Various Alternatives to achieve SDN Dhruv Dhody, Sr. System Architect, Huawei Technologies
Huawei India R&D Dhruv Dhody Who? A multinational networking and telecommunications equipment and services company headquartered in Shenzhen. We are the largest telecommunications equipment maker in the world. Over 140,000 employees and 21 R&D institutes. First and biggest R&D center outside of China. High end communication software platforms/components/ applications. Over 2600 engineers. 11+ years in Huawei (Bangalore, Beijing, Santa Clara) Network OS dept with specialization in Traffic Engineering and Path Computation Lead a Research, Standards & Prototypes team 3 RFC / 8 WG documents / 13 Patents
SDN, Lets Recap!
Why SDN? Computing Trends are Driving Network Change Changing traffic patterns The consumerization of IT (BYOD) The rise of cloud services Big data means more bandwidth Complexity that leads to stasis Limitation of Current Networks Inability to scale Vendor dependence Add/Move devices Implementing network wide policy Time consuming & Manual Prone to errors Link oversubscription to provision scalability Lengthy vendor equipment product cycles Lack of standard, open interfaces
Software-defined networking (SDN) is an approach to computer networking that allows network administrators to manage network services through abstraction of lower-level functionality.
SDN - Definition The physical separation of the network control plane from the forwarding plane, and where a control plane controls several devices. Dynamic Manageable Cost Effective Adaptable Directly programmable: Network control is directly programmable because it is decoupled from forwarding functions. Agile: Abstracting control from forwarding lets administrators dynamically adjust network-wide traffic flow to meet changing needs. Centrally managed: Network intelligence is (logically) centralized in software-based SDN controllers that maintain a global view of the network. Programmatically configured: SDN lets network managers configure, manage, secure, and optimize network resources very quickly via dynamic, automated SDN programs. Open standardsbased and vendorneutral: When implemented through open standards, SDN simplifies network design and operation because instructions are provided by SDN controllers instead of multiple, vendor-specific devices and protocols.
SDN Applications SDN @ ONF Programmatically communicate via NBI SDN Controller Abstract view of network Controlling SDN Datapaths SDN Datapath Network Device SDN CDPI Programmatic Control Capability and reporting Events SDN NBIs Provide abstract network views Direct expression of network behavior (intent)
Multi-Layer SDN SDN's logically centralized network intelligence and ability to leverage cloud computing for almost unlimited compute power enables it to evaluate all layers of the network concurrently to determine where best to send traffic.. Today, a service is typically transported at a single layer. With multi-layer SDN, a network can transport services over the most efficient technology, not just the predefined transport technology. Ex. If bandwidth at a particular layer is exhausted in some portion of the network, multi-layer SDN can evaluate options and dynamically add bandwidth from a lower layer or reroute traffic from upper layers around the point of congestion.
E2E SDN Orchestration of E2E service delivery across all network domains Distributed control planes with multiple cooperating controllers ƒewbi (east-west) for controller to controller communications across domains Enhanced SBI for support of specific network technologies and types Enhanced NBI for support of customer/network applications Network virtualization and control capability Cross layer coordination (e.g., IP routing + Optical Transport)
SDN Alternatives (looking beyond OpenFlow) PCE ALTO I2RS ACTN SR
PCE Path Computation Element PCE is an entity that is capable of computing a network path or route based on a network graph and applying computational constraints Specializes in complex path computation across various domains on behalf of its path computation client (PCC) with enhanced scalability. Stateless PCE provides mechanisms to perform path computations in response to PCC requests. It utilize only the TE link information database to do this computation (TEDB). Stateful PCE: Along with network state (TEDB), it also stores the state of all the computed paths or LSPs and their resources (LSPDB). Enhanced algorithms at stateful PCE PCE-Initiated: Setup, maintenance and teardown of PCE-initiated LSPs from a central PCE server.
Stateful PCE Abstraction & Algorithms over Stateful PCE Stateful PCE Server Stateful PCE as evolutionary approach to SDN. PCEP Protocol PCC PCC In SP network with existing investment in IP/MPLS devices, active stateful PCE can offer centralized control over the LSPs as a simple evolutionary approach for SDN.
Stateful PCE OF-Based SDN Stateful PCE New protocol - OF Only software update for edge router (PCC). New hardware might be needed Opens up the control of data flows to customizable software. Controlling devices using a central orchestrator Continue to use existing signaling mechanism (RSVP) or use segment routing (SR) PCE Server acts as the SDN controller. PCE capable to compute, initiate, control and maintain the LSP.
