In article #003 and #004 you learned how RARE/freeRouter is controlling a P4 dataplane (BMv2 or TOFINO virtual model). We also demonstrated that this setup could be integrated into real networks. However, these P4 dataplanes are not suitable for day to day real operation as it have inherent software limitations. While freeRouter native software dataplane presents the advantage to get the entire feature set and is sufficient to handle a home network traffic load, we investigated a way to improve dataplane performance. In that context we considered to study:

Requirement

Basic Linux/Unix knowledge
Basic networking knowledge

Overview

However, XDP model was not complete enough in order to compile router.p4 and we could not generate the corresponding kernel bypass code with ELTE T4P4S based on BMv2 V1Model.p4. (A GitHub issue is still pending). In that context, Csaba freeRouter lead developer decided to develop P4Emu a software dataplane that has the particularity to:

understand freeRouter control plane message meant to be addressed to a P4 dataplane
thus maintaining the control plane decoupled to the dataplane as it was the case with BMv2 and BF_SWITCHD

One would ask: Why write yet another software dataplane as freeRouter has already a working native software dataplane. This is a very good and valid question. The answer boils down in:

"decoupling control plane from the dataplane"

We will see in subsequent article how P4Emu unlock new valid uses cases.

Article objective

In this article we'll using freeRouter setup deployed in #004 and replace bf_switchd providing freeRouter INTEL/BAREFOOT TOFINO's dataplane by P4Emu/pcap.

It is important to note that though its name, P4Emu/pcap is not emulating V1Model. P4Emu is emulating router.p4 packet processing logic and uses a packet forwarding library to effectively transmit packets at specific ingress port to the right egress port defined by freeRouter control plane message.

Diagram

[ #005 ] - Cookbook

Install your favorite operating system

In our example we will use the same debian stable image (buster) installed as a VirtualBox VM as in #002.

and we add a bridge network interface to or laptop RJ45 connection.

Install FreeRouter as per #001 article: "Create freeRouter environment"

flush enp0s3 so that it can be controlled by dpdk

ip addr flush enp0s3

Add out of band management enp0s8 with Virtualbox

You can add a second Host-only interface (enp0s8) in VirtualBox in order to connect the ubuntu focal VM guest as you might lose connection when you flushed enp0s3.

mkdir -p ~/freeRouter/bin ~/freeRouter/lib ~/freeRouter/etc ~/freeRouter/log
cd ~/freeRouter/lib
wget http://freerouter.nop.hu/rtr.jar

Update & Upgrade system

tree freeRouter
freeRouter
├── bin   # binary files      
├── etc   # configuration files      
├── lib   # library files      
└── log   # log files

Install freeRouter net-tools

get freeRouter net-tools tarball

wget freerouter.nop.hu/rtr.tar

Install build tools

tar xvf rtr.tar -C ~/freeRouter/bin/

For those you would like to rebuild these binaries you can find the compilation shell script in freeRouter cloned git repository in: ~/freeRouter/src/native/c.sh

Create configuration files for router: freerouter

FreeRouter uses 2 configuration files in order to run, let's write these configuration files for R1 in ~/freeRouter/etc

freeRouter hardware configuration file: pcap-freerouter-hw.txt

int eth0 eth 0000.1111.00fb 127.0.0.1 22710 127.0.0.1 22709
tcp2vrf 2323 v1 23
tcp2vrf 9080 v1 9080

freeRouter software configuration file: pcap-freerouter-sw.txt

hostname pcap-freerouter
buggy
!
vrf definition v1
 exit
!
interface ethernet0
 description freerouter@P4_CPU_PORT[veth251]
 no shutdown
 no log-link-change
 exit
!
interface sdn1
 description freerouter@sdn1[enp0s3]
 mtu 9000
 vrf forwarding v1
 ipv4 address 192.168.0.131 255.255.255.0
 ipv6 address 2a01:e0a:159:2850::666 ffff:ffff:ffff:ffff::
 ipv6 enable
 no shutdown
 no log-link-change
 exit
!
!
!
!
!
!
!
!
!
!
!
!
!
!
server telnet tel
 security protocol telnet
 no exec authorization
 no login authentication
 vrf v1
 exit
!
server p4lang p4
 export-vrf v1 1
 export-port sdn1 1 0
 interconnect ethernet0
 vrf v1
 exit
!
end

