Ethernet. Access Technologies 2 Moldován István. Department of Telecommunications and Media Informatics

Transcription

1 Ethernet Access Technologies 2 Moldován István Budapest University of Technology and Economics Department of Telecommunications and Media Informatics

2 Ethernet Forwarding MAC Forwarding Topology VLAN Forwarding Topology Active (Spanning Tree) Topology Physical Topology

3 Ethernet Switches Layer 2 forwarding MAC address based Learns MAC addresses Store-and-forward operation No collision High speed backplane Many interfaces Different interface speeds Different media 3

4 Switches Standard refers them as bridges They divide the broadcast domains Types Unmanaged SOHO use, low level aggregation No support for STP nor VLAN Managed VLAN and STP support management interface L2/L3 4

5 P-to-P mode On links between bridges CSMA-CD not needed Separate RX/TX paths at phy No collision Full duplex Higher achievable BW Can be used Between bridges Between bridge-pc HUB and shared media can not use it 5

6 Ethernet local network design Hierachically Router Multiservice switch SWITCH, Bridge HUB 6

7 Metro Ethernet Triple Play SIP Proxy Server VOD VOD Server VOD Server Server POP Location Server TV Headend National IP Network Router GE B-RAS Metro Backbone GE 2 x GE 3 rd Party ISP Internet GE B.PON GE GE 100BaseFX G.PON GE EFM Aggregation Switch GE E.PON Page 7

8 Ethernet based transport in provider networks The Ethernet way Budapest University of Technology and Economics Department of Telecommunications and Media Informatics

9 Challenges Carrier grade requirements Scalability Service Quality Multicast Management Fault performance Provide Ethernet service Upgrade the cheap Ethernet (IEEE) Extend the proven MPLS (IETF)

10 Multicast Multicast possibilities Ethernet multicast support Ethernet multicast addresses - mapping Multicast support in switches IGMP support at BNG IGMP snooping in bridges A multicast manual constrain by VLANs VLANs for multicast trees Traffic can not leave the tree Basically broadcast within the VLAN, not the best solution Page 10

11 Multicast IGMP snooping The swich listens to IGMP join messages For an IGMP join adds an entry to the forwarding table Assigns the multicast traffic to a port An IGMP leave message removes the entry Simple, but violates the OSI layering L2 decision on L3 information IGMPv3 next upcoming standard Page 11

12 Multicast - DSLAM Different levels of IGMP handling Snooping Proxy Multicast router DSLAM should support at least proxy Decrease load on IGMP routers faster Multicast in home network HGW should also support snooping If not - broadcast Fast leave Page 12 Immediately blocks traffic

13 Carrier Ethernet: service types E-Line service: Ethernet Private Line Virtual Private Line Ethernet Internet Access CE UNI E-Line Point-to-Point EVC Carrier Ethernet Network UNI CE E-LAN Service: Multipoint L2 VPN Transzparent LAN Needed for IPTV multicast etc CE UNI E-LAN Carrier Ethernet Network UNI Multipoint-to-Multipoint EVC CE MEF által hitelesített Carrier Ethernet termékek UNI: User Network Interface, CE: Customer Equipment

14 IEEE 802.1Q - VLAN VLAN tag QoS: priority 12 bit VLAN ID: 4096 VLANs Pri CFI (3 bits) (1 bit) VLAN ID (12 bit) MAC DA MAC SA 802.1Q ethertype VLAN tag Data CRC Usage User identification Service identification The 4096 limit is there Too few for a provider! The most wide spread UNI Also we must be prepared to transfer VLAN tagged packets

15 Provider Bridges (IEEE 802.1ad) Also known as Q-in-Q Widely used 4K services (12-bits) Unique service ID (S-VID) Forwarding is the same, L2 learning bridge with STP, filtering for the outer VLAN (S-VID) Scalability 4K service

16 Provider Backbone Bridges 4K connected LAN Unique per service ID (LAN = I-SID) Forwarding is the same, L2 learning bridge with STP, filtering for the outer VLAN (B-VID) Service management is simple Scalability Massive sservice scalability (24-bit) Only learn MAC of the Provider bridges Mapping of C-MAC to VIDs

17 Comparison headers added

18 PB/PBB facts Scalability solved Cheap Ethernet switching remains Still no support for Traffic Engineering Protection/restoration based on STP Management is more complex Different layers of VLANs No adequate management Still not good in the core

19 PBT Goal Keep the Ethernet forwarding Change the control plane (no STP and learning) Set up paths manually = Traffic Engineering - Ethernet BVID=1 BVID=2 What we get: Point-point tunnel Traffic Engineering Protection

