---
# System prepended metadata

title: '網路模擬與分析(5/24): P4'
tags: [P4, Mininet]

---

# 網路模擬與分析(5/24): P4
###### tags: `Mininet`、`P4`

---

**--------------目前為純 code 及 result，詳解部分之後更新--------------**

---

## Homework-1
![](https://i.imgur.com/vYIcxKg.jpg)

`ip_forward.p4`

```
#include <core.p4>
#include <v1model.p4>
typedef bit<48> macAddr_t;
typedef bit<9> egressSpec_t;
  
header ethernet_t {
    bit<48> dstAddr;
    bit<48> srcAddr;
    bit<16> etherType;
}
 
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;
    bit<32> srcAddr;
    bit<32> dstAddr;
}
 
struct metadata {
}
 
struct headers {
    @name(".ethernet")
    ethernet_t ethernet;
    @name(".ipv4")
    ipv4_t     ipv4;
}
 
parser ParserImpl(packet_in packet, out headers hdr, inout metadata meta, inout standard_metadata_t standard_metadata) {

    @name(".parse_ethernet") state parse_ethernet {
        packet.extract(hdr.ethernet);
        transition select(hdr.ethernet.etherType) {
            16w0x800: parse_ipv4;
            default: accept;
        }
    }
    @name(".parse_ipv4") state parse_ipv4 {
        packet.extract(hdr.ipv4);
        transition accept;
    }
    @name(".start") state start {
        transition parse_ethernet;
    }
}
 
control egress(inout headers hdr, inout metadata meta, inout standard_metadata_t standard_metadata) {
    apply {
    }
}
 
control ingress(inout headers hdr, inout metadata meta, inout standard_metadata_t standard_metadata) {
    @name(".set_nhop") action set_nhop(macAddr_t dstAddr, egressSpec_t port) {
        //set the src mac address as the previous dst, this is not correct right?
        hdr.ethernet.srcAddr = hdr.ethernet.dstAddr;
 
        //set the destination mac address that we got from the match in the table
        hdr.ethernet.dstAddr = dstAddr;
 
        //set the output port that we also get from the table
        standard_metadata.egress_spec = port;
 
        //decrease ttl by 1
        hdr.ipv4.ttl = hdr.ipv4.ttl - 1;
    }
    @name("._drop") action _drop() {
        mark_to_drop(standard_metadata);
    }
    @name(".ipv4_lpm") table ipv4_lpm {
        actions = {
            set_nhop;
            _drop;
        }
        key = {
            hdr.ipv4.dstAddr: lpm;
        }
        size = 512;
        const default_action = _drop();
    }
    apply {
        ipv4_lpm.apply();
    }
}
 
control DeparserImpl(packet_out packet, in headers hdr) {
    apply {
        packet.emit(hdr.ethernet);
        packet.emit(hdr.ipv4);
    }
}
 
control verifyChecksum(inout headers hdr, inout metadata meta) {
    apply {
        verify_checksum(true, { 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);
    }
}
 
control computeChecksum(inout headers hdr, inout metadata meta) {
    apply {
        update_checksum(true, { 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);
    }
}
 
V1Switch(ParserImpl(), verifyChecksum(), ingress(), egress(), computeChecksum(), DeparserImpl()) main;
```

`p4app.json`

```
{
  "program": "ip_forward.p4",
  "switch": "simple_switch",
  "compiler": "p4c",
  "options": "--target bmv2 --arch v1model --std p4-16",
  "switch_cli": "simple_switch_CLI",
  "cli": true,
  "pcap_dump": false,
  "enable_log": true,
  "topo_module": {
    "file_path": "",
    "module_name": "p4utils.mininetlib.apptopo",
    "object_name": "AppTopoStrategies"
  },
  "controller_module": null,
  "topodb_module": {
    "file_path": "",
    "module_name": "p4utils.utils.topology",
    "object_name": "Topology"
  },
  "mininet_module": {
    "file_path": "",
    "module_name": "p4utils.mininetlib.p4net",
    "object_name": "P4Mininet"
  },
  "topology": {
    "assignment_strategy": "manual",
    "auto_arp_tables": "true",
    "auto_gw_arp": "true",
    "links": [["h1", "s1"], ["h2", "s1"], ["s1", "s2"], ["s2", "h3"]],
    "hosts": {
      "h1": {
        "ip": "10.0.1.1/24",
        "gw": "10.0.1.254",
        "commands":[["arp -d 10.0.1.254"],["arp -s 10.0.1.254 00:00:0a:00:01:FE"]]
      },
      "h2": {
        "ip": "10.0.1.2/24",
        "gw": "10.0.1.254",
        "commands":[["arp -d 10.0.1.254"],["arp -s 10.0.1.254 00:00:0a:00:01:FE"]]
      },
      "h3": {
        "ip": "10.0.2.1/24",
        "gw": "10.0.2.254"
      } 
    },
    "switches": {
      "s1": {
        "cli_input": "cmd1.txt",
        "program": "mac_forward.p4"
      },
      "s2": {
        "cli_input": "cmd2.txt",
        "program": "ip_forward.p4"
      }
    }
  }
}
```

