diff --git a/src/core/ipv4/ip.c b/src/core/ipv4/ip.c
index 096b9f9c..b4931073 100644
--- a/src/core/ipv4/ip.c
+++ b/src/core/ipv4/ip.c
@@ -114,14 +114,14 @@ ip_forward(struct pbuf *p, struct ip_hdr *iphdr, struct netif *inp)
   if (netif == NULL) {
     LWIP_DEBUGF(IP_DEBUG, ("ip_forward: no forwarding route for 0x%"X32_F" found\n",
                       iphdr->dest.addr));
-    snmp_inc_ipnoroutes();
+    snmp_inc_ipoutnoroutes();
     return (struct netif *)NULL;
   }
   /* Do not forward packets onto the same network interface on which
    * they arrived. */
   if (netif == inp) {
     LWIP_DEBUGF(IP_DEBUG, ("ip_forward: not bouncing packets back on incoming interface.\n"));
-    snmp_inc_ipnoroutes();
+    snmp_inc_ipoutnoroutes();
     return (struct netif *)NULL;
   }
 
@@ -129,10 +129,10 @@ ip_forward(struct pbuf *p, struct ip_hdr *iphdr, struct netif *inp)
   IPH_TTL_SET(iphdr, IPH_TTL(iphdr) - 1);
   /* send ICMP if TTL == 0 */
   if (IPH_TTL(iphdr) == 0) {
+    snmp_inc_ipinhdrerrors();
     /* Don't send ICMP messages in response to ICMP messages */
     if (IPH_PROTO(iphdr) != IP_PROTO_ICMP) {
       icmp_time_exceeded(p, ICMP_TE_TTL);
-      snmp_inc_icmpouttimeexcds();
     }
     return (struct netif *)NULL;
   }
@@ -149,7 +149,7 @@ ip_forward(struct pbuf *p, struct ip_hdr *iphdr, struct netif *inp)
 
   IP_STATS_INC(ip.fw);
   IP_STATS_INC(ip.xmit);
-    snmp_inc_ipforwdatagrams();
+  snmp_inc_ipforwdatagrams();
 
   PERF_STOP("ip_forward");
   /* transmit pbuf on chosen interface */
@@ -188,7 +188,7 @@ ip_input(struct pbuf *p, struct netif *inp) {
     pbuf_free(p);
     IP_STATS_INC(ip.err);
     IP_STATS_INC(ip.drop);
-    snmp_inc_ipunknownprotos();
+    snmp_inc_ipinhdrerrors();
     return ERR_OK;
   }
   /* obtain IP header length in number of 32-bit words */
@@ -217,7 +217,7 @@ ip_input(struct pbuf *p, struct netif *inp) {
     pbuf_free(p);
     IP_STATS_INC(ip.chkerr);
     IP_STATS_INC(ip.drop);
-    snmp_inc_ipindiscards();
+    snmp_inc_ipinhdrerrors();
     return ERR_OK;
   }
 #endif
@@ -279,6 +279,7 @@ ip_input(struct pbuf *p, struct netif *inp) {
     else
 #endif /* IP_FORWARD */
     {
+      snmp_inc_ipinaddrerrors();
       snmp_inc_ipindiscards();
     }
     pbuf_free(p);
@@ -302,6 +303,7 @@ ip_input(struct pbuf *p, struct netif *inp) {
       ntohs(IPH_OFFSET(iphdr))));
     IP_STATS_INC(ip.opterr);
     IP_STATS_INC(ip.drop);
+    /* unsupported protocol feature */
     snmp_inc_ipunknownprotos();
     return ERR_OK;
 #endif /* IP_REASSEMBLY */
@@ -313,6 +315,7 @@ ip_input(struct pbuf *p, struct netif *inp) {
     pbuf_free(p);
     IP_STATS_INC(ip.opterr);
     IP_STATS_INC(ip.drop);
+    /* unsupported protocol feature */
     snmp_inc_ipunknownprotos();
     return ERR_OK;
   }
@@ -359,7 +362,7 @@ ip_input(struct pbuf *p, struct netif *inp) {
 
     IP_STATS_INC(ip.proterr);
     IP_STATS_INC(ip.drop);
-    snmp_inc_ipunknownprotos();
+    snmp_inc_ipinunknownprotos();
   }
 #if LWIP_RAW
   } /* LWIP_RAW */
@@ -452,7 +455,7 @@ ip_output(struct pbuf *p, struct ip_addr *src, struct ip_addr *dest,
     LWIP_DEBUGF(IP_DEBUG | 2, ("ip_output: No route to 0x%"X32_F"\n", dest->addr));
 
     IP_STATS_INC(ip.rterr);
-    snmp_inc_ipoutdiscards();
+    snmp_inc_ipoutnoroutes();
     return ERR_RTE;
   }
 
diff --git a/src/core/ipv4/ip_frag.c b/src/core/ipv4/ip_frag.c
index 18e337b3..3a5d0737 100644
--- a/src/core/ipv4/ip_frag.c
+++ b/src/core/ipv4/ip_frag.c
@@ -43,11 +43,9 @@
 #include "lwip/ip.h"
 #include "lwip/ip_frag.h"
 #include "lwip/netif.h"
+#include "lwip/snmp.h"
 #include "lwip/stats.h"
 
