Merge pull request #12219 from cscarpitta/feature/srv6-usid-behavior-support

bgpd, zebra: Add support for SRv6 uSID Behaviors

bgpd/bgp_attr.c

@@ -4507,7 +4507,9 @@ bgp_size_t bgp_packet_attribute(struct bgp *bgp, struct peer *peer,
 			stream_put(s, &attr->srv6_l3vpn->sid,
 				   sizeof(attr->srv6_l3vpn->sid)); /* sid */
 			stream_putc(s, 0);      /* sid_flags */
-			stream_putw(s, 0xffff); /* endpoint */
+			stream_putw(s,
+				    attr->srv6_l3vpn
+					    ->endpoint_behavior); /* endpoint */
 			stream_putc(s, 0);      /* reserved */
 			stream_putc(
 				s,

bgpd/bgp_mplsvpn.c

@@ -1554,13 +1554,22 @@ void vpn_leak_from_vrf_update(struct bgp *to_bgp,	     /* to */
 
 	/* Set SID for SRv6 VPN */
 	if (from_bgp->vpn_policy[afi].tovpn_sid_locator) {
+		struct srv6_locator_chunk *locator =
+			from_bgp->vpn_policy[afi].tovpn_sid_locator;
 		encode_label(
 			from_bgp->vpn_policy[afi].tovpn_sid_transpose_label,
 			&label);
 		static_attr.srv6_l3vpn = XCALLOC(MTYPE_BGP_SRV6_L3VPN,
 				sizeof(struct bgp_attr_srv6_l3vpn));
 		static_attr.srv6_l3vpn->sid_flags = 0x00;
-		static_attr.srv6_l3vpn->endpoint_behavior = 0xffff;
+		static_attr.srv6_l3vpn->endpoint_behavior =
+			afi == AFI_IP
+				? (CHECK_FLAG(locator->flags, SRV6_LOCATOR_USID)
+					   ? SRV6_ENDPOINT_BEHAVIOR_END_DT4_USID
+					   : SRV6_ENDPOINT_BEHAVIOR_END_DT4)
+				: (CHECK_FLAG(locator->flags, SRV6_LOCATOR_USID)
+					   ? SRV6_ENDPOINT_BEHAVIOR_END_DT6_USID
+					   : SRV6_ENDPOINT_BEHAVIOR_END_DT6);
 		static_attr.srv6_l3vpn->loc_block_len =
 			from_bgp->vpn_policy[afi]
 				.tovpn_sid_locator->block_bits_length;
@@ -1587,12 +1596,17 @@ void vpn_leak_from_vrf_update(struct bgp *to_bgp,	     /* to */
 				.tovpn_sid_locator->prefix.prefix,
 		       sizeof(struct in6_addr));
 	} else if (from_bgp->tovpn_sid_locator) {
+		struct srv6_locator_chunk *locator =
+			from_bgp->tovpn_sid_locator;
 		encode_label(from_bgp->tovpn_sid_transpose_label, &label);
 		static_attr.srv6_l3vpn =
 			XCALLOC(MTYPE_BGP_SRV6_L3VPN,
 				sizeof(struct bgp_attr_srv6_l3vpn));
 		static_attr.srv6_l3vpn->sid_flags = 0x00;
-		static_attr.srv6_l3vpn->endpoint_behavior = 0xffff;
+		static_attr.srv6_l3vpn->endpoint_behavior =
+			CHECK_FLAG(locator->flags, SRV6_LOCATOR_USID)
+				? SRV6_ENDPOINT_BEHAVIOR_END_DT46_USID
+				: SRV6_ENDPOINT_BEHAVIOR_END_DT46;
 		static_attr.srv6_l3vpn->loc_block_len =
 			from_bgp->tovpn_sid_locator->block_bits_length;
 		static_attr.srv6_l3vpn->loc_node_len =

doc/user/zebra.rst

@@ -810,6 +810,36 @@ and this section also helps that case.
       !
    ...
 
