pimd: Pim Nexthop Tracking support with ECMP

In this patch, PIM nexthop tracking uses locally populated nexthop cached list
to determine ECMP based nexthop (w/ ECMP knob enabled), otherwise picks
the first nexthop as RPF.
Introduced '[no] ip pim ecmp' command to enable/disable PIM ECMP knob.
By default, PIM ECMP is disabled.
Intorudced '[no] ip pim ecmp rebalance' command to provide existing mcache
entry to switch new path based on hash chosen path.
Introduced, show command to display pim registered addresses and respective nexthops.
Introuduce, show command to find nexthop and out interface for (S,G) or (RP,G).
Re-Register an address with nexthop when Interface UP event received,
to ensure the PIM nexthop cache is updated (being PIM enabled).
During PIM neighbor UP, traverse all RPs and Upstreams nexthop and determine, if
any of nexthop's IPv4 address changes/resolves due to neigbor UP event.

Testing Done: Run various LHR, RP and FHR related cases to resolve RPF using
nexthop cache with ECMP knob disabled, performed interface/PIM neighbor flap events.
Executed pim-smoke with knob disabled.

Signed-off-by: Chirag Shah <chirag@cumulusnetworks.com>

1 files changed, 208 insertions, 8 deletions

diff --git a/pimd/pim_cmd.c b/pimd/pim_cmd.c
index 3c5a16ec68..6af072f32f 100644
--- a/pimd/pim_cmd.c
+++ b/pimd/pim_cmd.c
@@ -26,6 +26,8 @@
 #include "prefix.h"
 #include "zclient.h"
 #include "plist.h"
+#include "hash.h"
+#include "nexthop.h"
 
 #include "pimd.h"
 #include "pim_mroute.h"
@@ -55,6 +57,7 @@
 #include "pim_zlookup.h"
 #include "pim_msdp.h"
 #include "pim_ssm.h"
+#include "pim_nht.h"
 
 static struct cmd_node pim_global_node = {
   PIM_NODE,
@@ -2059,6 +2062,50 @@ static void pim_show_rpf(struct vty *vty, u_char uj)
   }
 }
 
+static int
+pim_print_pnc_cache_walkcb (struct hash_backet *backet, void *arg)
+{
+  struct pim_nexthop_cache *pnc = backet->data;
+  struct vty *vty = arg;
+  struct nexthop *nh_node = NULL;
+  ifindex_t first_ifindex;
+  struct interface *ifp = NULL;
+
+  if (!pnc)
+    return CMD_SUCCESS;
+
+  for (nh_node = pnc->nexthop; nh_node; nh_node = nh_node->next)
+    {
+      first_ifindex = nh_node->ifindex;
+      ifp = if_lookup_by_index (first_ifindex, VRF_DEFAULT);
+
+      vty_out (vty, "%-15s ", inet_ntoa (pnc->rpf.rpf_addr.u.prefix4));
+      vty_out (vty, "%-14s ", ifp ? ifp->name : "NULL");
+      vty_out (vty, "%s ", inet_ntoa (nh_node->gate.ipv4));
+      vty_out (vty, "%s", VTY_NEWLINE);
+    }
+  return CMD_SUCCESS;
+}
+
+static void
+pim_show_nexthop (struct vty *vty)
+{
+
+  if (pimg && !pimg->rpf_hash)
+    {
+      vty_out (vty, "no nexthop cache %s", VTY_NEWLINE);
+      return;
+    }
+
+  vty_out (vty, "Number of registered addresses: %lu %s",
+           pimg->rpf_hash->count, VTY_NEWLINE);
+  vty_out (vty, "Address         Interface      Nexthop%s", VTY_NEWLINE);
+  vty_out (vty, "-------------------------------------------%s", VTY_NEWLINE);
+
+  hash_walk (pimg->rpf_hash, pim_print_pnc_cache_walkcb, vty);
+
+}
+
 static void igmp_show_groups(struct vty *vty, u_char uj)
 {
   struct listnode  *ifnode;
@@ -2793,6 +2840,99 @@ DEFUN (show_ip_pim_rpf,
   return CMD_SUCCESS;
 }
 