Launch freeRouter control plane alongside P4Emu/pcap dataplane

Setup P4Emu dataplane communication channel via veth pair and interface adjustment (disable IPv6 at VM guest level, MTU 10240, disable TCP offload etc.)

echo 1 > /proc/sys/net/ipv6/conf/all/disable_ipv6
echo 1 > /proc/sys/net/ipv6/conf/default/disable_ipv6

ip link add veth251 type veth peer name veth250
ip link set veth250  up 
ip link set veth251  up 

ifconfig enp0s3 promisc
ifconfig veth250 promisc
ifconfig veth251 promisc

ip link set dev veth250 up mtu 10240
ip link set dev veth251 up mtu 10240
ip link set dev enp0s3 up mtu 10240
export TOE_OPTIONS="rx tx sg tso ufo gso gro lro rxvlan txvlan rxhash"

for TOE_OPTION in $TOE_OPTIONS; do
    /sbin/ethtool --offload veth250 "$TOE_OPTION" off &> /dev/null
    /sbin/ethtool --offload veth251 "$TOE_OPTION" off &> /dev/null
    /sbin/ethtool --offload enp0s3 "$TOE_OPTION" off &> /dev/null
done

freeRouter launch with supplied pcap-freerouter-hw.txt and pcap-freerouter-sw.txt with a console prompt

java -jar lib/rtr.jar routersc etc/pcap-freerouter-hw.txt etc/pcap-freerouter-sw.txt
info cfg.cfgInit.doInit:cfgInit.java:556 booting
info cfg.cfgInit.doInit:cfgInit.java:680 initializing hardware
info cfg.cfgInit.doInit:cfgInit.java:687 applying defaults
info cfg.cfgInit.doInit:cfgInit.java:695 applying configuration
info cfg.cfgInit.doInit:cfgInit.java:721 done
welcome
line ready
pcap-freerouter#

launch freeRouter pcapInt in order to stitch control plane and P4Emu/pcap dataplane communication

cd ~/freeRouter/bin
./pcapInt.bin veth251 22709 127.0.0.1 22710 127.0.0.1
binded to local port 127.0.0.1 22709.
will send to 127.0.0.1 22710.
pcap version: libpcap version 1.8.1
opening interface veth251 with pcap1.x api
serving others
>

Launch P4Emu/pcap software dataplane

sudo ./p4emu.bin  127.0.0.1 9080 0 veth250 enp0s3
cpu port is #0 of 2...
pcap version: libpcap version 1.8.1
connecting 127.0.0.1 9080.
opening interface veth250.
opening interface enp0s3.
rx: 'myaddr4' 'add' '224.0.0.0' '4' '0' '1' '' 
rx: 'myaddr4' 'add' '255.255.255.255' '32' '0' '1' '' 
rx: 'myaddr6' 'add' 'ff00::' '8' '0' '1' '' 
rx: 'myaddr4' 'add' '192.168.0.0' '24' '-1' '1' '' 
rx: 'myaddr4' 'add' '192.168.0.131' '32' '-1' '1' '' 
rx: 'myaddr6' 'add' '2a01:e0a:159:2850::' '64' '-1' '1' '' 
rx: 'myaddr6' 'add' '2a01:e0a:159:2850::666' '128' '-1' '1' '' 
rx: 'myaddr6' 'add' 'fe80::' '64' '-1' '1' '' 
rx: 'mylabel4' 'add' '615589' '1' '' 
rx: 'mylabel6' 'add' '1036348' '1' '' 
rx: 'state' '1' '1' '0' '' 
rx: 'mtu' '1' '9000' '' 
rx: 'portvrf' 'add' '1' '1' '' 
rx: 'keepalive' '' 
rx: 'keepalive' '' 
rx: 'neigh6' 'add' '11120' 'fe80::224:d4ff:fea0:cd3' '00:24:d4:a0:0c:d3' '1' '00:72:3e:18:1b:6f' '1' '' 
rx: 'keepalive' '' 
rx: 'keepalive' '' 
rx: 'keepalive' '' 
rx: 'neigh4' 'add' '29738' '192.168.0.254' '00:24:d4:a0:0c:d3' '1' '00:72:3e:18:1b:6f' '1' '' 
rx: 'keepalive' '' 
rx: 'neigh4' 'add' '40470' '192.168.0.62' 'e0:3f:49:6d:18:99' '1' '00:72:3e:18:1b:6f' '1' '' 
rx: 'keepalive' '' 
rx: 'keepalive' '' 
rx: 'keepalive' '' 
rx: 'keepalive' '' 
rx: 'keepalive' '' 
rx: 'neigh6' 'add' '45820' '2a01:e0a:159:2850:e23f:49ff:fe6d:1899' 'e0:3f:49:6d:18:99' '1' '00:72:3e:18:1b:6f' '1' '' 
rx: 'keepalive' '' 
rx: 'neigh6' 'add' '49055' 'fe80::e23f:49ff:fe6d:1899' 'e0:3f:49:6d:18:99' '1' '00:72:3e:18:1b:6f' '1' '' 
rx: 'neigh6' 'add' '33334' '2a01:e0a:159:2850::
...