+.. clicmd:: behavior usid
+
+   Specify the SRv6 locator as a Micro-segment (uSID) locator. When a locator is
+   specified as a uSID locator, all the SRv6 SIDs allocated from the locator by the routing
+   protocols are bound to the SRv6 uSID behaviors. For example, if you configure BGP to use
+   a locator specified as a uSID locator, BGP instantiates and advertises SRv6 uSID behaviors
+   (e.g., ``uDT4`` / ``uDT6`` / ``uDT46``) instead of classic SRv6 behaviors
+   (e.g., ``End.DT4`` / ``End.DT6`` / ``End.DT46``).
+
+::
+
+   router# configure terminal
+   router(config)# segment-routinig
+   router(config-sr)# srv6
+   router(config-srv6)# locators
+   router(config-srv6-locators)# locator loc1
+   router(config-srv6-locator)# prefix fc00:0:1::/48 block-len 32 node-len 16 func-bits 16
+   router(config-srv6-locator)# behavior usid
+
+   router(config-srv6-locator)# show run
+   ...
+   segment-routing
+    srv6
+     locators
+      locator loc1
+       prefix fc00:0:1::/48
+       behavior usid
+      !
+   ...
+
 .. _multicast-rib-commands:
 
 Multicast RIB Commands

lib/srv6.c

@@ -241,6 +241,10 @@ json_object *srv6_locator_json(const struct srv6_locator *loc)
 	json_object_int_add(jo_root, "argumentBitsLength",
 			    loc->argument_bits_length);
 
+	/* set true if the locator is a Micro-segment (uSID) locator */
+	if (CHECK_FLAG(loc->flags, SRV6_LOCATOR_USID))
+		json_object_string_add(jo_root, "behavior", "usid");
+
 	/* set status_up */
 	json_object_boolean_add(jo_root, "statusUp",
 				loc->status_up);
@@ -286,6 +290,10 @@ json_object *srv6_locator_detailed_json(const struct srv6_locator *loc)
 	json_object_int_add(jo_root, "argumentBitsLength",
 			    loc->argument_bits_length);
 
+	/* set true if the locator is a Micro-segment (uSID) locator */
+	if (CHECK_FLAG(loc->flags, SRV6_LOCATOR_USID))
+		json_object_string_add(jo_root, "behavior", "usid");
+
 	/* set algonum */
 	json_object_int_add(jo_root, "algoNum", loc->algonum);
 

lib/srv6.h

@@ -92,6 +92,9 @@ struct srv6_locator {
 	bool status_up;
 	struct list *chunks;
 
+	uint8_t flags;
+#define SRV6_LOCATOR_USID (1 << 0) /* The SRv6 Locator is a uSID Locator */
+
 	QOBJ_FIELDS;
 };
 DECLARE_QOBJ_TYPE(srv6_locator);
@@ -116,6 +119,23 @@ struct srv6_locator_chunk {
 	uint8_t proto;
 	uint16_t instance;
 	uint32_t session_id;
+
+	uint8_t flags;
+};
+
+/*
+ * SRv6 Endpoint Behavior codepoints, as defined by IANA in
+ * https://www.iana.org/assignments/segment-routing/segment-routing.xhtml
+ */
+enum srv6_endpoint_behavior_codepoint {
+	SRV6_ENDPOINT_BEHAVIOR_RESERVED       = 0x0000,
+	SRV6_ENDPOINT_BEHAVIOR_END_DT6        = 0x0012,
+	SRV6_ENDPOINT_BEHAVIOR_END_DT4        = 0x0013,
+	SRV6_ENDPOINT_BEHAVIOR_END_DT46       = 0x0014,
+	SRV6_ENDPOINT_BEHAVIOR_END_DT6_USID   = 0x003E,
+	SRV6_ENDPOINT_BEHAVIOR_END_DT4_USID   = 0x003F,
+	SRV6_ENDPOINT_BEHAVIOR_END_DT46_USID  = 0x0040,
+	SRV6_ENDPOINT_BEHAVIOR_OPAQUE         = 0xFFFF,
 };
 
 struct nexthop_srv6 {

lib/zclient.c

@@ -1088,6 +1088,7 @@ int zapi_srv6_locator_chunk_encode(struct stream *s,
 	stream_putc(s, c->node_bits_length);
 	stream_putc(s, c->function_bits_length);
 	stream_putc(s, c->argument_bits_length);
+	stream_putc(s, c->flags);
 	return 0;
 }
 
