MikroTik – RouterOSv7 first look – L3 ASIC performance testing

When MikroTik announced the CRS3xx series switches a few years ago, one of the most exciting aspects of that news release was the prospect of L3 forwarding in hardware on very inexpensive devices.

A quick review of the Marvell Prestera ASIC family showed a number of advanced routing, switching, MPLS and VxLAN capabilites.

Fast forward to 2020, where MikroTik has started to enable some of those features in RouterOS v7 beta.

Now we can finally take some of the CRS3xx switches and test their capabilities with L3 forwarding performance in hardware


CRS 3xx series capabilities overview

Before getting into the testing, it’s probably helpful to review some of the basic specs and capabilities of the CRS3xx switch line.

Here is a chart from MikroTik that outlines ACL rule count, Unicast FDB entries and MTU size.

CRS 3xx model comparison

MIkroTik has been working on the development of the features listed below to offload into hardware.

For the tests in this article, we’ll be using IPv4 Unicast and Inter-VLAN routing.

Supported feature list

Currently, the following switches are supported.

For the testing in this article, we are using the CRS317-1G-16S+

Switches supported by 7.1beta2



Performance testing – overview

The physical setup for testing is fairly straightforward.

  • HP DL380 gen7 with ProxMox PVE 6.2-4
  • 2 x 10G Multimode OM4 fiber jumpers
  • 4 x 10G Multimode SFPs
  • CRS 317-1G-16S+ running RouterOS 7.1beta2

The logical setup is also very straightforward

  • ProxMox/KVM hypervisor using PVE 6.2-4
  • Two RFC1918 subnets and VLANs to test intervlan routing performance
  • Two Ubuntu 20.04 LTS VMs
  • iperf3 on both Ubuntu VMs

MikroTik Configuration


Test #1 – iperf3 testing at 96 byte MTU

CPU – 0% to 3%

CRS 317 – interface sfp-sfpplus15

iperf3 results

Test #2 – iperf3 testing at 512 byte MTU

CPU – 0% to 3%

CRS 317 – interface sfp-sfpplus15

iperf3 results

Test #3 – iperf3 testing at 1500 byte MTU

CPU – 0% to 3%

CRS 317 – interface sfp-sfpplus15

iperf3 results

Conclusions

The initial results are very promising. Getting close to 10G sustained L3 throughput using an ASIC on a device that lists for $399 USD is unheard of.

The most noteworthy items for improvement are the number of TCP retransmits in the iperf testing and the speed reduction as the MTU is reduced.

Normally, most ASIC based platforms will push 96 bytes through as fast as 1500 bytes. The retransmits suggest that more work is needed in the way RouterOS interfaces with the switching buffers for L3 HW offload

This is also on a beta version of RouterOS that will still go through many revisions before going into prod so I would expect to see the performance to improve as the code matures.

All things considered though, things are looking great to take the CRS3xx series and be able to deploy them as a true L3 switch in prod sometime in 2021.

Cisco to MikroTik – Switching and VLANs

 

 

About the Cisco to MikroTik series

One of the most difficult configuration challenges for MikroTik equipment seems to be switching and VLANs in the CRS series. Admittedly, the revamp of VLAN configuration for MikroTik CRS switches in early 2018 made things a lot easier. But, sometimes there is still confusion on how to configure VLANs and IP addresses in VLANs with MikroTik RouterOS operating on a switch.

This will only cover VLAN configuration for CRS 3xx series switches in RouterOS as SwitchOS is not nearly as common in operational deployments.

CRS 1xx/2xx series use an older style of configuration and seem to be on the way out so I’m not 100% sure whether or not i’ll write a similar guide on that series.

If you’ve been in networking for a while, you probably started with learning the Cisco CLI. Therefore, it is helpful to compare the commands if you want to implement a network with a MikroTik and Cisco switches.

This is the fourth post in a series that creates a Rosetta stone between IOS and RouterOS. Here are some of the others:

Click here for the first article in this series – “Cisco to MikroTik BGP command translation”
Click here for the second article in this series – “Cisco to MikroTik OSPF command translation”
Click here for the third article in the series – “Cisco to MikroTik MPLS command translation”

While many commands have almost the exact same information, others are as close as possible. Since there isn’t always an exact match, sometimes you may have to run two or three commands to get the information needed.

Hardware for testing

In the last article, we began using EVE-NG instead of GNS3 to emulate both Cisco IOS and RouterOS so we could compare the different commands and ensure the translation was as close as possible. However in switching, we still have to use real hardware at least in the realm of MikroTik – Cisco has IOSvL2 images that can be used in EVE-NG for switching.

Notes on hardware bridging in the CRS series

Bridging is a very confusing topic within the realm of MikroTik equipment. It is often associated with CPU forwarding and is generally seen as something to be avoided if at all possible.

