Network Architecture with Software Programmability Cisco Metro Fabric Design

Transcription

1 Network Architecture with Software Programmability Cisco Metro Fabric Design Jiri Chaloupka - Technical Marketing Engineer released: 10/2017

2 Cisco SP Fabric Designs principals: Simple, Scalable, Automatable Network Location Metro & Access Core Peering Designs Metro Fabric Core Fabric Peering Fabric Building Blocks CLOS Fabric SR/EVPN Automation Telemetry and Analytics YANG data models

3 Cisco Metro Fabric - High-Level Design PE Layer ASR9000 Segment Routing End-to-End TI-LFA SRTE Policy Programmability (XTC) Aggregation Access ASR903 RSP3 -> NCS5500 IGP1+SR IGP2+SR ZTP/ZTD Telemetry N/Y (ops) PCEP BGP-SRTE IOS-XR common OS ASR900 -> NCS5500 ASR920 IOS-XR based access NG Metro Overlay Service Provisioning (NSO) Data Path Programming (XTC) N/Y (prov.) Interconnecting Not Otherwise Specified Fabric NG Metro OSTCD sbgp (L3VPN, EVPN) N/Y = NETCONF/YANG OSTCD = Other Service Terminating Compass Design

4 Cisco Metro Fabric - High-Level Design PE Layer ASR9000 Access Simplification Segment Routing End-to-End TI-LFA SRTE Policy Programmability (XTC) Access ASR903 RSP3 -> NCS5500 IGP1+SR ZTP/ZTD Telemetry N/Y (ops) PCEP BGP-SRTE IOS-XR common OS ASR900 -> NCS5500 ASR920 IOS-XR based access NG Metro Overlay Service Provisioning (NSO) Data Path Programming (XTC) N/Y (prov.) Interconnecting Not Otherwise Specified Fabric NG Metro OSTCD sbgp (L3VPN, EVPN) N/Y = NETCONF/YANG OSTCD = Other Service Terminating Compass Design

5 Cisco Metro Fabric: what is? Compass Metro Design is a design: For SP Metro Network (Access, Aggregation) and Mobile Backhauling Built on top the successful Cisco Evolved Programmable Network (EPN 5.0) architecture Evolution of existing Unified MPLS Architecture Transport and Services Simplification Network Programmability with Segment-Routing and XTC Automated Service Provisioning with NSO Unified BGP based control plane for Layer 2 (EVPN) and L3 services (BGP L3VPN) Based on IOS-XR end-to-end Enhanced and simplified operations with Automation and Analytics

6 Cisco Metro Fabric: who is this for? Compass Metro Design targets customers who: Need a lean, simple and scalable design that will support future growth Need to build a network ready for 5G and IoT Are looking for an SDN ready solution Want to evolve their existing Unified MPLS Network Want to offer new services with guarantees SLAs Want an industry leading/future proof architecture

7 Compass Metro Fabric Compass Design Building Blocks CLOS Fabric Automation Segment Routing BGP VPN Industry lead ASR9K Highly dense and scalable NCS 5500 Programmability and analytics with YANG data models and telemetry Unified Forwarding Plane with Explicit Path Control and Traffic Engineering Common Control Plane for L2, L3 and IRB

8 Unified MPLS Transport Model Baseline Fixed Access Network IS-IS L1 Aggregation Network IS-IS L2 Core Network IS-IS L2 Aggregation Network IS-IS L2 AS-B AS-A AS-C Mobile Access Network IS-IS L1 PAN Inline RR next-hop-self AGN-ASBR next-hop-self CN-ASBR next-hop-self CN-ASBR next-hop-self AGN-ASBR next-hop-self PAN Inline RR next-hop-self FAN ebgp IPv4+label MTG ebgp IPv4+label CSG FAN ibgp IPv4+label AGN-RR ibgp IPv4+label RR CN-RR RR ibgp IPv4+label AGN-RR RR ibgp IPv4+label ibgp IPv4+label CSG MTG FAN AGN-SE CSG ibgp Hierarchical LSP ebgp LSP ibgp Hierarchical LSP ebgp LSP ibgp Hierarchical LSP LDP LSP LDP LSP LDP LSP LDP LSP LDP LSP