-#define IP_REASS_BUFSIZE 5760
-#define IP_REASS_MAXAGE 3
-
 static u8_t ip_reassbuf[IP_HLEN + IP_REASS_BUFSIZE];
 static u8_t ip_reassbitmap[IP_REASS_BUFSIZE / (8 * 8) + 1];
 static const u8_t bitmap_bits[8] = { 0xff, 0x7f, 0x3f, 0x1f,
@@ -110,6 +108,10 @@ ip_reass_tmr(void)
   if (ip_reasstmr > 0) {
     ip_reasstmr--;
     LWIP_DEBUGF(IP_REASS_DEBUG, ("ip_reass_tmr: timer dec %"U16_F"\n",(u16_t)ip_reasstmr));
+    if (ip_reasstmr == 0) {
+      /* reassembly timed out */
+      snmp_inc_ipreasmfails();
+    }
   }
 }
 
@@ -128,6 +130,7 @@ ip_reass(struct pbuf *p)
   u16_t i;
 
   IPFRAG_STATS_INC(ip_frag.recv);
+  snmp_inc_ipreasmreqds();
 
   iphdr = (struct ip_hdr *) ip_reassbuf;
   fraghdr = (struct ip_hdr *) p->payload;
@@ -164,6 +167,7 @@ ip_reass(struct pbuf *p)
        ("ip_reass: fragment outside of buffer (%"S16_F":%"S16_F"/%"S16_F").\n", offset,
         offset + len, IP_REASS_BUFSIZE));
       ip_reasstmr = 0;
+      snmp_inc_ipreasmfails();
       goto nullreturn;
     }
 
@@ -276,10 +280,12 @@ ip_reass(struct pbuf *p)
           i += q->len;
         }
         IPFRAG_STATS_INC(ip_frag.fw);
+        snmp_inc_ipreasmoks();
       } else {
         LWIP_DEBUGF(IP_REASS_DEBUG,
           ("ip_reass: pbuf_alloc(PBUF_LINK, ip_reasslen=%"U16_F", PBUF_POOL) failed\n", ip_reasslen));
         IPFRAG_STATS_INC(ip_frag.memerr);
+        snmp_inc_ipreasmfails();
       }
       LWIP_DEBUGF(IP_REASS_DEBUG, ("ip_reass: p %p\n", (void*)p));
       return p;
@@ -368,6 +374,7 @@ ip_frag(struct pbuf *p, struct netif *netif, struct ip_addr *dest)
       pbuf_chain(header, rambuf);
       netif->output(netif, header, dest);
       IPFRAG_STATS_INC(ip_frag.xmit);
+      snmp_inc_ipfragcreates();
       pbuf_free(header);
     } else {
       LWIP_DEBUGF(IP_REASS_DEBUG, ("ip_frag: pbuf_alloc() for header failed\n"));
@@ -377,5 +384,6 @@ ip_frag(struct pbuf *p, struct netif *netif, struct ip_addr *dest)
     left -= cop;
   }
   pbuf_free(rambuf);
+  snmp_inc_ipfragoks();
   return ERR_OK;
 }
diff --git a/src/include/ipv4/lwip/ip_frag.h b/src/include/ipv4/lwip/ip_frag.h
index 137712e6..0ba28d7c 100644
--- a/src/include/ipv4/lwip/ip_frag.h
+++ b/src/include/ipv4/lwip/ip_frag.h
@@ -39,8 +39,17 @@
 #include "lwip/netif.h"
 #include "lwip/ip_addr.h"
 
-#ifndef IP_REASS_INTERVAL
+/* IP reassemly timer interval in milliseconds */
 #define IP_REASS_INTERVAL 1000
+
+/* IP reassemly default age in seconds */
+#ifndef IP_REASS_MAXAGE
+#define IP_REASS_MAXAGE 3
+#endif
+
+/* IP reassembly buffer size (minus IP header) */
+#ifndef IP_REASS_BUFSIZE
+#define IP_REASS_BUFSIZE 5760
 #endif
 
 void ip_frag_init(void);
diff --git a/src/include/lwip/opt.h b/src/include/lwip/opt.h
index 541f93c6..eeb3a57e 100644
--- a/src/include/lwip/opt.h
+++ b/src/include/lwip/opt.h
@@ -216,10 +216,15 @@ a lot of data that needs to be copied, this should be set high. */
 #define IP_FRAG                         1
 #endif
 
+/** Global default value for Time To Live used by transport layers. */
+#ifndef IP_DEFAULT_TTL
+#define IP_DEFAULT_TTL                  255
+#endif
+
 /* ---------- ICMP options ---------- */
 
 #ifndef ICMP_TTL
-#define ICMP_TTL                        255
+#define ICMP_TTL                        (IP_DEFAULT_TTL)
 #endif
 
 /* ---------- RAW options ---------- */
@@ -229,7 +234,7 @@ a lot of data that needs to be copied, this should be set high. */
 #endif
 
 #ifndef RAW_TTL
-#define RAW_TTL                        255
+#define RAW_TTL                        (IP_DEFAULT_TTL)
 #endif
 
 /* ---------- DHCP options ---------- */
@@ -245,7 +250,8 @@ a lot of data that needs to be copied, this should be set high. */
 #endif
 
 /* ---------- SNMP options ---------- */
-/** @todo SNMP isn't functional yet. */
+/** @todo SNMP isn't functional yet. 
+    @note UDP must be available for SNMP transport */
 #ifndef LWIP_SNMP
 #define LWIP_SNMP                       0
 #endif
@@ -260,7 +266,7 @@ a lot of data that needs to be copied, this should be set high. */
 #endif
 
 #ifndef UDP_TTL
-#define UDP_TTL                         255
+#define UDP_TTL                         (IP_DEFAULT_TTL)
 #endif
 
 /* ---------- TCP options ---------- */
@@ -269,7 +275,7 @@ a lot of data that needs to be copied, this should be set high. */
 #endif
 
 #ifndef TCP_TTL
-#define TCP_TTL                         255
+#define TCP_TTL                         (IP_DEFAULT_TTL)
 #endif
 
 #ifndef TCP_WND