[ovs-dev] [PATCH 4/6] Add support for set_mpls_ttl action

Simon Horman horms at verge.net.au
Wed Nov 28 08:27:14 UTC 2012


This adds support for the OpenFlow 1.1+ set_mpls_ttl action.
And also adds an NX set_mpls_ttl action.

The handling of the TTL modification is entirely handled in userspace.

Reviewed-by: Isaku Yamahata <yamahata at valinux.co.jp>
Signed-off-by: Simon Horman <horms at verge.net.au>

---

v2.9
* Update tests for upstream changes

v2.8
* No change

v2.7
* Encode action as OFP11 action in OFP11+ messages

v2.6
* Rebase

v2.5
* First post
---
 include/openflow/nicira-ext.h |   12 ++++++++
 lib/ofp-actions.c             |   30 ++++++++++++++++++++
 lib/ofp-actions.h             |   10 +++++++
 lib/ofp-parse.c               |   17 +++++++++++
 lib/ofp-util.def              |    2 ++
 ofproto/ofproto-dpif.c        |   13 +++++++++
 tests/ofproto-dpif.at         |   63 +++++++++++++++++++++++++++++++++++++++++
 utilities/ovs-ofctl.8.in      |    4 +++
 8 files changed, 151 insertions(+)

diff --git a/include/openflow/nicira-ext.h b/include/openflow/nicira-ext.h
index afa9d1b..d4285a9 100644
--- a/include/openflow/nicira-ext.h
+++ b/include/openflow/nicira-ext.h
@@ -306,6 +306,7 @@ enum nx_action_subtype {
     NXAST_WRITE_METADATA,       /* struct nx_action_write_metadata */
     NXAST_PUSH_MPLS,            /* struct nx_action_push_mpls */
     NXAST_POP_MPLS,             /* struct nx_action_pop_mpls */
+    NXAST_SET_MPLS_TTL,         /* struct nx_action_ttl */
     NXAST_DEC_MPLS_TTL,         /* struct nx_action_header */
 };
 
@@ -2234,4 +2235,15 @@ struct nx_action_pop_mpls {
 };
 OFP_ASSERT(sizeof(struct nx_action_pop_mpls) == 16);
 
+/* Action structure for NXAST_SET_MPLS_TTL. */
+struct nx_action_mpls_ttl {
+    ovs_be16 type;                  /* OFPAT_POP_MPLS. */
+    ovs_be16 len;                   /* Length is 8. */
+    ovs_be32 vendor;                /* NX_VENDOR_ID. */
+    ovs_be16 subtype;               /* NXAST_SET_MPLS_TTL. */
+    uint8_t  ttl;                   /* TTL */
+    uint8_t  pad[5];
+};
+OFP_ASSERT(sizeof(struct nx_action_pop_mpls) == 16);
+
 #endif /* openflow/nicira-ext.h */
diff --git a/lib/ofp-actions.c b/lib/ofp-actions.c
index a79ecd4..ce48829 100644
--- a/lib/ofp-actions.c
+++ b/lib/ofp-actions.c
@@ -412,6 +412,12 @@ ofpact_from_nxast(const union ofp_action *a, enum ofputil_action_code code,
         break;
     }
 
+    case OFPUTIL_NXAST_SET_MPLS_TTL: {
+        struct nx_action_mpls_ttl *nxamt = (struct nx_action_mpls_ttl *)a;
+        ofpact_put_SET_MPLS_TTL(out)->ttl = nxamt->ttl;
+        break;
+    }
+
     case OFPUTIL_NXAST_DEC_MPLS_TTL:
         ofpact_put_DEC_MPLS_TTL(out);
         break;
@@ -792,6 +798,12 @@ ofpact_from_openflow11(const union ofp_action *a, struct ofpbuf *out)
         return nxm_reg_load_from_openflow12_set_field(
             (const struct ofp12_action_set_field *)a, out);
 
