Added quality of service(QOS) via Differentiated services (#330)

* Added quality of service(QOS) via Differentiated services

* Altered to classify network traffic in Ingress

* Updated readme for QoS
This commit is contained in:
nikkytub 2020-03-13 10:35:35 +05:30 committed by GitHub
parent 05174e8a95
commit 971ceb7d90
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
12 changed files with 896 additions and 0 deletions

View File

@ -25,6 +25,7 @@ you get started with P4 programming, organized into several modules:
* [Source Routing](./exercises/source_routing)
* [Calculator](./exercises/calc)
* [Load Balancing](./exercises/load_balance)
* [Quality of Service](./exercises/qos)
5. Stateful Packet Processing
* [Firewall](./exercises/firewall)

3
exercises/qos/Makefile Normal file
View File

@ -0,0 +1,3 @@
BMV2_SWITCH_EXE = simple_switch_grpc
include ../../utils/Makefile

After

Width:  |  Height:  |  Size: 67 B

166
exercises/qos/README.md Normal file
View File

@ -0,0 +1,166 @@
# Implementing QOS
## Introduction
The objective of this tutorial is to extend basic L3 forwarding with
an implementation of Quality of Service (QOS) using Differentiated Services.
Diffserv is simple and scalable. It classifies and manages network traffic and provides QOS on modern IP networks.
As before, we have already defined the control plane rules for
routing, so you only need to implement the data plane logic of your P4
program.
> **Spoiler alert:** There is a reference solution in the `solution`
> sub-directory. Feel free to compare your implementation to the reference.
## Step 1: Run the (incomplete) starter code
The directory with this README also contains a skeleton P4 program,
`qos.p4`, which initially implements L3 forwarding. Your job (in the
next step) will be to extend it to properly set the `diffserv` bits.
Before that, let's compile the incomplete `qos.p4` and bring up a
network in Mininet to test its behavior.
1. In your shell, run:
```bash
make
```
This will:
* compile `qos.p4`, and
* start a Mininet instance with three switches (`s1`, `s2`, `s3`) configured
in a triangle. There are 5 hosts. `h1` and `h11` are connected to `s1`.
`h2` and `h22` are connected to `s2` and `h3` is connected to `s3`.
* The hosts are assigned IPs of `10.0.1.1`, `10.0.2.2`, etc
(`10.0.<Switchid>.<hostID>`).
* The control plane programs the P4 tables in each switch based on
`sx-runtime.json`
2. We want to send traffic from `h1` to `h2`. If we
capture packets at `h2`, we should see the right diffserv value.
![Setup](setup.png)
3. You should now see a Mininet command prompt. Open two terminals
for `h1` and `h2`, respectively:
```bash
mininet> xterm h1 h2
```
4. In `h2`'s XTerm, start the server that captures packets:
```bash
./receive.py
```
5. In `h1`'s XTerm, send one packet per second to `h2` using send.py
say for 30 seconds.
To send UDP:
```bash
./send.py --p=UDP --des=10.0.2.2 --m="P4 is cool" --dur=30
```
To send TCP:
```bash
./send.py --p=TCP --des=10.0.2.2 --m="P4 is cool" --dur=30
```
The message "P4 is cool" should be received in `h2`'s xterm,
6. At `h2`, the `ipv4.tos` field (DiffServ+ECN) is always 1
7. type `exit` to close each XTerm window
Your job is to extend the code in `qos.p4` to implement the diffserv logic
for setting the diffserv flag.
## Step 2: Implement Diffserv
The `qos.p4` file contains a skeleton P4 program with key pieces of
logic replaced by `TODO` comments. These should guide your
implementation---replace each `TODO` with logic implementing the
missing piece.
First we have to change the ipv4_t header by splitting the TOS field
into DiffServ and ECN fields. Remember to update the checksum block
accordingly. Then, in the egress control block we must compare the
protocol in IP header with IP protocols. Based on the traffic classes
and priority, the `diffserv` flag will be set.
A complete `qos.p4` will contain the following components:
1. Header type definitions for Ethernet (`ethernet_t`) and IPv4 (`ipv4_t`).
2. Parsers for Ethernet, IPv4,
3. An action to drop a packet, using `mark_to_drop()`.
4. An action (called `ipv4_forward`), which will:
1. Set the egress port for the next hop.
2. Update the ethernet destination address with the address of
the next hop.
3. Update the ethernet source address with the address of the switch.
4. Decrement the TTL.
5. An ingress control block that checks the protocols and sets the ipv4.diffserv.
6. A deparser that selects the order in which headers are inserted into the outgoing
packet.
7. A `package` instantiation supplied with the parser, control,
checksum verification and recomputation and deparser.
## Step 3: Run your solution
Follow the instructions from Step 1. This time, when your message from
`h1` is delivered to `h2`, you should see `tos` values change from 0x1
to 0xb9 for UDP and 0xb1 for TCP. It depends upon the action you choose
in Ingress processing.
To easily track the `tos` values you may want to redirect the output
of `h2` to a file by running the following for `h2`
```bash
./receive.py > h2.log
```
and just print the `tos` values `grep tos h2.log` in a separate window
```
tos = 0xb9
tos = 0xb9
tos = 0xb9
tos = 0xb9
tos = 0xb9
tos = 0xb9
tos = 0xb9
tos = 0xb9
tos = 0xb1
tos = 0xb1
tos = 0xb1
tos = 0xb1
tos = 0xb1
tos = 0xb1
tos = 0xb1
tos = 0xb1
```
### Food for thought
How can we let the user use other protocols?
### Troubleshooting
There are several ways that problems might manifest:
1. `qos.p4` fails to compile. In this case, `make` will report the
error emitted from the compiler and stop.
2. `qos.p4` compiles but does not support the control plane rules in
the `sX-runtime.json` files that `make` tries to install using
a Python controller. In this case, `make` will log the controller output
in the `logs` directory. Use these error messages to fix your `qos.p4`
implementation.
3. `qos.p4` compiles, and the control plane rules are installed, but
the switch does not process packets in the desired way. The
`/tmp/p4s.<switch-name>.log` files contain trace messages
describing how each switch processes each packet. The output is
detailed and can help pinpoint logic errors in your implementation.
The `build/<switch-name>-<interface-name>.pcap` also contains the
pcap of packets on each interface. Use `tcpdump -r <filename> -xxx`
to print the hexdump of the packets.
#### Cleaning up Mininet
In the latter two cases above, `make` may leave a Mininet instance
running in the background. Use the following command to clean up
these instances:
```bash
make stop
```

