diff --git a/doc/bird.sgml b/doc/bird.sgml
index f3c2c026..d20d4309 100644
--- a/doc/bird.sgml
+++ b/doc/bird.sgml
@@ -1068,14 +1068,15 @@ inherited from templates can be updated by new definitions.
 
 	<tag><label id="proto-rpki-reload">rpki reload <m/switch/</tag>
 	Import or export filters may depend on route RPKI status (using
-	<cf/roa_check()/ operator). In contrast to to other filter operators,
-	this status for the same route may change as the content of ROA tables
-	changes. When this option is active, BIRD activates automatic reload of
-	the appropriate subset of prefixes imported or exported by the channels
-	whenever ROA tables are updated (after a short settle
-	time). When disabled, route reloads have to be requested manually. The
-	option is ignored if <cf/roa_check()/ is not used in channel filters.
-	Note that for BGP channels, automatic reload requires
+	<cf/roa_check()/ or <cf/aspa_check()/ operators). In contrast to other
+	filter operators, this status for the same route may change as the
+	content of ROA and ASPA tables changes. When this option is active, BIRD
+	activates automatic reload of the appropriate subset of prefixes imported
+	or exported by the channels whenever ROA and ASPA
+	tables are updated (after a short settle time). When disabled, route
+	reloads have to be requested manually. The option is ignored if neither
+	<cf/roa_check()/ nor <cf/aspa_check()/ is used in channel filters. Note
+	that for BGP channels, automatic reload requires
 	<ref id="bgp-import-table" name="import table"> or
 	<ref id="bgp-export-table" name="export table"> (for respective
 	direction). Default: on.
@@ -1979,16 +1980,67 @@ of a set" operation - it can be used on:
     clist that is also a member of the pair/quad set).
 </itemize>
 
-<p>There is one operator related to ROA infrastructure - <cf/roa_check()/. It
-examines a ROA table and does <rfc id="6483"> route origin validation for a
-given network prefix. The basic usage is <cf>roa_check(<m/table/)</cf>, which
-checks the current route (which should be from BGP to have AS_PATH argument) in
-the specified ROA table and returns ROA_UNKNOWN if there is no relevant ROA,
-ROA_VALID if there is a matching ROA, or ROA_INVALID if there are some relevant
-ROAs but none of them match. There is also an extended variant
-<cf>roa_check(<m/table/, <m/prefix/, <m/asn/)</cf>, which allows to specify a
-prefix and an ASN as arguments.
+<p>There are also operators related to RPKI infrastructure used to run
+<rfc id="6483"> route origin validation and (draft) AS path validation.
 
+<itemize>
+  <item><cf>roa_check(<m/table/)</cf> checks the current route in the specified
+  ROA table and returns <cf>ROA_UNKNOWN</cf>, <cf>ROA_INVALID</cf> or <cf>ROA_VALID</cf>,
+  if the validation result is unknown, invalid, or valid, respectively. The result is
+  valid if there is a matching ROA, it is invalid if there is either matching ROA
+  with a different ASN, or any covering ROA with shorter maximal prefix length.
+
+  <item><cf>roa_check(<m/table/, <m/prefix/, <m/asn/)</cf> is an explicit version
+  of the ROA check if the user for whatever reason needs to check a different prefix
+  or different ASN than the default one. The equivalent call of the short variant
+  is <cf>roa_check(<m/table/, net, bgp_path.last)</cf> and it is faster
+  to call the short variant.
+
+  <item><cf>aspa_check_downstream(<m/table/)</cf> checks the current route
+  in the specified ASPA table and returns <cf>ASPA_UNKNOWN</cf>, <cf>ASPA_INVALID</cf>,
+  or <cf>ASPA_VALID</cf> if the validation result is unknown, invalid, or valid,
+  respectively. The result is valid if there is a full coverage of matching
+  ASPA records according to the Algorithm for Downstream Paths by the (draft).
+  This operator is not present if BGP is not compiled in.
+
+  <item><cf>aspa_check_upstream(<m/table/)</cf> checks the current route
+  in the specified ASPA table as the former operator, but it applies the
+  (stricter) Algorithm for Upstream Paths by the (draft).
+  This operator is not present if BGP is not compiled in.
+
+  <item><cf>aspa_check(<m/table/, <m/path/, <m/is_upstream/)</cf> is
+  an explicit version of the former two ASPA check operators. The equivalent
+  of <cf>aspa_check_downstream</cf> is <cf>aspa_check(<m/table/, bgp_path, false)</cf>
+  and for <cf>aspa_check_upstream</cf> it is
+  <cf>aspa_check(<m/table/, bgp_path, true)</cf>.
+  Note: the ASPA check does not include the local ASN in the AS path.
+  Also, <cf>ASPA_INVALID</cf> is returned for an empty AS path
+  or for AS path containing <cf>CONFED_SET</cf> or <cf>CONFED_SEQUENCE</cf> blocks,
+  as the (draft) stipulates.
+</itemize>
+
+<p>The following example checks for ROA and ASPA on routes from a customer:
+
+<code>
+roa6 table r6;
+aspa table at;
+attribute int valid_roa;
+attribute int valid_aspa;
+
+filter customer_check {
+  case roa_check(r6) {
+    ROA_INVALID: reject "Invalid ROA";
+    ROA_VALID: valid_roa = 1;
+  }
+
+  case aspa_check_upstream(at) {
+    ASPA_INVALID: reject "Invalid ASPA";
+    ASPA_VALID: valid_aspa = 1;
+  }
+
+  accept;
+}
+</code>
 