+    case OFPUTIL_OFPAT11_SET_MPLS_TTL: {
+        struct ofp11_action_mpls_ttl *oamt = (struct ofp11_action_mpls_ttl *)a;
+        ofpact_put_SET_MPLS_TTL(out)->ttl = oamt->mpls_ttl;
+        break;
+    }
+
     case OFPUTIL_OFPAT11_DEC_MPLS_TTL:
         ofpact_put_DEC_MPLS_TTL(out);
         break;
@@ -1143,6 +1155,7 @@ ofpact_check__(const struct ofpact *a, const struct flow *flow, int max_ports,
     }
 
     case OFPACT_DEC_TTL:
+    case OFPACT_SET_MPLS_TTL:
     case OFPACT_DEC_MPLS_TTL:
     case OFPACT_SET_TUNNEL:
     case OFPACT_SET_QUEUE:
@@ -1381,6 +1394,11 @@ ofpact_to_nxast(const struct ofpact *a, struct ofpbuf *out)
         ofpact_dec_ttl_to_nxast(ofpact_get_DEC_TTL(a), out);
         break;
 
+    case OFPACT_SET_MPLS_TTL:
+        ofputil_put_NXAST_SET_MPLS_TTL(out)->ttl
+            = ofpact_get_SET_MPLS_TTL(a)->ttl;
+        break;
+
     case OFPACT_DEC_MPLS_TTL:
         ofputil_put_NXAST_DEC_MPLS_TTL(out);
         break;
@@ -1556,6 +1574,7 @@ ofpact_to_openflow10(const struct ofpact *a, struct ofpbuf *out)
     case OFPACT_REG_MOVE:
     case OFPACT_REG_LOAD:
     case OFPACT_DEC_TTL:
+    case OFPACT_SET_MPLS_TTL:
     case OFPACT_DEC_MPLS_TTL:
     case OFPACT_SET_TUNNEL:
     case OFPACT_WRITE_METADATA:
@@ -1685,6 +1704,11 @@ ofpact_to_openflow11(const struct ofpact *a, struct ofpbuf *out)
         ofpact_dec_ttl_to_openflow11(ofpact_get_DEC_TTL(a), out);
         break;
 
+    case OFPACT_SET_MPLS_TTL:
+        ofputil_put_OFPAT11_SET_MPLS_TTL(out)->mpls_ttl
+            = ofpact_get_SET_MPLS_TTL(a)->ttl;
+        break;
+
     case OFPACT_DEC_MPLS_TTL:
         ofputil_put_OFPAT11_DEC_MPLS_TTL(out);
         break;
@@ -1835,6 +1859,7 @@ ofpact_outputs_to_port(const struct ofpact *ofpact, uint16_t port)
     case OFPACT_REG_MOVE:
     case OFPACT_REG_LOAD:
     case OFPACT_DEC_TTL:
+    case OFPACT_SET_MPLS_TTL:
     case OFPACT_DEC_MPLS_TTL:
     case OFPACT_SET_TUNNEL:
     case OFPACT_WRITE_METADATA:
@@ -2060,6 +2085,11 @@ ofpact_format(const struct ofpact *a, struct ds *s)
         print_dec_ttl(ofpact_get_DEC_TTL(a), s);
         break;
 
+    case OFPACT_SET_MPLS_TTL:
+        ds_put_format(s, "set_mpls_ttl(%"PRIu8")",
+                      ofpact_get_SET_MPLS_TTL(a)->ttl);
+        break;
+
     case OFPACT_DEC_MPLS_TTL:
         ds_put_cstr(s, "dec_mpls_ttl");
         break;
diff --git a/lib/ofp-actions.h b/lib/ofp-actions.h
index da5aaac..90ff06b 100644
--- a/lib/ofp-actions.h
+++ b/lib/ofp-actions.h
@@ -71,6 +71,7 @@
     DEFINE_OFPACT(REG_MOVE,        ofpact_reg_move,      ofpact)    \
     DEFINE_OFPACT(REG_LOAD,        ofpact_reg_load,      ofpact)    \
     DEFINE_OFPACT(DEC_TTL,         ofpact_cnt_ids,       cnt_ids)   \
+    DEFINE_OFPACT(SET_MPLS_TTL,    ofpact_mpls_ttl,      ofpact)    \
     DEFINE_OFPACT(DEC_MPLS_TTL,    ofpact_null,          ofpact)    \
     DEFINE_OFPACT(PUSH_MPLS,       ofpact_push,          ofpact)    \
     DEFINE_OFPACT(POP_MPLS,        ofpact_pop_mpls,      ofpact)    \
@@ -451,6 +452,15 @@ struct ofpact_cnt_ids {
     uint16_t cnt_ids[];
 };
 
