diff --git a/libraries/io/eth/tb/vhdl/tb_eth_tester_pkg.vhd b/libraries/io/eth/tb/vhdl/tb_eth_tester_pkg.vhd
index 9944c99cc36839ec843daa0ece9a3b2d1ca04c9b..c9b0eda575608fee82832627600a7d808f1248c0 100644
--- a/libraries/io/eth/tb/vhdl/tb_eth_tester_pkg.vhd
+++ b/libraries/io/eth/tb/vhdl/tb_eth_tester_pkg.vhd
@@ -46,6 +46,9 @@ PACKAGE tb_eth_tester_pkg is
   -- Ethernet packet length in octets inclduing eth header and CRC
   FUNCTION func_eth_tester_eth_packet_length(block_len : NATURAL) RETURN NATURAL;
 
+  -- Ethernet packet lenght on link including c_network_eth_preamble_len and one idle word
+  FUNCTION func_eth_tester_eth_packet_on_link_length(block_len : NATURAL) RETURN NATURAL;
+
 END tb_eth_tester_pkg;
 
 
@@ -76,5 +79,10 @@ PACKAGE BODY tb_eth_tester_pkg IS
     RETURN c_eth_len;
   END func_eth_tester_eth_packet_length;
 
+  FUNCTION func_eth_tester_eth_packet_on_link_length(block_len : NATURAL) RETURN NATURAL IS
+  BEGIN
+    RETURN c_network_eth_preamble_len + func_eth_tester_eth_packet_length(block_len) + c_word_sz;
+  END func_eth_tester_eth_packet_on_link_length;
+
 END tb_eth_tester_pkg;