Ethernet Access Technologies 2 Moldovn Istvn Department of - - PowerPoint PPT Presentation

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Ethernet Access Technologies 2 Moldovn Istvn Department of - - PowerPoint PPT Presentation

Feb 19, 2023 823 likes •1.27k views

Ethernet Access Technologies 2 Moldovn Istvn Department of Budapest University of Technology and Economics Telecommunications and Media Informatics Ethernet Forwarding BME-TMIT MAC Forwarding Topology VLAN Forwarding Topology Active

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SLIDE 1

Budapest University of Technology and Economics Department of Telecommunications and Media Informatics

Ethernet

Access Technologies 2 Moldován István

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SLIDE 2

BME-TMIT

Ethernet Forwarding

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

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SLIDE 3

BME-TMIT

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
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SLIDE 4

BME-TMIT

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
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SLIDE 5

BME-TMIT

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
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SLIDE 6

BME-TMIT

6

Ethernet local network design

  • Hierachically

HUB SWITCH, Bridge Multiservice switch Router

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SLIDE 7

BME-TMIT

Page 7

Metro Ethernet

Metro Backbone

National IP Network

GE

Aggregation Switch

2 x GE GE GE

VOD Server

TV Headend

3rd Party ISP

VOD Server VOD Server

POP

B-RAS Router

Internet

E.PON EFM G.PON 100BaseFX B.PON GE GE GE GE

Location Server

SIP Proxy Server

Triple Play

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SLIDE 8

Budapest University of Technology and Economics Department of Telecommunications and Media Informatics

Ethernet based transport in provider networks

The Ethernet way

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SLIDE 9

BME-TMIT

Challenges

  • Carrier grade requirements
  • Scalability
  • Service Quality
  • Multicast
  • Management

– Fault – performance

Upgrade the cheap Ethernet (IEEE) Extend the proven MPLS (IETF) Provide Ethernet service

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SLIDE 10

BME-TMIT

Page 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

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SLIDE 11

BME-TMIT

Page 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
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SLIDE 12

BME-TMIT

Page 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
  • Immediately blocks traffic
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SLIDE 13

BME-TMIT

Carrier Ethernet: service types

  • E-Line service:
  • Ethernet Private Line
  • Virtual Private Line
  • Ethernet Internet Access
  • E-LAN Service:
  • Multipoint L2 VPN
  • Transzparent LAN
  • Needed for IPTV multicast etc

E-Line E-LAN

Point-to-Point EVC Carrier Ethernet Network UNI: User Network Interface, CE: Customer Equipment

CE UNI UNI CE

Multipoint-to-Multipoint EVC

Carrier Ethernet Network

CE UNI

MEF által hitelesített Carrier Ethernet termékek

CE UNI

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SLIDE 14

BME-TMIT

IEEE 802.1Q - VLAN

  • VLAN tag
  • QoS: priority
  • 12 bit VLAN ID: 4096 VLANs
  • 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

MAC DA MAC SA 802.1Q ethertype VLAN tag

Data

CRC VLAN ID (12 bit) Pri (3 bits) CFI (1 bit)

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BME-TMIT

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
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SLIDE 16

BME-TMIT

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
  • uter 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
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BME-TMIT

Comparison – headers added

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SLIDE 18

BME-TMIT

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…
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SLIDE 19

BME-TMIT

PBT

  • Goal
  • Keep the Ethernet forwarding
  • Change the control plane (no STP and learning)
  • Set up paths ”manually“

= Traffic Engineering - Ethernet

  • What we get:
  • Point-point tunnel
  • Traffic Engineering
  • Protection

BVID=1 BVID=2 BVID=1 BVID=2

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BME-TMIT

PBT

  • Provider Backbone Transport – IEEE 802.1Qay
  • Nortel started
  • based on PBB
  • Uses the existing technologies
  • Deterministic QoS for service is the target
  • scalability
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BME-TMIT

PBT - operation

  • Data plane
  • Static forwarding tables
  • Addressing

– 60 bit MAC + VLAN based

  • Totally different control plane
  • Manual
  • MPLS based
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SLIDE 22

BME-TMIT

Ethernet Transport technology use

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

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Budapest University of Technology and Economics Department of Telecommunications and Media Informatics

Ethernet based transport in provider networks

The other way – IP/MPLS

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BME-TMIT

24 | Áramkör kapcsolt Ethernet? | Moldován István | Elsinco szeminárium | 12 Szeptember 2007

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
  • The solution inherits all MPLS solutions
  • Traffic Engineering, protection, OAM

CE CE PE PE

SP

CE CE PE PE

SP

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SLIDE 25

BME-TMIT

Ethernet Szolgáltatások 25 moldovan@tmit.bme.hu

Reserved Sequence Number EXP TTL 1 Label (VC) EXP TTL Label (Tunnel) 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 Layer2 PDU Control Word