@@ -1109,6 +1110,7 @@ int zapi_srv6_locator_chunk_decode(struct stream *s,
 	STREAM_GETC(s, c->node_bits_length);
 	STREAM_GETC(s, c->function_bits_length);
 	STREAM_GETC(s, c->argument_bits_length);
+	STREAM_GETC(s, c->flags);
 	return 0;
 
 stream_failure:

tests/topotests/srv6_locator_usid/expected_chunks_1.json

@@ -0,0 +1 @@
+[]

tests/topotests/srv6_locator_usid/expected_chunks_2.json

@@ -0,0 +1,8 @@
+[
+  {
+    "name": "loc1",
+    "chunks": [
+      "fc00:0:1::/48"
+    ]
+  }
+]

tests/topotests/srv6_locator_usid/expected_chunks_3.json

@@ -0,0 +1 @@
+[]

tests/topotests/srv6_locator_usid/expected_chunks_4.json

@@ -0,0 +1 @@
+[]

tests/topotests/srv6_locator_usid/expected_chunks_5.json

@@ -0,0 +1,2 @@
+[
+]

tests/topotests/srv6_locator_usid/expected_chunks_6.json

@@ -0,0 +1,2 @@
+[
+]

tests/topotests/srv6_locator_usid/expected_chunks_7.json

@@ -0,0 +1,2 @@
+[
+]

tests/topotests/srv6_locator_usid/expected_chunks_8.json

@@ -0,0 +1,2 @@
+[
+]

tests/topotests/srv6_locator_usid/expected_locators_1.json

@@ -0,0 +1,20 @@
+{
+  "locators":[
+    {
+      "name": "loc1",
+      "prefix": "fc00:0:1::/48",
+      "blockBitsLength": 32,
+      "nodeBitsLength": 16,
+      "functionBitsLength": 16,
+      "argumentBitsLength": 0,
+      "behavior": "usid",
+      "statusUp": true,
+      "chunks": [
+        {
+          "prefix": "fc00:0:1::/48",
+          "proto": "system"
+        }
+      ]
+    }
+  ]
+}

tests/topotests/srv6_locator_usid/expected_locators_2.json

@@ -0,0 +1,20 @@
+{
+  "locators":[
+    {
+      "name": "loc1",
+      "prefix": "fc00:0:1::/48",
+      "blockBitsLength": 32,
+      "nodeBitsLength": 16,
+      "functionBitsLength": 16,
+      "argumentBitsLength": 0,
+      "behavior": "usid",
+      "statusUp": true,
+      "chunks": [
+        {
+          "prefix": "fc00:0:1::/48",
+          "proto": "sharp"
+        }
+      ]
+    }
+  ]
+}

tests/topotests/srv6_locator_usid/expected_locators_3.json

@@ -0,0 +1,20 @@
+{
+  "locators":[
+    {
+      "name": "loc1",
+      "prefix": "fc00:0:1::/48",
+      "blockBitsLength": 32,
+      "nodeBitsLength": 16,
+      "functionBitsLength": 16,
+      "argumentBitsLength": 0,
+      "behavior": "usid",
+      "statusUp": true,
+      "chunks": [
+        {
+          "prefix": "fc00:0:1::/48",
+          "proto": "system"
+        }
+      ]
+    }
+  ]
+}

