Aggregating multiple ISP links with ML PPP

This lab shows an example of aggregating multiple independent ISP links with MPD5.

Here is the concept:

And here is this lab detailed diagram:

This chapter will describe how to start each routers and configuring the 3 central routers.

More information on these BSDRP lab scripts available on How to build a BSDRP router lab.

Start the Virtual lab (example using bhyve):

# ./tools/BSDRP-lab-bhyve.sh -n 6
Setting-up a virtual lab with 6 VM(s):
- Working directory: /tmp/BSDRP
- Each VM has 1 core(s) and 512M RAM
- Emulated NIC: virtio-net
- Switch mode: bridge + tap
- 0 LAN(s) between all VM
- Full mesh Ethernet links between each VM
VM 1 has the following NIC:
- vtnet0 connected to VM 2
- vtnet1 connected to VM 3
- vtnet2 connected to VM 4
- vtnet3 connected to VM 5
- vtnet4 connected to VM 6
VM 2 has the following NIC:
- vtnet0 connected to VM 1
- vtnet1 connected to VM 3
- vtnet2 connected to VM 4
- vtnet3 connected to VM 5
- vtnet4 connected to VM 6
VM 3 has the following NIC:
- vtnet0 connected to VM 1
- vtnet1 connected to VM 2
- vtnet2 connected to VM 4
- vtnet3 connected to VM 5
- vtnet4 connected to VM 6
VM 4 has the following NIC:
- vtnet0 connected to VM 1
- vtnet1 connected to VM 2
- vtnet2 connected to VM 3
- vtnet3 connected to VM 5
- vtnet4 connected to VM 6
VM 5 has the following NIC:
- vtnet0 connected to VM 1
- vtnet1 connected to VM 2
- vtnet2 connected to VM 3
- vtnet3 connected to VM 4
- vtnet4 connected to VM 6
VM 6 has the following NIC:
- vtnet0 connected to VM 1
- vtnet1 connected to VM 2
- vtnet2 connected to VM 3
- vtnet3 connected to VM 4
- vtnet4 connected to VM 5
For connecting to VM'serial console, you can use:
- VM 1 : cu -l /dev/nmdm1B
- VM 2 : cu -l /dev/nmdm2B
- VM 4 : cu -l /dev/nmdm4B
- VM 3 : cu -l /dev/nmdm3B
- VM 5 : cu -l /dev/nmdm5B
- VM 6 : cu -l /dev/nmdm6B

Router 2 is configured for rate-limiting traffic at 1 Mb/s on interface to/from R1.

sysrc hostname=R2
sysrc ifconfig_vtnet0="inet 10.0.12.2/24"
sysrc ifconfig_vtnet3="inet 10.0.25.2/24"
sysrc defaultrouter="10.0.25.5"
sysrc firewall_enable=YES
sysrc firewall_script="/etc/ipfw.rules"

cat > /etc/ipfw.rules <<EOF
#!/bin/sh
fwcmd="/sbin/ipfw"
kldstat -q -m dummynet || kldload dummynet
# Flush out the list before we begin.
${fwcmd} -f flush
${fwcmd} pipe 10 config bw 1Mbit/s
${fwcmd} pipe 20 config bw 1Mbit/s
#Traffic getting out vtnet0 is limited to 1Mbit/s
${fwcmd} add 1000 pipe 10 all from any to any out via vtnet0
#Traffic getting int vtnet0 is limited to 1Mbit/s
${fwcmd} add 2000 pipe 20 all from any to any in via vtnet0
#We don't want to block traffic, only shape some
${fwcmd} add 3000 allow ip from any to any
EOF

service netif restart
service routing restart
service ipfw start
hostname R2
config save

Router 3 is configured for rate-limiting traffic at 20 Mb/s on interface to/from R1.

sysrc hostname=R3
sysrc ifconfig_vtnet0="inet 10.0.13.3/24"
sysrc ifconfig_vtnet3="inet 10.0.35.3/24"
sysrc defaultrouter="10.0.35.5"
sysrc firewall_enable=YES
sysrc firewall_script="/etc/ipfw.rules"

cat > /etc/ipfw.rules <<EOF
#!/bin/sh
fwcmd="/sbin/ipfw"
kldstat -q -m dummynet || kldload dummynet
# Flush out the list before we begin.
${fwcmd} -f flush
${fwcmd} pipe 10 config bw 2Mbit/s
${fwcmd} pipe 20 config bw 2Mbit/s
#Traffic getting out vtnet0 is limited to 2Mbit/s
${fwcmd} add 1000 pipe 10 all from any to any out via vtnet0
#Traffic getting int vtnet0 is limited to 2Mbit/s
${fwcmd} add 2000 pipe 20 all from any to any in via vtnet0
#We don't want to block traffic, only shape some
${fwcmd} add 3000 allow ip from any to any
EOF

service netif restart
service routing restart
service ipfw start
hostname R3
config save

