- Author: Pim van Pelt, Rogier Krieger
- Reviewers: Coloclue Network Committee
- Status: Draft - Review - Published
Almost precisely two years ago, in February of 2021, I created a loadtesting environment at [Coloclue] to prove that a provider of L2 connectivity between two datacenters in Amsterdam was not incurring jitter or loss on its services – I wrote up my findings in [an article], which demonstrated that the service provider indeed provides a perfect service. One month later, in March 2021, I briefly ran [VPP] on one of the routers at Coloclue, but due to lack of time and a few technical hurdles along the way, I had to roll back [ref].
The Problem
Over the years, Coloclue AS8283 continues to suffer from packet loss in its network. Taking a look
at a simple traceroute, in this case from IPng AS8298, shows very high variance and packetlo
when entering the network (at hop 5 in a router called eunetworks-2.router.nl.coloclue.net):
My traceroute [v0.94]
squanchy.ipng.ch (194.1.193.90) -> 185.52.227.1 2023-02-24T09:03:36+0100
Keys: Help Display mode Restart statistics Order of fields quit
Packets Pings
Host Loss% Snt Last Avg Best Wrst StDev
1. chbtl0.ipng.ch 0.0% 49904 1.3 0.9 0.7 1.7 0.2
2. chrma0.ipng.ch 0.0% 49904 1.7 1.2 1.2 2.1 0.9
3. defra0.ipng.ch 0.0% 49904 6.3 6.2 6.0 19.2 1.3
4. nlams0.ipng.ch 0.0% 49904 12.7 12.6 12.4 19.8 1.8
5. bond0-105.eunetworks-2.router.nl.coloclue.net 0.2% 49903 98.8 12.3 12.0 272.8 23.0
6. 185.52.227.1 6.6% 49903 15.3 12.5 12.3 308.7 20.4
The last two hops show the packet loss well north of 6.5%, some paths are better, some are worse, but notably when more than one router is in the path, it’s difficult to pinpoint where or what is responsible. But honestly, any source will reveal packet loss and high variance when traversing through one or more Coloclue routers, to more or lesser degree:
————— | ———————
| 
The screenshots above are smokeping from (left) a machine at AS8283 Coloclue (in Amsterdam, the Netherlands), and from (right) a machine at AS8298 IPng (in Brüttisellen, Switzerland), both are showing ~4.8-5.0% packetlo and high variance in end to end latency. No bueno!
Isolating a Device Under Test
Because Coloclue has several routers, I want to ensure that traffic traverses only the one router under test. I decide to use an allocated but currently unused IPv4 prefix and announce that only from one of the four routers, so that all traffic to and from that /24 goes over that router. Coloclue uses a piece of software called Kees, a set of Python and Jinja2 scripts to generate a Bird1.6 configuration for each router. This is great because that allows me to add a small feature to get what I need: beacons.
Setting up the beacon
A beacon is a prefix that is sent to (some, or all) peers on the internet to attract traffic in a
particular way. I added a function called is_coloclue_beacon() which reads the input YAML file and
uses a construction similar to the existing feature for “supernets”. It determines if a given prefix
must be announced to peers and upstreams. Any IPv4 and IPv6 prefixes from the beacons list will be
then matched in is_coloclue_beacon() and announced. For the curious, [this
commit] holds the
logic and tests to ensure this is safe.
Based on a per-router config (eg. vars/eunetworks-2.router.nl.coloclue.net.yml) I can now add the
following YAML stanza:
coloclue:
beacons:
- prefix: "185.52.227.0"
length: 24
comment: "VPP test prefix (pim, rogier)"
And further, from this router, I can forward all traffic destined to this /24 to a machine running
in EUNetworks (my Dell R630 called hvn0.nlams2.ipng.ch), using a simple static route:
statics:
...
- route: "185.52.227.0/24"
via: "94.142.240.71"
comment: "VPP test prefix (pim, rogier)"
After running Kees, I can now see traffic for that /24 show up on my machine. The last step is to
ensure that traffic that is destined for the beacon will always traverse back over eunetworks-2.