+/* OFPACT_SET_MPLS_TTL.
+ *
+ * Used for NXAST_SET_MPLS_TTL */
+struct ofpact_mpls_ttl {
+    struct ofpact ofpact;
+
+    uint8_t ttl;
+};
+
 /* OFPACT_GOTO_TABLE
  *
  * Used for OFPIT11_GOTO_TABLE */
diff --git a/lib/ofp-parse.c b/lib/ofp-parse.c
index 38792b1..61e5d28 100644
--- a/lib/ofp-parse.c
+++ b/lib/ofp-parse.c
@@ -319,6 +319,18 @@ parse_dec_ttl(struct ofpbuf *b, char *arg)
 }
 
 static void
+parse_set_mpls_ttl(struct ofpbuf *b, const char *arg)
+{
+    struct ofpact_mpls_ttl *mpls_ttl = ofpact_put_SET_MPLS_TTL(b);
+
+    if (*arg == '\0') {
+        ovs_fatal(0, "parse_set_mpls_ttl: expected ttl.");
+    }
+
+    mpls_ttl->ttl = atoi(arg);
+}
+
+static void
 set_field_parse(const char *arg, struct ofpbuf *ofpacts)
 {
     char *orig = xstrdup(arg);
@@ -550,6 +562,11 @@ parse_named_action(enum ofputil_action_code code, const struct flow *flow,
         parse_dec_ttl(ofpacts, arg);
         break;
 
+    case OFPUTIL_NXAST_SET_MPLS_TTL:
+    case OFPUTIL_OFPAT11_SET_MPLS_TTL:
+        parse_set_mpls_ttl(ofpacts, arg);
+        break;
+
     case OFPUTIL_OFPAT11_DEC_MPLS_TTL:
     case OFPUTIL_NXAST_DEC_MPLS_TTL:
         ofpact_put_DEC_MPLS_TTL(ofpacts);
diff --git a/lib/ofp-util.def b/lib/ofp-util.def
index 09f9a5a..d403bcb 100644
--- a/lib/ofp-util.def
+++ b/lib/ofp-util.def
@@ -30,6 +30,7 @@ OFPAT11_ACTION(OFPAT11_SET_NW_TOS,   ofp_action_nw_tos,   0, "mod_nw_tos")
 //OFPAT11_ACTION(OFPAT11_SET_NW_ECN,   ofp11_action_nw_ecn, "0, mod_nw_ecn")
 OFPAT11_ACTION(OFPAT11_SET_TP_SRC,   ofp_action_tp_port,  0, "mod_tp_src")
 OFPAT11_ACTION(OFPAT11_SET_TP_DST,   ofp_action_tp_port,  0, "mod_tp_dst")
+OFPAT11_ACTION(OFPAT11_SET_MPLS_TTL, ofp11_action_mpls_ttl, 0, "set_mpls_ttl")
 OFPAT11_ACTION(OFPAT11_DEC_MPLS_TTL, ofp_action_header,   0, "dec_mpls_ttl")
 OFPAT11_ACTION(OFPAT11_PUSH_VLAN,    ofp11_action_push,   0, "push_vlan")
 OFPAT11_ACTION(OFPAT11_POP_VLAN,     ofp_action_header,   0, "pop_vlan")
@@ -65,6 +66,7 @@ NXAST_ACTION(NXAST_CONTROLLER,      nx_action_controller,   0, "controller")
 NXAST_ACTION(NXAST_DEC_TTL_CNT_IDS, nx_action_cnt_ids,      1, NULL)
 NXAST_ACTION(NXAST_WRITE_METADATA,  nx_action_write_metadata, 0,
              "write_metadata")
+NXAST_ACTION(NXAST_SET_MPLS_TTL,    nx_action_mpls_ttl,     0, "set_mpls_ttl")
 NXAST_ACTION(NXAST_DEC_MPLS_TTL,    nx_action_header,       0, "dec_mpls_ttl")
 NXAST_ACTION(NXAST_PUSH_MPLS,       nx_action_push,         0, "push_mpls")
 NXAST_ACTION(NXAST_POP_MPLS,        nx_action_pop_mpls,     0, "pop_mpls")
diff --git a/ofproto/ofproto-dpif.c b/ofproto/ofproto-dpif.c
index 33bfb6b..a58e8de 100644
--- a/ofproto/ofproto-dpif.c
+++ b/ofproto/ofproto-dpif.c
@@ -5682,6 +5682,15 @@ compose_dec_ttl(struct action_xlate_ctx *ctx, struct ofpact_cnt_ids *ids)
     }
 }
 