 <sect>Control structures
 <label id="control-structures">
@@ -5722,6 +5774,10 @@ affected routes after RPKI update, see option <ref id="proto-rpki-reload"
 name="rpki reload">. Or you can use a BIRD client command <cf>reload in
 <m/bgp_protocol_name/</cf> for manual call of revalidation of all routes.
 
+<p>The same protocol, since version 2, also receives and maintains a set
+of ASPAs. You can then validate AS paths using function <cf/aspa_check()/
+in (import) filters.
+
 <sect1>Supported transports
 <p>
 <itemize>
@@ -5741,6 +5797,7 @@ define more RPKI protocols generally.
 protocol rpki [&lt;name&gt;] {
         roa4 { table &lt;tab&gt;; };
         roa6 { table &lt;tab&gt;; };
+	aspa { table &lt;tab&gt;; };
         remote &lt;ip&gt; | "&lt;domain&gt;" [port &lt;num&gt;];
         port &lt;num&gt;;
         local address &lt;ip&gt;;
@@ -5756,10 +5813,12 @@ protocol rpki [&lt;name&gt;] {
                 remote public key "&lt;/path/to/known_host&gt;";
                 user "&lt;name&gt;";
         };
+	max version 2;
+	min version 2;
 }
 </code>
 
-<p>Alse note that you have to specify the ROA channel. If you want to import
+<p>Alse note that you have to specify the ROA and ASPA channels. If you want to import
 only IPv4 prefixes you have to specify only roa4 channel. Similarly with IPv6
 prefixes only. If you want to fetch both IPv4 and even IPv6 ROAs you have to
 specify both channels.
@@ -5806,6 +5865,16 @@ specify both channels.
 	instead. This may be useful for implementing loose RPKI check for
 	blackholes. Default: disabled.
 
+	<tag>min version <m/num/</tag>
+	Minimal allowed version of the RTR protocol. BIRD will refuse to
+	downgrade a connection below this version and drop the session instead.
+	Default: 0
+
+	<tag>max version <m/num/</tag>
+	Maximal allowed version of the RTR protocol. BIRD will start with this
+        version. Use this option if sending version 2 to your cache causes
+        problems. Default: 2
+
         <tag>transport tcp { <m/TCP transport options.../ }</tag> Transport over
         TCP, it's the default transport. Cannot be combined with a SSH transport.
         Default: TCP, no authentication.
diff --git a/filter/test.conf b/filter/test.conf
index 53e1376d..6ceab152 100644
--- a/filter/test.conf
+++ b/filter/test.conf
@@ -2439,11 +2439,11 @@ function t_aspa_check()
 
 	p1.prepend(65542);
 	bt_assert(aspa_check(at, p1, false) = ASPA_VALID);
-	bt_assert(aspa_check(at, p1, true) = ASPA_INVALID_LEAK);
+	bt_assert(aspa_check(at, p1, true) = ASPA_INVALID);
 
 	p1.prepend(65555);
 	bt_assert(aspa_check(at, p1, false) = ASPA_UNKNOWN);
-	bt_assert(aspa_check(at, p1, true) = ASPA_INVALID_LEAK);
+	bt_assert(aspa_check(at, p1, true) = ASPA_INVALID);
 
 	bgppath p2 = +empty+;
 	p2.prepend(65554);
@@ -2454,13 +2454,13 @@ function t_aspa_check()
 
 	p2.prepend(65543);
 	bt_assert(aspa_check(at, p2, false) = ASPA_UNKNOWN);
-	bt_assert(aspa_check(at, p2, true) = ASPA_INVALID_LEAK);
+	bt_assert(aspa_check(at, p2, true) = ASPA_INVALID);
 
 	bgppath p3 = +empty+;
 	p3.prepend(65541);
 	p3.prepend(65544);
-	bt_assert(aspa_check(at, p3, false) = ASPA_INVALID_LEAK);
-	bt_assert(aspa_check(at, p3, true) = ASPA_INVALID_LEAK);
+	bt_assert(aspa_check(at, p3, false) = ASPA_INVALID);
+	bt_assert(aspa_check(at, p3, true) = ASPA_INVALID);
 }
 