ALTO Application-Layer Traffic Optimization Protocol provides simple mechanism to provide basic, abstract but useful network information to applications. Application can make use of this information to use network efficiently. Extension to ALTO are proposed for Abstract network topology graph Traffic Engineering This protocol developed on top of existing HTTP (REST-ful) using JSON Usecases Peer to Peer File sharing CDN Real-time Communication Live media streaming Service aware parameters Calendering
PCE+ALTO for Data Centre Interconnect DC 1 DC 2 DC 3 DC 4 DC 5 Application Stratum NET Arbiter + PCE Cross Stratum Optimization (CSO) - Optimization of Datacenter and Network resources - which can only be achieved via joint effort & information exchange - to cross optimize between stratums. Arbitration Layer APP Arbiter ALTO PCEP Application DC resources Optimization Network resource Optimization Network Stratum Net-Arbiter uses stateful PCE to query and obtain the network status PCE ALTO Initially for P2P file sharing (torrents) & CDN to get simple network cost map HTTP/Restful/JSON ALTO extensions to support DC and network costs and events Joint optimized DC application resources along with network resources. DC Migration, Schedule Backup, DC & Network Events CSO
Abstracted graph Abstract Graph Application Controller Abstract Topology Network Controller HYD (User region) DLI (Data Center) BLR BOM Access to an Abstract network topology, could allow an Application to understand network in a much better way find bottleneck, make dynamic decision with network conditions in mind
I2RS: Interface to Routing System SDN focuses on programming the data plane Switch programming (cross-connects) Forwarding (FIB) There are many functions and features not covered Control of routers Control of routing protocols Management of the routing system Existing techniques are non-standard Using CLI to achieve these functions is very frustrating Expensive, time-consuming, error-prone, risky Need for a standard approach Strong desire for a simple and standard approach
I2RS Usecases for I2RS Programming and managing the RIB BGP use cases Traffic steering and classification DDoS mitigation Topology reading, monitoring, and control Service chaining I2RS to use Netconf/Restconf/Yang as the base
Netconf / Restconf / Yang Netconf Network Management Protocol Remote primitives to view/manipulate data Encoding data as per the data model Think SNMP Transaction based (network wide) Yang Data Model Explicit precise structure, syntax and semantics of the (externally visible) data Think MIB Configuration data as well as state Also events Restconf A REST protocol over HTTP accessing data defined in YANG using datastores defined in NETCONF. Netconf/Restconf/Yang as a base to manipulate state on the device!! (I2RS)
ACTN - Abstraction & Control of Transport Networks Multi-layered multi-domain Network Technology, administrative or vendor islands Interoperability for dealing with different domains is a perpetual problem for operators. New service introduction with connections that traverse multiple domains Need significant planning Manual operations to interface different vendor equipment and technology across IP and Optical layers. Facilitate virtual network operations Creation of a virtualized environment allowing operators to view and control multi-subnet multi-technology networks into a single virtualized network. Accelerate rapid service deployment of new services including more dynamic and elastic services improve overall network operations and scaling of existing services. Hierarchy of controllers
6 5 8 ACTN Customer A Control Customer B Control Customer C Control A.1 1 1 3 1 2 5 4 2 3 6 6 3 A.2 B.1 1 3 1 1 3 3 B.2 C.1 1 3 C.3 1 5 8 1 3 4 6 8 2 5 4 B.3 C.2 Creates abstraction topology per application/client need A.3 PNC Multi Domain Service Coordinator 1 2 2 3 4 PNC Physical Network Control like PCE 5 6 A.1 1 2 1 3 4 1 2 3 3 4 A.2 6 5 6 5 B.1 B.2 3 4 Multi-domain network topology 1 2 4 8 7 5 6 1 2 4 3 C.2 A.3 C.3 5 5 6 B.3
Segment Routing (SR) Simplicity - Less numbers of protocols and interactions and automated FRR for any topology Scale - Avoid thousands of labels and TE LSPs in the network Leverage all services supported over MPLS today (L3/L2 VPN, TE, IPv6) Bring the network closer to the applications Segment Routing Segment How Applications the source chooses a path and encodes it in the packet header as an ordered list of segments an identifier for any type of instruction Service Context Locator Distributed by IGP MPLS Label Stack IPv6 List of segment in routing extension header Through PCE get optimized path Applications can interact and make changes through PCE Only the ingress needs to change the segment-list!
SR & SDN SR supports a simple but efficient capacity planning process based on centralized optimization SR optimizes network resources by providing a very simple support for ECMPbased shortest-path flows SR provides much better scaling SR provides guaranteed-frr for any topology SR provides ultimate virtualization as the network does not contain any application state. The state is in the packet. It is encoded as a list of segments SR provides very frequent transaction-based application as the network does not hold any state for the SR-encoded flows Application aware routing using SR
Conclusion
There is more than one way to look at SDN.. PCE, BGP, Netconf, Yang, ALTO Most Vendor companies are exploring these options. Re-using existing building blocks need to be looked into Retain some of the investment made in current network As well as leverage benefit of SDN SDN in Enterprise and Datacenter is different from SDN in carriers network
Inline with ODL architecture Support Multiple Southbound/Data-Plane Elements OpenFlow, NetConf, SNMP, BGP-LS, PCEP, LISP etc Support IETF protocols to control physical and virtual routers and switches Border Gateway Protocol Link State (BGP-LS) Path Computation Element Protocol (PCEP)
Thank You!