`cmd1.txt`

```
table_add mac_forward forward 00:00:0a:00:01:01 => 1
table_add mac_forward forward 00:00:0a:00:01:02 => 2
table_add mac_forward forward 00:00:0a:00:01:FE => 3
```


`cmd2.txt`

```
table_add ipv4_lpm set_nhop 10.0.1.1/32 => 00:00:0a:00:01:01 1
table_add ipv4_lpm set_nhop 10.0.1.2/32 => 00:00:0a:00:01:02 1
table_add ipv4_lpm set_nhop 10.0.2.1/32 => 00:00:0a:00:02:01 2
```

`p4run`

![](https://i.imgur.com/Tijd9jH.jpg)

---

## Register

![](https://i.imgur.com/OVpwK0O.jpg)


`ip_forwarding.p4`:

```
 #include <core.p4>
 #include <v1model.p4>
 typedef bit<48> macAddr_t;
 typedef bit<9> egressSpec_t;
 	
 header ethernet_t {
 		bit<48> dstAddr;
 		bit<48> srcAddr;
 		bit<16> etherType;
 }
 
 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;
 		bit<32> srcAddr;
 		bit<32> dstAddr;
 }
 
 struct metadata {
 }
 
 struct headers {
 		@name(".ethernet")
 		ethernet_t ethernet;
 		@name(".ipv4")
 		ipv4_t     ipv4;
 }
 
 parser ParserImpl(packet_in packet, out headers hdr, inout metadata meta, inout standard_metadata_t standard_metadata) {

 		@name(".parse_ethernet") state parse_ethernet {
 				packet.extract(hdr.ethernet);
 				transition select(hdr.ethernet.etherType) {
 						16w0x800: parse_ipv4;
 						default: accept;
 				}
 		}
 		@name(".parse_ipv4") state parse_ipv4 {
 				packet.extract(hdr.ipv4);
 				transition accept;
 		}
 		@name(".start") state start {
 				transition parse_ethernet;
 		}
 }
 
 control egress(inout headers hdr, inout metadata meta, inout standard_metadata_t standard_metadata) {
 		register<bit<32>>(15) qdepth;   
 		apply {
 			qdepth.write((bit<32>)standard_metadata.egress_port, (bit<32>)standard_metadata.deq_qdepth);
 		}
 }
 
 control ingress(inout headers hdr, inout metadata meta, inout standard_metadata_t standard_metadata) {
 		@name(".set_nhop") action set_nhop(macAddr_t dstAddr, egressSpec_t port) {
 				//set the src mac address as the previous dst, this is not correct right?
 				hdr.ethernet.srcAddr = hdr.ethernet.dstAddr;
 
 				//set the destination mac address that we got from the match in the table
 				hdr.ethernet.dstAddr = dstAddr;
 
 				//set the output port that we also get from the table
 				standard_metadata.egress_spec = port;
 
 				//decrease ttl by 1
 				hdr.ipv4.ttl = hdr.ipv4.ttl - 1;
 		}
 		@name("._drop") action _drop() {
 				mark_to_drop(standard_metadata);
 		}
 		@name(".ipv4_lpm") table ipv4_lpm {
 				actions = {
 						set_nhop;
 						_drop;
 				}
 				key = {
 						hdr.ipv4.dstAddr: lpm;
 				}
 				size = 512;
 				const default_action = _drop();
 		}
 		apply {
 				ipv4_lpm.apply();
 		}
 }
 
 control DeparserImpl(packet_out packet, in headers hdr) {
 		apply {
 				packet.emit(hdr.ethernet);
 				packet.emit(hdr.ipv4);
 		}
 }
 
 control verifyChecksum(inout headers hdr, inout metadata meta) {
 		apply {
 				verify_checksum(true, { 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);
 		}
 }
 
 control computeChecksum(inout headers hdr, inout metadata meta) {
 		apply {
 				update_checksum(true, { 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);
 		}
 }
 
 V1Switch(ParserImpl(), verifyChecksum(), ingress(), egress(), computeChecksum(), DeparserImpl()) main;
```