+DEFUN (show_ip_pim_nexthop,
+       show_ip_pim_nexthop_cmd,
+       "show ip pim nexthop",
+       SHOW_STR
+       IP_STR
+       PIM_STR
+       "PIM cached nexthop rpf information\n")
+{
+  pim_show_nexthop (vty);
+
+  return CMD_SUCCESS;
+}
+
+DEFUN (show_ip_pim_nexthop_lookup,
+       show_ip_pim_nexthop_lookup_cmd,
+       "show ip pim nexthop-lookup A.B.C.D A.B.C.D",
+       SHOW_STR
+       IP_STR
+       PIM_STR
+       "PIM cached nexthop rpf lookup\n"
+       "Source/RP address\n"
+       "Multicast Group address\n")
+{
+  struct pim_nexthop_cache pnc;
+  struct prefix nht_p;
+  int result = 0;
+  struct in_addr src_addr, grp_addr;
+  struct in_addr vif_source;
+  const char *addr_str, *addr_str1;
+  struct prefix grp;
+  struct pim_nexthop nexthop;
+  char nexthop_addr_str[PREFIX_STRLEN];
+  char grp_str[PREFIX_STRLEN];
+
+  addr_str = (const char *)argv[0];
+  result = inet_pton (AF_INET, addr_str, &src_addr);
+  if (result <= 0)
+    {
+      vty_out (vty, "Bad unicast address %s: errno=%d: %s%s",
+               addr_str, errno, safe_strerror (errno), VTY_NEWLINE);
+      return CMD_WARNING;
+    }
+
+  if (pim_is_group_224_4 (src_addr))
+    {
+      vty_out (vty, "Invalid argument. Expected Valid Source Address.%s", VTY_NEWLINE);
+      return CMD_WARNING;
+    }
+
+  addr_str1 = (const char *)argv[1];
+  result = inet_pton (AF_INET, addr_str1, &grp_addr);
+  if (result <= 0)
+    {
+      vty_out (vty, "Bad unicast address %s: errno=%d: %s%s",
+               addr_str, errno, safe_strerror (errno), VTY_NEWLINE);
+      return CMD_WARNING;
+    }
+
+  if (!pim_is_group_224_4 (grp_addr))
+    {
+      vty_out (vty, "Invalid argument. Expected Valid Multicast Group Address.%s", VTY_NEWLINE);
+      return CMD_WARNING;
+    }
+
+  if (!pim_rp_set_upstream_addr (&vif_source, src_addr, grp_addr))
+    return CMD_SUCCESS;
+
+  memset (&pnc, 0, sizeof (struct pim_nexthop_cache));
+  nht_p.family = AF_INET;
+  nht_p.prefixlen = IPV4_MAX_BITLEN;
+  nht_p.u.prefix4 = vif_source;
+  grp.family = AF_INET;
+  grp.prefixlen = IPV4_MAX_BITLEN;
+  grp.u.prefix4 = grp_addr;
+  memset (&nexthop, 0, sizeof (nexthop));
+
+  if ((pim_find_or_track_nexthop (&nht_p, NULL, NULL, &pnc)) == 1)
+    {
+      //Compute PIM RPF using Cached nexthop
+      pim_ecmp_nexthop_search (&pnc, &nexthop, &nht_p, &grp, 0);
+    }
+  else
+    pim_ecmp_nexthop_lookup (&nexthop, vif_source, &nht_p, &grp, 0);
+
+  pim_addr_dump ("<grp?>", &grp, grp_str, sizeof (grp_str));
+  pim_addr_dump ("<nexthop?>", &nexthop.mrib_nexthop_addr,
+                 nexthop_addr_str, sizeof (nexthop_addr_str));
+  vty_out (vty, "Group %s --- Nexthop %s Interface %s %s", grp_str,
+           nexthop_addr_str, nexthop.interface->name, VTY_NEWLINE);
+
+  return CMD_SUCCESS;
+}
+
 static void show_multicast_interfaces(struct vty *vty)
 {
   struct listnode  *node;
@@ -2871,15 +3011,17 @@ DEFUN (show_ip_multicast,
 	  PIM_MAX_USABLE_VIFS,
 	  VTY_NEWLINE);
 