 bt_test_suite(t_aspa_check, "Testing ASPA");
diff --git a/nest/config.Y b/nest/config.Y
index c0b468e4..f58f9edd 100644
--- a/nest/config.Y
+++ b/nest/config.Y
@@ -177,7 +177,7 @@ CF_ENUM(T_ENUM_RTS, RTS_, STATIC, INHERIT, DEVICE, STATIC_DEVICE, REDIRECT,
 CF_ENUM(T_ENUM_SCOPE, SCOPE_, HOST, LINK, SITE, ORGANIZATION, UNIVERSE, UNDEFINED)
 CF_ENUM(T_ENUM_RTD, RTD_, UNICAST, BLACKHOLE, UNREACHABLE, PROHIBIT)
 CF_ENUM(T_ENUM_ROA, ROA_, UNKNOWN, VALID, INVALID)
-CF_ENUM(T_ENUM_ASPA, ASPA_, UNKNOWN, VALID, INVALID_EMPTY, INVALID_LEAK, INVALID_CONFED)
+CF_ENUM(T_ENUM_ASPA, ASPA_, UNKNOWN, VALID, INVALID)
 CF_ENUM_PX(T_ENUM_AF, AF_, AFI_, IPV4, IPV6)
 CF_ENUM(T_ENUM_MPLS_POLICY, MPLS_POLICY_, NONE, STATIC, PREFIX, AGGREGATE, VRF)
 
diff --git a/nest/proto.c b/nest/proto.c
index ea521ceb..4d9d5354 100644
--- a/nest/proto.c
+++ b/nest/proto.c
@@ -613,6 +613,11 @@ channel_roa_subscribe_filter(struct channel *c, int dir)
       found = 1;
       break;
 
+    case FI_ASPA_CHECK_EXPLICIT:
+      tab = fi->i_FI_ASPA_CHECK_EXPLICIT.rtc->table;
+      if (valid) channel_roa_subscribe(c, tab, dir);
+      found = 1;
+      break;
     default:
       break;
     }
diff --git a/nest/route.h b/nest/route.h
index c6446446..5ff99a1c 100644
--- a/nest/route.h
+++ b/nest/route.h
@@ -932,9 +932,7 @@ void ea_show_nexthop_list(struct cli *c, struct nexthop_adata *nhad);
 enum aspa_result {
   ASPA_UNKNOWN = 0,
   ASPA_VALID,
-  ASPA_INVALID_EMPTY,
-  ASPA_INVALID_CONFED,
-  ASPA_INVALID_LEAK,
+  ASPA_INVALID,
 };
 
 int net_roa_check(rtable *tab, const net_addr *n, u32 asn);
diff --git a/nest/rt-table.c b/nest/rt-table.c
index d74dfad9..e2497311 100644
--- a/nest/rt-table.c
+++ b/nest/rt-table.c
@@ -731,12 +731,12 @@ enum aspa_result aspa_check(rtable *tab, const adata *path, bool force_upstream)
 
   /* No support for confed paths */
   if (as_path_contains_confed(path))
-    return ASPA_INVALID_CONFED;
+    return ASPA_INVALID;
 
   /* Check path length */
   uint len = as_path_getlen(path);
   if (len == 0)
-    return ASPA_INVALID_EMPTY;
+    return ASPA_INVALID;
 
   /* Normalize the AS Path: drop stuffings */
   u32 *asns = alloca(sizeof(u32) * len);
@@ -796,7 +796,7 @@ end_of_aspa:;
 	min_up = ap;
       else if (ap && !up)
 	/* Exists but doesn't allow this upstream */
-	return ASPA_INVALID_LEAK;
+	return ASPA_INVALID;
     }
 
     /* Fast path for no ASPA here */
@@ -844,7 +844,7 @@ end_of_aspa:;
     return ASPA_UNKNOWN;
 
   /* Now there is surely a valley there. */
-  return ASPA_INVALID_LEAK;
+  return ASPA_INVALID;
 }
 
 struct rte_storage *
diff --git a/proto/bgp/config.Y b/proto/bgp/config.Y
index ab6b899c..90dfc905 100644
--- a/proto/bgp/config.Y
+++ b/proto/bgp/config.Y
@@ -40,7 +40,7 @@ CF_ENUM(T_ENUM_BGP_ORIGIN, ORIGIN_, IGP, EGP, INCOMPLETE)
 
 CF_KEYWORDS(CEASE, PREFIX, LIMIT, HIT, ADMINISTRATIVE, SHUTDOWN, RESET, PEER,
 	CONFIGURATION, CHANGE, DECONFIGURED, CONNECTION, REJECTED, COLLISION,
-	OUT, OF, RESOURCES, ASPA_CHECK_CUSTOMER)
+	OUT, OF, RESOURCES, ASPA_CHECK_UPSTREAM, ASPA_CHECK_DOWNSTREAM)
 
 %type<i> bgp_cease_mask bgp_cease_list bgp_cease_flag bgp_role_name
 
@@ -384,23 +384,23 @@ CF_CLI(RELOAD BGP OUT, proto_patt, [<name>], [[Refresh routes to neighbor]])
 }
 