Coloclue has VRRP and sometimes another router might be the logical router. With a little trick on
my machine, I can force traffic by means of policy based routing:
pim@hvn0-nlams2:~$ sudo ip ro add default via 94.142.240.254
pim@hvn0-nlams2:~$ sudo ip ro add prohibit 185.52.227.0/24
pim@hvn0-nlams2:~$ sudo ip addr add 185.52.227.1/32 dev lo
pim@hvn0-nlams2:~$ sudo ip rule add from 185.52.227.0/24 lookup 10
pim@hvn0-nlams2:~$ sudo ip ro add default via 94.142.240.253 table 10
First, I set the default gateway to be the VRRP address that floats between multiple routers. Then,
I will set a prohibit route for the covering /24, which means the machine will send an ICMP
unreachable (rather than discarding the packets), which can be useful later. Next, I’ll add .1 as an
IPv4 address onto loopback, after which the machine will start replying to ICMP packets there with
icmp-echo rather than dst-unreach. To make sure routing is always symmetric, I’ll add an ip rule
which is a classifier that matches packets based on their source address, and then diverts these to
an alternate routing table, which has only one entry: send via .253 (which is eunetworks-2).
Let me show this in action:
pim@hvn0-nlams2:~$ dig +short -x 94.142.240.254
eunetworks-gateway-100.router.nl.coloclue.net.
pim@hvn0-nlams2:~$ dig +short -x 94.142.240.253
bond0-100.eunetworks-2.router.nl.coloclue.net.
pim@hvn0-nlams2:~$ dig +short -x 94.142.240.252
bond0-100.eunetworks-3.router.nl.coloclue.net.
pim@hvn0-nlams2:~$ ip -4 nei | grep '94.142.240.25[234]'
94.142.240.252 dev coloclue lladdr 64:9d:99:b1:31:db REACHABLE
94.142.240.253 dev coloclue lladdr 64:9d:99:b1:31:af REACHABLE
94.142.240.254 dev coloclue lladdr 64:9d:99:b1:31:db REACHABLE
In the output above, I can see that eunetworks-2 (94.142.240.253) has MAC address
64:9d:99:b1:31:af, and that eunetworks-3 (94.142.240.252) has MAC address 64:9d:99:b1:31:db.
My default gateway, handled by VRRP, is at .254 and it’s using the second MAC address, so I know that
eunetworks-3 is primary, and will handle my egress traffic.
Verifying symmetric routing of the beacon
A quick demonstration to show the symmetric routing case, I can tcpdump and see that my “usual”
egress traffic will be sent to the MAC address of the VRRP primary (which I showed to be
eunetworks-3 above), while traffic coming from 185.52.227.0/24 ought to be sent to the
MAC address of eunetworks-2 due to the ip rule and alternate routing table 10:
pim@hvn0-nlams2:~$ sudo tcpdump -eni coloclue host 194.1.163.93 and icmp
tcpdump: verbose output suppressed, use -v[v]... for full protocol decode
listening on coloclue, link-type EN10MB (Ethernet), snapshot length 262144 bytes
10:02:17.193844 64:9d:99:b1:31:af > 6e:fa:52:d0:c1:ff, ethertype IPv4 (0x0800), length 98:
194.1.163.93 > 94.142.240.71: ICMP echo request, id 16287, seq 1, length 64
10:02:17.193882 6e:fa:52:d0:c1:ff > 64:9d:99:b1:31:db, ethertype IPv4 (0x0800), length 98:
94.142.240.71 > 194.1.163.93: ICMP echo reply, id 16287, seq 1, length 64
10:02:19.276657 64:9d:99:b1:31:af > 6e:fa:52:d0:c1:ff, ethertype IPv4 (0x0800), length 98:
194.1.163.93 > 185.52.227.1: ICMP echo request, id 6646, seq 1, length 64
10:02:19.276694 6e:fa:52:d0:c1:ff > 64:9d:99:b1:31:af, ethertype IPv4 (0x0800), length 98:
185.52.227.1 > 194.1.163.93: ICMP echo reply, id 6646, seq 1, length 64
It takes a keen eye to spot the difference here the first packet (which is going to the main
IPv4 address 94.142.240.71), is returned via MAC address 64:9d:99:b1:31:db (the VRRP default
gateway), but the second one (going to the beacon 185.52.227.1) is returned via MAC address
64:9d:99:b1:31:af.
