_if_index0,
                                          sw_if_index1, enable_disable);

  switch (rv)
    {
    case 0:
      break;

    case VNET_API_ERROR_CANNOT_ENABLE_DISABLE_FEATURE:
      return clib_error_return (0, "Not configured, please 'set nsim' first");

    case VNET_API_ERROR_INVALID_SW_IF_INDEX:
      return clib_error_return
        (0, "Invalid interface, only works on physical ports");
      break;

    case VNET_API_ERROR_UNIMPLEMENTED:
      return clib_error_return (0,
                                "Device driver doesn't support redirection");
      break;

    default:
      return clib_error_return (0, "nsim_enable_disable returned %d", rv);
    }
  return 0;
}

/*?
 * Enable or disable network simulation cross-connect on two interfaces
 * The network simulator must have already been configured, see
 * the "nsim_configure" command.
 *
 * Place the interfaces into a bridge group, to ensure that
 * interfaces are in promiscuous mode.
 *
 * @cliexpar
 * To enable or disable network simulation cross-connect
 * @clistart
 * nsim cross-connect enable-disable TenGigabitEthernet2/0/0 TenGigabitEthernet2/0
 * nsim cross-connect enable-disable TenGigabitEthernet2/0/0 TenGigabitEthernet2/0 disable
 * @cliend
 * @cliexcmd{nsim enable-disable <intfc> <intfc> [disable]}
?*/
/* *INDENT-OFF* */
VLIB_CLI_COMMAND (nsim_enable_disable_command, static) =
{
  .path = "nsim cross-connect enable-disable",
  .short_help =
  "nsim cross-connect enable-disable <interface-name-1> "
  "<interface-name-2> [disable]",
  .function = nsim_cross_connect_enable_disable_command_fn,
};
/* *INDENT-ON* */

/* API message handler */
static void vl_api_nsim_cross_connect_enable_disable_t_handler
  (vl_api_nsim_cross_connect_enable_disable_t * mp)
{
  vl_api_nsim_cross_connect_enable_disable_reply_t *rmp;
  nsim_main_t *nsm = &nsim_main;
  int rv;
  u32 sw_if_index0, sw_if_index1;

  sw_if_index0 = clib_net_to_host_u32 (mp->sw_if_index0);
  sw_if_index1 = clib_net_to_host_u32 (mp->sw_if_index1);

  if (!vnet_sw_if_index_is_api_valid (sw_if_index0))
    {
      rv = VNET_API_ERROR_INVALID_SW_IF_INDEX;
      goto bad_sw_if_index;
    }
  if (!vnet_sw_if_index_is_api_valid (sw_if_index1))
    {
      rv = VNET_API_ERROR_INVALID_SW_IF_INDEX_2;
      goto bad_sw_if_index;
    }

  rv = nsim_cross_connect_enable_disable (nsm, sw_if_index0, sw_if_index1,
                                          (int) (mp->enable_disable));

  BAD_SW_IF_INDEX_LABEL;
  REPLY_MACRO (VL_API_NSIM_CROSS_CONNECT_ENABLE_DISABLE_REPLY);
}

/* API message handler */
static void vl_api_nsim_output_feature_enable_disable_t_handler
  (vl_api_nsim_output_feature_enable_disable_t * mp)
{
  vl_api_nsim_output_feature_enable_disable_reply_t *rmp;
  nsim_main_t *nsm = &nsim_main;
  int rv;
  VALIDATE_SW_IF_INDEX (mp);

  rv = nsim_output_feature_enable_disable (nsm, ntohl (mp->sw_if_index),
                                           (int) (mp->enable_disable));

  BAD_SW_IF_INDEX_LABEL;
  REPLY_MACRO (VL_API_NSIM_OUTPUT_FEATURE_ENABLE_DISABLE_REPLY);
}

/* API message handler */
static void
vl_api_nsim_configure_t_handler (vl_api_nsim_configure_t * mp)
{
  vl_api_nsim_configure_reply_t *rmp;
  nsim_main_t *nsm = &nsim_main;
  f64 delay, bandwidth, packet_size, drop_fraction;
  u32 packets_per_drop;
  int rv;

  delay = ((f64) (ntohl (mp->delay_in_usec))) * 1e-6;
  bandwidth = (f64) (clib_net_to_host_u64 (mp->bandwidth_in_bits_per_second));
  packet_size = (f64) (ntohl (mp->average_packet_size));

  packets_per_drop = ntohl (mp->packets_per_drop);
  if (packets_per_drop > 0)
    drop_fraction = 1.0 / (f64) (packets_per_drop);
  else
    drop_fraction = 0.0;

  rv = nsim_configure (nsm, bandwidth, delay, packet_size, drop_fraction);