Router 4 is configured for rate-limiting traffic at 3 Mb/s on interface to/from R1.

sysrc hostname=R4
sysrc ifconfig_vtnet0="inet 10.0.14.4/24"
sysrc ifconfig_vtnet3="inet 10.0.45.4/24"
sysrc defaultrouter="10.0.45.5"
sysrc firewall_enable=YES
sysrc firewall_script="/etc/ipfw.rules"

cat > /etc/ipfw.rules <<EOF
#!/bin/sh
fwcmd="/sbin/ipfw"
kldstat -q -m dummynet || kldload dummynet
# Flush out the list before we begin.
${fwcmd} -f flush
${fwcmd} pipe 10 config bw 3Mbit/s
${fwcmd} pipe 20 config bw 3Mbit/s
#Traffic getting out vtnet0 is limited to 3Mbit/s
${fwcmd} add 1000 pipe 10 all from any to any out via vtnet0
#Traffic getting int vten0 is limited to 3Mbit/s
${fwcmd} add 2000 pipe 20 all from any to any in via vtnet0
#We don't want to block traffic, only shape some
${fwcmd} add 3000 allow ip from any to any
EOF

service netif restart
service routing restart
service ipfw start
hostname R4
config save

Router 5 is the MLPPP server default gateway.

sysrc hostname=R5
sysrc ifconfig_vtnet1="inet 10.0.25.5/24"
sysrc ifconfig_vtnet2="inet 10.0.35.5/24"
sysrc ifconfig_vtnet3="inet 10.0.45.5/24"
sysrc ifconfig_vtnet4="inet 10.0.56.5/24"
sysrc static_routes="ISP1 ISP2 ISP3"
sysrc route_ISP1="-host 10.0.12.1 10.0.25.2"
sysrc route_ISP2="-host 10.0.13.1 10.0.35.3"
sysrc route_ISP3="-host 10.0.14.1 10.0.45.4"
service netif restart
service routing restart
hostname R5
config save

Router 6 is configured as a L2TP server.

sysrc hostname=R6
sysrc cloned_interfaces="lo1"
sysrc ifconfig_lo1="inet 10.6.6.6/32"
sysrc ifconfig_vtnet4="inet 10.0.56.62/24"
sysrc ifconfig_vtnet4_alias1="inet 10.0.56.63/32"
sysrc ifconfig_vtnet4_alias2="inet 10.0.56.64/32"
sysrc defaultrouter="10.0.56.5"
sysrc mpd_enable=YES
sysrc mpd_flags="-b -s ppp"
cat > /usr/local/etc/mpd5/mpd.conf <<EOF
default:
        load l2tp_server
l2tp_server:
        # IP Pool
        set ippool add pool1 10.0.16.10 10.0.16.100
        # Create bundle template named B
        create bundle template B
        # Enable IPv6
        set bundle enable ipv6cp
        # Configure interface
        set iface enable tcpmssfix
        # Handle IPCP configuration
        set ipcp yes vjcomp
        # Handle the IPCP configuration
        set ipcp ranges 10.0.16.1/24 ippool pool1
        # Create clonable link template named adsl1
        create link template L l2tp
        set link action bundle B
        set link enable multilink
        set link keep-alive 10 30
        set link mtu 1460
        set l2tp secret blah
        # SDSL1
        create link static sdsl1 L
        set l2tp self 10.0.56.62
        # set DOWNLOAD bandwidth of ISP1
        set link bandwidth 1000000
        set link enable incoming
        # SDSL2
        create link static sdsl2 L
        set l2tp self 10.0.56.63
        # set DOWNLOAD bandwidth of ISP2
        set link bandwidth 2000000
        set link enable incoming
        # SDSL3
        create link static sdsl3 L
        set l2tp self 10.0.56.64
        # set DOWNLOAD bandwidth of ISP3
        set link bandwidth 3000000
        set link enable incoming
EOF

service netif restart
service routing restart
service mpd5 start
hostname R6
config save