 /* ASPA shortcuts */
-term: ASPA_CHECK '(' rtable ')' { $$ =
+term: ASPA_CHECK_DOWNSTREAM '(' rtable ')' { $$ =
   f_new_inst(FI_ASPA_CHECK_EXPLICIT,
       f_new_inst(FI_EA_GET,
 	f_new_inst(FI_CONSTANT, (struct f_val) { .type = T_ROUTE, .val.rte = NULL, }),
 	ea_class_find_by_name("bgp_path")
-	),
+      ),
       f_new_inst(FI_CONSTANT, (struct f_val) { .type = T_BOOL, .val.i = 0, }),
       $3
   );
 }
 
-term: ASPA_CHECK_CUSTOMER '(' rtable ')' { $$ =
+term: ASPA_CHECK_UPSTREAM '(' rtable ')' { $$ =
   f_new_inst(FI_ASPA_CHECK_EXPLICIT,
       f_new_inst(FI_EA_GET,
 	f_new_inst(FI_CONSTANT, (struct f_val) { .type = T_ROUTE, .val.rte = NULL, }),
 	ea_class_find_by_name("bgp_path")
-	),
+      ),
       f_new_inst(FI_CONSTANT, (struct f_val) { .type = T_BOOL, .val.i = 1, }),
       $3
   );
diff --git a/proto/rpki/config.Y b/proto/rpki/config.Y
index 5dc27e53..16797206 100644
--- a/proto/rpki/config.Y
+++ b/proto/rpki/config.Y
@@ -33,8 +33,8 @@ rpki_check_unused_transport(void)
 CF_DECLS
 
 CF_KEYWORDS(RPKI, REMOTE, BIRD, PRIVATE, PUBLIC, KEY, TCP, SSH, TRANSPORT, USER,
-	    RETRY, REFRESH, EXPIRE, KEEP, IGNORE, MAX, LENGTH, LOCAL, ADDRESS,
-	    AUTHENTICATION, NONE, MD5, PASSWORD)
+	    RETRY, REFRESH, EXPIRE, KEEP, IGNORE, MAX, MIN, LENGTH, LOCAL, ADDRESS,
+	    AUTHENTICATION, NONE, MD5, PASSWORD, VERSION)
 
 %type <i> rpki_keep_interval
 
@@ -48,6 +48,8 @@ rpki_proto_start: proto_start RPKI {
   RPKI_CFG->retry_interval = RPKI_RETRY_INTERVAL;
   RPKI_CFG->refresh_interval = RPKI_REFRESH_INTERVAL;
   RPKI_CFG->expire_interval = RPKI_EXPIRE_INTERVAL;
+  RPKI_CFG->min_version = 0;
+  RPKI_CFG->max_version = RPKI_MAX_VERSION;
 };
 
 rpki_proto: rpki_proto_start proto_name '{' rpki_proto_opts '}' { rpki_check_config(RPKI_CFG); };
@@ -84,6 +86,14 @@ rpki_proto_item:
      RPKI_CFG->keep_expire_interval = $2;
    }
  | IGNORE MAX LENGTH bool { RPKI_CFG->ignore_max_length = $4; }
+ | MIN VERSION expr {
+     if ($3 > RPKI_MAX_VERSION) cf_error("RPKI version %u unsupported, min version must be in range 0-%u", $3, RPKI_MAX_VERSION);
+     RPKI_CFG->min_version = $3;
+   }
+ | MAX VERSION expr {
+     if ($3 > RPKI_MAX_VERSION) cf_error("RPKI version %u unsupported, max version must be in range 0-%u", $3, RPKI_MAX_VERSION);
+     RPKI_CFG->max_version = $3;
+   }
  ;
 
 rpki_keep_interval:
diff --git a/proto/rpki/packets.c b/proto/rpki/packets.c
index 07847db0..8fa61923 100644
--- a/proto/rpki/packets.c
+++ b/proto/rpki/packets.c
@@ -62,6 +62,7 @@ enum pdu_type {
   CACHE_RESET 			= 8,
   ROUTER_KEY 			= 9,
   ERROR 			= 10,
+  ASPA				= 11,
   PDU_TYPE_MAX
 };
 
@@ -76,7 +77,8 @@ static const char *str_pdu_type_[] = {
   [END_OF_DATA] 		= "End of Data",
   [CACHE_RESET] 		= "Cache Reset",
   [ROUTER_KEY] 			= "Router Key",
-  [ERROR] 			= "Error"
+  [ERROR] 			= "Error",
+  [ASPA]			= "ASPA",
 };
 
 static const char *str_pdu_type(uint type) {
@@ -193,6 +195,35 @@ struct pdu_error {
 				 * Error Diagnostic Message */
 } PACKED;
 