  REPLY_MACRO (VL_API_NSIM_CONFIGURE_REPLY);
}


/*
 * enable or disable the output_feature
 */
static clib_error_t *
nsim_output_feature_enable_disable_command_fn (vlib_main_t * vm,
                                               unformat_input_t * input,
                                               vlib_cli_command_t * cmd)
{
  nsim_main_t *nsm = &nsim_main;
  unformat_input_t _line_input, *line_input = &_line_input;
  u32 sw_if_index = ~0;
  int enable_disable = 1;
  int rv;

  /* Get a line of input. */
  if (!unformat_user (input, unformat_line_input, line_input))
    return 0;

  while (unformat_check_input (line_input) != UNFORMAT_END_OF_INPUT)
    {
      if (unformat (line_input, "disable"))
        enable_disable = 0;
      else if (unformat (line_input, "%U", unformat_vnet_sw_interface,
                         nsm->vnet_main, &sw_if_index))
        ;
      else
        {
          clib_error_t *error = clib_error_return (0, "unknown input `%U'",
                                                   format_unformat_error,
                                                   line_input);
          unformat_free (line_input);
          return error;
        }
    }

  unformat_free (line_input);

  if (sw_if_index == ~0)
    return clib_error_return (0, "Please specify one interface...");

  rv = nsim_output_feature_enable_disable (nsm, sw_if_index, enable_disable);

  switch (rv)
    {
    case 0:
      break;

    case VNET_API_ERROR_CANNOT_ENABLE_DISABLE_FEATURE:
      return clib_error_return (0, "Not configured, please 'set nsim' first");

    case VNET_API_ERROR_INVALID_SW_IF_INDEX:
      return clib_error_return
        (0, "Invalid interface, only works on physical ports");
      break;

    case VNET_API_ERROR_UNIMPLEMENTED:
      return clib_error_return (0,
                                "Device driver doesn't support redirection");
      break;

    default:
      return clib_error_return
        (0, "nsim_output_feature_enable_disable returned %d", rv);
    }
  return 0;
}

/*?
 * Enable or disable network simulation output feature on an interface
 * The network simulator must have already been configured, see
 * the "nsim_configure" command.
 *
 * @cliexpar
 * To enable or disable network simulation output feature
 * @clistart
 * nsim output-feature enable-disable TenGigabitEthernet2/0/0
 * nsim output-feature enable-disable TenGigabitEthernet2/0/0 disable
 * @cliend
 * @cliexcmd{nsim output-feature enable-disable <intfc> [disable]}
?*/
/* *INDENT-OFF* */
VLIB_CLI_COMMAND (nsim_output_feature_enable_disable_command, static) =
{
  .path = "nsim output-feature enable-disable",
  .short_help =
  "nsim output-feature enable-disable <interface-name> [disable]",
  .function = nsim_output_feature_enable_disable_command_fn,
};
/* *INDENT-ON* */

/* Set up the API message handling tables */
static clib_error_t *
nsim_plugin_api_hookup (vlib_main_t * vm)
{
  nsim_main_t *nsm = &nsim_main;
#define _(N,n)                                                  \
    vl_msg_api_set_handlers((VL_API_##N + nsm->msg_id_base),     \
                           #n,                                  \
                           vl_api_##n##_t_handler,              \
                           vl_noop_handler,                     \
                           vl_api_##n##_t_endian,               \
                           vl_api_##n##_t_print,                \
                           sizeof(vl_api_##n##_t), 1);
  foreach_nsim_plugin_api_msg;
#undef _

  return 0;
}

#define vl_msg_name_crc_list
#include <nsim/nsim_all_api_h.h>
#undef vl_msg_name_crc_list

static void
setup_message_id_table (nsim_main_t * nsm, api_main_t * am)
{
#define _(id,n,crc)   vl_msg_api_add_msg_name_crc (am, #n "_" #crc, id + nsm->msg_id_base);
  foreach_vl_msg_name_crc_nsim;
#undef _
}

static clib_error_t *
nsim_init (vlib_main_t * vm)
{
  nsim_main_t *nsm = &nsim_main;
  clib_error_t *error = 0;
  u8 *name;

  nsm->vlib_main = vm;
  nsm->vnet_main = vnet_get_main ();

  name = format (0, "nsim_%08x%c", api_version, 0);