-  vty_out(vty, "%s", VTY_NEWLINE);
-  vty_out(vty, "Upstream Join Timer: %d secs%s",
-	  qpim_t_periodic,
-	  VTY_NEWLINE);
-  vty_out(vty, "Join/Prune Holdtime: %d secs%s",
-	  PIM_JP_HOLDTIME,
-	  VTY_NEWLINE);
+  vty_out (vty, "%s", VTY_NEWLINE);
+  vty_out (vty, "Upstream Join Timer: %d secs%s",
+           qpim_t_periodic, VTY_NEWLINE);
+  vty_out (vty, "Join/Prune Holdtime: %d secs%s",
+           PIM_JP_HOLDTIME, VTY_NEWLINE);
+  vty_out (vty, "PIM ECMP: %s%s",
+           qpim_ecmp_enable ? "Enable" : "Disable", VTY_NEWLINE);
+  vty_out (vty, "PIM ECMP Rebalance: %s%s",
+           qpim_ecmp_rebalance_enable ? "Enable" : "Disable", VTY_NEWLINE);
 
-  vty_out(vty, "%s", VTY_NEWLINE);
+  vty_out (vty, "%s", VTY_NEWLINE);
 
   show_rpf_refresh_stats(vty, now, NULL);
 
@@ -3826,6 +3968,58 @@ DEFUN (no_ip_ssmpingd,
   return CMD_SUCCESS;
 }
 
+DEFUN (ip_pim_ecmp,
+       ip_pim_ecmp_cmd,
+       "ip pim ecmp",
+       IP_STR
+       "pim multicast routing\n"
+       "Enable PIM ECMP \n")
+{
+  qpim_ecmp_enable = 1;
+
+  return CMD_SUCCESS;
+}
+
+DEFUN (no_ip_pim_ecmp,
+       no_ip_pim_ecmp_cmd,
+       "no ip pim ecmp",
+       NO_STR
+       IP_STR
+       "pim multicast routing\n"
+       "Disable PIM ECMP \n")
+{
+  qpim_ecmp_enable = 0;
+
+  return CMD_SUCCESS;
+}
+
+DEFUN (ip_pim_ecmp_rebalance,
+       ip_pim_ecmp_rebalance_cmd,
+       "ip pim ecmp rebalance",
+       IP_STR
+       "pim multicast routing\n"
+       "Enable PIM ECMP \n"
+       "Enable PIM ECMP Rebalance\n")
+{
+  qpim_ecmp_rebalance_enable = 1;
+
+  return CMD_SUCCESS;
+}
+
+DEFUN (no_ip_pim_ecmp_rebalance,
+       no_ip_pim_ecmp_rebalance_cmd,
+       "no ip pim ecmp rebalance",
+       NO_STR
+       IP_STR
+       "pim multicast routing\n"
+       "Disable PIM ECMP \n"
+       "Disable PIM ECMP Rebalance\n")
+{
+  qpim_ecmp_rebalance_enable = 0;
+
+  return CMD_SUCCESS;
+}
+
 static int
 pim_cmd_igmp_start (struct vty *vty, struct interface *ifp)
 {
@@ -6191,6 +6385,10 @@ void pim_cmd_init()
   install_element (CONFIG_NODE, &no_ip_ssmpingd_cmd); 
   install_element (CONFIG_NODE, &ip_msdp_peer_cmd);
   install_element (CONFIG_NODE, &no_ip_msdp_peer_cmd);
+  install_element (CONFIG_NODE, &ip_pim_ecmp_cmd);
+  install_element (CONFIG_NODE, &no_ip_pim_ecmp_cmd);
+  install_element (CONFIG_NODE, &ip_pim_ecmp_rebalance_cmd);
+  install_element (CONFIG_NODE, &no_ip_pim_ecmp_rebalance_cmd);
 
   install_element (INTERFACE_NODE, &interface_ip_igmp_cmd);
   install_element (INTERFACE_NODE, &interface_no_ip_igmp_cmd); 
@@ -6246,6 +6444,8 @@ void pim_cmd_init()
   install_element (VIEW_NODE, &show_ip_rib_cmd);
   install_element (VIEW_NODE, &show_ip_ssmpingd_cmd);
   install_element (VIEW_NODE, &show_debugging_pim_cmd);
+  install_element (VIEW_NODE, &show_ip_pim_nexthop_cmd);
+  install_element (VIEW_NODE, &show_ip_pim_nexthop_lookup_cmd);
 
   install_element (ENABLE_NODE, &clear_ip_interfaces_cmd);
   install_element (ENABLE_NODE, &clear_ip_igmp_interfaces_cmd);