Verification

Check telnet access for freerouter@2323

FreeRouter telnet access from Virtualbox VM guest via port 2323

telnet localhost 2323
Trying ::1...
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
welcome
line ready
pcap-freerouter#

Check running-config

freerouter running configuration

pcap-freerouter#term len 0                                                       
pcap-freerouter#sh run                                                           
hostname pcap-freerouter
buggy
!
vrf definition v1
 exit
!
interface ethernet0
 description freerouter@P4_CPU_PORT[veth251]
 no shutdown
 no log-link-change
 exit
!
interface sdn1
 description freerouter@sdn1[enp0s3]
 mtu 9000
 macaddr 0072.3e18.1b6f
 vrf forwarding v1
 ipv4 address 192.168.0.131 255.255.255.0
 ipv6 address 2a01:e0a:159:2850::666 ffff:ffff:ffff:ffff::
 ipv6 enable
 no shutdown
 no log-link-change
 exit
!
!
!
!
!
!
!
!
!
!
!
!
!
!
server telnet tel
 security protocol telnet
 no exec authorization
 no login authentication
 vrf v1
 exit
!
server p4lang p4
 export-vrf v1 1
 export-port sdn1 1 0
 interconnect ethernet0
 vrf v1
 exit
!
end

Check control plane is communicating with bf_switchd p4 dataplane

pcap-freerouter#show interfaces summary                                          
interface  state  tx    rx      drop
ethernet0  up     8739  404545  0
sdn1       up     8535  400013  0

Connectivity IPv4/IPv6 check for freeRouter

Ping IPv4 from freerouter -> LAN router gateway

pcap-freerouter#ping 192.168.0.254 /vrf v1                                       
pinging 192.168.0.254, src=null, cnt=5, len=64, tim=1000, ttl=255, tos=0, sweep=false
.!!!!
result=80%, recv/sent/lost=4/5/1, rtt min/avg/max/total=1/1/2/1011

Ping IPv4 from freerouter -> LAN server

pcap-freerouter#ping 192.168.0.62 /vrf v1                                        
pinging 192.168.0.62, src=null, cnt=5, len=64, tim=1000, ttl=255, tos=0, sweep=false
.!!!!
result=80%, recv/sent/lost=4/5/1, rtt min/avg/max/total=1/1/2/1005

Please observe the 1st ICMP packet loss that triggered ARP learning for respectively 192.168.0.254 and 192.168.0.62.

IPv4 arp check

pcap-freerouter#sh ipv4 arp sdn1                                                 
mac             address        time      static
e03f.496d.1899  192.168.0.62   00:00:57  false    <----- Host server
0024.d4a0.0cd3  192.168.0.254  00:00:57  false    <----- LAN gateway

Ping IPv6 from freerouter -> LAN router

pcap-freerouter#ping 2a01:e0a:159:2850::1  /vrf v1                               
pinging 2a01:e0a:159:2850::1, src=null, cnt=5, len=64, tim=1000, ttl=255, tos=0, sweep=false
.!!!!
result=80%, recv/sent/lost=4/5/1, rtt min/avg/max/total=0/1/2/1004

Ping IPv6 from freerouter -> Host server and SSH connection test

pcap-freerouter#ping 2a01:e0a:159:2850:e23f:49ff:fe6d:1899  /vrf v1              
pinging 2a01:e0a:159:2850:e23f:49ff:fe6d:1899, src=null, cnt=5, len=64, tim=1000, ttl=255, tos=0, sweep=false
.!!!!
result=80%, recv/sent/lost=4/5/1, rtt min/avg/max/total=1/1/1/1006