Router 1 is configured as a simple L2TP MLPPP client router connected to 3 Internet link.

sysrc hostname=R1
sysrc ifconfig_vtnet0="inet 10.0.12.1/24"
sysrc ifconfig_vtnet1="inet 10.0.13.1/24"
sysrc ifconfig_vtnet2="inet 10.0.14.1/24"
sysrc static_routes="ISP1 ISP2 ISP3"
sysrc route_ISP1="-host 10.0.56.62 10.0.12.2"
sysrc route_ISP2="-host 10.0.56.63 10.0.13.3"
sysrc route_ISP3="-host 10.0.56.64 10.0.14.4"
sysrc mpd_enable=YES
sysrc mpd_flags="-b -s ppp"
cat > /usr/local/etc/mpd5/mpd.conf <<EOF
default:
        load l2tp_client
l2tp_client:
        # Create the bundle
        create bundle template B
        # Enable IPv6
        set bundle enable ipv6cp
        # Enable TCP MSS fix
        set iface enable tcpmssfix
        # Use this interface as default route
        set iface route default
        # Disable IPCP configuration for the iperf test
        #set ipcp yes vjcomp
        # Create clonable template link ADSL1
        create link template L l2tp
        set link action bundle B
        set link enable multilink
        set link keep-alive 10 30
        set link mtu 1460
        set l2tp secret blah
        # Retry indefinitly to redial
        set link max-redial 0
        # SDSL1
        create link static sdsl1 L
        set l2tp peer 10.0.56.62
        # Configure the UPLOAD bandwidth
        set link bandwidth 1000000
        open link
        # SDSL2
        create link static sdsl2 L
        set l2tp peer 10.0.56.63
        # Configure the UPLOAD bandwidth
        set link bandwidth 2000000
        open link
        # SDSL3
        create link static sdsl3 L
        set l2tp peer 10.0.56.64
        # Configure the UPLOAD bandwidth
        set link bandwidth 3000000
        open link
EOF

service netif restart
service routing restart
service mpd5 start
hostname R1
config save

Start iperf in server mode on R6:

[root@R6]~# iperf3 -s
-----------------------------------------------------------
Server listening on 5201
-----------------------------------------------------------

Now check the correct limited bandwitdh for each different links:

• Link to R6 across R2: 1Mb/s
• Link to R6 across R3: 2Mb/s
• Link to R6 across R4: 3Mb/s

[root@R1]~# iperf3 -i 0 -c 10.0.56.62
Connecting to host 10.0.56.62, port 5201
[  5] local 10.0.12.1 port 30648 connected to 10.0.56.62 port 5201
[ ID] Interval           Transfer     Bitrate         Retr  Cwnd
[  5]   0.00-10.00  sec  1.21 MBytes  1.02 Mbits/sec    0   65.1 KBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec  1.21 MBytes  1.02 Mbits/sec    0             sender
[  5]   0.00-10.51  sec  1.19 MBytes   953 Kbits/sec                  receiver

iperf Done.
[root@R1]~# iperf3 -i 0 -c 10.0.56.63
Connecting to host 10.0.56.63, port 5201
[  5] local 10.0.13.1 port 13090 connected to 10.0.56.63 port 5201
[ ID] Interval           Transfer     Bitrate         Retr  Cwnd
[  5]   0.00-10.00  sec  2.35 MBytes  1.97 Mbits/sec    0   65.1 KBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec  2.35 MBytes  1.97 Mbits/sec    0             sender
[  5]   0.00-10.26  sec  2.33 MBytes  1.91 Mbits/sec                  receiver

iperf Done.
[root@R1]~# iperf3 -i 0 -c 10.0.56.64
Connecting to host 10.0.56.64, port 5201
[  5] local 10.0.14.1 port 57319 connected to 10.0.56.64 port 5201
[ ID] Interval           Transfer     Bitrate         Retr  Cwnd
[  5]   0.00-10.00  sec  3.48 MBytes  2.92 Mbits/sec    0   65.1 KBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec  3.48 MBytes  2.92 Mbits/sec    0             sender
[  5]   0.00-10.16  sec  3.46 MBytes  2.86 Mbits/sec                  receiver

iperf Done.