202
exercises/qos/qos.p4 Normal file
View File

@ -0,0 +1,202 @@
/* -*- P4_16 -*- */
#include <core.p4>
#include <v1model.p4>
const bit<16> TYPE_IPV4 = 0x800;
/* IP protocols */
const bit<8> IP_PROTOCOLS_ICMP = 1;
const bit<8> IP_PROTOCOLS_IGMP = 2;
const bit<8> IP_PROTOCOLS_IPV4 = 4;
const bit<8> IP_PROTOCOLS_TCP = 6;
const bit<8> IP_PROTOCOLS_UDP = 17;
const bit<8> IP_PROTOCOLS_IPV6 = 41;
const bit<8> IP_PROTOCOLS_GRE = 47;
const bit<8> IP_PROTOCOLS_IPSEC_ESP = 50;
const bit<8> IP_PROTOCOLS_IPSEC_AH = 51;
const bit<8> IP_PROTOCOLS_ICMPV6 = 58;
const bit<8> IP_PROTOCOLS_EIGRP = 88;
const bit<8> IP_PROTOCOLS_OSPF = 89;
const bit<8> IP_PROTOCOLS_PIM = 103;
const bit<8> IP_PROTOCOLS_VRRP = 112;
/*************************************************************************
*********************** 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: split tos to two fields 6 bit diffserv and 2 bit ecn
*/
header ipv4_t {
bit<4> version;
bit<4> ihl;
bit<8> tos;
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;
}
struct metadata {
}
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) {
TYPE_IPV4: parse_ipv4;
default: accept;
}
}
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);
}
action ipv4_forward(macAddr_t dstAddr, egressSpec_t port) {
standard_metadata.egress_spec = port;
hdr.ethernet.srcAddr = hdr.ethernet.dstAddr;
hdr.ethernet.dstAddr = dstAddr;
hdr.ipv4.ttl = hdr.ipv4.ttl - 1;
}
/* TODO: Implement actions for different traffic classes */
table ipv4_lpm {
key = {
hdr.ipv4.dstAddr: lpm;
}
actions = {
ipv4_forward;
drop;
NoAction;
}
size = 1024;
default_action = NoAction();
}
/* TODO: set hdr.ipv4.diffserv on the basis of protocol */
apply {
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) {
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) {
apply {
/* TODO: replace tos with diffserv and ecn */
update_checksum(
hdr.ipv4.isValid(),
{ hdr.ipv4.version,
hdr.ipv4.ihl,
hdr.ipv4.tos,
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.ipv4);
}
}
/*************************************************************************
*********************** S W I T C H *******************************
*************************************************************************/
V1Switch(
MyParser(),
MyVerifyChecksum(),
MyIngress(),
MyEgress(),
MyComputeChecksum(),
MyDeparser()
) main;