tests/topotests/srv6_locator_usid/expected_locators_4.json

@@ -0,0 +1,35 @@
+{
+  "locators":[
+    {
+      "name": "loc1",
+      "prefix": "fc00:0:1::/48",
+      "blockBitsLength": 32,
+      "nodeBitsLength": 16,
+      "functionBitsLength": 16,
+      "argumentBitsLength": 0,
+      "behavior": "usid",
+      "statusUp": true,
+      "chunks": [
+        {
+          "prefix": "fc00:0:1::/48",
+          "proto": "system"
+        }
+      ]
+    },
+    {
+      "name": "loc2",
+      "prefix": "fc00:0:2::/48",
+      "blockBitsLength": 32,
+      "nodeBitsLength": 16,
+      "functionBitsLength": 16,
+      "argumentBitsLength": 0,
+      "statusUp": true,
+      "chunks": [
+        {
+          "prefix": "fc00:0:2::/48",
+          "proto": "system"
+        }
+      ]
+    }
+  ]
+}

tests/topotests/srv6_locator_usid/expected_locators_5.json

@@ -0,0 +1,36 @@
+{
+  "locators":[
+    {
+      "name": "loc1",
+      "prefix": "fc00:0:1::/48",
+      "blockBitsLength": 32,
+      "nodeBitsLength": 16,
+      "functionBitsLength": 16,
+      "argumentBitsLength": 0,
+      "behavior": "usid",
+      "statusUp": true,
+      "chunks": [
+        {
+          "prefix": "fc00:0:1::/48",
+          "proto": "system"
+        }
+      ]
+    },
+    {
+      "name": "loc2",
+      "prefix": "fc00:0:2::/48",
+      "blockBitsLength": 32,
+      "nodeBitsLength": 16,
+      "functionBitsLength": 16,
+      "argumentBitsLength": 0,
+      "behavior": "usid",
+      "statusUp": true,
+      "chunks": [
+        {
+          "prefix": "fc00:0:2::/48",
+          "proto": "system"
+        }
+      ]
+    }
+  ]
+}

tests/topotests/srv6_locator_usid/expected_locators_6.json

@@ -0,0 +1,35 @@
+{
+  "locators":[
+    {
+      "name": "loc1",
+      "prefix": "fc00:0:1::/48",
+      "blockBitsLength": 32,
+      "nodeBitsLength": 16,
+      "functionBitsLength": 16,
+      "argumentBitsLength": 0,
+      "behavior": "usid",
+      "statusUp": true,
+      "chunks": [
+        {
+          "prefix": "fc00:0:1::/48",
+          "proto": "system"
+        }
+      ]
+    },
+    {
+      "name": "loc2",
+      "prefix": "fc00:0:2::/48",
+      "blockBitsLength": 32,
+      "nodeBitsLength": 16,
+      "functionBitsLength": 16,
+      "argumentBitsLength": 0,
+      "statusUp": true,
+      "chunks": [
+        {
+          "prefix": "fc00:0:2::/48",
+          "proto": "system"
+        }
+      ]
+    }
+  ]
+}

tests/topotests/srv6_locator_usid/expected_locators_7.json

@@ -0,0 +1,19 @@
+{
+  "locators":[
+    {
+      "name": "loc2",
+      "prefix": "fc00:0:2::/48",
+      "statusUp": true,
+      "blockBitsLength": 32,
+      "nodeBitsLength": 16,
+      "functionBitsLength": 16,
+      "argumentBitsLength": 0,
+      "chunks":[
+        {
+          "prefix": "fc00:0:2::/48",
+          "proto": "system"
+        }
+      ]
+    }
+  ]
+}

tests/topotests/srv6_locator_usid/expected_locators_8.json

@@ -0,0 +1,4 @@
+{
+  "locators":[
+  ]
+}

tests/topotests/srv6_locator_usid/r1/setup.sh

@@ -0,0 +1,2 @@
+ip link add dummy0 type dummy
+ip link set dummy0 up

tests/topotests/srv6_locator_usid/r1/sharpd.conf

@@ -0,0 +1,7 @@
+hostname r1
+!
+log stdout notifications
+log monitor notifications
+log commands
+log file sharpd.log debugging
+!

tests/topotests/srv6_locator_usid/r1/zebra.conf

@@ -0,0 +1,20 @@
+hostname r1
+!
+! debug zebra events
+! debug zebra rib detailed
+!
+log stdout notifications
+log monitor notifications
+log commands
+log file zebra.log debugging
+!
+segment-routing
+ srv6
+  locators
+   locator loc1
+    prefix fc00:0:1::/48 func-bits 16 block-len 32 node-len 16
+    behavior usid
+   !
+  !
+ !
+!