The aggregated link bandwidth should be negotiated to 6Mb/s (1+2+3):

[root@R1]~# grep Bundle /var/log/ppp.log
Nov 12 06:04:54 router ppp[87823]: [B-1] Bundle: Interface ng0 created
Nov 12 06:04:54 router ppp[87823]: [B-1] Bundle: Status update: up 1 link, total bandwidth 2000000 bps
Nov 12 06:04:54 router ppp[87823]: [B-1] Bundle: Status update: up 2 links, total bandwidth 3000000 bps
Nov 12 06:04:54 router ppp[87823]: [B-1] Bundle: Status update: up 3 links, total bandwidth 6000000 bps

and iperf measurement close to 6Mb/s:

[root@R1]~# iperf3 -i 0 -c 10.6.6.6
Connecting to host 10.6.6.6, port 5201
[  5] local 10.0.16.10 port 51350 connected to 10.6.6.6 port 5201
[ ID] Interval           Transfer     Bitrate         Retr  Cwnd
[  5]   0.00-10.00  sec  6.42 MBytes  5.38 Mbits/sec    0   65.1 KBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec  6.42 MBytes  5.38 Mbits/sec    0             sender
[  5]   0.00-10.09  sec  6.40 MBytes  5.32 Mbits/sec                  receiver

iperf Done.

In the same time, if you start a “netstat -ihw 1” on R2, R3 and R4, you should see distributed traffic between them.

This lab will test mpd5 performance by aggregating 2 gigabit links.

Here is the concept:

This lab use 3 IBM System x3550 M3 with quad cores (Intel Xeon L5630 2.13GHz, hyper-threading disabled), quad NIC 82580 connected to the PCI-Express Bus and dual port Intel 10-Gigabit X540-AT2 connected to the PCI-Express Bus.

Router 1 is configured a a simple end-point.

Set the base parameters:

sysrc hostname=R1
sysrc ifconfig_ix0="1.1.1.1/24"
sysrc ifconfig_ix0_ipv6="inet6 2001:db8:1::1/64"
sysrc defaultrouter="1.1.1.2"
sysrc ipv6_defaultrouter="2001:db8:1::2"
service netif restart
service routing restart
config save

Router 2 is configured as a L2TP MLPPP client router.

Configure global parameters:

sysrc hostname=R2
sysrc ifconfig_ix0="1.1.1.2/24"
sysrc ifconfig_ix0_ipv6="inet6 2001:db8:1::2/64"
sysrc ifconfig_igb2="10.0.23.2/24"
sysrc ifconfig_igb3="10.1.23.2/24"
sysrc mpd_enable=YES
sysrc mpd_flags="-b -s ppp"

Configure mpd:

cat > /usr/local/etc/mpd5/mpd.conf <<'EOF'
default:
        load l2tp_client
l2tp_client:
        # Create the bundle
        create bundle template B
        # Enable IPv6
        set bundle enable ipv6cp
        # Disable compression (for iperf test)
        #set bundle enable compression
        #set ccp yes deflate
        # Enable TCP MSS fix
        set iface enable tcpmssfix
        # Use this interface as default route
        set iface route default
        # Disable IPCP configuration for the iperf test
        #set ipcp yes vjcomp
        # Create clonable template link
        create link template L l2tp
        set link action bundle B
        set link enable multilink
        set link keep-alive 10 30
        set link mtu 1460
        set l2tp secret blah
        set link max-redial 0
        # LINK1
        create link static link1 L
        set l2tp peer 10.0.23.3
        open link
        # LINK2
        create link static link2 L
        set l2tp peer 10.1.23.3
        open link
'EOF'

And apply your changes:

service netif restart
service routing restart
service mpd5 start
config save

Router 3 is configured as a (L2TP server).

Set the global parameters:

sysrc hostname=R3
sysrc cloned_interfaces="lo1"
sysrc ifconfig_lo1="inet 3.3.3.3/32"
sysrc ifconfig_lo1_ipv6="inet6 2001:db8:3::3/64"
sysrc ifconfig_igb2="10.0.23.3/24"
sysrc ifconfig_igb3="10.1.23.3/24"
sysrc mpd_enable=YES
sysrc mpd_flags="-b -s ppp"