+static void
+compose_set_mpls_ttl_action(struct action_xlate_ctx *ctx, uint8_t ttl)
+{
+    if (ctx->flow.dl_type == htons(ETH_TYPE_MPLS) ||
+        ctx->flow.dl_type == htons(ETH_TYPE_MPLS_MCAST)) {
+        set_mpls_lse_ttl(&ctx->flow.mpls_lse, ttl);
+    }
+}
+
 static bool
 compose_dec_mpls_ttl_action(struct action_xlate_ctx *ctx)
 {
@@ -6074,6 +6083,10 @@ do_xlate_actions(const struct ofpact *ofpacts, size_t ofpacts_len,
             compose_mpls_pop_action(ctx, ofpact_get_POP_MPLS(a)->ethertype);
             break;
 
+        case OFPACT_SET_MPLS_TTL:
+            compose_set_mpls_ttl_action(ctx, ofpact_get_SET_MPLS_TTL(a)->ttl);
+            break;
+
         case OFPACT_DEC_MPLS_TTL:
             if (compose_dec_mpls_ttl_action(ctx)) {
                 goto out;
diff --git a/tests/ofproto-dpif.at b/tests/ofproto-dpif.at
index d609a16..593780a 100644
--- a/tests/ofproto-dpif.at
+++ b/tests/ofproto-dpif.at
@@ -251,6 +251,9 @@ cookie=0x8 table=6 in_port=85 actions=mod_tp_src:85,controller,resubmit(86,7)
 cookie=0x9 table=7 in_port=86 actions=mod_tp_dst:86,controller,controller
 cookie=0xa dl_src=40:44:44:44:44:44 actions=push_mpls:0x8847,load:10->OXM_OF_MPLS_LABEL[[]],load:3->OXM_OF_MPLS_TC[[]],controller
 cookie=0xa dl_src=40:44:44:44:44:45 actions=push_mpls:0x8847,load:10->OXM_OF_MPLS_LABEL[[]],load:3->OXM_OF_MPLS_TC[[]],dec_mpls_ttl,controller
+cookie=0xa dl_src=40:44:44:44:44:46 actions=push_mpls:0x8847,load:10->OXM_OF_MPLS_LABEL[[]],load:3->OXM_OF_MPLS_TC[[]],set_mpls_ttl(10),controller
+cookie=0xa dl_src=40:44:44:44:44:47 actions=push_mpls:0x8847,load:10->OXM_OF_MPLS_LABEL[[]],load:3->OXM_OF_MPLS_TC[[]],dec_mpls_ttl,set_mpls_ttl(10),controller
+cookie=0xa dl_src=40:44:44:44:44:48 actions=push_mpls:0x8847,load:10->OXM_OF_MPLS_LABEL[[]],load:3->OXM_OF_MPLS_TC[[]],set_mpls_ttl(10),dec_mpls_ttl,controller
 cookie=0xb dl_src=50:55:55:55:55:55 dl_type=0x8847 actions=load:1000->OXM_OF_MPLS_LABEL[[]],controller
 cookie=0xd dl_src=60:66:66:66:66:66 actions=pop_mpls:0x0800,controller
 cookie=0xc dl_src=70:77:77:77:77:77 actions=push_mpls:0x8848,load:1000->OXM_OF_MPLS_LABEL[[]],load:7->OXM_OF_MPLS_TC[[]],controller
@@ -352,6 +355,63 @@ NXT_PACKET_IN (xid=0x0): cookie=0xa total_len=64 in_port=1 (via action) data_len
 mpls(label:10,tc:3,ttl:63,bos:1),metadata=0,in_port=0,vlan_tci=0x0000,dl_src=40:44:44:44:44:45,dl_dst=50:54:00:00:00:07
 ])
 