I’ve now ensured that traffic to and from 185.52.227.1 will always traverse through the DUT
(eunetworks-2 with MAC 64:9d:99:b1:31:af). Very elegant :-)
Installing VPP
I’ve written about this before, the general spiel is just following my previous article (I’m often very glad to read back my own articles as they serve as pretty good documentation to my forgetful chipmunk-sized brain!), so here, I’ll only recap what’s already written in [vpp-7]:
- Build VPP with Linux Control Plane
- Bring
eunetworks-2into maintenance mode, so we can safely tinker with it - Start services like ssh, snmp, keepalived and bird in a new
dataplanenamespace - Start VPP and give the LCP interface names the same as their original
- Slowly introduce the router: OSPF, OSPFv3, iBGP, members-bgp, eBGP, in that order
- Re-enable keepalived and let the machine forward traffic
- Stare at the latency graphs
1. BUILD: For the first step, the build is straight forward, and yields a VPP instance based on
vpp-ext-deps_23.06-1 at version 23.06-rc0~71-g182d2b466, which contains my
[LCPng] plugin. I then copy the packages to the router.
The router has an E-2286G CPU @ 4.00GHz with 6 cores and 6 hyperthreads. There’s a really handy tool
called likwid-topology that can show how the L1, L2 and L3 cache lines up with respect to CPU
cores. Here I learn that CPU (0+6) and (1+7) share L1 and L2 cache – so I can conclude that 0-5 are
CPU cores which share a hyperthread with 6-11 respectively.
I also see that L3 cache is shared across all of the cores+hyperthreads, which is normal. I decide
to give CPUs 0,1 and their hyperthread 6,7 to Linux for general purpose scheduling, and I want to
block the remaining CPUs and their hyperthreads to dedicated to VPP. So the kernel is rebooted with
isolcpus=2-5,8-11.
2. DRAIN: In the mean time, Rogier prepares the drain, which is two step process. First he marks all
the BGP sessions as graceful_shutdown: True, and waits for the traffic to die down. Then, he marks
the machine as maintenance_mode: True which will make Kees set OSPF cost to 65535 and avoid
attracting or sending traffic through this machine. After he submits these, we are free to tinker
with the router, as it will not affect any Coloclue members. Rogier also ensures we will have the
hand on this little machine in Amsterdam, by preparing an IPMI serial-over-lan connection and KVM.
3. PREPARE: Starting an ssh and snmpd in the dataplane is the most important part. This way, we will be able to scrape the machine using SNMP just as-if it were a Linux native router. And of course we will want to be able to log in to the router. I start with these two services, the only small note is that, because I want to run two copies (one in the default namespace and one additional one in the dataplane namespace), I’ll want to tweak the startup flags (pid file, config file, etc) a little bit:
## in snmpd-dataplane.service
ExecStart=/sbin/ip netns exec dataplane /usr/sbin/snmpd -LOw -u Debian-snmp \
-g vpp -I -smux,mteTrigger,mteTriggerConf -f -p /run/snmpd-dataplane.pid \
-C -c /etc/snmp/snmpd-dataplane.conf
## in ssh-dataplane.service
ExecStart=/usr/sbin/ip netns exec dataplane /usr/sbin/sshd \
-oPidFile=/run/sshd-dataplane.pid -D $SSHD_OPTS
4. LAUNCH: Now what’s left for us to do is switch from our SSH session to an IPMI serial-over-lan session so that we can safely transition to the VPP world. Rogier and I log in and share a tmux session, after which I bring down all ethernet links, remove VLAN sub-interfaces and the LACP BondEthernet, leaving only the main physical interfaces. I then set link down on them, and restart VPP – which will take all DPDK eligble interfaces that are link admin-down, and then let the magic happen:
root@eunetworks-2:~# vppctl show int
Name Idx State MTU (L3/IP4/IP6/MPLS) Counter Count
GigabitEthernet5/0/0 5 down 9000/0/0/0
GigabitEthernet6/0/0 6 down 9000/0/0/0
TenGigabitEthernet1/0/0 1 down 9000/0/0/0
TenGigabitEthernet1/0/1 2 down 9000/0/0/0
TenGigabitEthernet1/0/2 3 down 9000/0/0/0
TenGigabitEthernet1/0/3 4 down 9000/0/0/0
Dope! One way to trick the rest of the machine into thinking it hasn’t changed, is to recreate these
interfaces in the dataplane network namespace using their original interface names (eg.