  /* Ask for a correctly-sized block of API message decode slots */
  nsm->msg_id_base = vl_msg_api_get_msg_ids
    ((char *) name, VL_MSG_FIRST_AVAILABLE);

  error = nsim_plugin_api_hookup (vm);

  /* Add our API messages to the global name_crc hash table */
  setup_message_id_table (nsm, &api_main);

  vec_free (name);

  return error;
}

VLIB_INIT_FUNCTION (nsim_init);

/* *INDENT-OFF* */
VNET_FEATURE_INIT (nsim, static) =
{
  .arc_name = "device-input",
  .node_name = "nsim",
  .runs_before = VNET_FEATURES ("ethernet-input"),
};
/* *INDENT-ON */

/* *INDENT-OFF* */
VNET_FEATURE_INIT (nsim_feature, static) =
{
  .arc_name = "interface-output",
  .node_name = "nsim-output-feature",
  .runs_before = VNET_FEATURES ("interface-tx"),
};
/* *INDENT-ON */

/* *INDENT-OFF* */
VLIB_PLUGIN_REGISTER () =
{
  .version = VPP_BUILD_VER,
  .description = "Network Delay Simulator",
};
/* *INDENT-ON* */

static uword
unformat_delay (unformat_input_t * input, va_list * args)
{
  f64 *result = va_arg (*args, f64 *);
  f64 tmp;

  if (unformat (input, "%f us", &tmp))
    *result = tmp * 1e-6;
  else if (unformat (input, "%f ms", &tmp))
    *result = tmp * 1e-3;
  else if (unformat (input, "%f sec", &tmp))
    *result = tmp;
  else
    return 0;

  return 1;
}

static uword
unformat_bandwidth (unformat_input_t * input, va_list * args)
{
  f64 *result = va_arg (*args, f64 *);
  f64 tmp;

  if (unformat (input, "%f gbit", &tmp))
    *result = tmp * 1e9;
  else if (unformat (input, "%f gbyte", &tmp))
    *result = tmp * 8e9;
  else
    return 0;
  return 1;
}

static clib_error_t *
set_nsim_command_fn (vlib_main_t * vm,
                     unformat_input_t * input, vlib_cli_command_t * cmd)
{
  nsim_main_t *nsm = &nsim_main;
  f64 delay, bandwidth;
  f64 packet_size = 1500.0;
  f64 drop_fraction = 0.0;
  u32 packets_per_drop;
  u32 num_workers = vlib_num_workers ();
  int rv;

  while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
    {
      if (unformat (input, "delay %U", unformat_delay, &delay))
        ;
      else if (unformat (input, "bandwidth %U", unformat_bandwidth,
                         &bandwidth))
        ;
      else if (unformat (input, "packet-size %f", &packet_size))
        ;
      else if (unformat (input, "packets-per-drop %d", &packets_per_drop))
        {
          if (packets_per_drop > 0)
            drop_fraction = 1.0 / ((f64) packets_per_drop);
        }
      else if (unformat (input, "drop-fraction %f", &drop_fraction))
        {
          if (drop_fraction < 0.0 || drop_fraction > 1.0)
            return clib_error_return
              (0, "drop fraction must be between zero and 1");
        }
      else
        break;
    }

  rv = nsim_configure (nsm, bandwidth, delay, packet_size, drop_fraction);

  switch (rv)
    {
    case VNET_API_ERROR_INVALID_VALUE:
      return clib_error_return (0, "invalid bandwidth %.2f", bandwidth);

    case VNET_API_ERROR_INVALID_VALUE_2:
      return clib_error_return (0, "invalid delay %.2f", delay);

    case VNET_API_ERROR_INVALID_VALUE_3:
      return clib_error_return (0, "invalid packet size %.2f", packet_size);

    default:
      return clib_error_return (0, "error %d", rv);