9 Cisco Metro Fabric Overview NSO End-to-End Service Provisioning XTC/WAE- End-to-End Path optimization with SLAs Netconf/Yang PCEP BGP-LS BGP-LS PCEP Netconf/Yang Access Node NG Metro Fabric Metro Area 01 ABR Node P Nodes Core Network Core Network ABR Node NG Metro Fabric Metro Area 02 Access Node IGP with SR Extensions (TI-LFA) IGP with SR Extensions (TI-LFA) IGP with SR Extensions (TI-LFA) Services: BGP - L3VPN/L2VPN(EVPN), point-to-point services static PW Transport: Segment-Routing with TI-LFA

10 Evolve Networks Toward Agility and Speed Cloud Scale Networking Central Office NSO XTC Access Metro Network Domain Core Network Domain Data Center Domain EVPN/L3VPN Services VNF VNF VNF VNF Segment Routing Compute Leaf Spine Simplify Unified underlay with Segment Routing Automate E2E Cross-domain automation with model-driven programmability and streaming telemetry Virtualize Transform the CO into a data center to enable distributed service delivery and speed up service creation

11 End-to-End network design with Cisco IOS XR Consistent Operational Efficiency and Feature Set Across the Metro Core and DC Data Center Domain XRv9000 Central Offices NCS 1002 DCI Metro Network Domain Core Network Domain Data Center Domain NCS 5516 Central Offices NCS 5501/2 NCS 5508 NCS 5501/2 ASR 9K NCS 5516 ASR 9K Data Center Networking Compute UCS Central Offices NCS 1002 DCI Data Center Domain

12 Cisco Metro Fabric - Protocol Simplification Unified IP/MPLS Metro Fabric Apps Applications Applications Apps CLIs APIs BGP T-LDP Provisioning NSO Path Computation/ WAN optimization XTC/WAE Network Management Controller/ Orchestration BGP-LU APIs Router RSVP-TE BGP MPLS LDP IGP T-LDP/Static IGP/SR Router IP IP

13 Segment Routing Segment Routing Technical view Data Plane Path expressed in the packet Data Dynamic path MPLS (segment labels) IPv6 (+ SR extension header) Control Plane Routing protocols with extensions (IS-IS,OSPF, BGP) SDN controller (BGP LS, PCEP, NETCONF/YANG) Explicit path Paths options Dynamic (STP computation) Explicit (expressed in the packet)

14 IGP Prefix Segment Signaled by ISIS/OSPF Minor extensions to existing link-state routing protocols Shortest-path to IGP prefix Equal Cost MultiPath (ECMP)-aware Global significance in SR domain Label = SRGB + Index SRGB = Segment Routing Global Block Default SRGB: 16,000 23,999 Advertised as index Example 1: Best Path All nodes use default SRGB 16,000 23, /

15 IGP Prefix Segment Example 2: ECMP Signaled by ISIS/OSPF Minor extensions to existing link-state routing protocols 1 2 Shortest-path to IGP prefix Equal Cost MultiPath (ECMP)-aware Global significance in SR domain Label = SRGB + Index SRGB = Segment Routing Global Block Default SRGB: 16,000 23,999 Advertised as index /32 All nodes use default SRGB 16,000 23,

16 IGP Adjacency Segment Signaled by ISIS/OSPF Minor extensions to existing link-state routing protocols Forward on IGP adjacency Local significance Automatically allocated by router 1 2 Adj to Adj to

17 Combining IGP Segments Signaled by ISIS/OSPF Packet to 5 Steer traffic on any path through the network Path is specified by list of segments in packet header, a stack of labels No path is signaled No per-flow state is created Packet to

18 MPLS Data Plane Operations Segment IPv4: /32 or IPv6: 2001::0101:0104/128 Prefix-SID Payload Push Swap Payload Payload Pop Payload - Assumptions: SR enabled on all nodes LDP not enabled or SRpreferred on Node1 Node4 advertises its loopback v4 or v6 address with attached prefix-sid IPv4 address: /32 IPv6 prefix: 2001::0101:0104/128 Node4 requests default PHP functionality

19 Simple and Efficient Transport of MPLS services MP-BGP MPLS services ride on prefix segments Simple, one less protocol to operate (LDP) CE PE PE /32 Prefix-SID CE / ::a00:0/126 vrf RED SR Domain vrf RED