`cmd.txt`:

```
 set_queue_depth 50
 set_queue_rate 1000
 table_add ipv4_lpm set_nhop 10.0.1.1/32 => 00:00:0a:00:01:01 1
 table_add ipv4_lpm set_nhop 10.0.2.1/32 => 00:00:0a:00:02:01 2
```


`monitor_qlens1h2.sh`:
```
 #!/bin/bash

 CLI_PATH=/usr/local/bin/simple_switch_CLI

 #get current unix time in milliseconds
 prev_time=`date +%s%N | cut -b1-13`


 while true; do
 	qlen=`echo register_read qdepth 2 | $CLI_PATH --thrift-port 9090 | grep qdepth | awk '{print $3}'`       

 	now=`date +%s%N | cut -b1-13` 
 	time=$(echo "scale=2; ($now -  $prev_time) / 1000.0"| bc -l)
 	echo $time $qlen
 	sleep 0.1
 done
```



![](https://i.imgur.com/PNB5Y0E.png)

---

## Counter

![](https://i.imgur.com/KX646va.jpg)


`ip_forwarding.p4`:

```
 #include <core.p4>
 #include <v1model.p4>
 typedef bit<48> macAddr_t;
 typedef bit<9> egressSpec_t;

 const bit<4> MAX_PORT = 15;
 	
 header ethernet_t {
 		bit<48> dstAddr;
 		bit<48> srcAddr;
 		bit<16> etherType;
 }
 
 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;
 		bit<32> srcAddr;
 		bit<32> dstAddr;
 }
 
 struct metadata {
 }
 
 struct headers {
 		@name(".ethernet")
 		ethernet_t ethernet;
 		@name(".ipv4")
 		ipv4_t     ipv4;
 }
 
 parser ParserImpl(packet_in packet, out headers hdr, inout metadata meta, inout standard_metadata_t standard_metadata) {

 		@name(".parse_ethernet") state parse_ethernet {
 				packet.extract(hdr.ethernet);
 				transition select(hdr.ethernet.etherType) {
 						16w0x800: parse_ipv4;
 						default: accept;
 				}
 		}
 		@name(".parse_ipv4") state parse_ipv4 {
 				packet.extract(hdr.ipv4);
 				transition accept;
 		}
 		@name(".start") state start {
 				transition parse_ethernet;
 		}
 }
 
 control egress(inout headers hdr, inout metadata meta, inout standard_metadata_t standard_metadata) {
 		counter((bit<32>)MAX_PORT, CounterType.bytes) egressPortCounter;
 		apply {
 			egressPortCounter.count((bit<32>)standard_metadata.egress_port);
 		}
 }
 
 control ingress(inout headers hdr, inout metadata meta, inout standard_metadata_t standard_metadata) {
 		@name(".set_nhop") action set_nhop(macAddr_t dstAddr, egressSpec_t port) {
 				//set the src mac address as the previous dst, this is not correct right?
 				hdr.ethernet.srcAddr = hdr.ethernet.dstAddr;
 
 				//set the destination mac address that we got from the match in the table
 				hdr.ethernet.dstAddr = dstAddr;
 
 				//set the output port that we also get from the table
 				standard_metadata.egress_spec = port;
 
 				//decrease ttl by 1
 				hdr.ipv4.ttl = hdr.ipv4.ttl - 1;
 		}
 		@name("._drop") action _drop() {
 				mark_to_drop(standard_metadata);
 		}
 		@name(".ipv4_lpm") table ipv4_lpm {
 				actions = {
 						set_nhop;
 						_drop;
 				}
 				key = {
 						hdr.ipv4.dstAddr: lpm;
 				}
 				size = 512;
 				const default_action = _drop();
 		}
 		apply {
 				ipv4_lpm.apply();
 		}
 }
 
 control DeparserImpl(packet_out packet, in headers hdr) {
 		apply {
 				packet.emit(hdr.ethernet);
 				packet.emit(hdr.ipv4);
 		}
 }
 
 control verifyChecksum(inout headers hdr, inout metadata meta) {
 		apply {
 				verify_checksum(true, { 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);
 		}
 }
 
 control computeChecksum(inout headers hdr, inout metadata meta) {
 		apply {
 				update_checksum(true, { 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);
 		}
 }
 
 V1Switch(ParserImpl(), verifyChecksum(), ingress(), egress(), computeChecksum(), DeparserImpl()) main;
```