21
exercises/qos/receive.py Executable file
View File

@ -0,0 +1,21 @@
#!/usr/bin/env python
import sys
from scapy.all import sniff, get_if_list
def handle_pkt(pkt):
print "got a packet"
pkt.show2()
sys.stdout.flush()
def main():
iface = 'eth0'
print "sniffing on %s" % iface
sys.stdout.flush()
sniff(iface=iface, prn=lambda x: handle_pkt(x))
if __name__ == '__main__':
main()

View File

@ -0,0 +1,52 @@
{
"target": "bmv2",
"p4info": "build/qos.p4.p4info.txt",
"bmv2_json": "build/qos.json",
"table_entries": [
{
"table": "MyIngress.ipv4_lpm",
"match": {
"hdr.ipv4.dstAddr": ["10.0.1.1", 32]
},
"action_name": "MyIngress.ipv4_forward",
"action_params": {
"dstAddr": "08:00:00:00:01:01",
"port": 2
}
},
{
"table": "MyIngress.ipv4_lpm",
"match": {
"hdr.ipv4.dstAddr": ["10.0.1.11", 32]
},
"action_name": "MyIngress.ipv4_forward",
"action_params": {
"dstAddr": "08:00:00:00:01:11",
"port": 1
}
},
{
"table": "MyIngress.ipv4_lpm",
"match": {
"hdr.ipv4.dstAddr": ["10.0.2.0", 24]
},
"action_name": "MyIngress.ipv4_forward",
"action_params": {
"dstAddr": "08:00:00:00:02:00",
"port": 3
}
},
{
"table": "MyIngress.ipv4_lpm",
"match": {
"hdr.ipv4.dstAddr": ["10.0.3.0", 24]
},
"action_name": "MyIngress.ipv4_forward",
"action_params": {
"dstAddr": "08:00:00:00:03:00",
"port": 4
}
}
]
}

View File

@ -0,0 +1,51 @@
{
"target": "bmv2",
"p4info": "build/qos.p4.p4info.txt",
"bmv2_json": "build/qos.json",
"table_entries": [
{
"table": "MyIngress.ipv4_lpm",
"match": {
"hdr.ipv4.dstAddr": ["10.0.2.2", 32]
},
"action_name": "MyIngress.ipv4_forward",
"action_params": {
"dstAddr": "08:00:00:00:02:02",
"port": 2
}
},
{
"table": "MyIngress.ipv4_lpm",
"match": {
"hdr.ipv4.dstAddr": ["10.0.2.22", 32]
},
"action_name": "MyIngress.ipv4_forward",
"action_params": {
"dstAddr": "08:00:00:00:02:22",
"port": 1
}
},
{
"table": "MyIngress.ipv4_lpm",
"match": {
"hdr.ipv4.dstAddr": ["10.0.1.0", 24]
},
"action_name": "MyIngress.ipv4_forward",
"action_params": {
"dstAddr": "08:00:00:00:01:00",
"port": 3
}
},
{
"table": "MyIngress.ipv4_lpm",
"match": {
"hdr.ipv4.dstAddr": ["10.0.3.0", 24]
},
"action_name": "MyIngress.ipv4_forward",
"action_params": {
"dstAddr": "08:00:00:00:03:00",
"port": 4
}
}
]
}