enp1s0f3 for AMS-IX, and bond0 for the LACP signaled BondEthernet that we’ll create. Rogier
prepared an excellent vppcfg config file:
loopbacks:
loop0:
description: 'eunetworks-2.router.nl.coloclue.net'
lcp: 'loop0'
mtu: 9216
addresses: [ 94.142.247.3/32, 2a02:898:0:300::3/128 ]
bondethernets:
BondEthernet0:
description: 'Core: MLAG member switches'
interfaces: [ TenGigabitEthernet1/0/0, TenGigabitEthernet1/0/1 ]
mode: 'lacp'
load-balance: 'l34'
mac: '64:9d:99:b1:31:af'
interfaces:
GigabitEthernet5/0/0:
description: "igb 0000:05:00.0 eno1 # FiberRing"
lcp: 'eno1'
mtu: 9216
sub-interfaces:
205:
description: "Peering: Arelion"
lcp: 'eno1.205'
addresses: [ 62.115.144.33/31, 2001:2000:3080:ebc::2/126 ]
mtu: 1500
992:
description: "Transit: FiberRing"
lcp: 'eno1.992'
addresses: [ 87.255.32.130/30, 2a00:ec8::102/126 ]
mtu: 1500
GigabitEthernet6/0/0:
description: "igb 0000:06:00.0 eno2 # Free"
lcp: 'eno2'
mtu: 9216
state: down
TenGigabitEthernet1/0/0:
description: "i40e 0000:01:00.0 enp1s0f0 (bond-member)"
mtu: 9216
TenGigabitEthernet1/0/1:
description: "i40e 0000:01:00.1 enp1s0f1 (bond-member)"
mtu: 9216
TenGigabitEthernet1/0/2:
description: 'Core: link between eunetworks-2 and eunetworks-3'
lcp: 'enp1s0f2'
addresses: [ 94.142.247.246/31, 2a02:898:0:301::/127 ]
mtu: 9214
TenGigabitEthernet1/0/3:
description: "i40e 0000:01:00.3 enp1s0f3 # AMS-IX"
lcp: 'enp1s0f3'
mtu: 9216
sub-interfaces:
501:
description: "Peering: AMS-IX"
lcp: 'enp1s0f3.501'
addresses: [ 80.249.211.161/21, 2001:7f8:1::a500:8283:1/64 ]
mtu: 1500
511:
description: "Peering: NBIP-NaWas via AMS-IX"
lcp: 'enp1s0f3.511'
addresses: [ 194.62.128.38/24, 2001:67c:608::f200:8283:1/64 ]
mtu: 1500
BondEthernet0:
lcp: 'bond0'
mtu: 9216
sub-interfaces:
100:
description: "Cust: Members"
lcp: 'bond0.100'
mtu: 1500
addresses: [ 94.142.240.253/24, 2a02:898:0:20::e2/64 ]
101:
description: "Core: Powerbars"
lcp: 'bond0.101'
mtu: 1500
addresses: [ 172.28.3.253/24 ]
105:
description: "Cust: Members (no strict uRPF filtering)"
lcp: 'bond0.105'
mtu: 1500
addresses: [ 185.52.225.14/28, 2a02:898:0:21::e2/64 ]
130:
description: "Core: Link between eunetworks-2 and dcg-1"
lcp: 'bond0.130'
mtu: 1500
addresses: [ 94.142.247.242/31, 2a02:898:0:301::14/127 ]
2502:
description: "Transit: Fusix Networks"
lcp: 'bond0.2502'
mtu: 1500
addresses: [ 37.139.140.27/31, 2a00:a7c0:e20b:104::2/126 ]
We take this configuration and pre-generate a suitable VPP config, which exposes two little bugs
in vppcfg:
- Rogier had used captial letters in his IPv6 addresses (ie.
2001:2000:3080:0EBC::2), while the dataplane reports lower case (ie.2001:2000:3080:ebc::2), which consistently yield a diff that’s not there. I make a note to fix that. - When I create the initial
--novppconfig, there’s a bug invppcfgwhere I incorrectly reference a dataplane object which I haven’t initialized (because with--novppthe tool will not contact the dataplane at all. That one was easy to fix, which I did in [this commit]).