+/*
+ *0          8          16         24        31
+ *  .-------------------------------------------.
+ *  | Protocol |   PDU    |          |          |
+ *  | Version  |   Type   |   Flags  |   zero   |
+ *  |    2     |    11    |          |          |
+ *  +-------------------------------------------+
+ *  |                                           |
+ *  |                 Length                    |
+ *  |                                           |
+ *  +-------------------------------------------+
+ *  |                                           |
+ *  |    Customer Autonomous System Number      |
+ *  |                                           |
+ *  +-------------------------------------------+
+ *  |                                           |
+ *  ~    Provider Autonomous System Numbers     ~
+ *  |                                           |
+ *  ~-------------------------------------------~ */
+struct pdu_aspa {
+  u8 ver;
+  u8 type;
+  u8 flags;
+  u8 zero;
+  u32 len;
+  u32 customer_as_num;
+  u32 provider_as_nums[0];
+} PACKED;
+
 struct pdu_reset_query {
   u8 ver;
   u8 type;
@@ -230,9 +261,13 @@ static const size_t min_pdu_size[] = {
   [END_OF_DATA] 		= sizeof(struct pdu_end_of_data_v0),
   [CACHE_RESET] 		= sizeof(struct pdu_cache_response),
   [ROUTER_KEY] 			= sizeof(struct pdu_header), /* FIXME */
+  [ASPA]			= sizeof(struct pdu_aspa),
   [ERROR] 			= 16,
 };
 
+static inline int rpki_pdu_aspa_provider_asn_count(const struct pdu_aspa *pdu)
+{ return (pdu->len - sizeof(struct pdu_aspa)) / (sizeof(u32)); }
+
 static int rpki_send_error_pdu_(struct rpki_cache *cache, const enum pdu_error_type error_code, const u32 err_pdu_len, const struct pdu_header *erroneous_pdu, const char *fmt, ...);
 
 #define rpki_send_error_pdu(cache, error_code, err_pdu_len, erroneous_pdu, fmt...) ({ \
@@ -298,7 +333,7 @@ rpki_pdu_to_host_byte_order(struct pdu_header *pdu)
     struct pdu_end_of_data_v0 *eod0 = (void *) pdu;
     eod0->serial_num = ntohl(eod0->serial_num); /* Same either for version 1 */
 
-    if (pdu->ver == RPKI_VERSION_1)
+    if (pdu->ver > RPKI_VERSION_0)
     {
       struct pdu_end_of_data_v1 *eod1 = (void *) pdu;
       eod1->expire_interval = ntohl(eod1->expire_interval);
@@ -334,6 +369,21 @@ rpki_pdu_to_host_byte_order(struct pdu_header *pdu)
     break;
   }
 
+  case ASPA:
+  {
+    struct pdu_aspa *aspa = (void *) pdu;
+    int provider_asn_count = rpki_pdu_aspa_provider_asn_count(aspa);
+
+    /* Convert customer ASN */
+    aspa->customer_as_num = ntohl(aspa->customer_as_num);
+
+    /* Convert provider ASNs */
+    for (int i = 0; i < provider_asn_count ; i++)
+      aspa->provider_as_nums[i] = ntohl(aspa->provider_as_nums[i]);
+
+    break;
+  }
+
   case ROUTER_KEY:
     /* Router Key PDU is not supported yet */
 
@@ -359,6 +409,9 @@ rpki_pdu_to_host_byte_order(struct pdu_header *pdu)
 static struct pdu_header *
 rpki_pdu_back_to_network_byte_order(struct pdu_header *out, const struct pdu_header *in)
 {
+  /* Only valid for fixed-length PDUs */
+  ASSERT_DIE(in->type != ERROR && in->type != ASPA);
+
   memcpy(out, in, in->len);
   rpki_pdu_to_host_byte_order(out);
   return out;
@@ -392,7 +445,7 @@ rpki_log_packet(struct rpki_cache *cache, const struct pdu_header *pdu, const en
   case END_OF_DATA:
   {
     const struct pdu_end_of_data_v1 *eod = (void *) pdu;
-    if (eod->ver == RPKI_VERSION_1)
+    if (eod->ver > RPKI_VERSION_0)
       SAVE(bsnprintf(detail, sizeof(detail), "(session id: %u, serial number: %u, refresh: %us, retry: %us, expire: %us)", eod->session_id, eod->serial_num, eod->refresh_interval, eod->retry_interval, eod->expire_interval));
     else
       SAVE(bsnprintf(detail, sizeof(detail), "(session id: %u, serial number: %u)", eod->session_id, eod->serial_num));
@@ -460,6 +513,25 @@ rpki_log_packet(struct rpki_cache *cache, const struct pdu_header *pdu, const en
     break;
   }
 