Configure mpd5:

cat > /usr/local/etc/mpd5/mpd.conf <<'EOF'
default:
        load l2tp_server
l2tp_server:
        # IP Pool
        set ippool add pool1 10.3.23.10 10.3.23.100
        # Create bundle template named B
        create bundle template B
        # Enable compression (disabled on the client)
        set bundle enable compression
        set ccp yes deflate
        # Enable IPv6
        set bundle enable ipv6cp
        # Configure interface
        set iface enable tcpmssfix
        # Handle IPCP configuration
        set ipcp yes vjcomp
        # Handle the IPCP configuration
        set ipcp ranges 10.3.23.1/24 ippool pool1
        # Create clonable link template
        create link template L l2tp
        set link action bundle B
        set link enable multilink
        set link keep-alive 10 30
        set link mtu 1460
        set l2tp secret blah
        # LINK1
        create link static link1 L
        set l2tp self 10.0.23.3
        set link enable incoming
        # LINK2
        create link static link2 L
        set l2tp self 10.1.23.3
        set link enable incoming
'EOF'

if-up script (for installing routes to R1 subnet):

cat > /usr/local/etc/mpd5/if-up.sh <<'EOF'
#!/bin/sh
#mpd5 call script with options:
#interface proto local-ip remote-ip authname [ dns1 server-ip ] [ dns2 server-ip ] peer-address
#Examples
#command "/usr/local/etc/mpd5/if-up.sh ng0 inet 10.3.23.1/32 10.3.23.10 '-' '' '' '10.1.23.2'"
#command "/usr/local/etc/mpd5/if-up.sh ng0 inet6 fe80::5ef3:fcff:fee5:a4c0%ng0 fe80::5ef3:fcff:fee5:7338%ng0 '-' '10.1.23.2'"
#mpd5 wait for 0 as successful
set -e
logger "$0 called with parameters: $@"
remote_inet="1.1.1.0/24"
remote_inet6="2001:db8:1:: -prefixlen 64"
eval "
        if route get -net -\$2 \${remote_$2}; then
                logger \"route \${remote_$2} already present\"
                return 0
        else
                cmd=\"route add -\$2 \${remote_$2} \$4\"
        fi
"
if $cmd; then
        logger "$0: $cmd successfull"
        return 0
else
        logger "$0: $cmd failed"
        return 1
fi
'EOF'
chmod +x /usr/local/etc/mpd5/if-up.sh

Then the if-down script:

cat > /usr/local/etc/mpd5/if-down.sh <<'EOF'
#!/bin/sh
#mpd5 call script with options:
#interface proto local-ip remote-ip authname peer-address
#example:
#command "/urs/local/etc/mpd5/if-down.sh ng0 inet 10.3.23.1/32 10.3.23.10 '-' '10.0.23.2'"
logger "$0 called with parameters: $@"
remote_inet="1.1.1.0/24"
remote_net6="2001:db8:1::1 -prefixlen 64"
eval "
        if ! route get -net -\$2 ${remote_$2}; then
                logger "Route ${remote_inet} not in table"
                return 0
        else
                cmd=\"route del \${remote_$2} \$4\"
        fi
"
if $cmd; then
        logger "if-down: ${cmd} succesfull"
        return 0
else
        logger "if-down: ${cmd} failed"
        return 1
fi

'EOF'
chmod +x /usr/local/etc/mpd5/if-down.sh

And apply your changes:

service netif restart
service routing restart
service mpd5 start
config save

[root@bsdrp1]~# iperf -c 1.1.1.2 -t 60
------------------------------------------------------------
Client connecting to 1.1.1.2, TCP port 5001
TCP window size: 32.5 KByte (default)
------------------------------------------------------------
[  3] local 1.1.1.1 port 57149 connected with 1.1.1.2 port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-60.0 sec  24.5 GBytes  3.50 Gbits/sec

We start by testing each Gigabit links between R2 and R3 for measuring iperf value on standard gigabit link:

[root@R2]~# iperf -c 10.0.23.3 -t 60
------------------------------------------------------------
Client connecting to 10.0.23.3, TCP port 5001
TCP window size: 32.5 KByte (default)
------------------------------------------------------------
[  3] local 10.0.23.2 port 21046 connected with 10.0.23.3 port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-60.0 sec  6.54 GBytes   936 Mbits/sec
[root@R2]~# iperf -c 10.1.23.3 -t 60
------------------------------------------------------------
Client connecting to 10.1.23.3, TCP port 5001
TCP window size: 32.5 KByte (default)
------------------------------------------------------------
[  3] local 10.1.23.2 port 50717 connected with 10.1.23.3 port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-60.0 sec  6.55 GBytes   937 Mbits/sec

Iperf will use the MPPP tunnel extremity:

[root@R2]~# set DEST=`ifconfig ng0 | grep 'inet ' | cut -d ' ' -f 4`
[root@R2]~# iperf -c $DEST -t 60
------------------------------------------------------------
Client connecting to 10.3.23.1, TCP port 5001
TCP window size: 32.5 KByte (default)
------------------------------------------------------------
[  3] local 10.3.23.10 port 19383 connected with 10.3.23.1 port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-60.1 sec  6.14 GBytes   878 Mbits/sec

The value is almost the same than without MLPPP aggregated link, but correctly load-balanced across each link. iR2 stats during this test:

                    /0   /1   /2   /3   /4   /5   /6   /7   /8   /9   /10
     Load Average   ||||

      Interface           Traffic               Peak                Total
            ng0  in     17.271 Mb/s         18.694 Mb/s            3.743 GB
                 out   974.656 Mb/s       1055.503 Mb/s            7.324 GB

           igb3  in     11.405 Mb/s         12.261 Mb/s            3.456 GB
                 out   507.970 Mb/s        550.255 Mb/s           27.449 GB

           igb2  in     11.389 Mb/s         12.274 Mb/s            3.422 GB
                 out   508.061 Mb/s        550.328 Mb/s           18.673 GB

And the load show:

[root@R2]~# top -nCHSIzs1
last pid: 14152;  load averages:  0.94,  0.48,  0.21  up 0+23:54:56    12:40:23
155 processes: 5 running, 99 sleeping, 51 waiting

Mem: 3564K Active, 26M Inact, 384M Wired, 256K Cache, 17M Buf, 15G Free
Swap:


  PID USERNAME   PRI NICE   SIZE    RES STATE   C   TIME     CPU COMMAND
 8524 root       -16    -     0K    64K sleep   0   2:04  25.68% ng_queue{ng_queue2}
 8524 root       -16    -     0K    64K sleep   1   1:47  25.49% ng_queue{ng_queue1}
 8524 root       -16    -     0K    64K sleep   3   2:03  22.36% ng_queue{ng_queue0}
14149 root        36    0 32136K  3092K sbwait  1   0:06  21.88% iperf{iperf}
 8524 root       -16    -     0K    64K sleep   2   1:56  20.26% ng_queue{ng_queue3}
   11 root       -92    -     0K   816K WAIT    3   0:20   7.57% intr{irq286: igb3:que}
   11 root       -92    -     0K   816K WAIT    1   0:17   5.96% intr{irq279: igb2:que}
   11 root       -92    -     0K   816K WAIT    3   0:09   0.78% intr{irq281: igb2:que}
   11 root       -92    -     0K   816K WAIT    2   0:05   0.59% intr{irq280: igb2:que}
   11 root       -92    -     0K   816K WAIT    0   0:06   0.39% intr{irq278: igb2:que}
    0 root       -92    0     0K   560K -       1   0:00   0.10% kernel{igb3 que}

For information, using netblast (UDP packet generator) disturb the links:

netblast $DEST 9090 1470 30 `sysctl -n hw.ncpu`

and measure the bandwidth received on R3:

         0 pps    0.000 Mbps - 0 pkts in 0.522753682 ns
      2149 pps   25.277 Mbps - 1079 pkts in 0.501997052 ns
         0 pps    0.000 Mbps - 0 pkts in 0.501999569 ns
        45 pps    0.539 Mbps - 23 pkts in 0.502000238 ns
         0 pps    0.000 Mbps - 0 pkts in 0.502000362 ns
       713 pps    8.387 Mbps - 358 pkts in 0.501999604 ns
      2107 pps   24.786 Mbps - 1077 pkts in 0.511002670 ns
         0 pps    0.000 Mbps - 0 pkts in 0.501998712 ns
         0 pps    0.000 Mbps - 0 pkts in 0.501998967 ns
        21 pps    0.255 Mbps - 11 pkts in 0.508000385 ns
         0 pps    0.000 Mbps - 0 pkts in 0.501998785 ns

The packet generator prevent to manage keepalive:

Jan 27 10:50:38 R2 ppp: [link1] LCP: no reply to 1 echo request(s)
Jan 27 10:50:38 R2 ppp: [link2] LCP: no reply to 1 echo request(s)
Jan 27 10:50:48 R2 ppp: [link2] LCP: no reply to 2 echo request(s)
Jan 27 10:50:48 R2 ppp: [link2] LCP: peer not responding to echo requests
Jan 27 10:50:48 R2 ppp: [link2] LCP: state change Opened --> Stopping
Jan 27 10:50:48 R2 ppp: [link2] Link: Leave bundle "B-1"