20 Anycast Prefix Segment ID (SID) Same prefix advertised by multiple nodes Traffic forwarded to one of Anycast prefix- SIDs based on best IGP path If primary node fails, traffic is auto re-routed to other node DC (BGP-SR) WAN (IGP-SR) PEER

21 SR Segments IGP Prefix Segment Signaled by ISIS/OSPF Minor extensions to the existing link-state routing protocols (OSPF and IS-IS) Shortest-path to the IGP prefix Global in SR domain SRGB + Index => = SRGB: Segment Routing Global Block: default [ ] DC (BGP-SR) WAN (IGP-SR) 7 PEER IGP Adjacency Segment Signaled by ISIS/OSPF Minor extensions to the existing link-state routing protocols (OSPF and IS-IS) Forward on the IGP adjacency Local Automatically allocated by the router DC (BGP-SR) WAN (IGP-SR) 7 PEER

22 Binding-SID Stitching Illustration BSID: BSID: Node Node Node Node Node Node Node Node 10 All Nodes SRGB [16,000-23,999] Prefix-SID NodeX: 1600X Binding-SID X Y: 300XY Node 10 Assume Node1 can t push 8 labels to go to Node10 compress label stack by stitching SRTE Policies: Node1 pushes: 2 labels to go to Node4 Binding-SID to go to Node10 Node4 pops Binding-SID and pushes: 2 labels to go to Node7 Binding-SID to go to Node10 Node7 pops Binding-SID and pushes 2 labels to go to Node10

23 Cisco Metro Fabric - Transport IGP-SR/TI-LFA/SR-LDP_co-existence Configuration Example router isis 1 address-family ipv4 unicast metric-style wide segment-routing mpls! interface Loopback0 address-family ipv4 unicast prefix-sid prefix-sid index 1 IGP-SR router ospf 1 router-id segment-routing mpls segment-routing forwarding mpls area 0 interface Loopback0 passive enable prefix-sid index 1 TI-LFA SR/LDP Co-existence LDP->SR migration

24 Cisco Metro Fabric - Transport IGP-SR/TI-LFA/SR-LDP_co-existence Configuration Example router isis 1 address-family ipv4 unicast metric-style wide segment-routing mpls! interface Loopback0 address-family ipv4 unicast prefix-sid prefix-sid index 1 IGP-SR router ospf 1 router-id segment-routing mpls segment-routing forwarding mpls area 0 interface Loopback0 passive enable prefix-sid index 1 router isis 1 interface GigabitEthernet0/0/0/2 address-family ipv4 unicast fast-reroute per-prefix fast-reroute per-prefix ti-lfa TI-LFA router ospf 1 fast-reroute per-prefix fast-reroute per-prefix ti-lfa SR/LDP Co-existence LDP->SR migration

25 Cisco Metro Fabric - Transport IGP-SR/TI-LFA/SR-LDP_co-existence Configuration Example router isis 1 address-family ipv4 unicast metric-style wide segment-routing mpls! interface Loopback0 address-family ipv4 unicast prefix-sid index 1 IGP-SR router ospf 1 router-id segment-routing mpls segment-routing forwarding mpls area 0 interface Loopback0 passive enable prefix-sid index 1 router isis 1 interface GigabitEthernet0/0/0/2 address-family ipv4 unicast fast-reroute per-prefix fast-reroute per-prefix ti-lfa TI-LFA router ospf 1 fast-reroute per-prefix fast-reroute per-prefix ti-lfa router isis 1 address-family ipv4 unicast segment-routing mpls sr-prefer SR/LDP Co-existence LDP->SR migration router ospf 1 segment-routing mpls segment-routing sr-prefer

26 The next wave What is segment routing? An LS IGP protocol extension bringing network simplification/optimization The 2 faces of segment routing An IP/MPLS architecture designed with SDN in mind No LDP Lighter protocol suite Less adjacencies, less states to maintain No IGP to LDP synchronization Eliminates delays in activating a path Topology independent fast reroute using post convergence back up path 50 ms protection no microloops 100% coverage of network topologies Easy troubleshooting Centralized-only Balance Distributed-only Right balance between distributed intelligence and centralized optimization and programming SR-TE Wide applications (SP, OTT/Web, GET) across (WAN, Metro/Agg, DC) MPLS and IPv6 dataplanes SDN controller