+  case ASPA:
+  {
+    const struct pdu_aspa *aspa = (void *) pdu;
+    int provider_asn_count = rpki_pdu_aspa_provider_asn_count(aspa);
+
+    if (provider_asn_count <= 0)
+      SAVE(bsnprintf(detail + strlen(detail), sizeof(detail) - strlen(detail),
+	    "%u transit", aspa->customer_as_num));
+    else
+    {
+      SAVE(bsnprintf(detail + strlen(detail), sizeof(detail) - strlen(detail),
+	    "%u (providers", aspa->customer_as_num));
+      for (int i = 0; i < provider_asn_count; i++)
+	SAVE(bsnprintf(detail + strlen(detail), sizeof(detail) - strlen(detail),
+	      " %u%c", aspa->provider_as_nums[i], (i == provider_asn_count-1) ? ')' : ','));
+    }
+    break;
+  }
+
   default:
     *detail = '\0';
   }
@@ -561,7 +633,9 @@ rpki_check_receive_packet(struct rpki_cache *cache, const struct pdu_header *pdu
       }
       else if (!cache->last_update &&
 	       (pdu->ver <= RPKI_MAX_VERSION) &&
-	       (pdu->ver < cache->version))
+	       (pdu->ver < cache->version) &&
+	       (pdu->ver >= cache->min_version)
+	       )
       {
         CACHE_TRACE(D_EVENTS, cache, "Downgrade session to %s from %u to %u version", rpki_get_cache_ident(cache), cache->version, pdu->ver);
         cache->version = pdu->ver;
@@ -576,15 +650,21 @@ rpki_check_receive_packet(struct rpki_cache *cache, const struct pdu_header *pdu
     }
   }
 
-  if ((pdu->type >= PDU_TYPE_MAX) || (pdu->ver == RPKI_VERSION_0 && pdu->type == ROUTER_KEY))
+  if ((pdu->type >= PDU_TYPE_MAX) ||
+      (pdu->ver < RPKI_VERSION_1 && pdu->type == ROUTER_KEY) ||
+      (pdu->ver < RPKI_VERSION_2 && pdu->type == ASPA))
   {
     rpki_send_error_pdu(cache, UNSUPPORTED_PDU_TYPE, pdu_len, pdu, "Unsupported PDU type %u received", pdu->type);
     return RPKI_ERROR;
   }
 
-  if (pdu_len < min_pdu_size[pdu->type])
+  uint min_pdu_length = min_pdu_size[pdu->type];
+  if (pdu->type == END_OF_DATA && pdu->ver >= RPKI_VERSION_1)
+    min_pdu_length = sizeof(struct pdu_end_of_data_v1);
+
+  if (pdu_len < min_pdu_length)
   {
-    rpki_send_error_pdu(cache, CORRUPT_DATA, pdu_len, pdu, "Received %s packet with %d bytes, but expected at least %d bytes", str_pdu_type(pdu->type), pdu_len, min_pdu_size[pdu->type]);
+    rpki_send_error_pdu(cache, CORRUPT_DATA, pdu_len, pdu, "Received %s packet with %u bytes, but expected at least %u bytes", str_pdu_type(pdu->type), pdu_len, min_pdu_length);
     return RPKI_ERROR;
   }
 
@@ -611,7 +691,8 @@ rpki_handle_error_pdu(struct rpki_cache *cache, const struct pdu_error *pdu)
   case UNSUPPORTED_PROTOCOL_VER:
     CACHE_TRACE(D_PACKETS, cache, "Client uses unsupported protocol version");
     if (pdu->ver <= RPKI_MAX_VERSION &&
-	pdu->ver < cache->version)
+	pdu->ver < cache->version &&
+	pdu->ver >= cache->min_version)
     {
       CACHE_TRACE(D_EVENTS, cache, "Downgrading from protocol version %d to version %d", cache->version, pdu->ver);
       cache->version = pdu->ver;
@@ -789,6 +870,29 @@ rpki_handle_prefix_pdu(struct rpki_cache *cache, const struct pdu_header *pdu)
   return RPKI_SUCCESS;
 }
 
+static int
+rpki_handle_aspa_pdu(struct rpki_cache *cache, const struct pdu_header *pdu)
+{
+  struct pdu_aspa *aspa = (void *) pdu;
+  struct channel *channel = cache->p->aspa_channel;
+  uint providers_length = aspa->len - sizeof(struct pdu_aspa);
+
+  if (!channel)
+  {
+    CACHE_TRACE(D_ROUTES, cache, "Skip AS%u, missing aspa channel", aspa->customer_as_num);
+    return RPKI_ERROR;
+  }
+
+  cache->last_rx_prefix = current_time();
+
+  if (aspa->flags & RPKI_ADD_FLAG)
+    rpki_table_add_aspa(cache, channel, aspa->customer_as_num, aspa->provider_as_nums, providers_length);
+  else
+    rpki_table_remove_aspa(cache, channel, aspa->customer_as_num);
+
+  return RPKI_SUCCESS;
+}
+
 static uint
 rpki_check_interval(struct rpki_cache *cache, const char *(check_fn)(uint), uint interval)
 {
@@ -814,7 +918,7 @@ rpki_handle_end_of_data_pdu(struct rpki_cache *cache, const struct pdu_end_of_da
     return;
   }
 
-  if (pdu->ver == RPKI_VERSION_1)
+  if (pdu->ver > RPKI_VERSION_0)
   {
     if (!cf->keep_refresh_interval && rpki_check_interval(cache, rpki_check_refresh_interval, pdu->refresh_interval))
       cache->refresh_interval = pdu->refresh_interval;
@@ -898,6 +1002,10 @@ rpki_rx_packet(struct rpki_cache *cache, struct pdu_header *pdu)
     /* TODO: Implement Router Key PDU handling */
     break;
 
