diff --git a/include/sxmp/limits.h b/include/sxmp/limits.h
index 639c3b0..e532fb0 100644
--- a/include/sxmp/limits.h
+++ b/include/sxmp/limits.h
@@ -33,6 +33,8 @@
 
 #define MAX_SXMPLTHREADS  8
 
+#define MAX_MSGINPROCESS  1024
+
 #define MAX_STREAMS_TYPES  32767
 
 #define MAX_LINKS  32768
diff --git a/include/sxmp/version.h b/include/sxmp/version.h
index f1147e0..ad0c53c 100644
--- a/include/sxmp/version.h
+++ b/include/sxmp/version.h
@@ -30,6 +30,8 @@
 #define SXMP_MAJOR   4
 #define SXMP_MINOR   2
 
+#define V2_1_TPROT   "v2_1"
+
 typedef enum {
   V2 = 0,
   V2_1,
diff --git a/lib/channel.c b/lib/channel.c
index 370e7d6..2c3e8f6 100644
--- a/lib/channel.c
+++ b/lib/channel.c
@@ -160,7 +160,7 @@ sxchnl_t *sxchannel_open(sxlink_t *co, int type)
   pthread_mutex_unlock(&co->idx_msg_lock);
 
   if(msgidx == IDX_INVAL) {    r = SXE_MMESSAGES;    goto __reterr2;  }
-  else head->msgid = msgidx;
+  else head->msgid = (uint16_t)msgidx;
 
   /* now we're ready to write it */
   r = _sxmpl_writemsg(co, msg);
diff --git a/lib/link.c b/lib/link.c
index 661a72e..8f9d323 100644
--- a/lib/link.c
+++ b/lib/link.c
@@ -163,6 +163,7 @@ static int __get_channels_list(void *cctx, sexp_t *sx)
   if(co->cp_version == V2) {
     /* we're ready for messaging mode */
     co->flags |= SXMP_MESSAGINGMODE;
+    co->flags &= ~SXMP_BATCHMODE;
   }
 
   return SXE_SUCCESS;
@@ -189,6 +190,7 @@ static int __get_streams(void *cctx, sexp_t *sx)
     msg->mhead.payload_length = ulen + 1;
     /* and now we're ready to exit from batch mode */
     link->flags |= SXMP_MESSAGINGMODE;
+    link->flags &= ~SXMP_BATCHMODE;
 
     return SXE_SUCCESS;
   } else { /* set all streams available */
@@ -241,6 +243,7 @@ static int __get_streams(void *cctx, sexp_t *sx)
   }
 
   link->flags |= SXMP_MESSAGINGMODE;
+  link->flags &= ~SXMP_BATCHMODE;
 
   return SXE_SUCCESS;
 }
@@ -397,6 +400,11 @@ static int __set_channels_list(void *cctx, sexp_t *sx)
   sexp_t *isx, *iisx;
   int id, r;
 
+  /* determine how this function was called */
+  if(!strcmp(sx->list->val, "get-channels-list"))
+    co->cp_version = V2;
+  else co->cp_version = V2_1; /* last supported in this version */
+
   SEXP_ITERATE_LIST(sx, isx, idx) {
     if(!idx) continue;
 
@@ -441,7 +449,7 @@ static int __my_version_ack(void *cctx, sexp_t *sx)
     if(!idx) continue;
     if(idx > 2) return SXE_BADPROTO;
     if(isx->ty == SEXP_LIST) return SXE_BADPROTO;
-    if(!strcmp(isx->val, "v2_1")) link->cp_version = V2_1;
+    if(!strcmp(isx->val, V2_1_TPROT)) link->cp_version = V2_1;
     else link->cp_version = V_UNKNOWN;
   }
 
