diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c
index 53aad1a4..d93b2a55 100644
--- a/arch/x86/kernel/irq.c
+++ b/arch/x86/kernel/irq.c
@@ -283,7 +283,4 @@ leave_handler:
 	// timer interrupt?
 	if ((s->int_no == 32) || (s->int_no == 123))
 		scheduler(); // switch to a new task
-	// exists a new (driver) task with a higher priority?
-	else if ((s->int_no >= 32) && (get_highest_priority(CORE_ID) > per_core(current_task)->prio))
-		scheduler();
 }
diff --git a/drivers/net/rckemac.c b/drivers/net/rckemac.c
index 13a29bd7..69f4bdba 100644
--- a/drivers/net/rckemac.c
+++ b/drivers/net/rckemac.c
@@ -39,6 +39,7 @@
 #include <lwip/sys.h>
 #include <lwip/stats.h>
 #include <lwip/netif.h>
+#include <lwip/tcpip.h>
 #include <netif/etharp.h>
 #include <net/rckemac.h>
 
@@ -755,12 +756,14 @@ err_t rckemacif_init(struct netif* netif)
 	/* maximum transfer unit */
 	netif->mtu = 1500;
 	/* broadcast capability */
-	netif->flags |= NETIF_FLAG_BROADCAST | NETIF_FLAG_ETHARP | NETIF_FLAG_LINK_UP;
+	netif->flags |= NETIF_FLAG_BROADCAST | NETIF_FLAG_ETHARP;
 	/* hardware address length */
 	netif->hwaddr_len = 6;
 
 	rckemacif->ethaddr = (struct eth_addr *)netif->hwaddr;
 
+	tcpip_callback(netif_set_link_up, netif);
+
 	return ERR_OK;
 }
 #endif
diff --git a/drivers/net/rtl8139.c b/drivers/net/rtl8139.c
index c7978fdf..cc3ab28d 100644
--- a/drivers/net/rtl8139.c
+++ b/drivers/net/rtl8139.c
@@ -32,6 +32,7 @@
 #include <lwip/sys.h>
 #include <lwip/stats.h>
 #include <lwip/netif.h>
+#include <lwip/tcpip.h>
 #include <netif/etharp.h>
 #include <net/rtl8139.h>
 
@@ -440,12 +441,14 @@ err_t rtl8139if_init(struct netif* netif)
 	/* maximum transfer unit */
 	netif->mtu = 1500;
 	/* broadcast capability */
-	netif->flags |= NETIF_FLAG_BROADCAST | NETIF_FLAG_ETHARP | NETIF_FLAG_LINK_UP;
+	netif->flags |= NETIF_FLAG_BROADCAST | NETIF_FLAG_ETHARP;
 	/* hardware address length */
 	netif->hwaddr_len = 6;
 
 	rtl8139if->ethaddr = (struct eth_addr *)netif->hwaddr;
 
+	tcpip_callback(netif_set_link_up, netif);
+
 	return ERR_OK;
 }
 #endif
diff --git a/lwip/src/arch/sys_arch.c b/lwip/src/arch/sys_arch.c
index 781e3bdd..88b9e26b 100644
--- a/lwip/src/arch/sys_arch.c
+++ b/lwip/src/arch/sys_arch.c
@@ -83,10 +83,11 @@ void sys_msleep(u32_t ms)
 sys_thread_t sys_thread_new(const char *name, lwip_thread_fn thread, void *arg,
 		int stacksize, int prio)
 {
+	int err;
 	sys_thread_t tmp;
 
-	create_kernel_task(&tmp, thread, arg, prio);
-	kprintf("Created LWIP task %s with id %u\n", name, tmp);
+	err = create_kernel_task(&tmp, thread, arg, prio);
+	LWIP_DEBUGF(SYS_DEBUG, ("sys_thread_new: create_kernel_task %d, id = %u", err, tmp));
 
 	return tmp;
 }
@@ -166,6 +167,7 @@ u32_t sys_arch_mbox_fetch(sys_mbox_t * mbox, void **msg, u32_t timeout)
 	int err;
 
 	err = mailbox_ptr_fetch(&mbox->mailbox, msg, timeout);
+	LWIP_DEBUGF(SYS_DEBUG, ("sys_arch_mbox_fetch: %d\n", err));
 	if (!err)
 		return 0;
 