After that small detour, I can now proceed to configure the dataplane by offering the resulting VPP commands, like so:
root@eunetworks-2:~# vppcfg plan --novpp -c /etc/vpp/vppcfg.yaml \
-o /etc/vpp/config/vppcfg.vpp
[INFO ] root.main: Loading configfile /etc/vpp/vppcfg.yaml
[INFO ] vppcfg.config.valid_config: Configuration validated successfully
[INFO ] root.main: Configuration is valid
[INFO ] vppcfg.reconciler.write: Wrote 84 lines to /etc/vpp/config/vppcfg.vpp
[INFO ] root.main: Planning succeeded
root@eunetworks-2:~# vppctl exec /etc/vpp/config/vppcfg.vpp
5. UNDRAIN: The VPP dataplane comes to life, only to immediately hang. Whoops! What follows is a 90 minute forray into the innards of VPP (and Bird) which I haven’t yet fully understood, but will definitely want to learn more about (future article, anyone?) – but the TL/DR of our investigation is that if an IPv6 address is added to a loopback device, and an OSPFv3 (IPv6) stub area is created on it, as is common for IPv4 and IPv6 loopback addresses in OSPF, then the dataplane immediately hangs on the controlplane, but does continue to forward traffic.
However, we also find a workaround, which is to put the IPv6 loopback address on a physical interface instead of a loopback interface. Then, we observe a perfectly functioning dataplane, which has a working BondEthernet with LACP signalling:
root@eunetworks-2:~# vppctl show bond details
BondEthernet0
mode: lacp
load balance: l34
number of active members: 2
TenGigabitEthernet1/0/1
TenGigabitEthernet1/0/0
number of members: 2
TenGigabitEthernet1/0/0
TenGigabitEthernet1/0/1
device instance: 0
interface id: 0
sw_if_index: 8
hw_if_index: 8
root@eunetworks-2:~# vppctl show lacp
actor state partner state
interface name sw_if_index bond interface exp/def/dis/col/syn/agg/tim/act exp/def/dis/col/syn/agg/tim/act
TenGigabitEthernet1/0/0 1 BondEthernet0 0 0 1 1 1 1 1 1 0 0 1 1 1 1 0 1
LAG ID: [(ffff,64-9d-99-b1-31-af,0008,00ff,0001), (8000,02-1c-73-0f-8b-bc,0015,8000,8015)]
RX-state: CURRENT, TX-state: TRANSMIT, MUX-state: COLLECTING_DISTRIBUTING, PTX-state: PERIODIC_TX
TenGigabitEthernet1/0/1 2 BondEthernet0 0 0 1 1 1 1 1 1 0 0 1 1 1 1 0 1
LAG ID: [(ffff,64-9d-99-b1-31-af,0008,00ff,0002), (8000,02-1c-73-0f-8b-bc,0015,8000,0015)]
RX-state: CURRENT, TX-state: TRANSMIT, MUX-state: COLLECTING_DISTRIBUTING, PTX-state: PERIODIC_TX
6. WRAP UP: After doing a bit of standard issue ping / ping6 and show err and show log,
things are looking good. Rogier and I are now ready to slowly introduce the router: we first turn on
OSPF and OSPFv3, see adjacencies and BFD turn up. We make a note that enp1s0f2 (which is now a
LIP in the dataplane) does not have BFD while it does have OSPF, and the explanation for this is
that bond0 is connected to a switch, while enp1s0f2 is directly connected to its peer via a
cross connect cable, so if it fails, it’ll be able to use link-state to quickly reconverge, while
the ethernet link may still be up on bond0 if something along the transport path were to fail, so
BFD is the better choice there. Smart thinking, Coloclue!
root@eunetworks-2:~# birdc6 show ospf nei ospf1
BIRD 1.6.8 ready.
ospf1:
Router ID Pri State DTime Interface Router IP
94.142.247.1 1 Full/PtP 00:33 bond0.130 fe80::669d:99ff:feb1:394b
94.142.247.6 1 Full/PtP 00:31 enp1s0f2 fe80::669d:99ff:feb1:31d8
root@eunetworks-2:~# birdc show bfd ses
BIRD 1.6.8 ready.
bfd1:
IP address Interface State Since Interval Timeout
94.142.247.243 bond0.130 Up 2023-02-24 15:56:29 0.100 0.500
We are then ready to undrain iBGP and eBGP to members, transit and peering sessions. Rogier swiftly takes care of business, and the router finds its spot in the DFZ just a few minutes later:
root@eunetworks-2:~# birdc show route count
BIRD 1.6.8 ready.