@@ -458,7 +466,7 @@ static int __my_version_set(void *cctx, sexp_t *sx)
     if(!idx) continue;
     if(idx > 2) return SXE_BADPROTO;
     if(isx->ty == SEXP_LIST) return SXE_BADPROTO;
-    if(!strcmp(isx->val, "v2_1")) link->cp_version = V2_1;
+    if(!strcmp(isx->val, V2_1_TPROT)) link->cp_version = V2_1;
     else return SXE_FAILED; /* failed to set another version */
   }
 
diff --git a/lib/sxmplv2.c b/lib/sxmplv2.c
index 8423d98..41c5cd9 100644
--- a/lib/sxmplv2.c
+++ b/lib/sxmplv2.c
@@ -417,8 +417,8 @@ sxlink_t *__link_minimal_alloc(struct in_addr *addr)
   if(!co) { r = ENOMEM; goto __fail; }
   else memset(co, 0, sizeof(sxlink_t));
 
-  if(!(co->messages = malloc(sizeof(uintptr_t)*1024))) { r = ENOMEM; goto __fail; }
-  else memset(co->messages, 0, sizeof(uintptr_t)*1024);
+  if(!(co->messages = malloc(sizeof(uintptr_t)*MAX_MSGINPROCESS))) { r = ENOMEM; goto __fail; }
+  else memset(co->messages, 0, sizeof(uintptr_t)*MAX_MSGINPROCESS);
 
   if(!(co->pctx = malloc(sizeof(sxsession_ctx_t)))) { r = ENOMEM; goto __fail; }
   else memset(co->pctx, 0, sizeof(sxsession_ctx_t));
@@ -452,7 +452,7 @@ static int __link_second_alloc(sxlink_t *co)
   memset(&co->idx_ch, 0, sizeof(idx_allocator_t));
   memset(&co->idx_msg, 0, sizeof(idx_allocator_t));
   if((idx_allocator_init(&co->idx_ch, 512, 0))) goto __fail;
-  if((idx_allocator_init(&co->idx_msg, 1024, 0))) goto __fail;
+  if((idx_allocator_init(&co->idx_msg, MAX_MSGINPROCESS, 0))) goto __fail;
 
   if(!(co->channels = malloc(sizeof(uintptr_t)*512))) goto __fail;
   else memset(co->channels, 0, sizeof(uintptr_t)*512);
@@ -599,7 +599,7 @@ static void __link_destroy(sxlink_t *co)
   if(!_CONN_UCOUNT(co)) {
     /* go thru messages */
     pthread_mutex_lock(&co->idx_msg_lock);
-    for(i = 0; i < 1024; i++) {
+    for(i = 0; i < MAX_MSGINPROCESS; i++) {
       msg = co->messages[i];
       if(!msg) continue;
       else head = &msg->mhead;
@@ -731,6 +731,7 @@ static void *__sxmpl_thread(void *b)
 #ifdef _PERFPROFILE
     gettimeofday(&beg, NULL);
 #endif
+    memset(mhead, 0, sizeof(sxmplv2_head_t));
     rd = __conn_read(co, mhead, sizeof(sxmplv2_head_t));
 #ifdef _PERFPROFILE
     gettimeofday(&end, NULL);
@@ -775,7 +776,7 @@ static void *__sxmpl_thread(void *b)
         if(rd != mhead->payload_length) {
           mid = mhead->msgid;
           /* if we're need to do something */
-          if(mhead->msgid >= 1024) {
+          if(mhead->msgid >= MAX_MSGINPROCESS) {
             mhead->opcode = SXE_INVALINDEX;
             goto __return_error;
           } else {
@@ -817,17 +818,17 @@ static void *__sxmpl_thread(void *b)
           pthread_mutex_unlock(&(co->sslinout[1]));
           if(wr < 0) goto __finish;
         } else { /* it's came back */
+          mid = (ulong_t)mhead->msgid;
           /* reply came ... */
-          if(mhead->msgid >= 1024) {
+          if(mid > (MAX_MSGINPROCESS - 1)) {
           __inval_idx_nor:
-            fprintf(stderr, "[sxmplv2] Invalid index of the message.\n");
+            fprintf(stderr, "[sxmplv2] Invalid index of the message (%lu).\n", mid);
             goto __again;
           }
-          mid = mhead->msgid;
-          //hread_mutex_lock(&co->idx_msg_lock);
-          msg = co->messages[mid];
-          //hread_mutex_unlock(&co->idx_msg_lock);
-          if(!msg) goto __inval_idx_nor;
+
+          msg = co->messages[(int)mid];
+
+          if(!msg) { goto __inval_idx_nor;   }
 