27 Cisco Metro Fabric Overview NSO End-to-End Service Provisioning XTC/WAE- End-to-End Path optimization with SLAs Netconf/Yang PCEP BGP-LS BGP-LS PCEP Netconf/Yang Access Node NG Metro Fabric Metro Area 01 ABR Node P Nodes Core Network Core Network ABR Node NG Metro Fabric Metro Area 02 Access Node IGP with SR Extensions (TI-LFA) IGP with SR Extensions (TI-LFA) IGP with SR Extensions (TI-LFA) Services: BGP - L3VPN/L2VPN(EVPN), point-to-point services static PW Transport: Segment-Routing with TI-LFA

28 BGP-LS Overview Optimal Path Computation for Multi-area TE Solution is BGP, not IGP. BGP-LS is an address-family afi=16388, safi=71 Defined to carry IGP link-state database via BGP Supports both IS-IS and OSPF Delivers topology information to outside agents Domain 0 BGP-LS PCE BGP-LS BGP-LS RR Traffic Engineering Databse (TED) Domain 1 Domain 2

29 PCEP Architectural Introduction Path computation Large, multi-domain and multi-layer networks Path computation element (PCE) PCEP PCE LSP DB TED Computes network paths (topology, paths, etc.) Stores TE topology database (synchronized with network) May initiate path creation Stateful - stores path database included resources used (synchronized with network) PCC Path computation client (PCC) May send path computation requests to PCE May send path state updates to PCE Used between head-end router (PCC) and PCE to: Request/receive path from PCE subject to constraints State synchronization between PCE and router Hybrid CSPF PCC PCC PCC Open/Close/Keepalive Open/Close/Keepalive Request Reply Notification Notification PCE PCE PCE

30 XR Transport Controller (XTC) An IOS XR-powered Stateful Path Computation Element (PCE) Multi-Domain topology Collection Real-time reactive feed Computation Native SR-TE algorithms backed by extensive scientific research 1 SR PCE Multi-Domain Topology Collection BGP-LS ISIS / OSPF North-Bound API Computation Deployment PCEP (1) SIGCOMM 2015 whitepaper

31 WAN Automation Engine (WAE) Multi-layer, multi-vendor network model for path visibility and path computation APIs for planning, optimization, forecasting and traffic engineering WAE is NOT a controller but leverages controllers WAE Network Model

32 Cisco Metro Fabric Overview NSO End-to-End Service Provisioning XTC/WAE- End-to-End Path optimization with SLAs Netconf/Yang PCEP BGP-LS BGP-LS PCEP Netconf/Yang Access Node NG Metro Fabric Metro Area 01 ABR Node P Nodes Core Network Core Network ABR Node NG Metro Fabric Metro Area 02 Access Node IGP with SR Extensions (TI-LFA) IGP with SR Extensions (TI-LFA) IGP with SR Extensions (TI-LFA) Services: BGP - L3VPN/L2VPN(EVPN), point-to-point services static PW Transport: Segment-Routing with TI-LFA

33 L2VPN Technologies Evolution Native L2 Bridging Technologies.1ad/qinq: High VLAN scale.1ah: High VLAN and MAC scale Q 802.1Q 802.1ad qinq 802.1ad qinq 802.1ah PBB Trill L2VPN Technologies L2VPN: P2P or MP L2 over MPLS EoMPLS, VPLS/PBB- VPLS L2 over IP L2TPv3 DC Overlay Overlay VXLAN NV-GRE STT EVPN (Ethernet VPN) From MAC Bridging to MAC Routing

34 EVPN - End-to-End Control-Plane Common EVPN Control Plane based on BGP: EVPN, PBB-EVPN, EVPN-VPWS Evolution: IP, MPLS (IGP/SR), MPLS-PBB IP,MPLS,VXLAN IP,MPLS,VXLAN Service Provider Network Data Center Network overlap A1 Acess PE1 PE2 WAN/Core DCI DCI Spine Spine Leaf Leaf Leaf VM VM VM Existing Solution: L2/L3VPN (BGP,T-LDP) - VPLS, EoMPLS VPLS, OTV Trill, Fabric-Path IP, IGP, MPLS (LDP), RSVP-TE, BGP-LU IP, MPLS, L2 L2, STP, VLAN