`monitor_s1h2bw.sh`:

```
 #!/bin/bash

 CLI_PATH=/usr/local/bin/simple_switch_CLI

 bytes_s1h2=0
 pre_bytes_s1h2=0

 #get current unix time in milliseconds
 prev_time=`date +%s%N | cut -b1-13`


 while true; do
 	bytes_s1h2=`echo counter_read egressPortCounter 2 | $CLI_PATH --thrift-port 9090 | grep egressPortCounter | tr '=' ' ' | tr ')' ' ' | awk '{print $6}'`       

 	now=`date +%s%N | cut -b1-13` 
 
 	if [ ! $pre_bytes_s1h2 -eq 0 ];then
 		thr=`echo "scale=2;($bytes_s1h2-$pre_bytes_s1h2) * 8.0  / ($now-$pre_time)" | bc -l`
 		echo "BW consumption (s1-h2):" $thr "kbps"      
 	fi

 	pre_bytes_s1h2=$bytes_s1h2
 	pre_time=$now
 	sleep 1
 done
```

![](https://i.imgur.com/Gx6uhXU.png)


---

### HomeWork-2

![](https://i.imgur.com/7UTze78.png)

`p4app.json`:

```
 {
 	"program": "ip_forward.p4",
 	"switch": "simple_switch",
 	"compiler": "p4c",
 	"options": "--target bmv2 --arch v1model --std p4-16",
 	"switch_cli": "simple_switch_CLI",
 	"cli": true,
 	"pcap_dump": false,
 	"enable_log": false,
 	"topo_module": {
 		"file_path": "",
 		"module_name": "p4utils.mininetlib.apptopo",
 		"object_name": "AppTopoStrategies"
 	},
 	"controller_module": null,
 	"topodb_module": {
 		"file_path": "",
 		"module_name": "p4utils.utils.topology",
 		"object_name": "Topology"
 	},
 	"mininet_module": {
 		"file_path": "",
 		"module_name": "p4utils.mininetlib.p4net",
 		"object_name": "P4Mininet"
 	},
 	"topology": {
 		"assignment_strategy": "manual",
 		"auto_arp_tables": "true",
 		"auto_gw_arp": "true",
 		"links": [["h1", "s1"], ["h2", "s1"], ["h3", "s2"], ["h4", "s2"], ["h5", "s3"], ["h6", "s3"], ["s1", "s2"], ["s1", "s3"], ["s2", "s3"]],
 		"hosts": {
 			"h1": {
 				"ip": "10.0.1.1/24",
 				"gw": "10.0.1.254"
 			},
 			"h2": {
 				"ip": "10.0.1.2/24",
 				"gw": "10.0.1.254"
 			},
 			"h3": {
 				"ip": "10.0.2.1/24",
 				"gw": "10.0.2.254"
 			},
 			"h4": {
 				"ip": "10.0.2.2/24",
 				"gw": "10.0.2.254"
 			},
 			"h5": {
 				"ip": "10.0.3.1/24",
 				"gw": "10.0.3.254"
 			},
 			"h6": {
 				"ip": "10.0.3.2/24",
 				"gw": "10.0.3.254"
 			}
 		},
 		"switches": {
 			"s1": {
 				"cli_input": "cmd1.txt",
 				"program": "ip_forward.p4"
 			},
 			"s2": {
 				"cli_input": "cmd2.txt",
 				"program": "ip_forward.p4"
 			},
 			"s3": {
 				"cli_input": "cmd3.txt",
 				"program": "ip_forward.p4"
 			}
 		}
 	}
 }
```