+dnl Modified MPLS controller action.
+AT_CHECK([ovs-ofctl monitor br0 65534 -P nxm --detach --pidfile 2> ofctl_monitor.log])
+
+for i in 1 2 3; do
+    ovs-appctl netdev-dummy/receive p1 'in_port(1),eth(src=40:44:44:44:44:46,dst=50:54:00:00:00:07),eth_type(0x0800),ipv4(src=192.168.0.1,dst=192.168.0.2,proto=6,tos=0,ttl=64,frag=no)'
+done
+
+OVS_WAIT_UNTIL([ovs-appctl -t ovs-ofctl exit])
+AT_CHECK([cat ofctl_monitor.log], [0], [dnl
+NXT_PACKET_IN (xid=0x0): cookie=0xa total_len=64 in_port=1 (via action) data_len=64 (unbuffered)
+mpls(label:10,tc:3,ttl:10,bos:1),metadata=0,in_port=0,vlan_tci=0x0000,dl_src=40:44:44:44:44:46,dl_dst=50:54:00:00:00:07
+dnl
+NXT_PACKET_IN (xid=0x0): cookie=0xa total_len=64 in_port=1 (via action) data_len=64 (unbuffered)
+mpls(label:10,tc:3,ttl:10,bos:1),metadata=0,in_port=0,vlan_tci=0x0000,dl_src=40:44:44:44:44:46,dl_dst=50:54:00:00:00:07
+dnl
+NXT_PACKET_IN (xid=0x0): cookie=0xa total_len=64 in_port=1 (via action) data_len=64 (unbuffered)
+mpls(label:10,tc:3,ttl:10,bos:1),metadata=0,in_port=0,vlan_tci=0x0000,dl_src=40:44:44:44:44:46,dl_dst=50:54:00:00:00:07
+])
+
+dnl Modified MPLS controller action.
+AT_CHECK([ovs-ofctl monitor br0 65534 -P nxm --detach --pidfile 2> ofctl_monitor.log])
+
+for i in 1 2 3; do
+    ovs-appctl netdev-dummy/receive p1 'in_port(1),eth(src=40:44:44:44:44:47,dst=50:54:00:00:00:07),eth_type(0x0800),ipv4(src=192.168.0.1,dst=192.168.0.2,proto=6,tos=0,ttl=64,frag=no)'
+done
+
+OVS_WAIT_UNTIL([ovs-appctl -t ovs-ofctl exit])
+AT_CHECK([cat ofctl_monitor.log], [0], [dnl
+NXT_PACKET_IN (xid=0x0): cookie=0xa total_len=64 in_port=1 (via action) data_len=64 (unbuffered)
+mpls(label:10,tc:3,ttl:10,bos:1),metadata=0,in_port=0,vlan_tci=0x0000,dl_src=40:44:44:44:44:47,dl_dst=50:54:00:00:00:07
+dnl
+NXT_PACKET_IN (xid=0x0): cookie=0xa total_len=64 in_port=1 (via action) data_len=64 (unbuffered)
+mpls(label:10,tc:3,ttl:10,bos:1),metadata=0,in_port=0,vlan_tci=0x0000,dl_src=40:44:44:44:44:47,dl_dst=50:54:00:00:00:07
+dnl
+NXT_PACKET_IN (xid=0x0): cookie=0xa total_len=64 in_port=1 (via action) data_len=64 (unbuffered)
+mpls(label:10,tc:3,ttl:10,bos:1),metadata=0,in_port=0,vlan_tci=0x0000,dl_src=40:44:44:44:44:47,dl_dst=50:54:00:00:00:07
+])
+
+dnl Modified MPLS controller action.
+AT_CHECK([ovs-ofctl monitor br0 65534 -P nxm --detach --pidfile 2> ofctl_monitor.log])
+
+for i in 1 2 3; do
+    ovs-appctl netdev-dummy/receive p1 'in_port(1),eth(src=40:44:44:44:44:48,dst=50:54:00:00:00:07),eth_type(0x0800),ipv4(src=192.168.0.1,dst=192.168.0.2,proto=6,tos=0,ttl=64,frag=no)'
+done
+
+OVS_WAIT_UNTIL([ovs-appctl -t ovs-ofctl exit])
+AT_CHECK([cat ofctl_monitor.log], [0], [dnl
+NXT_PACKET_IN (xid=0x0): cookie=0xa total_len=64 in_port=1 (via action) data_len=64 (unbuffered)
+mpls(label:10,tc:3,ttl:9,bos:1),metadata=0,in_port=0,vlan_tci=0x0000,dl_src=40:44:44:44:44:48,dl_dst=50:54:00:00:00:07
+dnl
+NXT_PACKET_IN (xid=0x0): cookie=0xa total_len=64 in_port=1 (via action) data_len=64 (unbuffered)
+mpls(label:10,tc:3,ttl:9,bos:1),metadata=0,in_port=0,vlan_tci=0x0000,dl_src=40:44:44:44:44:48,dl_dst=50:54:00:00:00:07
+dnl
+NXT_PACKET_IN (xid=0x0): cookie=0xa total_len=64 in_port=1 (via action) data_len=64 (unbuffered)
+mpls(label:10,tc:3,ttl:9,bos:1),metadata=0,in_port=0,vlan_tci=0x0000,dl_src=40:44:44:44:44:48,dl_dst=50:54:00:00:00:07
+])
+
 dnl Modified MPLS actions.
 AT_CHECK([ovs-ofctl monitor br0 65534 -P nxm --detach --pidfile 2> ofctl_monitor.log])
 
