This presentation discusses the design and evaluation of two open-source implementations of the LTE EPC, one based on SDN principles and the other based on NFV, and presents a performance comparison of the two approaches. Speaker: Mythili Vutukuru

1. Redesigning the LTE Packet Core
with NFV and SDN
Mythili Vutukuru
Assistant Professor, CSE
IIT Bombay

2. Network Func<on Virtualiza<on (NFV)
Source: http://www.globalservices.bt.com/uk/en/point-of-view/nfv

3. SoAware Defined Networking (SDN)
Source: http://cacm.acm.org/magazines/2014/10/178789-abstractions-for-software-deOined-networks/

4. Why SDN and NFV?
• Why NFV?
– Easier to develop software appliances
– Elastic scaling with distributed software
• Why SDN?
– Flexibility in changing control plane logic
– Easier scaling of commodity data plane
• Applications
– Middleboxes (Oirewalls, DPI, load balancers)
– Appliances in telecom networks (LTE packet core, customer
premise equipment)

5. LTE Evolved Packet Core (EPC)
Attach/register
Data
• Complex functionality in hardware appliances
• DifOicult to scale, inOlexible, expensive

6. Proposal: NFV EPC
• Flexible, scalable software appliances
• Use commodity high-end servers, data centers

7. Proposal: SDN EPC
• Flexible software-based control plane
• Commodity SDN switches in data plane

8. So, what is the future of EPC?
• Several proposals that use NFV and SDN to redesign LTE
packet core in 5G and beyond.
• Probably no clear winner: which design is better depends
on several factors.
• A few commercial startups in trial mode.
• No open-source software implementation to compare
performance of various designs
– A few frameworks focus on standards compliance only
– No published performance comparison of prototypes
– DifOicult for researchers to compare across designs

9. Our work: Enable Performance
Comparison of EPC Design Choices
• Goals:
– Develop various candidate EPC prototypes
– Common framework to compare design choices
– Implement features that impact performance
– Modular, extensible, open-source code
• Non goals: full standards compliance, real
life deployments

10. Our NFV-based EPC
• RAN simulator to simulate user+base station
• Multi-threaded program to simulate multiple users
• Simulated users can attach, detach, send data trafOic to sink

11. Our SDN-based EPC
• Floodlight SDN controller and Open vSwitch SDN switches
• SDN switch (“Default Switch”) connects RAN to EPC

12. Experimental Setup
• NFV EPC
– OpenStack private cloud
– Components run on KVM-based VMs
• SDN EPC
– Software SDN switches: OpenvSwitch on Linux
– Floodlight controller on high end server
– Some experiments with all components on same
physical machine – to overcome network bottleneck
• Similar CPU and memory for both setups for fair
comparison

13. Experimental Method
• Experiments
– Users in simulated RAN continuously register and
detach (control plane)
– Attached simulated users continuously pump TCP
trafOic (data plane)
• Metrics
– Control plane throughput (number of registrations/sec)
– Data plane throughput (bps forwarded by gateways)
– Latency, processing overheads

14. Results: Control Plane
NFV SDN
• NFV EPC gives much higher control throughput
• SDN EPC limited by controller -switch communication
• Latency and processing overhead comparable
~9,000 req/s
~3,000 req/s

15. Results: Data Plane
NFV SDN
• SDN EPC handles much higher data plane trafOic
• NFV EPC limited by OS network stack in the VM and host
~120 Mbps
~45 Gbps

16. Summary of results
• NFV or SDN for EPC? Well, it depends on…
– Mix of trafOic (control vs. data)
– SpeciOic implementation used
• Performance of both prototypes can be improved
– Distributed / hierarchical SDN controllers
– Optimized NFV data plane (e.g., using DPDK)
– Elastic, scalable network functions
• Many other points to explore in the design space
• Our comparison is not the Oinal word; only the
beginning of an exploration of design choices

17. Ongoing research using our code
• Design of a multicore VNF when using kernel bypass like
DPDK: how to steer packets to app cores?
– Hardware multiqueue or software distribution
– Partition using application sematics or TCP header?

18. Our code on GitHub
• https://github.com/networkedsystemsIITB
• v1.0 of both EPCs released in June 2016
• v1.1 of NFV EPC (distributed EPC) released Nov 2016
• v2.0 of both EPCs expected in next few months
– Hierarchical SDN controllers
– Improved data plane using Intel DPDK, netmap
– Userspace network stack based on multicore-TCP