OpenMUL tops SIFY Trial

OpenMUL recently topped the phase 1 field trial of BGP Peering Router for ICT Solution provider SIFY. We delivered 60% better results than our nearest competitor ONOS which is backed by biggest names in the industry. Classic David vs Goliath story. Download a copy of the test report here

OpenMUL to feature in Metro-Ethernet GEN15 showcase

Three of the biggest names in Metro Ethernet –  WebNMS, Omnitron & Veryx  will be showcasing their end-to-end orchestrated platform integrated with OpenMUL SDN controller in this year’s MEF-GEN15 showcase – The premier event for Metro-Ethernet. The showcase event highlights new services & technology innovation from top 14 applicants.

The showcase will focus on the following :
– Elastic service creation and delivery
– Automated service turn-up testing & active performance monitoring
– Dynamic bandwidth on-demand
– OpenMUL based software abstraction of network control plane and data forwarding plane
– Cloud-based self-service Customer SLA port

A high-five to WebNMS, Omnitron & Veryx from OpenMUL team.

The nuances of implementing centralized SDN control plane

There have been many recent debates about centralized control planes vs central control. Our team has been working on abstracting stock Linux managed centralized control plane abstracted on Openflow for sometime and hence this topic is that much more interesting to us.

As Ivan rightly pointed out, implementing data-plane functionality like LLDP, ARP, BFD or STP on top of controller is not so practical. In this post, I would analyze each of these protocols and what makes it easy/hard for such implementations:


Traditionally, LLDP is implemented in Data-plane and normally contains the info about MAC/PHY information, port/system names of neigbours and so on. This information is stored in Data-base and queried using SNMP or other management protocols to discover topology. There were no evident scalability issues. SDN controllers started using LLDP with Openflow packet-in/packet-out exchanges to find out topology and hence calculate routes between nodes. Why can’t such a scheme scale ? For a standard switch with 48-ports, we would need to process 48 LLDP packets per sec (if interval is 1s per LLDP packet). So for a very sizeable 100 switch topology we would have 4800 packets per second. Is that really a big deal for modern multi-threaded controller software running of top-end Intel boxes ? Our experience says “NO”. In our lab, the root-cause of scalability was that almost all available Openflow switches won’t process slow-path packet-in/outs well while doing TCAM flow modification, stats update etc. And this lets all hell break lose at controller’s side.

Winding back, controllers started using LLDP at the first place because there was no standard Openflow way to plumb LLDP topology information from the switches. But even with that, switch software will need to handle slow path messages as well as TCAM updates and what not in an efficient manner.

Bottom line – Well designed switch software along with Openflow spec modification would really solve this issue once and for all.

2) ARP

ARP is a tricky area and difficult to label as a DP only entity. Think what would happen if we ask the already over-burdened OF switches to do distributed ARP for implementing centralized VLANs spanning multi-switches. Not going to happen soon. AFAIK, ARP has been implemented as control-plane as well data-plane entity by different vendors. But it always requires close co-ordination between the two.

So, what exactly is the scalability concern of having ARP on a central controller ? For a conservative estimate of around 8k next-hops we would need to handle few thousand ARP request/responses per ARP timeout (which is normally ~ 60s range). This again is not a problem in itself.

So, what happens when switch (temporarily) stops sending ARP packet-in/outs due to issues mentioned in 1 ? Again no big problem, if you have segregated L3 and next-hop flows in separate flow-tables such that ARP changes only reflect in the next-hop table and there is no touching L3 (routes) flow table.

Finally there is one more concern : If next-hop is not resolved does the switch send line-rate traffic to controller ? Nope, the controller can always direct such misses to itself using a meter (OF1.3 feature). Per (unresolved) next-hop meters for send-to controller flows solved all scalability issues for us.

3) BFD

BFD has always been a data-plane entity. Many vendors also have ASIC support for BFD these days. If ONF can improve the OF spec to programmatically enable BFD on a given object of interest (port/tunnel) and send periodic updates on its status to controller, there should be no scaling issues.

4) STP

Firstly, anybody should be my guest if they are still using STP based design in their networks. Secondly, even if it is needed, Openflow has it covered by having different port-states which can be modified based on DP’s STP port-state and having it notified to controller.

In the next blog, we will try to analyze the scaling issues of centralized control plane from routing protocols perspective and what can be done with Openflow alone. We already know NSX-DLR and NSX-edge implement such functionality for sometime now.

Shout out to ONF – Please solve ARP, LLDP & BFD in upcoming Openflow spec releases.


OpenMUL powers Pusan University’s WiFi SDN research

Pusan University recently concluded their work on using Openflow Wifi Access points to do smart traffic control and hand-offs.  Read the full paper here.

OpenMUL was used as the SDN Controller for their research work. Apart from providing a solid core platform, OpenMUL provided a flexible abstraction layer which helped them to write highly customized system apps in a jiffy.

It is really amazing that SDN/Openflow is being applied to so many areas. Keep up the good  job @Pusan University team !!!

OpenMUL advances with Concave LTS Release

OpenMUL SDN controller’s latest release code named “Concave” is now available.This is the first major LTS release of OpenMUL since its inception and available for immediate download. 

What is under the hood :

  • 250K+ lines of code
  • PRISM SDN logical router (more info here)
  • Standalone REST-api based GUI (Beta)
  • Support for AVIOR Opensource GUI
  • Enhanced infrastructure for distributed core applications
  • High availability support for major components (active-standby)
  • Adaptive service chaining application
  • Loop detection/prevention in topology
  • OF domain multi-path connector services
  • Various Openflow switches (OF1.3/1.4) validated to work flawlessly
  • Persistent DB storage of all active configuration elements
  • Performance improvements (>10Million flow mod/sec &
  • Huge number of bug fixes
  • Native python app support
  • Developer friendly documentation

OpenMUL team thanks all its users and well wishers for great support and helping it become a huge trending project in SDxCentral.

OpenMUL Team
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OpenMUL scores big win

OpenMUL has been selected as SDN platform of choice for advanced multi-site & multi-city IoT infrastructure project which will utilize core values of SDN/NFV to build innovative, flexible & scalable IoT provisioning & monitoring cloud framework. This project will be handled by multi-company consortium led by NTELS and funded by Institute for Information & Communications Technology Promotion (IITP), Govt of South-Korea.

After a stringent evaluation of various SDN controllers, OpenMUL was selected based on its scalability, performance and its flex-plug modular architecture which are must have for a project of such a big scale. The fact that OpenMUL can easily work as a geo-distributed cluster using MBGP (multi-protocol BGP) and can be easily extended to support new south-bound protocols in addition to Openflow were the major points why the consortium decided to choose OpenMUL.

As seen in the figure, OpenMUL will be used to control IoT common gateways (using Openflow and other south-bound protocols) and provision multi-site dynamic service chaining in conjunction with IoT management platform.

OpenMUL team thanks everyone involved and will extend its full support for success of this project and its deployment in making future IoT enabled smart cities.