6239493 of 6239493 routes for 907650 networks
root@eunetworks-2:~# birdc6 show route count
BIRD 1.6.8 ready.
1152345 of 1152345 routes for 169987 networks
root@eunetworks-2:~# vppctl show ip fib sum
ipv4-VRF:0, fib_index:0, flow hash:[src dst sport dport proto flowlabel ] epoch:0 flags:none
locks:[adjacency:1, default-route:1, lcp-rt:1, ]
Prefix length Count
0 1
4 2
8 16
9 13
10 38
11 103
12 299
13 577
14 1214
15 2093
16 13477
17 8250
18 13824
19 24990
20 43089
21 51191
22 109106
23 97073
24 542106
27 3
28 13
29 32
30 36
31 41
32 788
root@eunetworks-2:~# vppctl show ip6 fib sum
ipv6-VRF:0, fib_index:0, flow hash:[src dst sport dport proto flowlabel ] epoch:0 flags:none
locks:[adjacency:1, default-route:1, lcp-rt:1, ]
Prefix length Count
128 863
127 4
126 4
125 1
120 2
64 22
60 17
52 2
49 2
48 80069
47 3535
46 3411
45 1726
44 14909
43 1041
42 2529
41 932
40 14126
39 1459
38 1654
37 988
36 6640
35 1374
34 3419
33 3707
32 22819
31 294
30 589
29 4373
28 196
27 20
26 15
25 8
24 30
23 7
22 7
21 3
20 15
19 1
10 1
0 1
One thing that I really appreciate is how … normal … this machine looks, with no interfaces in
the default namespace, but after switching to the dataplane network namespace using nsenter, there
they are and they look (unsurprisingly, because we configured them that way), identical to what was
running before, except now all goverend by VPP instead of the Linux kernel:
root@eunetworks-2:~# ip -br l
lo UNKNOWN 00:00:00:00:00:00 <LOOPBACK,UP,LOWER_UP>
root@eunetworks-2:~# nsenter --net=/var/run/netns/dataplane
root@eunetworks-2:~# ip -br l
lo UNKNOWN 00:00:00:00:00:00 <LOOPBACK,UP,LOWER_UP>
eno1 UP ac:1f:6b:e0:b1:0c <BROADCAST,MULTICAST,UP,LOWER_UP>
eno2 DOWN ac:1f:6b:e0:b1:0d <BROADCAST,MULTICAST>
enp1s0f2 UP 64:9d:99:b1:31:ad <BROADCAST,MULTICAST,UP,LOWER_UP>
enp1s0f3 UP 64:9d:99:b1:31:ac <BROADCAST,MULTICAST,UP,LOWER_UP>
bond0 UP 64:9d:99:b1:31:af <BROADCAST,MULTICAST,UP,LOWER_UP>
loop0 UP de:ad:00:00:00:00 <BROADCAST,MULTICAST,UP,LOWER_UP>
eno1.205@eno1 UP ac:1f:6b:e0:b1:0c <BROADCAST,MULTICAST,UP,LOWER_UP>
eno1.992@eno1 UP ac:1f:6b:e0:b1:0c <BROADCAST,MULTICAST,UP,LOWER_UP>
enp1s0f3.501@enp1s0f3 UP 64:9d:99:b1:31:ac <BROADCAST,MULTICAST,UP,LOWER_UP>
enp1s0f3.511@enp1s0f3 UP 64:9d:99:b1:31:ac <BROADCAST,MULTICAST,UP,LOWER_UP>
bond0.100@bond0 UP 64:9d:99:b1:31:af <BROADCAST,MULTICAST,UP,LOWER_UP>
bond0.101@bond0 UP 64:9d:99:b1:31:af <BROADCAST,MULTICAST,UP,LOWER_UP>
bond0.105@bond0 UP 64:9d:99:b1:31:af <BROADCAST,MULTICAST,UP,LOWER_UP>
bond0.130@bond0 UP 64:9d:99:b1:31:af <BROADCAST,MULTICAST,UP,LOWER_UP>
bond0.2502@bond0 UP 64:9d:99:b1:31:af <BROADCAST,MULTICAST,UP,LOWER_UP>
root@eunetworks-2:~# ip -br a
lo UNKNOWN 127.0.0.1/8 ::1/128
eno1 UP fe80::ae1f:6bff:fee0:b10c/64
eno2 DOWN
enp1s0f2 UP 94.142.247.246/31 2a02:898:0:300::3/128 2a02:898:0:301::/127 fe80::669d:99ff:feb1:31ad/64
enp1s0f3 UP fe80::669d:99ff:feb1:31ac/64
bond0 UP fe80::669d:99ff:feb1:31af/64
loop0 UP 94.142.247.3/32 fe80::dcad:ff:fe00:0/64
eno1.205@eno1 UP 62.115.144.33/31 2001:2000:3080:ebc::2/126 fe80::ae1f:6bff:fee0:b10c/64
eno1.992@eno1 UP 87.255.32.130/30 2a00:ec8::102/126 fe80::ae1f:6bff:fee0:b10c/64