@@ -496,6 +556,9 @@ AT_CHECK([ovs-ofctl dump-flows br0 | ofctl_strip | sort], [0], [dnl
  cookie=0x9, table=7, n_packets=2, n_bytes=120, in_port=86 actions=mod_tp_dst:86,CONTROLLER:65535,CONTROLLER:65535
  cookie=0xa, n_packets=3, n_bytes=180, dl_src=40:44:44:44:44:44 actions=push_mpls:0x8847,load:0xa->OXM_OF_MPLS_LABEL[[]],load:0x3->OXM_OF_MPLS_TC[[]],CONTROLLER:65535
  cookie=0xa, n_packets=3, n_bytes=180, dl_src=40:44:44:44:44:45 actions=push_mpls:0x8847,load:0xa->OXM_OF_MPLS_LABEL[[]],load:0x3->OXM_OF_MPLS_TC[[]],dec_mpls_ttl,CONTROLLER:65535
+ cookie=0xa, n_packets=3, n_bytes=180, dl_src=40:44:44:44:44:46 actions=push_mpls:0x8847,load:0xa->OXM_OF_MPLS_LABEL[[]],load:0x3->OXM_OF_MPLS_TC[[]],set_mpls_ttl(10),CONTROLLER:65535
+ cookie=0xa, n_packets=3, n_bytes=180, dl_src=40:44:44:44:44:47 actions=push_mpls:0x8847,load:0xa->OXM_OF_MPLS_LABEL[[]],load:0x3->OXM_OF_MPLS_TC[[]],dec_mpls_ttl,set_mpls_ttl(10),CONTROLLER:65535
+ cookie=0xa, n_packets=3, n_bytes=180, dl_src=40:44:44:44:44:48 actions=push_mpls:0x8847,load:0xa->OXM_OF_MPLS_LABEL[[]],load:0x3->OXM_OF_MPLS_TC[[]],set_mpls_ttl(10),dec_mpls_ttl,CONTROLLER:65535
  cookie=0xb, n_packets=3, n_bytes=180, dl_src=50:55:55:55:55:55,dl_type=0x8847 actions=load:0x3e8->OXM_OF_MPLS_LABEL[[]],CONTROLLER:65535
  cookie=0xc, n_packets=3, n_bytes=180, dl_src=70:77:77:77:77:77 actions=push_mpls:0x8848,load:0x3e8->OXM_OF_MPLS_LABEL[[]],load:0x7->OXM_OF_MPLS_TC[[]],CONTROLLER:65535
  cookie=0xd, n_packets=3, n_bytes=180, dl_src=60:66:66:66:66:66 actions=pop_mpls:0x0800,CONTROLLER:65535
diff --git a/utilities/ovs-ofctl.8.in b/utilities/ovs-ofctl.8.in
index c83f4ef..8e5a8ab 100644
--- a/utilities/ovs-ofctl.8.in
+++ b/utilities/ovs-ofctl.8.in
@@ -1009,6 +1009,10 @@ invalid ttl packets.  If controller ids are not specified, the
 ``packet_in'' message will be sent only to the controllers having
 controller id zero which have registered for the invalid ttl packets.
 .
+.IP \fBset_mpls_ttl\fR:\fIttl\fR
+Set the TTL of the outer MPLS label of a packet.
+\fIttl\fR should be in the range 0 to 255 inclusive.
+.
 .IP \fBdec_mpls_ttl\fR
 Decrement TTL of the outer MPLS label of a packet.  If the TTL is initially
 zero, no decrement occurs.  Instead, a ``packet-in'' message with reason
-- 
1.7.10.4




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