tests/topotests/srv6_locator_usid/test_srv6_locator_usid.py

@@ -0,0 +1,276 @@
+#!/usr/bin/env python
+
+# Copyright (c) 2022, University of Rome Tor Vergata
+# Authored by Carmine Scarpitta <carmine.scarpitta@uniroma2.it>
+#
+# Permission to use, copy, modify, and/or distribute this software
+# for any purpose with or without fee is hereby granted, provided
+# that the above copyright notice and this permission notice appear
+# in all copies.
+#
+# THE SOFTWARE IS PROVIDED "AS IS" AND NETDEF DISCLAIMS ALL WARRANTIES
+# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL NETDEF BE LIABLE FOR
+# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY
+# DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
+# WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
+# ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
+# OF THIS SOFTWARE.
+#
+
+"""
+test_srv6_locator_usid.py:
+Test for SRv6 Locator uSID on zebra
+"""
+
+import os
+import sys
+import json
+import pytest
+import functools
+
+CWD = os.path.dirname(os.path.realpath(__file__))
+sys.path.append(os.path.join(CWD, "../"))
+
+# pylint: disable=C0413
+from lib import topotest
+from lib.topogen import Topogen, TopoRouter, get_topogen
+from lib.topolog import logger
+
+pytestmark = [pytest.mark.bgpd, pytest.mark.sharpd]
+
+
+def open_json_file(filename):
+    try:
+        with open(filename, "r") as f:
+            return json.load(f)
+    except IOError:
+        assert False, "Could not read file {}".format(filename)
+
+
+def setup_module(mod):
+    tgen = Topogen({None: "r1"}, mod.__name__)
+    tgen.start_topology()
+    for rname, router in tgen.routers().items():
+        router.run("/bin/bash {}/{}/setup.sh".format(CWD, rname))
+        router.load_config(
+            TopoRouter.RD_ZEBRA, os.path.join(
+                CWD, "{}/zebra.conf".format(rname))
+        )
+        router.load_config(
+            TopoRouter.RD_SHARP, os.path.join(
+                CWD, "{}/sharpd.conf".format(rname))
+        )
+    tgen.start_router()
+
+
+def teardown_module(mod):
+    tgen = get_topogen()
+    tgen.stop_topology()
+
+
+def _check_srv6_locator(router, expected_locator_file):
+    logger.info("checking zebra locator status")
+    output = json.loads(
+        router.vtysh_cmd("show segment-routing srv6 locator json")
+    )
+    expected = open_json_file("{}/{}".format(CWD, expected_locator_file))
+    return topotest.json_cmp(output, expected)
+
+
+def _check_sharpd_chunk(router, expected_chunk_file):
+    logger.info("checking sharpd locator chunk status")
+    output = json.loads(
+        router.vtysh_cmd("show sharp segment-routing srv6 json")
+    )
+    expected = open_json_file("{}/{}".format(CWD, expected_chunk_file))
+    return topotest.json_cmp(output, expected)
+
+
+def check_srv6_locator(router, expected_file):
+    func = functools.partial(_check_srv6_locator, router, expected_file)
+    success, result = topotest.run_and_expect(func, None, count=5, wait=3)
+    assert result is None, "Failed"
+
+
+def check_sharpd_chunk(router, expected_file):
+    func = functools.partial(_check_sharpd_chunk, router, expected_file)
+    success, result = topotest.run_and_expect(func, None, count=5, wait=3)
+    assert result is None, "Failed"
+
+
+def test_srv6_usid_locator_configuration():
+    tgen = get_topogen()
+    if tgen.routers_have_failure():
+        pytest.skip(tgen.errors)
+    router = tgen.gears["r1"]
+
+    # FOR DEVELOPER:
+    # If you want to stop some specific line and start interactive shell,
+    # please use tgen.mininet_cli() to start it.
+
+    logger.info("Verify SRv6 Locators instantiated from config file")
+    check_srv6_locator(router, "expected_locators_1.json")
+    check_sharpd_chunk(router, "expected_chunks_1.json")
+
+
+def test_srv6_usid_locator_get_chunk():
+    tgen = get_topogen()
+    if tgen.routers_have_failure():
+        pytest.skip(tgen.errors)
+    router = tgen.gears["r1"]
+
+    # FOR DEVELOPER:
+    # If you want to stop some specific line and start interactive shell,
+    # please use tgen.mininet_cli() to start it.
+
+    logger.info("Get chunk for the locator loc1")
+    router.vtysh_cmd("sharp srv6-manager get-locator-chunk loc1")
+    check_srv6_locator(router, "expected_locators_2.json")