Please observe the 1st ICMP packet loss that triggered IPv6 neighbor discovery for respectively 2a01:e0a:159:2850::1 and 2a01:e0a:159:2850:e23f:49ff:fe6d:1899

IPv6 neighbor discovery check

pcap-freerouter#show ipv6 neighbors sdn1                                         
mac             address                                time      static  router
0024.d4a0.0cd3  2a01:e0a:159:2850::1                   00:00:53  false   false
e03f.496d.1899  2a01:e0a:159:2850:e23f:49ff:fe6d:1899  00:00:53  false   false
0024.d4a0.0cd3  fe80::224:d4ff:fea0:cd3                00:00:53  false   false
e03f.496d.1899  fe80::e23f:49ff:fe6d:1899              00:00:53  false   false

Initiate IPv4 ssh from freerouter -> LAN router gateway

pcap-freerouter#ssh 192.168.0.62 /vrf v1 /user my-nas                           
 - connecting to 192.168.0.62 22
password: *******
                
 - securing connection

Last login: Mon Jul  6 15:05:38 2020 from 192.168.0.77
FreeBSD 11.3-RELEASE-p9 (FreeNAS.amd64) #0 r325575+588899735f7(HEAD): Mon Jun  1 15:04:31 EDT 2020

        FreeNAS (c) 2009-2020, The FreeNAS Development Team
        All rights reserved.
        FreeNAS is released under the modified BSD license.

        For more information, documentation, help or support, go here:
        http://freenas.org
Welcome to FreeNAS
MY-NAS%

Initiate IPv6 ssh from freerouter -> LAN router gateway

pcap-freerouter#ssh 2a01:e0a:159:2850:e23f:49ff:fe6d:1899  /vrf v1 /user my-nas 
 - connecting to 2a01:e0a:159:2850:e23f:49ff:fe6d:1899 22
password: *******
                
 - securing connection

Last login: Tue Jul  7 16:01:54 2020 from 2a01:e0a:159:2850::666
FreeBSD 11.3-RELEASE-p9 (FreeNAS.amd64) #0 r325575+588899735f7(HEAD): Mon Jun  1 15:04:31 EDT 2020

        FreeNAS (c) 2009-2020, The FreeNAS Development Team
        All rights reserved.
        FreeNAS is released under the modified BSD license.

        For more information, documentation, help or support, go here:
        http://freenas.org
Welcome to FreeNAS
MY-NAS%

Conclusion

In this article you:

had a demonstration of how to integrate freeRouter into a local area network (Similar to article #002)
However instead of using bmv2 or TOFINO we used a P4Emu/pcap dataplane
communication between freeRouter control plane and P4Emu/pcap is ensured by pcapInt via veth pair [ veth250 - veth251 ]
In this example the freeRouter with P4Emu/pcap has only 1 dataplane interface that is bound to enp0s3 VM interface exposed to the local network as a bridged interface

[ #005 ] RARE/FreeRouter-101 - key take-away

FreeRouter is using UNIX socket in order to forward packet dedicated to control plane + dataplane communication.

This essential paradigm is used to ensure communication between freeRouter and P4Emu/pcap dataplane. It is ensured by pcapInt binary from freeRouter net-tools that will bind freeRouter socket (veth251@locathost:22710) to a virtual network interface (veth250@localhost:22709) connected to CPU_PORT 0.

freeRouter is the control plane for P4Emu/pcap dataplane

freeRouter is doing all the control plane route computation and write/modify/remove message entry P4 entries are created/modified/removed accordingly from P4Emu/pcap tables. Although the name is P4Emu, it does not emulate BMv2 V1Model.p4, but rather router.p4

In this setup the combination of freeRouter/pcap deliver a solution for SOHO network having 1GE links

However, 1GE traffic rate require 50% of one CPU thread. Nevertheless, traffic rate achieved is higher with P4Emu/pcap than freeRouter native software packet forwarding software.

In subsequent article we will see how we can improve the latter requirement implied by P4Emu/pcap.

Blog

RARE/FreeRouter-101 [ #005 ] - "I can also understand freeRouter talking to BMv2 or BF_SWITCHD !"