VC Label L2 header Original Ethernet Frame Tunnel Label

Data Plane : EoMPLS packet

  • 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
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BME-TMIT

Ethernet Szolgáltatások 26 moldovan@tmit.bme.hu

Pseudo-Wire reference model

|<--- Emulated Service:FR/Ether/ATM/PPP/HDLC --->|

|<------ PW:Pseudowire VC ----->| |<-- FR -->| Ethernet ATM/PPP/HDLC |<--FR -->| Ethernet ATM/PPP/HDLC

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 IP/MPLS Core

Attachment VC / L2 circuit Attachment VC / L2 circuit Attachment VC / L2 circuit

Site1A Site 2A

Attachment VC / L2 circuit

PE1

Site1B Site 2B

PE2

CE 1A CE 2A CE 1B CE 2B PSN Tunnel: (IP/)MPLS Tunnel MPLS (LDP or RSVP-TE)

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BME-TMIT

Ethernet Szolgáltatások 27 moldovan@tmit.bme.hu

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

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
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SLIDE 28

BME-TMIT

Ethernet Szolgáltatások 28 moldovan@tmit.bme.hu

VPLS

PE

Service Provider Backbone

PE PE VPLS

  • A

VPLS

  • B

VPLS

  • B

VPLS

  • A

Emulated LAN CE

  • 1

CE

  • 2’

CE

  • 2

CE

  • 1’

Bridged LAN

Customer Edges (CE): Client side device, tyically Ethernet Provider Edges (PE): VPLS inteligence, start/end Core: just forwarding

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BME-TMIT

Ethernet Szolgáltatások 29 moldovan@tmit.bme.hu

VPLS example

Full Mesh PEs are acting like a bridge towards the CE nodes

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BME-TMIT

Ethernet Szolgáltatások 30 moldovan@tmit.bme.hu

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

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BME-TMIT

Ethernet Szolgáltatások 31 moldovan@tmit.bme.hu

Number of PE in VLAN Number of LSPs Number of Retransmissions/ Broadcast 5 20 4 10 90 9 20 380 19 40 1 560 39

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
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BME-TMIT

Ethernet Szolgáltatások 32 moldovan@tmit.bme.hu

MPLS core

PE CE CE PE CE

MPLS core

PE CE CE PE CE

E.g ARP-request E.g ARP-reply

VPLS – Flooding & forwarding

  • Flooding

(Broadcast, Multicast, Unknown Unicast)

  • Dynamic learning
  • f MAC

addresses on PHY and VCs

  • Forwarding

– Physical Port – Virtual Circuit

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BME-TMIT

Ethernet Szolgáltatások 33 moldovan@tmit.bme.hu

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, …

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BME-TMIT

Ethernet Szolgáltatások 34 moldovan@tmit.bme.hu

Hierarchical VPLS

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BME-TMIT

Ethernet Szolgáltatások 35 moldovan@tmit.bme.hu

H-VPLS

MPLS core MPLS edge Ethernet edge p2p or ring

H-VPLS

n-PE u-PE u-PE n-PE

MPLS core MPLS edge Ethernet edge

VPLS

n-PE CE CE n-PE

VPLS – Architectures

  • VPLS
  • One big hierarchy
  • MPLS to the Edge
  • H-VPLS
  • 2 level Hierarchy
  • MPLS or

Ethernet Edge

  • MPLS core
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BME-TMIT

Ethernet Szolgáltatások 36 moldovan@tmit.bme.hu

VPLS proposal Auto-discovery Signalling / label distribution Draft Kompella VPLS BGP BGP Draft Lasserre-Vkompella VPLS None (several options possible) LDP

VPN Discovery Signaling Centralized DNS, LDAP, Radius Directory Services Distributed BGP Label Distribution Protocol (LDP, BGP)

VPLS signaling and auto-discovery

  • 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.)

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BME-TMIT

Ethernet Szolgáltatások 37 moldovan@tmit.bme.hu

.1 .2 .5 .4 .3

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

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BME-TMIT

Ethernet Szolgáltatások 38 moldovan@tmit.bme.hu

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

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BME-TMIT

Ethernet Szolgáltatások 39 moldovan@tmit.bme.hu

*optionally including a DCN supporting management and control plane communications **802.1p (8 Class of Service) ***802.1p default = PQ

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 802.3 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)

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BME-TMIT

Ethernet Szolgáltatások 40 moldovan@tmit.bme.hu

WDM SDH RPR Ethernet Over MPLS Q-in-Q VPLS VPWS L2TPv3 L2VPN Customers do NOT care about technology! They are interested in the SERVICE!

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?
  • Depend:
  • SP strategy
  • Service definition
  • Existing

investments

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BME-TMIT

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!

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Budapest University of Technology and Economics Department of Telecommunications and Media Informatics

Thank You for your attention