+    check_sharpd_chunk(router, "expected_chunks_2.json")
+
+
+def test_srv6_usid_locator_release_chunk():
+    tgen = get_topogen()
+    if tgen.routers_have_failure():
+        pytest.skip(tgen.errors)
+    router = tgen.gears["r1"]
+
+    # FOR DEVELOPER:
+    # If you want to stop some specific line and start interactive shell,
+    # please use tgen.mininet_cli() to start it.
+
+    logger.info("Release chunk for the locator loc1")
+    router.vtysh_cmd("sharp srv6-manager release-locator-chunk loc1")
+    check_srv6_locator(router, "expected_locators_3.json")
+    check_sharpd_chunk(router, "expected_chunks_3.json")
+
+
+def test_srv6_usid_locator_create_locator():
+    tgen = get_topogen()
+    if tgen.routers_have_failure():
+        pytest.skip(tgen.errors)
+    router = tgen.gears["r1"]
+
+    # FOR DEVELOPER:
+    # If you want to stop some specific line and start interactive shell,
+    # please use tgen.mininet_cli() to start it.
+
+    logger.info("Create an additional SRv6 Locator")
+    router.vtysh_cmd(
+        """
+        configure terminal
+         segment-routing
+          srv6
+           locators
+            locator loc2
+             prefix fc00:0:2::/48 func-bits 16 block-len 32 node-len 16
+        """
+    )
+    check_srv6_locator(router, "expected_locators_4.json")
+    check_sharpd_chunk(router, "expected_chunks_4.json")
+
+
+def test_srv6_usid_locator_set_behavior_usid():
+    tgen = get_topogen()
+    if tgen.routers_have_failure():
+        pytest.skip(tgen.errors)
+    router = tgen.gears["r1"]
+
+    # FOR DEVELOPER:
+    # If you want to stop some specific line and start interactive shell,
+    # please use tgen.mininet_cli() to start it.
+
+    logger.info(
+        "Specify the SRv6 Locator loc2 as a Micro-segment (uSID) Locator"
+    )
+    router.vtysh_cmd(
+        """
+        configure terminal
+         segment-routing
+          srv6
+           locators
+            locator loc2
+             behavior usid
+        """
+    )
+    check_srv6_locator(router, "expected_locators_5.json")
+    check_sharpd_chunk(router, "expected_chunks_5.json")
+
+
+def test_srv6_usid_locator_unset_behavior_usid():
+    tgen = get_topogen()
+    if tgen.routers_have_failure():
+        pytest.skip(tgen.errors)
+    router = tgen.gears["r1"]
+
+    # FOR DEVELOPER:
+    # If you want to stop some specific line and start interactive shell,
+    # please use tgen.mininet_cli() to start it.
+
+    logger.info("Clear Micro-segment (uSID) Locator flag for loc2")
+    router.vtysh_cmd(
+        """
+        configure terminal
+         segment-routing
+          srv6
+           locators
+            locator loc2
+             no behavior usid
+        """
+    )
+    check_srv6_locator(router, "expected_locators_6.json")
+    check_sharpd_chunk(router, "expected_chunks_6.json")
+
+
+def test_srv6_usid_locator_delete():
+    tgen = get_topogen()
+    if tgen.routers_have_failure():
+        pytest.skip(tgen.errors)
+    router = tgen.gears["r1"]
+
+    # FOR DEVELOPER:
+    # If you want to stop some specific line and start interactive shell,
+    # please use tgen.mininet_cli() to start it.
+
+    logger.info(
+        "Delete locator loc1 and verify that the chunk is released automatically"
+    )
+    router.vtysh_cmd(
+        """
+        configure terminal
+         segment-routing
+          srv6
+           locators
+            no locator loc1
+        """
+    )
+    check_srv6_locator(router, "expected_locators_7.json")
+    check_sharpd_chunk(router, "expected_chunks_7.json")
+
+
+def test_srv6_usid_locator_delete_all():
+    tgen = get_topogen()
+    if tgen.routers_have_failure():
+        pytest.skip(tgen.errors)
+    router = tgen.gears["r1"]
+
+    # FOR DEVELOPER:
+    # If you want to stop some specific line and start interactive shell,
+    # please use tgen.mininet_cli() to start it.
+
+    logger.info("Delete all the SRv6 configuration")
+    router.vtysh_cmd(
+        """
+        configure terminal
+         segment-routing
+          no srv6
+        """
+    )
+    check_srv6_locator(router, "expected_locators_8.json")
+    check_sharpd_chunk(router, "expected_chunks_8.json")
+
+
+if __name__ == "__main__":
+    args = ["-s"] + sys.argv[1:]
+    sys.exit(pytest.main(args))