View File

@ -0,0 +1,40 @@
{
"target": "bmv2",
"p4info": "build/qos.p4.p4info.txt",
"bmv2_json": "build/qos.json",
"table_entries": [
{
"table": "MyIngress.ipv4_lpm",
"match": {
"hdr.ipv4.dstAddr": ["10.0.3.3", 32]
},
"action_name": "MyIngress.ipv4_forward",
"action_params": {
"dstAddr": "08:00:00:00:03:03",
"port": 1
}
},
{
"table": "MyIngress.ipv4_lpm",
"match": {
"hdr.ipv4.dstAddr": ["10.0.1.0", 24]
},
"action_name": "MyIngress.ipv4_forward",
"action_params": {
"dstAddr": "08:00:00:00:01:00",
"port": 2
}
},
{
"table": "MyIngress.ipv4_lpm",
"match": {
"hdr.ipv4.dstAddr": ["10.0.2.0", 24]
},
"action_name": "MyIngress.ipv4_forward",
"action_params": {
"dstAddr": "08:00:00:00:02:00",
"port": 3
}
}
]
}

56
exercises/qos/send.py Executable file
View File

@ -0,0 +1,56 @@
#!/usr/bin/env python
import argparse
import socket
from scapy.all import sendp, send, hexdump, get_if_list, get_if_hwaddr
from scapy.all import Ether, IP, UDP, TCP
from time import sleep
def get_if():
iface = None
for i in get_if_list():
if "eth0" in i:
iface = i
break
if not iface:
print "Cannot find eth0 interface"
exit(1)
return iface
def main():
parser = argparse.ArgumentParser()
parser.add_argument("--p", help="Protocol name To send TCP/UDP etc packets", type=str)
parser.add_argument("--des", help="IP address of the destination", type=str)
parser.add_argument("--m", help="Raw Message", type=str)
parser.add_argument("--dur", help="in seconds", type=str)
args = parser.parse_args()
if args.p and args.des and args.m and args.dur:
addr = socket.gethostbyname(args.des)
iface = get_if()
if args.p == 'UDP':
pkt = Ether(src=get_if_hwaddr(iface), dst="ff:ff:ff:ff:ff:ff") / IP(dst=addr, tos=1) / UDP(dport=4321, sport=1234) / args.m
pkt.show2()
try:
for i in range(int(args.dur)):
sendp(pkt, iface=iface)
sleep(1)
except KeyboardInterrupt:
raise
elif args.p == 'TCP':
pkt = Ether(src=get_if_hwaddr(iface), dst="ff:ff:ff:ff:ff:ff") / IP(dst=addr, tos=1) / TCP() / args.m
pkt.show2()
try:
for i in range(int(args.dur)):
sendp(pkt, iface=iface)
sleep(1)
except KeyboardInterrupt:
raise
if __name__ == '__main__':
main()

BIN
exercises/qos/setup.png Normal file

Binary file not shown.

