cleaning text

Author: edgar-costa

README.md

@@ -4,7 +4,7 @@ This repository contains a compilation of useful resources for data plane progra
 for the ones wanting to learn how to write **P4-16** programs and test them in a virtual environment.
 
 A big part of the materials come from the Advanced Topics in Communication Networks lecture taught
-at ETH Zurich. For more information visit our [website](https://adv-net.ethz.ch/2019/).
+at ETH Zurich. For more information visit our [website](https://adv-net.ethz.ch/).
 
 ## What will you find here ?
 

exercises/04-MPLS/README.md

@@ -0,0 +1,247 @@
+/* -*- P4_16 -*- */
+#include <core.p4>
+#include <v1model.p4>
+
+const bit<16> TYPE_IPV4 = 0x800;
+
+/* TODO 1.1: Create a new etherType for MPLS protocol, which will be used to identify it from the ethernet header. */
+
+#define CONST_MAX_PORTS 	32
+#define CONST_MAX_LABELS 	10
+
+/*************************************************************************
+*********************** H E A D E R S  ***********************************
+*************************************************************************/
+
+typedef bit<9>  egressSpec_t;
+typedef bit<48> macAddr_t;
+typedef bit<32> ip4Addr_t;
+
+header ethernet_t {
+    macAddr_t dstAddr;
+    macAddr_t srcAddr;
+    bit<16>   etherType;
+}
+
+/* TODO 1.2: Create a header for MPLS protocol, called "mpls_t". The header should have 4 fields like we described in the README. */
+
+header ipv4_t {
+    bit<4>    version;
+    bit<4>    ihl;
+    bit<8>    diffserv;
+    bit<16>   totalLen;
+    bit<16>   identification;
+    bit<3>    flags;
+    bit<13>   fragOffset;
+    bit<8>    ttl;
+    bit<8>    protocol;
+    bit<16>   hdrChecksum;
+    ip4Addr_t srcAddr;
+    ip4Addr_t dstAddr;
+}
+
+/* TODO 2.1: Note that we have created this metadata struct, which will help us identify packets read from ingress and egress routers. */
+
+struct metadata {
+    bit<1> is_ingress_border;
+    bit<1> is_egress_border;
+}
+
+/* TODO 1.3: Add the newly-defined "mpls_t" header to the struct "headers". The "mpls_t" header should go in between of "ethernet_t" and "ipv4_t". */
+
+struct headers {
+    ethernet_t              ethernet;
+    ipv4_t                  ipv4;
+}
+
+/*************************************************************************
+*********************** P A R S E R  ***********************************
+*************************************************************************/
+
+parser MyParser(packet_in packet,
+                out headers hdr,
+                inout metadata meta,
+                inout standard_metadata_t standard_metadata) {
+
+    state start {
+        transition parse_ethernet;
+    }
+
+    state parse_ethernet {
+        packet.extract(hdr.ethernet);
+        transition select(hdr.ethernet.etherType) {
+
+            /* TODO 1.5: Call the MPLS parser in case an MPLS packet is detected. */
+            
+            TYPE_IPV4: parse_ipv4;
+            default: accept;
+        }
+    }
+
+    /* TODO 1.4: Create a parser that extracts the MPLS header that you have created. */
+
+    state parse_ipv4 {
+        packet.extract(hdr.ipv4);
+        transition accept;
+    }
+}
+
+/*************************************************************************
+************   C H E C K S U M    V E R I F I C A T I O N   *************
+*************************************************************************/
+
+control MyVerifyChecksum(inout headers hdr, inout metadata meta) {
+    apply {  }
+}
+
+
+/*************************************************************************
+**************  I N G R E S S   P R O C E S S I N G   *******************
+*************************************************************************/
+
+control MyIngress(inout headers hdr,
+                  inout metadata meta,
+                  inout standard_metadata_t standard_metadata) {
+        
+    action drop() {
+        mark_to_drop(standard_metadata);
+    }
+            
+    /* TODO 2.3: Create the action set_is_ingress_border. */
+
+    /* TODO 2.2: Create the table check_is_ingress_border. */