`ip_forwarding.p4`

```
 #include <core.p4>
 #include <v1model.p4>
 typedef bit<48> macAddr_t;
 typedef bit<9> egressSpec_t;

 const bit<4> MAX_PORT = 15;
 	
 header ethernet_t {
 		bit<48> dstAddr;
 		bit<48> srcAddr;
 		bit<16> etherType;
 }
 
 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;
 		bit<32> srcAddr;
 		bit<32> dstAddr;
 }
 
 struct metadata {
 }
 
 struct headers {
 		@name(".ethernet")
 		ethernet_t ethernet;
 		@name(".ipv4")
 		ipv4_t     ipv4;
 }
 
 parser ParserImpl(packet_in packet, out headers hdr, inout metadata meta, inout standard_metadata_t standard_metadata) {

 		@name(".parse_ethernet") state parse_ethernet {
 				packet.extract(hdr.ethernet);
 				transition select(hdr.ethernet.etherType) {
 						16w0x800: parse_ipv4;
 						default: accept;
 				}
 		}
 		@name(".parse_ipv4") state parse_ipv4 {
 				packet.extract(hdr.ipv4);
 				transition accept;
 		}
 		@name(".start") state start {
 				transition parse_ethernet;
 		}
 }
 
 control egress(inout headers hdr, inout metadata meta, inout standard_metadata_t standard_metadata) {
 		counter((bit<32>)MAX_PORT, CounterType.bytes) egressPortCounter;
 		apply {
 			egressPortCounter.count((bit<32>)standard_metadata.egress_port);
 		}
 }
 
 control ingress(inout headers hdr, inout metadata meta, inout standard_metadata_t standard_metadata) {
 		@name(".set_nhop") action set_nhop(macAddr_t dstAddr, egressSpec_t port) {
 				//set the src mac address as the previous dst, this is not correct right?
 				hdr.ethernet.srcAddr = hdr.ethernet.dstAddr;
 
 				//set the destination mac address that we got from the match in the table
 				hdr.ethernet.dstAddr = dstAddr;
 
 				//set the output port that we also get from the table
 				standard_metadata.egress_spec = port;
 
 				//decrease ttl by 1
 				hdr.ipv4.ttl = hdr.ipv4.ttl - 1;
 		}
 		@name("._drop") action _drop() {
 				mark_to_drop(standard_metadata);
 		}
 		@name(".ipv4_lpm") table ipv4_lpm {
 				actions = {
 						set_nhop;
 						_drop;
 				}
 				key = {
 						hdr.ipv4.dstAddr: lpm;
 				}
 				size = 512;
 				const default_action = _drop();
 		}
 		apply {
 				ipv4_lpm.apply();
 		}
 }
 
 control DeparserImpl(packet_out packet, in headers hdr) {
 		apply {
 				packet.emit(hdr.ethernet);
 				packet.emit(hdr.ipv4);
 		}
 }
 
 control verifyChecksum(inout headers hdr, inout metadata meta) {
 		apply {
 				verify_checksum(true, { 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);
 		}
 }
 
 control computeChecksum(inout headers hdr, inout metadata meta) {
 		apply {
 				update_checksum(true, { 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);
 		}
 }
 
 V1Switch(ParserImpl(), verifyChecksum(), ingress(), egress(), computeChecksum(), DeparserImpl()) main;
```

`cmd1.txt`:

```
 table_add ipv4_lpm set_nhop 10.0.1.1/32 => 00:00:0a:00:01:01 1
 table_add ipv4_lpm set_nhop 10.0.1.2/32 => 00:00:0a:00:01:02 2
 table_add ipv4_lpm set_nhop 10.0.2.1/32 => 00:00:0a:00:02:01 3
 table_add ipv4_lpm set_nhop 10.0.2.2/32 => 00:00:0a:00:02:02 3
 table_add ipv4_lpm set_nhop 10.0.3.1/32 => 00:00:0a:00:03:01 4
 table_add ipv4_lpm set_nhop 10.0.3.2/32 => 00:00:0a:00:03:02 4
```

`cmd2.txt`:

```
 table_add ipv4_lpm set_nhop 10.0.1.1/32 => 00:00:0a:00:01:01 3
 table_add ipv4_lpm set_nhop 10.0.1.2/32 => 00:00:0a:00:01:02 3
 table_add ipv4_lpm set_nhop 10.0.2.1/32 => 00:00:0a:00:02:01 1
 table_add ipv4_lpm set_nhop 10.0.2.2/32 => 00:00:0a:00:02:02 2
 table_add ipv4_lpm set_nhop 10.0.3.1/32 => 00:00:0a:00:03:01 4
 table_add ipv4_lpm set_nhop 10.0.3.2/32 => 00:00:0a:00:03:02 4
```