After

Width:  |  Height:  |  Size: 101 KiB

View File

@ -0,0 +1,276 @@
/* -*- P4_16 -*- */
#include <core.p4>
#include <v1model.p4>
const bit<16> TYPE_IPV4 = 0x800;
/* IP protocols */
const bit<8> IP_PROTOCOLS_ICMP = 1;
const bit<8> IP_PROTOCOLS_IGMP = 2;
const bit<8> IP_PROTOCOLS_IPV4 = 4;
const bit<8> IP_PROTOCOLS_TCP = 6;
const bit<8> IP_PROTOCOLS_UDP = 17;
const bit<8> IP_PROTOCOLS_IPV6 = 41;
const bit<8> IP_PROTOCOLS_GRE = 47;
const bit<8> IP_PROTOCOLS_IPSEC_ESP = 50;
const bit<8> IP_PROTOCOLS_IPSEC_AH = 51;
const bit<8> IP_PROTOCOLS_ICMPV6 = 58;
const bit<8> IP_PROTOCOLS_EIGRP = 88;
const bit<8> IP_PROTOCOLS_OSPF = 89;
const bit<8> IP_PROTOCOLS_PIM = 103;
const bit<8> IP_PROTOCOLS_VRRP = 112;
/*************************************************************************
*********************** 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;
}
header ipv4_t {
bit<4> version;
bit<4> ihl;
bit<6> diffserv;
bit<2> ecn;
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;
}
struct metadata {
}
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) {
TYPE_IPV4: parse_ipv4;
default: accept;
}
}
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);
}
action ipv4_forward(macAddr_t dstAddr, egressSpec_t port) {
standard_metadata.egress_spec = port;
hdr.ethernet.srcAddr = hdr.ethernet.dstAddr;
hdr.ethernet.dstAddr = dstAddr;
hdr.ipv4.ttl = hdr.ipv4.ttl - 1;
}
/* Default Forwarding */
action default_forwarding() {
hdr.ipv4.diffserv = 0;
}
/* Expedited Forwarding */
action expedited_forwarding() {
hdr.ipv4.diffserv = 46;
}
/* Voice Admit */
action voice_admit() {
hdr.ipv4.diffserv = 44;
}
/* Assured Forwarding */
/* Class 1 Low drop probability */
action af_11() {
hdr.ipv4.diffserv = 10;
}
/* Class 1 Med drop probability */
action af_12() {
hdr.ipv4.diffserv = 12;
}
/* Class 1 High drop probability */
action af_13() {
hdr.ipv4.diffserv = 14;
}
/* Class 2 Low drop probability */
action af_21() {
hdr.ipv4.diffserv = 18;
}
/* Class 2 Med drop probability */
action af_22() {
hdr.ipv4.diffserv = 20;
}
/* Class 2 High drop probability */
action af_23() {
hdr.ipv4.diffserv = 22;
}
/* Class 3 Low drop probability */
action af_31() {
hdr.ipv4.diffserv = 26;
}
/* Class 3 Med drop probability */
action af_32() {
hdr.ipv4.diffserv = 28;
}
/* Class 3 High drop probability */
action af_33() {
hdr.ipv4.diffserv = 30;
}
/* Class 4 Low drop probability */
action af_41() {
hdr.ipv4.diffserv = 34;
}
/* Class 4 Med drop probability */
action af_42() {
hdr.ipv4.diffserv = 36;
}
/* Class 4 High drop probability */
action af_43() {
hdr.ipv4.diffserv = 38;
}
table ipv4_lpm {
key = {
hdr.ipv4.dstAddr: lpm;
}
actions = {
ipv4_forward;
drop;
NoAction;
}
size = 1024;
default_action = NoAction();
}
apply {
if (hdr.ipv4.isValid()) {
if (hdr.ipv4.protocol == IP_PROTOCOLS_UDP) {
expedited_forwarding();
}
else if (hdr.ipv4.protocol == IP_PROTOCOLS_TCP) {
voice_admit();
}
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) {
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) {
apply {
update_checksum(
hdr.ipv4.isValid(),
{ hdr.ipv4.version,
hdr.ipv4.ihl,
hdr.ipv4.diffserv,
hdr.ipv4.ecn,
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.ipv4);
}
}
/*************************************************************************
*********************** S W I T C H *******************************
*************************************************************************/
V1Switch(
MyParser(),
MyVerifyChecksum(),
MyIngress(),
MyEgress(),
MyComputeChecksum(),
MyDeparser()
) main;

View File

@ -0,0 +1,28 @@
{
"hosts": {
"h1": {"ip": "10.0.1.1/31", "mac": "08:00:00:00:01:01",
"commands":["route add default gw 10.0.1.0 dev eth0",
"arp -i eth0 -s 10.0.1.0 08:00:00:00:01:00"]},
"h11": {"ip": "10.0.1.11/31", "mac": "08:00:00:00:01:11",
"commands":["route add default gw 10.0.1.10 dev eth0",
"arp -i eth0 -s 10.0.1.10 08:00:00:00:01:00"]},
"h2": {"ip": "10.0.2.2/31", "mac": "08:00:00:00:02:02",
"commands":["route add default gw 10.0.2.3 dev eth0",
"arp -i eth0 -s 10.0.2.3 08:00:00:00:02:00"]},
"h22": {"ip": "10.0.2.22/31", "mac": "08:00:00:00:02:22",
"commands":["route add default gw 10.0.2.23 dev eth0",
"arp -i eth0 -s 10.0.2.23 08:00:00:00:02:00"]},
"h3": {"ip": "10.0.3.3/31", "mac": "08:00:00:00:03:03",
"commands":["route add default gw 10.0.3.2 dev eth0",
"arp -i eth0 -s 10.0.3.2 08:00:00:00:03:00"]}
},
"switches": {
"s1": { "runtime_json" : "s1-runtime.json" },
"s2": { "runtime_json" : "s2-runtime.json" },
"s3": { "runtime_json" : "s3-runtime.json" }
},
"links": [
["h1", "s1-p2"], ["h11", "s1-p1"], ["s1-p3", "s2-p3"], ["s1-p4", "s3-p2"],
["s3-p3", "s2-p4"], ["h2", "s2-p2"], ["h22", "s2-p1"], ["h3", "s3-p1"]
]
}