+
+    action add_mpls_header(bit<20> tag) {
+
+        // We add the mpls header
+        hdr.mpls.setValid();
+        hdr.mpls.label = tag;
+        hdr.ethernet.etherType = TYPE_MPLS;
+    }
+
+    /* TODO 2.5: Create the table fec_to_label. */
+
+    action mpls_forward(macAddr_t dstAddr, egressSpec_t port) {
+        hdr.ethernet.srcAddr = hdr.ethernet.dstAddr;
+        hdr.ethernet.dstAddr = dstAddr;
+
+        standard_metadata.egress_spec = port;
+        hdr.mpls.ttl = hdr.mpls.ttl - 1;
+    }
+
+    /* TODO 3.2: Create the table mpls_tbl. */
+
+    /* TODO 3.5: Create the action ipv4_forward. */
+
+    /* TODO 3.4: Create the table ipv4_lpm. */
+
+    apply {
+
+            // We check if it is an ingress border port
+            check_is_ingress_border.apply();
+
+            if(meta.is_ingress_border == 1){
+
+                // We need to check if the header is valid since mpls label is based on dst ip
+                if(hdr.ipv4.isValid()){
+                    
+                    // We add the label based on the destination
+                    fec_to_label.apply();
+                }
+            }
+            
+            /* TODO 3.1: Uncomment the following lines. */
+
+            // We select the egress port based on the mpls label
+            //if(hdr.mpls.isValid()){
+            //    mpls_tbl.apply();
+            //}
+
+            /* TODO 3.4 Uncomment the following lines. */
+
+            // Normal forwarding
+            //else if (hdr.ipv4.isValid())
+            //{
+            //   ipv4_lpm.apply();
+            //}
+
+    }
+}
+
+/*************************************************************************
+****************  E G R E S S   P R O C E S S I N G   *******************
+*************************************************************************/
+
+control MyEgress(inout headers hdr,
+                 inout metadata meta,
+                 inout standard_metadata_t standard_metadata) {
+    
+    action is_egress_border(){
+        
+        // We remove the mpls header
+        hdr.mpls.setInvalid();
+        hdr.ethernet.etherType = TYPE_IPV4;
+        hdr.ipv4.ttl = hdr.ipv4.ttl - 1;
+    }
+
+    /* TODO 4.1: Create the table check_is_egress_border.  */
+
+    apply { 
+        // We check if it is an egress border port
+        if (hdr.mpls.isValid()){
+            check_is_egress_border.apply();
+        }     
+    }
+}
+
+/*************************************************************************
+*************   C H E C K S U M    C O M P U T A T I O N   **************
+*************************************************************************/
+
+control MyComputeChecksum(inout headers  hdr, inout metadata meta) {
+
+    /* TODO 3.6 Uncomment to update the checksum field once the ttl changes.  */
+
+    //apply {
+    //    update_checksum(
+	//        hdr.ipv4.isValid(),
+    //        { hdr.ipv4.version,
+	//          hdr.ipv4.ihl,
+    //          hdr.ipv4.diffserv,
+    //          hdr.ipv4.totalLen,
+    //          hdr.ipv4.identification,
+    //          hdr.ipv4.flags,
+    //          hdr.ipv4.fragOffset,
+    //          hdr.ipv4.ttl,
+    //          hdr.ipv4.protocol,
+    //          hdr.ipv4.srcAddr,
+    //          hdr.ipv4.dstAddr },
+    //          hdr.ipv4.hdrChecksum,
+    //          HashAlgorithm.csum16);
+    //}
+}
+
+/*************************************************************************
+***********************  D E P A R S E R  *******************************
+*************************************************************************/
+
+control MyDeparser(packet_out packet, in headers hdr) {
+    apply {
+        packet.emit(hdr.ethernet);
+        packet.emit(hdr.mpls);
+        packet.emit(hdr.ipv4);
+    }
+}
+
+/*************************************************************************
+***********************  S W I T C H  *******************************
+*************************************************************************/
+
+V1Switch(
+MyParser(),
+MyVerifyChecksum(),
+MyIngress(),
+MyEgress(),
+MyComputeChecksum(),
+MyDeparser()
+) main;