20 PBT Provider Backbone Transport IEEE 802.1Qay Nortel started based on PBB Uses the existing technologies Deterministic QoS for service is the target scalability

21 PBT - operation Data plane Static forwarding tables Addressing 60 bit MAC + VLAN based Totally different control plane Manual MPLS based

22 Ethernet Transport technology use PBB Voice IP/MPLS mag Data 802.1Q PB PBT Video 802.1Q: 4K user PB: 4K service, Not too many MAC PB Q-in-Q IEEE 802.1ad PBB Mac-in-Mac IEEE 802.1ah PBT PBB-TE IEEE 802.1Qay PBB: good scalability Added value: TE, OAM

23 Ethernet based transport in provider networks The other way IP/MPLS Budapest University of Technology and Economics Department of Telecommunications and Media Informatics

24 MPLS Pseudowire - WPWS Ethernet p2p service IETF pwe3 study group, the draft name Martini encapsulation MPLS label is encapsulated, multiple virtual connections within an UNI (VC) Forwarding based on tunnel label CE PE SP PE CE The solution inherits all MPLS solutions Traffic Engineering, protection, OAM 24 Áramkör kapcsolt Ethernet? Moldován István Elsinco szeminárium 12 Szeptember 2007

25 Data Plane : EoMPLS packet Label (Tunnel) EXP 0 TTL Label (VC) EXP 1 TTL Reserved Sequence Number Control Word Layer2 PDU Tunnel label : LSP label to get the packet from ingress PE to egress PE (IGP label or RSVP (TE) label) VC Label : demultiplexing label identifying an emulated VC Identifies outgoing interface/vlan Control Word : extra information regarding the VC VC Label TTL = 2 L2 header moldovan@tmit.bme.hu Tunnel Label VC Label Original Ethernet Frame Ethernet Szolgáltatások 25

26 Pseudo-Wire reference model <--- Emulated Service:FR/Ether/ATM/PPP/HDLC ---> <-- FR --> < PW:Pseudowire VC -----> <--FR --> Ethernet Ethernet ATM/PPP/HDLC ATM/PPP/HDLC Site1A CE 1A Attachment VC / L2 circuit PE1 PSN Tunnel: (IP/)MPLS Tunnel MPLS (LDP or RSVP-TE) IP/MPLS Core PE2 Attachment VC / L2 circuit CE 1B Site1B Site 2B Site 2A CE 2A Attachment VC / L2 circuit Attachment VC / L2 circuit CE 2B ES Emulated Services: FR/Ether/ATM/PPP/HDLC Attachment VC (AVC): FR DLCI/Ethernet VLAN/ATM PVC/PPP/HDLC PW Pseudo-Wire: Emulated VC (EVC): MPLS LSP PSN Packet Switched Network (Tunnel): MPLS LSP or RSVP-TE moldovan@tmit.bme.hu Ethernet Szolgáltatások 26

27 Comment on VPWS: MTU EoMPLS does not support fragmentation MTU > layer2 VLAN frame No e2e detection MTU in core should be bigger MTU values a PE-CE should match MTU set them correctly MTU Calculations for EoMPLS: Max Frame Size = Link Header + labels + Transported L2 Header + Payload Transported Ethernet Header: AToM removes (1) Preamble (2) SFD (3) FCS Ethernet II Encapsulation 18 Bytes Ethernet SNAP 26 Bytes Dot1q tag(s) 4 Bytes per tag Labels : usually 2 labels Example : Ethernet II + dot1q tag + 2 labels + Ethernet II + 2 dot1q tags (QinQ) + Payload 18B 4B 8B 18B 8B 1500B moldovan@tmit.bme.hu Ethernet Szolgáltatások 27

28 VPLS VPLS - A VPLS - B PE CE - 1 VPLS - B PE Service Provider Backbone CE - 2 CE - 1 PE Bridged LAN VPLS - A Emulated LAN Customer Edges (CE): Client side device, tyically Ethernet Provider Edges (PE): VPLS inteligence, start/end Core: just forwarding CE - 2 moldovan@tmit.bme.hu Ethernet Szolgáltatások 28

29 VPLS example Full Mesh PEs are acting like a bridge towards the CE nodes moldovan@tmit.bme.hu Ethernet Szolgáltatások 29

30 VPLS Operation VPLS instance : Service identifier (Svc-id) Full mesh tunnels Targeted LDP messages Forwarding: learning bridge Flooding Split-horizon never send to the receiving interface moldovan@tmit.bme.hu Ethernet Szolgáltatások 30

31 Why not VPLS End-to-End? VPLS scalability eg. 5 PE - 20 LSP, 40 PE: 1,536. High bandwidth waste because of broadcasts VPLS new requirements Protection, OAM, mapping Number of PE in VLAN Number of Retransmissions/ Broadcast Number of LSPs moldovan@tmit.bme.hu Ethernet Szolgáltatások 31