enp1s0f3.501@enp1s0f3 UP 80.249.211.161/21 2001:7f8:1::a500:8283:1/64 fe80::669d:99ff:feb1:31ac/64
enp1s0f3.511@enp1s0f3 UP 194.62.128.38/24 2001:67c:608::f200:8283:1/64 fe80::669d:99ff:feb1:31ac/64
bond0.100@bond0 UP 94.142.240.253/24 2a02:898:0:20::e2/64 fe80::669d:99ff:feb1:31af/64
bond0.101@bond0 UP 172.28.3.253/24 fe80::669d:99ff:feb1:31af/64
bond0.105@bond0 UP 185.52.225.14/28 2a02:898:0:21::e2/64 fe80::669d:99ff:feb1:31af/64
bond0.130@bond0 UP 94.142.247.242/31 2a02:898:0:301::14/127 fe80::669d:99ff:feb1:31af/64
bond0.2502@bond0 UP 37.139.140.27/31 2a00:a7c0:e20b:104::2/126 fe80::669d:99ff:feb1:31af/64
Of course, VPP handles all the traffic through the machine, and the only traffic that Linux will see is that which is destined to the controlplane (eg, to one of the IPv4 or IPv6 addresses or multicast/broadcast groups that they are participating in), so things like tcpdump or SNMP won’t really work.
However, due to my [vpp-snmp-agent], which is
feeding as an AgentX behind an snmpd that in turn is running in the dataplane namespace, SNMP scrapes
work as they did before, albeit with a few different interface names.
6. Earlier, I had failed over keepalived and stopped the service. This way, the peer router
on eunetworks-3 would pick up all outbound traffic to the virtual IPv4 and IPv6 for our users'
default gateway. Because we’re mainly interested in non-intrusively measuring the BGP beacon (which
is forced to always go through this machine), and we know some of our members use BGP and take a
preference over this router because it’s connected to AMS-IX, we make a decision to leave keepalived
turned off for now.
But, traffic is flowing, and in fact a little bit more throughput, possibly because traffic flows faster when there’s not 5% packet loss on certain egress paths? I don’t know but OK, moving along!
Results
Clearly VPP is a winner in this scenario. If you recall the traceroute from before the operation, the latency
was good up until nlams0.ipng.ch, after which loss occured and variance was very high. Rogier and
I let the VPP instance run overnight, and started this traceroute after our maintenance was
concluded:
My traceroute [v0.94]
squanchy.ipng.ch (194.1.163.90) -> 185.52.227.1 2023-02-25T09:48:46+0100
Keys: Help Display mode Restart statistics Order of fields quit
Packets Pings
Host Loss% Snt Last Avg Best Wrst StDev
1. chbtl0.ipng.ch 0.0% 51796 0.6 0.2 0.1 1.7 0.2
2. chrma0.ipng.ch 0.0% 51796 1.6 1.0 0.9 5.5 1.2
3. defra0.ipng.ch 0.0% 51796 7.0 6.5 6.4 27.7 1.9
4. nlams0.ipng.ch 0.0% 51796 12.7 12.6 12.5 43.8 3.9
5. bond0-105.eunetworks-2.router.nl.coloclue.net 0.0% 51796 13.3 13.0 12.8 138.9 11.1
6. 185.52.227.1 0.0% 51796 13.6 12.7 12.3 46.6 8.3
This mtr shows clear network weather with absolutely no packets dropped from Brüttisellen (near Zurich, Switzerland) all the way to the BGP beacon running in EUNetworks in Amsterdam. Considering I’ve been running VPP for a few years now, including writing the code necessary to plumb the dataplane interfaces through to Linux so that a higher order control plane (such as Bird, or FRR) can manipulate them, I am reasonably bullish, but I do hope to convert others.
