diff --git a/lwip/src/Makefile b/lwip/src/Makefile
index df040b06..76be2a21 100644
--- a/lwip/src/Makefile
+++ b/lwip/src/Makefile
@@ -1,4 +1,4 @@
-SUBDIRS = api core #netif
+SUBDIRS = api core netif
 
 default:
 	$(MAKE) all
diff --git a/lwip/src/core/Makefile b/lwip/src/core/Makefile
index a6d046e6..3111abfc 100644
--- a/lwip/src/core/Makefile
+++ b/lwip/src/core/Makefile
@@ -1,4 +1,5 @@
-C_source = init.c mem.c memp.c netif.c pbuf.c stats.c udp.c tcp.c
+C_source = dhcp.c raw.c init.c mem.c memp.c netif.c pbuf.c stats.c udp.c tcp.c tcp_in.c tcp_out.c
+SUBDIRS = ipv4
 
 OBJS += $(patsubst %.c, %.o, $(filter %.c, $(C_source)))
 
@@ -7,18 +8,22 @@ OBJS += $(patsubst %.c, %.o, $(filter %.c, $(C_source)))
 	$(CC) -c $(CFLAGS) -o $@ $< 
 
 default:
+	for i in $(SUBDIRS); do $(MAKE) -C $$i default; done
 	$(MAKE) all
 
 all:
+	for i in $(SUBDIRS); do $(MAKE) -C $$i all; done
 	$(MAKE) $(LIBLWIP)
 
 $(LIBLWIP): $(OBJS)
 	$(AR) $(ARFLAGS) $(LIBLWIP) $(OBJS)
 
 clean:
+	for i in $(SUBDIRS); do $(MAKE) -C $$i clean; done
 	$(RM) *.o *~ 
 
 depend:
+	for i in $(SUBDIRS); do $(MAKE) -C $$i depend; done
 	$(CC) -MM $(CFLAGS) $(C_source) $(CPP_source) > Makefile.dep
 
 -include Makefile.dep
diff --git a/lwip/src/core/ipv4/Makefile b/lwip/src/core/ipv4/Makefile
new file mode 100644
index 00000000..de3fb439
--- /dev/null
+++ b/lwip/src/core/ipv4/Makefile
@@ -0,0 +1,25 @@
+C_source = autoip.c inet.c inet_chksum.c ip.c ip_frag.c icmp.c igmp.c ip_addr.c
+
+OBJS += $(patsubst %.c, %.o, $(filter %.c, $(C_source)))
+
+# other implicit rules
+%.o : %.c
+	$(CC) -c $(CFLAGS) -o $@ $< 
+
+default:
+	$(MAKE) all
+
+all:
+	$(MAKE) $(LIBLWIP)
+
+$(LIBLWIP): $(OBJS)
+	$(AR) $(ARFLAGS) $(LIBLWIP) $(OBJS)
+
+clean:
+	$(RM) *.o *~ 
+
+depend:
+	$(CC) -MM $(CFLAGS) $(C_source) $(CPP_source) > Makefile.dep
+
+-include Makefile.dep
+# DO NOT DELETE
diff --git a/lwip/src/include/arch/sys_arch.h b/lwip/src/include/arch/sys_arch.h
index 6dca368b..ccb0e567 100644
--- a/lwip/src/include/arch/sys_arch.h
+++ b/lwip/src/include/arch/sys_arch.h
@@ -1,33 +1,6 @@
 /*
- * Copyright (c) 2001-2003 Swedish Institute of Computer Science.
- * All rights reserved. 
- * 
- * Redistribution and use in source and binary forms, with or without modification, 
- * are permitted provided that the following conditions are met:
- *
- * 1. Redistributions of source code must retain the above copyright notice,
- *    this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright notice,
- *    this list of conditions and the following disclaimer in the documentation
- *    and/or other materials provided with the distribution.
- * 3. The name of the author may not be used to endorse or promote products
- *    derived from this software without specific prior written permission. 
- *
- * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED 
- * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 
- * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT 
- * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 
- * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT 
- * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
- * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
- * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING 
- * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY 
- * OF SUCH DAMAGE.
- *
- * This file is part of the lwIP TCP/IP stack.
- * 
- * Author: Adam Dunkels <adam@sics.se>
- *
+ * Copyright (c) 2010 Stefan Lankes, Chair for Operating Systems, RWTH Aachen University, Germany
+ * All rights reserved
  */
 #ifndef __ARCH_SYS_ARCH_H__
 #define __ARCH_SYS_ARCH_H__
@@ -43,23 +16,5 @@ typedef sem_t* sys_sem_t;
 typedef mailbox_t* sys_mbox_t;
 typedef tid_t*  sys_thread_t;
 
-/*
-#include <errno.h>
-
-#define SYS_MBOX_NULL NULL
-#define SYS_SEM_NULL  NULL
-
-typedef u32_t sys_prot_t;
-
-struct sys_sem;
-typedef struct sys_sem * sys_sem_t;
-
-
-struct sys_mbox;
-typedef struct sys_mbox *sys_mbox_t;
-
-struct sys_thread;
-typedef struct sys_thread * sys_thread_t;*/
-
 #endif /* __ARCH_SYS_ARCH_H__ */