35 EVPN Next generation network services Single service for any application E2E control and automation across domains ELINE ELAN ETREE L3 VPN VPWS VPLS P2MP VPLS DC Fabric RFC 2547 VXLAN DCI VPLS / L3 VPN EVPN SR SR-TE MPLS VXLAN Access Agg Core Agg DC Optimized CapEx: - Open Standards & Multi-vendor - Active-Active multi-homing - Enhanced load balancing Reduced OpEx: - Integrated L2 & L3 service, any application: faster time to market, certification - E2E control and automation Increased Customer Value - Inter-domain SLA, faster convergence - Better stability: no flood - Granular policy control

36 What is EVPN? EVPN family introduces next generation solutions for Ethernet services BGP control-plane for Ethernet Segment and MAC distribution and learning over MPLS core Same principles and operational experience of IP VPNs No use of Pseudowires Uses MP2P tunnels for unicast Multi-destination frame delivery via ingress replication (via MP2P tunnels) or LSM Multi-vendor solutions Cisco leader in industry standardization efforts P2P EVPN-VPWS draft-ietf-bess-evpnvpws EVPN Multipoint RFC 7432 RFC 7432 RFC 7623 EVPN PBB-EVPN

37 Ethernet VPN Highlights Next generation solution for Ethernet multipoint (E-LAN) services Data-plane address learning from Access Control-plane address advertisement / learning over Core PEs run Multi-Protocol BGP to advertise & learn Customer MAC addresses (C- MACs) over Core Same operational principles of L3VPN Learning on PE Access Circuits via dataplane transparent learning VID 100 SMAC: M1 DMAC: F.F.F CE1 C- MAC:M1 PE1 PE2 PE3 PE4 CE3 C- MAC:M3 No pseudowire full-mesh required Unicast: use MP2P tunnels Multicast: use ingress replication over MP2P tunnels or use LSM BGP MAC adv. Route EVPN NLRI MAC M1 via PE1 Standardized at IETF RFC 7432

38 Next-Generation Solutions for L2/L3VPN Solving VPLS challenges for per-flow Redundancy M1 M2 Existing VPLS solutions do not offer an All- Active per-flow redundancy Looping of Traffic Flooded from PE CE1 Echo! PE1 PE2 PE3 PE4 CE2 Duplicate Frames from Floods from the Core M1 CE1 PE1 PE3 CE2 Duplicate! M2 MAC Flip-Flopping over Pseudowire PE2 PE4 E.g. Port-Channel Load-Balancing does not produce a consistent hash-value for a frame with the same source MAC (e.g. non MAC based Hash-Schemes) M1 CE1 PE1 PE2 MAC Flip-Flop PE3 PE4 CE2 M2

39 EVPN - Components L2 and L3 in the same instance! EVPN Instance (EVI) Ethernet Segment BGP Routes BGP Route Attributes PE EVI spans all PEs participating in an EVPN MAC-VRF: A VRF table for MACs on a PE Encompass one or more bridge-domains, depending on service interface type Port-based VLAN-based (shown above) VLAN-bundling BD BD MAC VRF MAC VRF VLAN aware bundling (NEW) SHD ESI1 MHD ESI2 CE1 CE2 Represents a site connected to one or more PEs Uniquely identified by a 10-byte global Ethernet Segment Identifier (ESI) Could be a single device or an entire network Single-Homed Device (SHD) Multi-Homed Device (MHD) PE1 PE2 Single-Homed Network (SHN) Multi-Homed Network (MHN) EVPN and PBB-EVPN define a single new BGP NLRI used to carry all EVPN routes NLRI has a new SAFI (70) Routes serve control plane purposes, including: MAC / IP address reachability MAC mass withdrawal Split-Horizon label adv. Aliasing Route Types [1] Ethernet Auto-Discovery (AD) Route [2] MAC Advertisement Route [3] Inclusive Multicast Route [4] Ethernet Segment Route (5) IP Prefix Advertisement Route Multicast endpoint discovery Redundancy group discovery Designated forwarder election Extended Communities ESI MPLS Label ES-Import MAC Mobility Default Gateway Router s MAC New BGP extended communities defined Expand information carried in BGP routes, including: MAC address moves C-MAC flush notification Redundancy mode MAC / IP bindings of a GW Split-horizon label encoding