zebra/zapi_msg.c

@@ -2710,6 +2710,7 @@ int zsend_srv6_manager_get_locator_chunk_response(struct zserv *client,
 	chunk.keep = 0;
 	chunk.proto = client->proto;
 	chunk.instance = client->instance;
+	chunk.flags = loc->flags;
 
 	zclient_create_header(s, ZEBRA_SRV6_MANAGER_GET_LOCATOR_CHUNK, vrf_id);
 	zapi_srv6_locator_chunk_encode(s, &chunk);

zebra/zebra_srv6.c

@@ -177,6 +177,58 @@ struct srv6_locator *zebra_srv6_locator_lookup(const char *name)
 	return NULL;
 }
 
+void zebra_notify_srv6_locator_add(struct srv6_locator *locator)
+{
+	struct listnode *node;
+	struct zserv *client;
+
+	/*
+	 * Notify new locator info to zclients.
+	 *
+	 * The srv6 locators and their prefixes are managed by zserv(zebra).
+	 * And an actual configuration the srv6 sid in the srv6 locator is done
+	 * by zclient(bgpd, isisd, etc). The configuration of each locator
+	 * allocation and specify it by zserv and zclient should be
+	 * asynchronous. For that, zclient should be received the event via
+	 * ZAPI when a srv6 locator is added on zebra.
+	 * Basically, in SRv6, adding/removing SRv6 locators is performed less
+	 * frequently than adding rib entries, so a broad to all zclients will
+	 * not degrade the overall performance of FRRouting.
+	 */
+	for (ALL_LIST_ELEMENTS_RO(zrouter.client_list, node, client))
+		zsend_zebra_srv6_locator_add(client, locator);
+}
+
+void zebra_notify_srv6_locator_delete(struct srv6_locator *locator)
+{
+	struct listnode *n;
+	struct srv6_locator_chunk *c;
+	struct zserv *client;
+
+	/*
+	 * Notify deleted locator info to zclients if needed.
+	 *
+	 * zclient(bgpd,isisd,etc) allocates a sid from srv6 locator chunk and
+	 * uses it for its own purpose. For example, in the case of BGP L3VPN,
+	 * the SID assigned to vpn unicast rib will be given.
+	 * And when the locator is deleted by zserv(zebra), those SIDs need to
+	 * be withdrawn. The zclient must initiate the withdrawal of the SIDs
+	 * by ZEBRA_SRV6_LOCATOR_DELETE, and this notification is sent to the
+	 * owner of each chunk.
+	 */
+	for (ALL_LIST_ELEMENTS_RO((struct list *)locator->chunks, n, c)) {
+		if (c->proto == ZEBRA_ROUTE_SYSTEM)
+			continue;
+		client = zserv_find_client(c->proto, c->instance);
+		if (!client) {
+			zlog_warn("Not found zclient(proto=%u, instance=%u).",
+				  c->proto, c->instance);
+			continue;
+		}
+		zsend_zebra_srv6_locator_delete(client, locator);
+	}
+}
+
 struct zebra_srv6 *zebra_srv6_get_default(void)
 {
 	static struct zebra_srv6 srv6;