+  case ASPA:
+    rpki_handle_aspa_pdu(cache, (void *) pdu);
+    break;
+
   default:
     CACHE_TRACE(D_PACKETS, cache, "Received unsupported type (%u)", pdu->type);
   };
diff --git a/proto/rpki/packets.h b/proto/rpki/packets.h
index d6f8a249..f7897d9a 100644
--- a/proto/rpki/packets.h
+++ b/proto/rpki/packets.h
@@ -23,8 +23,10 @@
  * 	   +4 bytes (Length of inserted text)
  * 	 +800 bytes (UTF-8 text 400*2 bytes)
  * 	------------
- * 	= 848 bytes (Maximal expected PDU size) */
-#define RPKI_PDU_MAX_LEN	848
+ * 	= 848 bytes (Maximal expected PDU size)
+ *
+ * Received ASPA PDU can have any size, so let's start with 4k */
+#define RPKI_PDU_MAX_LEN	4096
 
 /* RX buffer size has a great impact to scheduler granularity */
 #define RPKI_RX_BUFFER_SIZE	4096
diff --git a/proto/rpki/rpki.c b/proto/rpki/rpki.c
index 2c8ac44c..adb073b2 100644
--- a/proto/rpki/rpki.c
+++ b/proto/rpki/rpki.c
@@ -137,6 +137,33 @@ rpki_table_remove_roa(struct rpki_cache *cache, struct channel *channel, const n
   rte_update(channel, &pfxr->n, NULL, p->p.main_source);
 }
 
+void
+rpki_table_add_aspa(struct rpki_cache *cache, struct channel *channel,
+    u32 customer, void *providers, uint providers_length)
+{
+  struct rpki_proto *p = cache->p;
+
+  net_addr_union n = { .aspa = NET_ADDR_ASPA(customer) };
+
+  ea_list *ea = NULL;
+  ea_set_attr_u32(&ea, &ea_gen_preference, 0, channel->preference);
+  ea_set_attr_u32(&ea, &ea_gen_source, 0, RTS_RPKI);
+
+  ea_set_attr_data(&ea, &ea_gen_aspa_providers, 0, providers, providers_length);
+
+  rte e0 = { .attrs = ea, .src = p->p.main_source, };
+
+  rte_update(channel, &n.n, &e0, p->p.main_source);
+}
+
+void
+rpki_table_remove_aspa(struct rpki_cache *cache, struct channel *channel, u32 customer)
+{
+  struct rpki_proto *p = cache->p;
+  net_addr_union n = { .aspa = NET_ADDR_ASPA(customer) };
+  rte_update(channel, &n.n, NULL, p->p.main_source);
+}
+
 void
 rpki_start_refresh(struct rpki_proto *p)
 {
@@ -144,6 +171,8 @@ rpki_start_refresh(struct rpki_proto *p)
     rt_refresh_begin(&p->roa4_channel->in_req);
   if (p->roa6_channel)
     rt_refresh_begin(&p->roa6_channel->in_req);
+  if (p->aspa_channel)
+    rt_refresh_begin(&p->aspa_channel->in_req);
 
   p->refresh_channels = 1;
 }
@@ -160,6 +189,8 @@ rpki_stop_refresh(struct rpki_proto *p)
     rt_refresh_end(&p->roa4_channel->in_req);
   if (p->roa6_channel)
     rt_refresh_end(&p->roa6_channel->in_req);
+  if (p->aspa_channel)
+    rt_refresh_end(&p->aspa_channel->in_req);
 }
 
 /*
@@ -608,7 +639,8 @@ rpki_init_cache(struct rpki_proto *p, struct rpki_config *cf)
 
   cache->state = RPKI_CS_SHUTDOWN;
   cache->request_session_id = 1;
-  cache->version = RPKI_MAX_VERSION;
+  cache->version = cf->max_version;
+  cache->min_version = cf->min_version;
 
   cache->refresh_interval = cf->refresh_interval;
   cache->retry_interval = cf->retry_interval;
@@ -714,6 +746,23 @@ rpki_reconfigure_cache(struct rpki_proto *p UNUSED, struct rpki_cache *cache, st
     return NEED_RESTART;
   }
 
+  if (new->min_version > cache->version)
+  {
+    CACHE_TRACE(D_EVENTS, cache, "Protocol min version %u higher than current version %u",
+	new->min_version, cache->version);
+    return NEED_RESTART;
+  }
+  else
+    cache->min_version = new->min_version;
+
+  if (new->max_version < cache->version)
+  {
+    CACHE_TRACE(D_EVENTS, cache, "Protocol max version %u lower than current version %u",
+	new->max_version, cache->version);
+    cache->version = new->max_version;
+    try_reset = 1;
+  }
+
   if (old->tr_config.type != new->tr_config.type)
   {
     CACHE_TRACE(D_EVENTS, cache, "Transport type changed");
@@ -814,7 +863,8 @@ rpki_reconfigure(struct proto *P, struct proto_config *CF)
   struct rpki_cache *cache = p->cache;
 