This computer now forwards packets like a boss, its packet loss is →
Looking at the local situation, from a hypervisor running at IPng Networks in Equinix AM3 via FrysIX
through VPP and into the dataplane of the Coloclue router eunetworks-2 , shows quite reasonable
throughput as well:
root@eunetworks-2:~# traceroute hvn0.nlams3.ipng.ch
traceroute to 46.20.243.179 (46.20.243.179), 30 hops max, 60 byte packets
1 enp1s0f3.eunetworks-3.router.nl.coloclue.net (94.142.247.247) 0.087 ms 0.078 ms 0.071 ms
2 frys-ix.ip-max.net (185.1.203.135) 1.288 ms 1.432 ms 1.479 ms
3 hvn0.nlams3.ipng.ch (46.20.243.179) 0.524 ms 0.534 ms 0.531 ms
root@eunetworks-2:~# iperf3 -c 46.20.243.179 -P 10
Connecting to host 46.20.243.179, port 5201
...
[SUM] 0.00-10.00 sec 6.70 GBytes 5.76 Gbits/sec 192 sender
[SUM] 0.00-10.03 sec 6.58 GBytes 5.64 Gbits/sec receiver
root@eunetworks-2:~# iperf3 -c 46.20.243.179 -P 10 -R
Connecting to host 46.20.243.179, port 5201
Reverse mode, remote host 46.20.243.179 is sending
...
[SUM] 0.00-10.03 sec 6.07 GBytes 5.20 Gbits/sec 54623 sender
[SUM] 0.00-10.00 sec 6.03 GBytes 5.18 Gbits/sec receiver
And the smokepings look just plain gorgeous:
————— | ———————
| 
The screenshots above are smokeping from (left) a machine at AS8283 Coloclue (in Amsterdam, the Netherlands), and from (right) a machine at AS8298 IPng (in Brüttisellen, Switzerland), both are showing no packetloss and clearly improved performance in end to end latency. Super!
What’s next
The performance of the one router we upgraded definitely improved, no question about that. But there’s a couple of things that I think we still need to do, so Rogier and I rolled back the change to the previous situation and kernel based routing.
- We didn’t migrate keepalived, although IPng runs this in our DDLN [colocation] site, so I’m pretty confident that it will work.
- Kees and Ansible at Coloclue will need a few careful changes, to facilitate ongoing automation, think of dataplane and controlplane firewalls, sysctls (uRPF et al), fastnetmon, and so on will need a meaningful overhaul.
- There’s an unknown dataplane hang with Bird IPv6 enables a
stubOSPF interface on interfacelo0. We worked around that by putting the loopback IPv6 address on another interface, but this needs to be fully understood. - Completely unrelated to Coloclue, there’s one dataplane hang regarding IPv6 RA/NS and/or BFD
and/or Linux Control Plane that the VPP developer community is hunting down - it happens with
my plugin but also with [TNSR] (who used the upstream
linux-cpplugin). I’ve been working with a few folks from Netgate and customers of IPng Networks to try to find the root cause, as AS8298 has been bitten by this a few times over the last ~quarter or so. I cannot recommend in good faith running VPP until this is sorted out.
As an important side note, VPP is not well enough understood at Coloclue - rolling this out further
risks making me a single point of failure in the networking committee, and I’m not comfortable taking
that responsibility. I recommend that Coloclue network committee members gain experience with VPP,
DPDK, vppcfg and the other ecosystem tools, and that at least the bird6 OSPF issue and possible
IPv6 NS/RA issue are understood, before making the jump to the VPP world.