zebra/zebra_srv6.h

@@ -61,6 +61,9 @@ extern void zebra_srv6_locator_add(struct srv6_locator *locator);
 extern void zebra_srv6_locator_delete(struct srv6_locator *locator);
 extern struct srv6_locator *zebra_srv6_locator_lookup(const char *name);
 
+void zebra_notify_srv6_locator_add(struct srv6_locator *locator);
+void zebra_notify_srv6_locator_delete(struct srv6_locator *locator);
+
 extern void zebra_srv6_init(void);
 extern struct zebra_srv6 *zebra_srv6_get_default(void);
 extern bool zebra_srv6_is_enable(void);

zebra/zebra_srv6_vty.c

@@ -172,6 +172,9 @@ DEFUN (show_srv6_locator_detail,
 		vty_out(vty, "Argument-Bit-Len: %u\n",
 			locator->argument_bits_length);
 
+		if (CHECK_FLAG(locator->flags, SRV6_LOCATOR_USID))
+			vty_out(vty, "Behavior: uSID\n");
+
 		vty_out(vty, "Chunks:\n");
 		for (ALL_LIST_ELEMENTS_RO((struct list *)locator->chunks, node,
 					  chunk)) {
@@ -369,6 +372,38 @@ DEFPY (locator_prefix,
 	return CMD_SUCCESS;
 }
 
+DEFPY (locator_behavior,
+       locator_behavior_cmd,
+       "[no] behavior usid",
+       NO_STR
+       "Configure SRv6 behavior\n"
+       "Specify SRv6 behavior uSID\n")
+{
+	VTY_DECLVAR_CONTEXT(srv6_locator, locator);
+
+	if (no && !CHECK_FLAG(locator->flags, SRV6_LOCATOR_USID))
+		/* SRv6 locator uSID flag already unset, nothing to do */
+		return CMD_SUCCESS;
+
+	if (!no && CHECK_FLAG(locator->flags, SRV6_LOCATOR_USID))
+		/* SRv6 locator uSID flag already set, nothing to do */
+		return CMD_SUCCESS;
+
+	/* Remove old locator from zclients */
+	zebra_notify_srv6_locator_delete(locator);
+
+	/* Set/Unset the SRV6_LOCATOR_USID */
+	if (no)
+		UNSET_FLAG(locator->flags, SRV6_LOCATOR_USID);
+	else
+		SET_FLAG(locator->flags, SRV6_LOCATOR_USID);
+
+	/* Notify the new locator to zclients */
+	zebra_notify_srv6_locator_add(locator);
+
+	return CMD_SUCCESS;
+}
+
 static int zebra_sr_config(struct vty *vty)
 {
 	struct zebra_srv6 *srv6 = zebra_srv6_get_default();
@@ -399,6 +434,8 @@ static int zebra_sr_config(struct vty *vty)
 			if (locator->argument_bits_length)
 				vty_out(vty, " arg-len %u",
 					locator->argument_bits_length);
+			if (CHECK_FLAG(locator->flags, SRV6_LOCATOR_USID))
+				vty_out(vty, "    behavior usid");
 			vty_out(vty, "\n");
 			vty_out(vty, "   exit\n");
 			vty_out(vty, "   !\n");
@@ -435,6 +472,7 @@ void zebra_srv6_vty_init(void)
 
 	/* Command for configuration */
 	install_element(SRV6_LOC_NODE, &locator_prefix_cmd);
+	install_element(SRV6_LOC_NODE, &locator_behavior_cmd);
 
 	/* Command for operation */
 	install_element(VIEW_NODE, &show_srv6_locator_cmd);