   if (!proto_configure_channel(&p->p, &p->roa4_channel, proto_cf_find_channel(CF, NET_ROA4)) ||
-      !proto_configure_channel(&p->p, &p->roa6_channel, proto_cf_find_channel(CF, NET_ROA6)))
+      !proto_configure_channel(&p->p, &p->roa6_channel, proto_cf_find_channel(CF, NET_ROA6)) ||
+      !proto_configure_channel(&p->p, &p->aspa_channel, proto_cf_find_channel(CF, NET_ASPA)))
     return NEED_RESTART;
 
   if (rpki_reconfigure_cache(p, cache, new, old) != SUCCESSFUL_RECONF)
@@ -836,6 +886,7 @@ rpki_init(struct proto_config *CF)
 
   proto_configure_channel(&p->p, &p->roa4_channel, proto_cf_find_channel(CF, NET_ROA4));
   proto_configure_channel(&p->p, &p->roa6_channel, proto_cf_find_channel(CF, NET_ROA6));
+  proto_configure_channel(&p->p, &p->aspa_channel, proto_cf_find_channel(CF, NET_ASPA));
 
   return P;
 }
@@ -949,6 +1000,11 @@ rpki_show_proto_info(struct proto *P)
       channel_show_info(p->roa6_channel);
     else
       cli_msg(-1006, "  No roa6 channel");
+
+    if (p->aspa_channel)
+      channel_show_info(p->aspa_channel);
+    else
+      cli_msg(-1006, "  No aspa channel");
   }
 }
 
@@ -966,6 +1022,9 @@ rpki_show_proto_info(struct proto *P)
 void
 rpki_check_config(struct rpki_config *cf)
 {
+  if (cf->min_version > cf->max_version)
+    cf_error("Impossible min/max version for RPKI: %u/%u", cf->min_version, cf->max_version);
+
   /* Do not check templates at all */
   if (cf->c.class == SYM_TEMPLATE)
     return;
@@ -1020,7 +1079,7 @@ struct protocol proto_rpki = {
   .init = 		rpki_init,
   .start = 		rpki_start,
   .postconfig = 	rpki_postconfig,
-  .channel_mask =	(NB_ROA4 | NB_ROA6),
+  .channel_mask =	(NB_ROA4 | NB_ROA6 | NB_ASPA),
   .show_proto_info =	rpki_show_proto_info,
   .shutdown = 		rpki_shutdown,
   .copy_config = 	rpki_copy_config,
diff --git a/proto/rpki/rpki.h b/proto/rpki/rpki.h
index 31278860..d09644b6 100644
--- a/proto/rpki/rpki.h
+++ b/proto/rpki/rpki.h
@@ -29,7 +29,8 @@
 
 #define RPKI_VERSION_0		0
 #define RPKI_VERSION_1		1
-#define RPKI_MAX_VERSION 	RPKI_VERSION_1
+#define RPKI_VERSION_2		2
+#define RPKI_MAX_VERSION 	RPKI_VERSION_2
 
 
 /*
@@ -60,6 +61,7 @@ struct rpki_cache {
   u8 request_session_id;		/* 1: have to request new session id; 0: we have already received session id */
   u32 serial_num;			/* Serial number denotes the logical version of data from cache server */
   u8 version;				/* Protocol version */
+  u8 min_version;			/* Minimum allowed protocol version */
   btime last_update;			/* Last successful synchronization with cache server */
   btime last_rx_prefix;			/* Last received prefix PDU */
 
@@ -83,6 +85,9 @@ const char *rpki_cache_state_to_str(enum rpki_cache_state state);
 void rpki_table_add_roa(struct rpki_cache *cache, struct channel *channel, const net_addr_union *pfxr);
 void rpki_table_remove_roa(struct rpki_cache *cache, struct channel *channel, const net_addr_union *pfxr);
 
+void rpki_table_add_aspa(struct rpki_cache *cache, struct channel *channel, u32 customer, void *providers, uint providers_length);
+void rpki_table_remove_aspa(struct rpki_cache *cache, struct channel *channel, u32 customer);
+
 void rpki_start_refresh(struct rpki_proto *p);
 void rpki_stop_refresh(struct rpki_proto *p);
 
@@ -112,6 +117,7 @@ struct rpki_proto {
 
   struct channel *roa4_channel;
   struct channel *roa6_channel;
+  struct channel *aspa_channel;
   u8 refresh_channels;			/* For non-incremental updates using rt_refresh_begin(), rt_refresh_end() */
 };
 
@@ -129,6 +135,8 @@ struct rpki_config {
   u8 keep_retry_interval:1;		/* Do not overwrite retry interval by cache server update */
   u8 keep_expire_interval:1;		/* Do not overwrite expire interval by cache server update */
   u8 ignore_max_length:1;		/* Ignore received max length and use MAX_PREFIX_LENGTH instead */
+  u8 min_version;			/* Minimum version allowed */
+  u8 max_version;			/* Maximum version allowed (to start with) */
 };
 
 void rpki_check_config(struct rpki_config *cf);