There are a few reasons for this…

1. Within routers, bridging generally does rely on the CPU for forwarding and the throughput is limited to the size of the CPU.

2. In the previous generation of CRS configuration, bridging was not the best way to configure the switch – using the port master/slave option would trigger hardware forwarding.

After MikroTik revamped the switch config for VLANs in 2018 to utilize the bridge, it more closely resembles the style of configuration for Metro Ethernet Layer 2 as well as vendors like Juniper that use the ‘bridge-domain’ style of config.

Using the bridge for hardware offload of L2 traffic

Note the Hw. Offload verification under this bridge port in the CRS317

It is important to realize that bridging in the CRS, when used for VLAN configuration is actually using the switch ASIC to forward traffic and not the CPU.

In this instance, the bridge is merely used as a familiar configuration tool to tie ports and VLANs together but does in fact allow for the forwarding of traffic in hardware at wirespeed.

Cisco to MikroTik – command translation

Cisco commandMikroTik Command
interface FastEthernet5/0/47
switchport access vlan 100
switchport mode access
end
/interface bridge port
add bridge=bridge1 interface=sfp-sfpplus1 pvid=100
interface GigabitEthernet5/0/4
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 200
switchport mode trunk
end
/interface bridge vlan
add bridge=bridge1 tagged=sfp-sfpplus1 vlan-ids=200
interface Vlan200
ip address 172.16.1.254 255.255.255.0
end
/interface vlan
add interface=bridge1 name=vlan200 vlan-id=200
/interface bridge vlan
add bridge=bridge1 tagged=sfp-sfpplus1,bridge1 vlan-ids=200
/ip address
add address=172.16.1.254/24 interface=vlan200 network=172.16.1.0
spanning-tree mode mst
/interface bridge
add fast-forward=no name=bridge1 priority=0 protocol-mode=mstp region-name=main vlan-filtering=yes
interface FastEthernet5/0/47
switchport access vlan 200
switchport mode access
spanning-tree portfast
end
interface bridge port set edge=yes-discover
interface GigabitEthernet5/0/4
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 200
switchport mode trunk
channel-group 1 mode active
end

interface Port-channel1
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 200
switchport mode trunk
end
interface bonding
add mode=802.3ad name=Po1 slaves=sfp-sfpplus1,sfp-sfpplus3 \
transmit-hash-policy=layer-2-and-3

/interface bridge vlan
add bridge=bridge1 tagged=Po1,bridge1 vlan-ids=200
show mac address-tableinterface bridge host print
show mac address-table vlan 200interface bridge host print where vid=200
show mac address-table interface Gi5/0/4interface bridge host print where interface=sfp-sfpplus1
show interfaces trunk
show vlan
interface bridge vlan print
show spanning-tree
interface bridge monitor
show etherchannel summaryinterface bonding print detail


Examples of the MikroTik RouterOS commands from the table above



Untagged switch port

This command will create an untagged or “access” switch port on VLAN 100

Tagged switch port

This command will create a tagged or “trunk” switch port on VLAN 200. Additional VLANs can be tagged on a port by using the same syntax and adding a new VLAN number.

Layer 3 VLAN Interface

Similar to a Cisco SVI (but dependent on the CPU and not an ASIC) this command will create a layer 3 interface on VLAN 200

Multiple STP

This command will set the bridge loop prevention protocol to Multiple Spanning Tree. As a general observation, MSTP tends to be the most compatible across vendors as some vendors like Cisco use a proprietary version of Rapid STP.

STP Edge port

This is referred to as “portfast” in the Cisco world and allows a port facing a device that isn’t a bridge or a switch to transition immediately to forwarding but if it detects a BPDU, it will revert to normal STP operation. (this is the difference between edge=yes and edge=yes-discover)

LACP Bonding

This command will create a bonding interface which is similar to a Port Channel in Cisco’s switches. Two or more physical interfaces can be selected to bond together and then the 802.3ad mode is selected which is LACP. You can also select the hashing policy and ideally it should match what the device on the other end is set for to get the best distribution of traffic and avoid interoperability issues.

View the MAC table of the switch

This print command will show all learned MAC addresses and associated VLANs in the CAM table of the switch

View the MAC table for VLAN 200 in the switch

This print command will show all learned MAC addresses in VLAN 200.

View the MAC table for bonding interface Po1 in the switch

This print command will show all learned MAC addresses on port Po1.

View the current VLANs configured in the switch 

The bridge vlan print command will show all configured VLANs in the switch.

View Bridge Spanning Tree information 

The bridge monitor command will show the configuration details and current state of spanning tree including the root bridge and root port

LACP Bonding information

This command will show the details of the LACP configuration and whether the bonding interface is running which indicates a valid LACP neighbor.