@@ -186,7 +188,7 @@ void sys_mbox_free(sys_mbox_t* mbox)
  */
 u32_t sys_arch_mbox_tryfetch(sys_mbox_t* mbox, void** msg)
 {
-	mailbox_ptr_tryfetch(&mbox->mailbox, msg);
+	return mailbox_ptr_tryfetch(&mbox->mailbox, msg);
 }
 
 /* sys_mbox_new(): create a new mailbox with a minimum size of "size"
@@ -207,14 +209,14 @@ void sys_mbox_set_invalid(sys_mbox_t* mbox)
 }
 
 /* sys_mbox_trypost(): try to post data to the mailbox
- * Note: There is at the moment no try post implemented
- * so we use the normal post instead
+ *
  */
 err_t sys_mbox_trypost(sys_mbox_t *mbox, void *msg)
 {
 	int err;
 
 	err = mailbox_ptr_trypost(&mbox->mailbox, msg);
+	LWIP_DEBUGF(SYS_DEBUG, ("sys_mbox_trypost: %d"\n, err));
 
 	return err;
 }
diff --git a/lwip/src/include/lwipopts.h b/lwip/src/include/lwipopts.h
index 4ecdc944..0e1b40c7 100644
--- a/lwip/src/include/lwipopts.h
+++ b/lwip/src/include/lwipopts.h
@@ -62,7 +62,7 @@
 /**
  * TCP_SND_BUF: TCP sender buffer space (bytes). 
  */
-#define TCP_SND_BUF		2048
+#define TCP_SND_BUF		(16*1024)
 
 /**
  * LWIP_BROADCAST_PING==1: respond to broadcast pings (default is unicast only)
@@ -118,6 +118,59 @@
  */
 #define DEFAULT_THREAD_PRIO	NORMAL_PRIO
 
+/**
+ * TCP_MSS: TCP Maximum segment size. (default is 536, a conservative default,
+ * you might want to increase this.)
+ * For the receive side, this MSS is advertised to the remote side
+ * when opening a connection. For the transmit size, this MSS sets
+ * an upper limit on the MSS advertised by the remote host.
+ */
+#define TCP_MSS			2048
+
+/**
+ * PBUF_POOL_SIZE: the number of buffers in the pbuf pool. 
+ */
+#define PBUF_POOL_SIZE		0x80
+
+/**
+ * MEMP_NUM_UDP_PCB: the number of UDP protocol control blocks. One
+ * per active UDP "connection".
+ * (requires the LWIP_UDP option)
+ */
+#define MEMP_NUM_UDP_PCB	0x30
+
+/**
+ * MEMP_NUM_TCP_PCB: the number of simulatenously active TCP connections.
+ * (requires the LWIP_TCP option)
+ */
+#define MEMP_NUM_TCP_PCB	0x30
+
+/**
+ * MEMP_NUM_TCP_PCB_LISTEN: the number of listening TCP connections.
+ * (requires the LWIP_TCP option)
+ */
+#define MEMP_NUM_TCP_PCB_LISTEN	0x30
+
+/**
+ * MEM_SIZE: the size of the heap memory. If the application will send
+ * a lot of data that needs to be copied, this should be set high.
+ */
+#define MEM_SIZE		(4*0x100000)
+
+/**
+ * MEMP_NUM_TCPIP_MSG_API: the number of struct tcpip_msg, which are used
+ * for callback/timeout API communication. 
+ * (only needed if you use tcpip.c)
+ */
+#define MEMP_NUM_TCPIP_MSG_API		0x40
+
+/**
+ * MEMP_NUM_TCPIP_MSG_INPKT: the number of struct tcpip_msg, which are used
+ * for incoming packets. 
+ * (only needed if you use tcpip.c)
+ */
+#define MEMP_NUM_TCPIP_MSG_INPKT	0x40
+
 /* DEBUG options */
 #define LWIP_DEBUG		1
 #define DHCP_DEBUG		LWIP_DBG_OFF