`cmd3.txt`:

```
 table_add ipv4_lpm set_nhop 10.0.1.1/32 => 00:00:0a:00:01:01 3
 table_add ipv4_lpm set_nhop 10.0.1.2/32 => 00:00:0a:00:01:02 3
 table_add ipv4_lpm set_nhop 10.0.2.1/32 => 00:00:0a:00:02:01 4
 table_add ipv4_lpm set_nhop 10.0.2.2/32 => 00:00:0a:00:02:02 4
 table_add ipv4_lpm set_nhop 10.0.3.1/32 => 00:00:0a:00:03:01 1
 table_add ipv4_lpm set_nhop 10.0.3.2/32 => 00:00:0a:00:03:02 2
```

`monitor_bw.sh`:

```
 #!/bin/bash

 CLI_PATH=/usr/local/bin/simple_switch_CLI

 bytes_s1s2=0
 pre_bytes_s1s2=0
 bytes_s2s3=0
 pre_bytes_s2s3=0
 bytes_s1s3=0
 pre_bytes_s1s3=0

 #get current unix time in milliseconds
 prev_time=`date +%s%N | cut -b1-13`

 while true; do
 	bytes_s1s2=`echo counter_read egressPortCounter 3 | $CLI_PATH --thrift-port 9090 | grep egressPortCounter | tr '=' ' ' | tr ')' ' ' | awk '{print $6}'`    

 	bytes_s2s3=`echo counter_read egressPortCounter 4 | $CLI_PATH --thrift-port 9091 | grep egressPortCounter | tr '=' ' ' | tr ')' ' ' | awk '{print $6}'` 

 	bytes_s1s3=`echo counter_read egressPortCounter 2 | $CLI_PATH --thrift-port 9090 | grep egressPortCounter | tr '=' ' ' | tr ')' ' ' | awk '{print $6}'`    

 	now=`date +%s%N | cut -b1-13` 
 
 	if [ ! $pre_bytes_s1s2 -eq 0 ];then
 		thr=`echo "scale=2;($bytes_s1s2-$pre_bytes_s1s2) * 8.0  / ($now-$pre_time)" | bc -l`
 		echo "BW consumption (s1-s2):" $thr "kbps"      
 	fi

 	if [ ! $pre_bytes_s2s3 -eq 0 ];then
 		thr=`echo "scale=2;($bytes_s2s3-$pre_bytes_s2s3) * 8.0  / ($now-$pre_time)" | bc -l`
 		echo "BW consumption (s2-s3):" $thr "kbps"      
 	fi

 	if [ ! $pre_bytes_s1s3 -eq 0 ];then
 		thr=`echo "scale=2;($bytes_s1s3-$pre_bytes_s1s3) * 8.0  / ($now-$pre_time)" | bc -l`
 		echo "BW consumption (s1-s3):" $thr "kbps"      
 	fi

 	pre_bytes_s1s2=$bytes_s1s2
 	pre_bytes_s2s3=$bytes_s2s3
 	pre_bytes_s1s3=$bytes_s1s3
 	pre_time=$now
 	sleep 1
 done
```

![](https://i.imgur.com/vwo9Xzz.png)


---![](https://i.imgur.com/zdvAxQQ.png)


## Reference

1. https://www.dropbox.com/sh/9qzkarvkwehgn9q/AAC7bRd4iRZGzjY2CNrzRALVa/p4-utils-example/monitor_qlen?dl=0&subfolder_nav_tracking=1
2. https://www.dropbox.com/sh/9qzkarvkwehgn9q/AAAbkvWk1ncN-VTVC2nESmnva/p4-utils-example/monitor_linkbw?dl=0&subfolder_nav_tracking=1
3. https://firebasestorage.googleapis.com/v0/b/gitbook-28427.appspot.com/o/assets%2F-MU7EdDCmxVnXY6VZf4s%2F-MbhgN_2rlw0NOQ5gjQo%2F-Mbhgax8c08-AhQiYYSw%2F2p4.tar.gz?alt=media&token=841c33f6-e286-43d7-b683-25d0747a304b