Future of PCE. Dhruv Dhody, Sr. System Architect, Huawei Technologies

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1 Future of PCE Dhruv Dhody, Sr. System Architect, Huawei Technologies

2 What is PCE?

3 A Path Computation Element (PCE) is an entity (component, application, or network node) that is capable of computing a network path or route based on a network graph and applying computational constraints.

4 PCE What? PCE Path Computation Element Server or high end router PCC Path Computation Client Ingress, NMS PCEP PCE Protocol to communicate between PCC and PCE(s) A TCP based protocol PCE specializes in complex path computation across various domains on behalf of its path computation client (PCC) with enhanced scalability. Instead of head-end router doing the path computation, it is ask PCEs to cooperate and obtain E2E path.

5 PCE Where?

6 PCE, The Journey so far

7 A brief history of PCE PCE Intradomain P2MP Hierarchy of PCE (H-PCE) BRPC PCE Inter-domain Protection Path GMPLS network Confidentiality in PCEP Objective Functions Inter-layer

8 And then, Stateful PCE Stateless PCE provides mechanisms to perform path computations in response to PCC requests. It utilized only the Traffic Engineering database (TEDB) to do this computation. Along with network state (TEDB), Stateful PCE also stores the state of all the computed paths or LSPs and their resources (LSP-DB). Stateful PCE TEDB Passive It uses the TEDB and LSPDB while path computation, but computation is done only when requested by PCC. LSPDB Active It allows the LSP to be delegated to the PCE where PCE becomes the owner of the LSP and can change any attribute of the LSP at anytime.

9 Stateful PCE Function Meaning Message Capability Negotiation Both the PCC and the PCE must announce during PCEP session establishment that they support PCEP Stateful PCE. Open State Synchronization After the session between the PCC and a stateful PCE is initialized, the PCE ust lear the state of a PCC s LSPs efore it a perfor path computations or update LSP attributes in a PCC. PCRpt (report) LSP State Report A PCC sends an LSP state report to a PCE whenever the state of an LSP changes. PCRpt LSP Control Delegation A PCC grants to a PCE the right to update LSP attributes on one or more LSPs; the PCE becomes the authoritative sour e of the LSP s attributes as long as the delegation is in effect; the PCC may withdraw the delegation or the PCE may give up the delegation. (active stateful PCE only) PCRpt, PCUpd LSP Update Request A PCE requests modification of attributes on a PCC's LSP. (active stateful PCE only) PCUpd (update)

10 Global Reoptimization Stateful PCE automatically reoptimize the network paths such that overall network gets opti ized LSP path taken completely depend on the order of tunnel configuration. Problems PCE Solution The order in which LSP are setup can lead to blocking resources for other LSPs. To resolve such deadlock, the administrator intervention is required. Many links in the network remain unutilized Active Stateful PCE can modify the LSP path at any time This allow stateful PCE to automatically re-optimize the global network without traffic disruption

11 PCE-Initiated Setup, maintenance and teardown of PCE-initiated LSPs Under the stateful PCE model, without the need for local configuration on the PCC Allowing for a dynamic network that is centrally co trolled a d deployed Environments where the LSP placement needs to change in response to applicatio de a ds LSP Initiate via PCEP Agile software-driven network operation, and can be seamlessly integrated into a controller-based network architecture A new PCInitiate Message

12 PCE with Segment Routing (SR) SR Path Stateful PCE with SR PCEP Protocol PCE prepare label stack of node and adjacency labels payload PCE Optimization PCE can respond to network events like congested links and update the label stack no RSVP-TE signaling PCE is the magic component of SR!!

13 Stateful PCE Extn Optical GMPLS controlled Networks Support for flex-grid, WSON Inter-Layer, VNTM P2MP Others Support for Multicast Service MVPN, IPTV Sync Optimization Delegating P2MP Path Computations and optimizations Backup Stateful PCE Inter-domain and Inter-layer considerations

14 PCE in SDN!!!

15 PCE & SDN 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.

16 PCE in ODL PCEP session Stateful PCE Instantiation Capability Support for SR PCEP

17 ABNO: Application-Based Network Operation PCE at the heart of the ABNO architecture providing a set of tools for path computation, multi-layer control, state and instantiation etc using existing building blocks!

18 APP+NET Application Stratum 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. App Arbiter Net Arbiter PCE plays a crucial role in network optimization by understanding the application needs! Network Stratum PCE

19 ACTN Customer Controller Abstraction and Control of Transport Networks Multi-domain Service coordinator CNC 1 MDSC 2 PCE Network controllers PNC 1 PNC 2 MPLS Core Access/MPLS-TP BH PCE PCE PNC 4 Access/MPLS TP BH PNC 3 Optical Core PCE PCE EP 1 EP 2 EP 3

20 ACTN Ability to build virtual network operation on multi-layer, multidomain topology Policy Enforcement Ability to request/ respond/ instantiate VNs Dynamic/On-demand VN Modification Ability to Coordinate multi-domain path computation Ability to perform E2E Path Restoration PCE

21 PCE, What's next?

22 Towards PCECC PCECC PCE as a central controller Stateful PCE with Initiation PCEP PCEP Protocol Protocol RSVP Signaling All nodes are PCC PCC PCC Free from signaling protocols PCECC communicates to all nodes PCECC responsible for label allocation Central controller!

23 With Segment Routing Use of PCEP for Label (SR-SID) Distribution Use Node label for Best Effort SR-BE LSP Use Label Stack of Node and Adjacency for Traffic Engineered SR-TE LSP. PCE can also be used for Label management

24 Modes Basic SR-BE SR-TE Forwarding similar to RSVP-TE without RSVPTE signaling Forwarding similar to LDP without LDP/IGP-SR signaling Forwarding similar to IGP-SR-TE Use of local label along the LSP path Use of SR Node label (global) to distribute label map Use of SR node and Adj label allocated and distributed by PCECC PCECC allocates local label and downloads to LSR PCECC allocates global label and distribute them Rest processing similar to stateful PCE Each LSR rely on local IGP for the next hop Rest processing similar to stateful PCE with SR

25 Basic Mode Path: RT1 RT4 RT6 1. Request PCECC to initiate LSP LabelUpd to download labels along the path 2. PCECC computes the path and allocates label along the path for each node 3. PCE sends PCInitiate message to the ingress and Ingress sends PCRpt message back 4. PCECC sends PCLabelUpd to each node along the path with label information to download 1026 payload 1028 payload 5. PCECC sends PCUpd to the ingress and PCC sends PCRpt back with status-up.

26 With SR PCE allocates Labels (SID) for node, Adjacency. LabelUpd for label mapping for node and adjacency payload 4106 payload

27 But, that s not it

28 PCE in NFV SFC PCE at the Infrastructure layer Can be a VNF itself? Service Function Chaining via PCE The Northbound PCE(P) IoT Abstract Topology PCEP-LS or TED export REST interfaces Smart Cities PCE in IPv6-based Deterministic Networks

29 Thank You!