           /* ok now we'are copy data and unlock wait mutex */
           memcpy(&msg->mhead, mhead, sizeof(sxmplv2_head_t));
@@ -836,7 +837,7 @@ static void *__sxmpl_thread(void *b)
       } else if(mhead->attr & SXMSG_LINK) { /* link layer messages */
         if(mhead->attr & SXMSG_CLOSED) goto __finish; /* close the link */
         if(mhead->attr & SXMSG_PULSE) { /* it's a link pulse messages */
-          /* TODO: other service messages */
+          /* FIXME: special sxmpv2.1 top layer messages - should be here */
           if(mhead->opcode == SXE_RAPIDMSG) { /* custom pulse */
             sx = parse_sexp(bbuf, mhead->payload_length);
             if(sx && co->ssys->on_pulse) co->ssys->on_pulse(co, sx);
@@ -1075,6 +1076,7 @@ sxlink_t *sxlink_master_accept(sxhub_t *ssys, int sck, struct in_addr *addr)
       if(rd == -1) { r = SXE_LINKERROR; goto __fail3; }
       if(rd != head->payload_length) { r = SXE_LINKERROR; goto __fail3; }
       bbuf[rd] = '\0';
+
       sx = parse_sexp(bbuf, rd);
       if(!sx) goto __fail3;
 
@@ -1085,6 +1087,7 @@ sxlink_t *sxlink_master_accept(sxhub_t *ssys, int sck, struct in_addr *addr)
       r = __eval_syssexp(co, sx);
       memcpy(head, &msg->mhead, sizeof(sxmplv2_head_t));
       head->opcode = r;
+
       if(r != SXE_SUCCESS) { /* we finish */
         head->payload_length = 0;
         __conn_write(co, head, sizeof(sxmplv2_head_t));
@@ -1167,6 +1170,12 @@ sxlink_t *sxlink_master_accept(sxhub_t *ssys, int sck, struct in_addr *addr)
   return NULL;
 }
 
+enum {
+  _SYNC_ON_CHANNELS = 0,
+  _SYNC_ON_VERSION = 1,
+  _SYNC_ON_STREAMS = 2,
+};
+
 sxlink_t *sxlink_connect(sxhub_t *ssys, const char *host,
                          int port, const char *SSL_cert, const char *login,
                          const char *passwd)
@@ -1174,7 +1183,7 @@ sxlink_t *sxlink_connect(sxhub_t *ssys, const char *host,
   sxlink_t *co = __link_minimal_alloc(NULL);
   struct hostent *host_;
   struct sockaddr_in addr;
-  int r = SXE_SUCCESS, sck;
+  int r = SXE_SUCCESS, sck, i, sync_state = _SYNC_ON_CHANNELS;
 #ifdef WIN32
   WSADATA wsaData;
 #endif
@@ -1184,8 +1193,8 @@ sxlink_t *sxlink_connect(sxhub_t *ssys, const char *host,
   sxmplv2_head_t *head;
   sxmplv2_bundle_t *bundle;
   sxmsg_t *msg;
-  size_t rd, wr;
-  int i;
+  size_t rd, wr, ln;
+  sexp_t *sx;
 
   r = SXE_IGNORED;
   if(!host || !SSL_cert) goto __fail;
@@ -1311,28 +1320,40 @@ sxlink_t *sxlink_connect(sxhub_t *ssys, const char *host,
   bbuf += sizeof(sxmplv2_head_t);
   head = (sxmplv2_head_t *)buf;
 