40 EVPN VPWS Benefits of EVPN applied to point-to-point services No signaling of PWs. Instead signals MP2P LSPs instead (ala L3VPN) All-active CE multi-homing (per-flow LB) Single-active CE multi-homing (per-service LB) Relies on a sub-set of EVPN routes to advertise Ethernet Segment and AC reachability CE1 ES1 Control-plane attachment circuit advertisement over the Core MPLS PE2 VPWS Service Config: EVI = 100 Local AC ID = AC2 Remote AC ID = AC1 CE2 ES2 PE discovery & signaling via a single protocol BGP Per-EVI Ethernet Auto-Discovery route Handles double-sided provisioning with remote PE autodiscovery VPWS Service Config: EVI = 100 Local AC ID = AC1 Remote AC ID = AC2 ES1 I have a P2P service that needs to communicate with the PE(s) that own of AC = AC2 BGP Eth. Auto- Discovery Route EVPN NLRI AC AC1 via PE1

41 EVPN Ethernet access Single/Dual Homed Solution, Legacy L2 access LACP PE1 A1 PE1 A2 PE1 A1 MPLS Core MPLS Core A1 STP/REP/ G MPLS Core Ethernet PE2 EVPN-MPLS A1 Ethernet PE2 EVPN-MPLS A2 PE2 EVPN-MPLS

42 EVPN Seamless integration VPLS, VPWS, Ethernet LACP CE VPWS B1 VM VM VM Leaf Leaf Leaf Spine Spine DCI DCI MPLS Core DCI DCI EVPN - VXLAN A1 A2 VPLS EVPN - MPLS

43 Symmetric Anycast IRB Routing and Bridging in the same instance All-Active Multi-homed Access WITHOUT: mlag (mlacp) VSS/vPCE DCI DCI DC Fabric - MPLS/VXLAN L3 : RT2 [MAC/IP] - host-route RT5: [prefix] L2: RT2 [MAC/IP] L2: RT2 [MAC/IP] Leaf Leaf Leaf Anycast IRB Anycast IRB VM VM VM

44 Cisco Metro Fabric Overview NSO End-to-End Service Provisioning XTC/WAE- End-to-End Path optimization with SLAs Netconf/Yang PCEP BGP-LS BGP-LS PCEP Netconf/Yang Access Node NG Metro Fabric Metro Area 01 ABR Node P Nodes Core Network Core Network ABR Node NG Metro Fabric Metro Area 02 Access Node IGP with SR Extensions (TI-LFA) IGP with SR Extensions (TI-LFA) IGP with SR Extensions (TI-LFA) Services: BGP - L3VPN/L2VPN(EVPN), point-to-point services static PW Transport: Segment-Routing with TI-LFA

45 NSO Main Features Applications Service Manager Device Manager Engineers REST, NETCONF, Java, Python, Erlang, CLI, Web UI Network Element Drivers (NEDs) NETCONF, REST, SNMP, CLI, etc VNFM Controller Apps EMS and NMS Service Model Device Model Logically centralized network services Data models for data structures Structured representations of: Service instances Network configuration and state Mapping service operations to network configuration changes Transactional integrity Multiprotocol and multivendor support Physical Networks Virtual Networks Network Apps

46 Cisco Metro Fabric Overview NSO End-to-End Service Provisioning XTC/WAE- End-to-End Path optimization with SLAs Netconf/Yang PCEP BGP-LS BGP-LS PCEP Netconf/Yang Access Node NG Metro Fabric Metro Area 01 ABR Node P Nodes Core Network Core Network ABR Node NG Metro Fabric Metro Area 02 Access Node IGP with SR Extensions (TI-LFA) IGP with SR Extensions (TI-LFA) IGP with SR Extensions (TI-LFA) Services: BGP - L3VPN/L2VPN(EVPN), point-to-point services static PW Transport: Segment-Routing with TI-LFA

47 Cisco Metro Fabric Design Benefits Simple, scalable and automatable design End-to-End unified forwarding plane based on Segment Routing Less than 50ms convergence with TI-LFA based protection Full path programmability with guaranteed SLAs Flexible service/ workload placement Improved operational efficiency with a simplified protocol stack and modern tooling for automation Programmability and analytics with YANG data models and Telemetry

48 SRv6 VPN and TE on NCS Jiri Chaloupka - Technical Marketing Engineer Jisu Bhattacharya - Principal Engineer John Bettink - Distinguished Engineer Clarence Filsfils - Cisco Fellow

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