diff --git a/docs/config.md b/docs/config.md
index 1b75b8ed..26a317b1 100644
--- a/docs/config.md
+++ b/docs/config.md
@@ -694,6 +694,8 @@ Attribute | Description | Default
 `network-ipv6-address` | Overwrite network interface IPv6 address |
 `destination-ipv4-address` | Overwrite the IPv4 destination address |
 `destination-ipv6-address` | Overwrite the IPv6 destination address |
+`access-ipv4-source-address` | Overwrite the access IPv4 source address (client) |
+`access-ipv6-source-address` | Overwrite the access IPv6 source address (client) |
 `threaded` | Run those streams in separate threads | false
 `thread-group` | Assign this stream to thread group (1-255) | 0 (thread per stream)
 
@@ -702,6 +704,10 @@ For L2TP downstream traffic the IPv4 TOS is applied to the outer IPv4 and inner
 The `pps` option supports also float numbers like 0.1, or 2.5 PPS and has priority over `bps`
 where second is only a helper to calculate the `pps` based on given `bps` and `length`.
 
+The options `access-ipv4-source-address` and `access-ipv6-source-address` are used
+to test the BNG RPF functionality with traffic send from source addresses different
+to those assigned to the client. 
+
 ## Access-Line
 
 This section describes all attributes of the `access-line` hierarchy.
diff --git a/src/bbl_config.c b/src/bbl_config.c
index fe7e5e56..47db286b 100644
--- a/src/bbl_config.c
+++ b/src/bbl_config.c
@@ -748,6 +748,20 @@ json_parse_stream (bbl_ctx_s *ctx, json_t *stream, bbl_stream_config *stream_con
     }
     if (!stream_config->pps) stream_config->pps = 1;
 
+    if (json_unpack(stream, "{s:s}", "access-ipv4-source-address", &s) == 0) {
+        if (!inet_pton(AF_INET, s, &stream_config->ipv4_access_src_address)) {
+            fprintf(stderr, "JSON config error: Invalid value for stream->access-ipv4-source-address\n");
+            return false;
+        }
+    }
+
+    if (json_unpack(stream, "{s:s}", "access-ipv6-source-address", &s) == 0) {
+        if (!inet_pton(AF_INET6, s, &stream_config->ipv6_access_src_address)) {
+            fprintf(stderr, "JSON config error: Invalid value for stream->access-ipv6-source-address\n");
+            return false;
+        }
+    }
+
     if (json_unpack(stream, "{s:s}", "network-ipv4-address", &s) == 0) {
         if (!inet_pton(AF_INET, s, &stream_config->ipv4_network_address)) {
             fprintf(stderr, "JSON config error: Invalid value for stream->network-ipv4-address\n");
diff --git a/src/bbl_stream.c b/src/bbl_stream.c
index cca72e90..134284a3 100644
--- a/src/bbl_stream.c
+++ b/src/bbl_stream.c
@@ -155,7 +155,11 @@ bbl_stream_build_access_pppoe_packet(bbl_stream *stream) {
             pppoe.protocol = PROTOCOL_IPV4;
             pppoe.next = &ipv4;
             /* Source address */
-            ipv4.src = session->ip_address;
+            if(stream->config->ipv4_access_src_address) {
+                ipv4.src = stream->config->ipv4_access_src_address;
+            } else {
+                ipv4.src = session->ip_address;
+            }
             /* Destination address */
             if(stream->config->ipv4_destination_address) {
                 ipv4.dst = stream->config->ipv4_destination_address;
@@ -180,10 +184,14 @@ bbl_stream_build_access_pppoe_packet(bbl_stream *stream) {
             pppoe.protocol = PROTOCOL_IPV6;
             pppoe.next = &ipv6;
             /* Source address */
-            if(stream->config->type == STREAM_IPV6) {
-                ipv6.src = session->ipv6_address;
+            if(*(uint64_t*)stream->config->ipv6_access_src_address) {
+                ipv6.src = stream->config->ipv6_access_src_address;
             } else {
-                ipv6.src = session->delegated_ipv6_address;
+                if(stream->config->type == STREAM_IPV6) {
+                    ipv6.src = session->ipv6_address;
+                } else {
+                    ipv6.src = session->delegated_ipv6_address;
+                }
             }
             /* Destination address */
             if(*(uint64_t*)stream->config->ipv6_destination_address) {
@@ -195,7 +203,6 @@ bbl_stream_build_access_pppoe_packet(bbl_stream *stream) {
                     ipv6.dst = network_if->ip6.address;
                 }
             }
-            ipv6.src = session->ipv6_address;
             ipv6.ttl = 64;
             ipv6.tos = config->priority;
             ipv6.protocol = IPV6_NEXT_HEADER_UDP;
@@ -403,7 +410,11 @@ bbl_stream_build_access_ipoe_packet(bbl_stream *stream) {
             eth.type = ETH_TYPE_IPV4;
             eth.next = &ipv4;
             /* Source address */
-            ipv4.src = session->ip_address;
+            if(stream->config->ipv4_access_src_address) {
+                ipv4.src = stream->config->ipv4_access_src_address;
+            } else {
+                ipv4.src = session->ip_address;
+            }
             /* Destination address */
             if(stream->config->ipv4_destination_address) {
                 ipv4.dst = stream->config->ipv4_destination_address;
@@ -428,10 +439,14 @@ bbl_stream_build_access_ipoe_packet(bbl_stream *stream) {
             eth.type = ETH_TYPE_IPV6;
             eth.next = &ipv6;
             /* Source address */
-            if(stream->config->type == STREAM_IPV6) {
-                ipv6.src = session->ipv6_address;
+            if(*(uint64_t*)stream->config->ipv6_access_src_address) {
+                ipv6.src = stream->config->ipv6_access_src_address;
             } else {
-                ipv6.src = session->delegated_ipv6_address;
+                if(stream->config->type == STREAM_IPV6) {
+                    ipv6.src = session->ipv6_address;
+                } else {
+                    ipv6.src = session->delegated_ipv6_address;
+                }
             }
             /* Destination address */
             if(*(uint64_t*)stream->config->ipv6_destination_address) {
@@ -443,7 +458,6 @@ bbl_stream_build_access_ipoe_packet(bbl_stream *stream) {
                     ipv6.dst = network_if->ip6.address;
                 }
             }
-            ipv6.src = session->ipv6_address;
             ipv6.ttl = 64;
             ipv6.tos = config->priority;
             ipv6.protocol = IPV6_NEXT_HEADER_UDP;
diff --git a/src/bbl_stream.h b/src/bbl_stream.h
index 7577a4ef..f4592db4 100644
--- a/src/bbl_stream.h
+++ b/src/bbl_stream.h
@@ -34,6 +34,8 @@ typedef struct bbl_stream_config_
     uint8_t  priority; /* IPv4 TOS or IPv6 TC */
     uint8_t  vlan_priority;
 
+    uint32_t ipv4_access_src_address; /* overwrite default IPv4 access address */
+    ipv6addr_t ipv6_access_src_address; /* overwrite default IPv6 access address */
     uint32_t ipv4_network_address; /* overwrite default IPv4 network address */
     ipv6addr_t ipv6_network_address; /* overwrite default IPv6 network address */
     uint32_t ipv4_destination_address; /* overwrite IPv4 destination address */