32 VPLS Flooding & forwarding CE E.g ARP-request PE PE CE CE MPLS core Flooding (Broadcast, Multicast, Unknown Unicast) CE PE E.g ARP-reply PE CE Dynamic learning of MAC addresses on PHY and VCs CE MPLS core Forwarding Physical Port Virtual Circuit Ethernet Szolgáltatások 32

33 VPLS scalability- hierarchical MTU - Multi-Tenant Unit: owned by multiple users, bridge VPLS can be extended to the MTUs MAC/VLAN scalability increased More complex MTU Hierarchical VPLS HUB pseudowire (hub PW) between PEs spoke PW between MTU-PE Spoke PW can be QiQ, MPLS, moldovan@tmit.bme.hu Ethernet Szolgáltatások 33

34 Hierarchical VPLS Ethernet Szolgáltatások 34

35 VPLS Architectures CE n-pe VPLS n-pe CE VPLS One big hierarchy MPLS to the Edge Ethernet edge MPLS core MPLS edge H-VPLS u-pe n-pe H-VPLS H-VPLS n-pe u-pe 2 level Hierarchy MPLS or Ethernet Edge MPLS core Ethernet edge p2p or ring MPLS core MPLS edge moldovan@tmit.bme.hu Ethernet Szolgáltatások 35

36 VPLS signaling and auto-discovery VPN Discovery Centralized DNS, LDAP, Radius Directory Services Distributed BGP Signaling Label Distribution Protocol (LDP, BGP) VPLS requires full mesh of LSPs between PEs: Manual procedures (static) Provisioning systems(nms/oss) Signalling protocols: LDP ( Lasserre-V. Kompella draft) BGP ( Kompella draft, Juniper) other (Radius, DNS, stb.) VPLS proposal Auto-discovery Signalling / label distribution Draft Kompella VPLS BGP BGP Draft Lasserre-Vkompella VPLS None (several options possible) LDP moldovan@tmit.bme.hu Ethernet Szolgáltatások 36

37 VPLS related issues Problems: One big switch visible, but in fact many VCs What if one VC fails? How to find the problem root cause? Emulated LAN model All devices are equal peers: Routing protocol interaction Traffic patterns QoS policies Security policies Troubleshooting Ethernet Szolgáltatások 37

38 Some unuseful properties VPLS with more than 2 ports, RSTP is not an option VPLS is a"fat yellow cable" style shared media. No tunneling for user BPDUs no redundancy VPLS and 802.1ad Provider Bridges are similar from this point of view CE = Switch OR Router Other things to take into consideration when using VPLS to connect CE devices moldovan@tmit.bme.hu Ethernet Szolgáltatások 38

39 Ethernet UNI many requirements Ethernet UNI - Where user traffic enters the network ITU-T G.8012/Y.1308 Carry informational elements of three planes : Data (or User) Plane* Control Plane (e.g., related to BPDUs, ASON etc.) Management Plane "Standard IEEE Ethernet PHY and MAC" Functions of the Ethernet UNI include: Customer separation (Security) Rate policing (Bandwidth, BW granularity) Marking** (CoS transparency) Queuing*** (PQ+CBWFQ) Accounting (operational statistics) other (e.g. filtering, OAM, L2CP, VLAN transparency, etc.) Not provided at the UNI: Synchronization (CES) *optionally including a DCN supporting management and control plane communications **802.1p (8 Class of Service) ***802.1p default = PQ moldovan@tmit.bme.hu Ethernet Szolgáltatások 39

40 Ethernet transport alternatives- Ethernet over anything Ethernet over legacy networks ATM: rfc2684-b FR: rfc2427-b PPP: rfc2878 Ethernet over Ethernet QinQ, MACinMAC Ethernet over SDH GFP, VCAT, LCAS Ethernet over IP/MPLS L2TPv3 VPWS, VPLS Ethernet over WDM Ethernet over RPR Which technology to use? What Service to offer? L2VPN WDM L2TPv3 Depend: SDH Q-in-Q VPWS SP strategy Ethernet Over MPLS Service definition Existing investments RPR VPLS Customers do NOT care about technology! They are interested in the SERVICE! Ethernet Szolgáltatások 40

41 Conclusions All are assuming Ethernet aggregation All provide basic Ethernet level connectivity All provide similar ways for service identfication S-VLANs PPPoE still can be used Support for Multicast QoS handling is similar Or can be mapped (DSL line PVCs-> VLANs) No specific requirements! 41

42 Thank You for your attention Budapest University of Technology and Economics Department of Telecommunications and Media Informatics