    case 0:
      break;
    }

  vlib_cli_output (vm, "Configured link delay %.2f ms, %.2f ms round-trip",
                   nsm->delay * 1e3, 2.0 * nsm->delay * 1e3);
  if (nsm->drop_fraction > 0.0)
    vlib_cli_output (vm, "... simulating a network drop fraction of %.5f",
                     nsm->drop_fraction);


  if (num_workers)
    vlib_cli_output (vm, "Sim uses %llu bytes per thread, %llu bytes total",
                     nsm->mmap_size, nsm->mmap_size * num_workers);
  else
    vlib_cli_output (vm, "Sim uses %llu bytes total", nsm->mmap_size);

  return 0;
}

/*?
 * Configure the network simulation cross-connect
 * Once the simulator is configured, use the "nsim enable-disable" command
 * to set up a cross-connect with the supplied delay characteristics.
 *
 * The cross connect configuration may be changed without restarting vpp
 * but it is good practice to shut down the interfaces.
 *
 * @cliexpar
 * To configure the network delay simulator:
 * @clistart
 * set nsim delay 10.0 ms bandwidth 5.5 gbit packet-size 128
 *
 * @cliend
 * @cliexcmd{set nsim delay <nn> bandwidth <bb> packet-size <nn>}
?*/
/* *INDENT-OFF* */
VLIB_CLI_COMMAND (set_nsim_command, static) =
{
  .path = "set nsim",
  .short_help = "set nsim delay <time> bandwidth <bps> packet-size <nbytes>\n"
  "    [packets-per-drop <nn>][drop-fraction <f64: 0.0 - 1.0>]",
  .function = set_nsim_command_fn,
};
/* *INDENT-ON*/


static clib_error_t *
show_nsim_command_fn (vlib_main_t * vm,
                      unformat_input_t * input, vlib_cli_command_t * cmd)
{
  nsim_main_t *nsm = &nsim_main;
  u32 num_workers = vlib_num_workers ();
  int verbose = 0;

  if (nsm->is_configured == 0)
    return clib_error_return (0, "Network simulator not configured");

  if (nsm->sw_if_index0 == 0)
    return clib_error_return (0, "Network simulator not enabled");

  if (unformat (input, "verbose"))
    verbose = 1;

  vlib_cli_output (vm, "Network simulator cross-connects %U and %U",
                   format_vnet_sw_if_index_name,
                   nsm->vnet_main, nsm->sw_if_index0,
                   format_vnet_sw_if_index_name,
                   nsm->vnet_main, nsm->sw_if_index1);

  vlib_cli_output (vm,
                   "...inserting link delay of %.2f ms, %.2f ms round-trip",
                   nsm->delay * 1e3, 2.0 * nsm->delay * 1e3);

  if (nsm->drop_fraction > 0.0)
    vlib_cli_output (vm, "... simulating a network drop fraction of %.5f",
                     nsm->drop_fraction);

  if (verbose)
    {

      vlib_cli_output (vm, "  Configured bandwidth: %.2f gbit/sec",
                       nsm->bandwidth / 1e9);
      vlib_cli_output (vm, "  Configured packet size: %f", nsm->packet_size);
      if (num_workers)
        vlib_cli_output
          (vm, "  Sim uses %llu bytes per thread, %llu bytes total",
           nsm->mmap_size, nsm->mmap_size * num_workers);
      else
        vlib_cli_output (vm, "  Sim uses %llu bytes total", nsm->mmap_size);
    }

  return 0;
}

/*?
 * Display state info for the network delay simulator.
 *
 * @cliexpar
 * To display the state of the network simulator
 * @clistart
 * show nsim verbose
 * Network simulator cross-connects TenGigabitEthernet2/0/0 and TenGigabitEthernet2/0/1
 * ...inserting link delay of 10.00 ms, 20.00 ms round-trip
 *  Configured bandwidth: 10.10 gbit/sec
 *  Configured packet size: 128
 *  Sim uses 157814784 bytes total
 * @cliend
 * @cliexcmd{show nsim}
?*/

/* *INDENT-OFF* */
VLIB_CLI_COMMAND (show_nsim_command, static) =
{
  .path = "show nsim",
  .short_help = "Display network delay simulator configuration",
  .function = show_nsim_command_fn,
};
/* *INDENT-ON* */

/*
 * fd.io coding-style-patch-verification: ON
 *
 * Local Variables:
 * eval: (c-set-style "gnu")
 * End:
 */