-  sexp_t *sx;
-  size_t ln;
-  while(co->flags & SXMP_BATCHMODE) {
-    /* form a message -- credentials */
-    ln = snprintf(bbuf, 65535 - sizeof(sxmplv2_head_t), "(auth-set-credentials \"%s\" \"%s\")",
-                  login ? login : "nil", passwd ? passwd : "nil");
+  /* authentification first both V2 and newer */
+  /* form a message -- credentials */
+  ln = snprintf(bbuf, 65535 - sizeof(sxmplv2_head_t), "(auth-set-credentials \"%s\" \"%s\")",
+                login ? login : "nil", passwd ? passwd : "nil");
+
+  head->opcode = SXE_SUCCESS;
+  head->payload_length = ln;
+  wr = __conn_write(co, buf, ln + sizeof(sxmplv2_head_t));
+  if(wr < 0) goto __fail2;
+
+  rd = __conn_read(co, head, sizeof(sxmplv2_head_t));
+  if(rd < 0) goto __fail2;
+  if(head->opcode != SXE_SUCCESS) {
+    r = head->opcode;
+    goto __fail2;
+  }
 
+  /* since V2.1 syncronization should be done here */
+  while(co->flags & SXMP_BATCHMODE) {
     head->opcode = SXE_SUCCESS;
-    head->payload_length = ln;
-    wr = __conn_write(co, buf, ln + sizeof(sxmplv2_head_t));
-    if(wr < 0) goto __fail2;
 
-    rd = __conn_read(co, head, sizeof(sxmplv2_head_t));
-    if(rd < 0) goto __fail2;
-    if(head->opcode != SXE_SUCCESS) {
-      r = head->opcode;
-      goto __fail2;
+    switch(sync_state) {
+    case _SYNC_ON_CHANNELS: /* ok, get available channels */
+      ln = snprintf(bbuf, 65535 - sizeof(sxmplv2_head_t), "(!@c>)");
+      break;
+    case _SYNC_ON_VERSION:
+      ln = snprintf(bbuf, 65535 - sizeof(sxmplv2_head_t), "(!@v> %s)", V2_1_TPROT);
+      break;
+    case _SYNC_ON_STREAMS:
+      ln = snprintf(bbuf, 65535 - sizeof(sxmplv2_head_t), "(!@s>)");
+      break;
     }
 
-    /* ok, get available channels */
-    head->opcode = SXE_SUCCESS;
-    ln = snprintf(bbuf, 65535 - sizeof(sxmplv2_head_t), "(get-channels-list)");
+    /* write a message */
     head->payload_length = ln;
     wr = __conn_write(co, buf, ln + sizeof(sxmplv2_head_t));
     if(wr < 0) goto __fail2;
@@ -1340,7 +1361,10 @@ sxlink_t *sxlink_connect(sxhub_t *ssys, const char *host,
     rd = __conn_read(co, head, sizeof(sxmplv2_head_t));
     if(rd < 0) goto __fail2;
     if(head->opcode != SXE_SUCCESS) goto __fail2;
-    if(!head->payload_length) goto __fail2;
+    if(!head->payload_length) {
+      sync_state++;
+      continue;
+    }
     rd = __conn_read(co, bbuf, head->payload_length);
     if(rd < 0) goto __fail2;
 
@@ -1352,13 +1376,15 @@ sxlink_t *sxlink_connect(sxhub_t *ssys, const char *host,
     if(!r) r = SXE_SUCCESS;
     destroy_sexp(sx);
 
-    /* write back */
-    head->opcode = r;
-    head->payload_length = 0;
-    wr = __conn_write(co, head, sizeof(sxmplv2_head_t));
-    if(wr < 0) {
-      r = SXE_LINKERROR; goto __fail2;}
-    if(r != SXE_SUCCESS) { r = SXE_LINKERROR; goto __fail2;}
+    if(sync_state != _SYNC_ON_STREAMS) {
+          /* write back */
+          head->opcode = r;
+          head->payload_length = 0;
+          wr = __conn_write(co, head, sizeof(sxmplv2_head_t));
+          if(wr < 0) {          r = SXE_LINKERROR; goto __fail2;}
+          if(r != SXE_SUCCESS) { r = SXE_LINKERROR; goto __fail2;}
+        }
+    sync_state++;
   }
 
   /* if we're there - negotiation is done, going to init messaging mode */