Transcript Ethernet-Backoff - University of Ottawa

Offering Ethernet Services in Provider Networks
Bijan Raahemi
Research and Innovation Center
Alcatel Canada
Outline
>
Introduction
•
•
>
Metro Ethernet Network Solutions
•
•
•
>
Infrastructure
Ethernet Services
Provider Bridged Networks
GMPLS-Enabled Metro Networks
MPLS-Enabled Metro Networks
VPLS, Providing Ethernet Connectivity over Provider Networks
•
•
VPLS Model
Scaling VPLS
Ethernet-Services-in-Provider-Networks
14 April 2004
— 2 —
Why Talking about … ?
>
Why Are We Talking about Services?
• Past Focus  Infrastructure
• Today’s Focus  Revenue Generating Services
• Infrastructure: Becoming commodity products (with Equipment
vendors trying to minimize costs and maximize reliability)
•
>
Services: This is the area where companies (whether they're carriers or
vendors) can really differentiate themselves – Providing Service over
(commodity) infrastructure.
It is not a matter of transmitting bits and bytes any more!
Why Are We Talking about Ethernet?
•
•
•
•
More than 90% of desktop computers terminates on Ethernet networks
It is a standard and low cost technology
Proposals in MEF, IETF, and ITU to extend Ethernet in Metro
10G WAN PHY extends Ethernet into Wide Area Networks (Standard
completed in 2002)
Ethernet-Services-in-Provider-Networks
14 April 2004
— 3 —
Ethernet Services Market
U.S Ethernet Services Forecast
Revenue (USD Millions)
4,000
>
>
EIA
EPL
3,000
2,500
2,000
1,500
1,000
500
2002
>
VPLS
3,500
2003
2004
Ethernet Private Line (EPL) Point-to-Point
Ethernet Internet Access (EIA)
Ethernet Multipoint (VPLS)
Ethernet-Services-in-Provider-Networks
14 April 2004
2005
2006
CAGR 58.6%
CAGR 102.4%
CAGR 134.2%
— 4 —
2007
Source: Yankee Group
August 2003
Infrastructure
>
Ethernet Over Dark Fiber
•
Connecting Ethernet switches via dark fibers
•
Easy and cheap
• Supports Ethernet Virtual Private Line, and Ethernet Virtual Private LAN service
• Drawbacks:
– No OAM capability
– Cannot easily accommodate the dedicated switching bandwidth to individual
subscribers (for Ethernet private lines)
>
Ethernet Over SONET/SDH
•
Ethernet frames are encapsulated into GFP frames,
• Mapped into a SONET channel using virtual concatenation,
• LCAS can be used to keep a connection running at a reduced rate if members of
the virtual concatenation group fail, or add more members if the customer
requests additional bandwidth.
Ethernet-Services-in-Provider-Networks
14 April 2004
— 5 —
Infrastructure (cont’d)
>
Ethernet over ATM
•
The IEEE 802.1Q (priority information) is mapped to the right ATM virtual circuit and
service class.
• Allows a network operator to support Ethernet services with the end-to-end QOS and
resiliency associated with ATM SLAs.
• It also provides flexibility in service topology, from point-to-point, to multipoint, with optional
levels of oversubscription.
• Drawback: Costly (for Greenfield deployment)
>
Resilient Packet Ring (RPR),
IEEE 802.17
•
Supports a significant degree of bandwidth efficiency on rings through the implementation
of bandwidth sharing, spatial reuse, and statistical multiplexing.
• Supports sub 50ms ring-based resiliency on packet switched network architectures.
• Can run over SONET/SDH or native Ethernet transport networks
>
Ethernet Over IP/MPLS
(we will talk more about this later in this presentation)
•
Pseudowire
• VPLS
Ethernet-Services-in-Provider-Networks
14 April 2004
— 6 —
What’s Going on…. in Industry?
Most carriers have multiple Ethernet services delivery technologies.
Most boxes in the network support them.
>
Ethernet services can be supported by many network infrastructures:
ATM , IP/MPLS, SONET/SDH, WDM
•
SONET/SDH equipment providers support Ethernet services using a mix of GFP, VCAT,
LCAS, and RPR, leveraging the installed base of transmission equipment and its proven
OAM and protection.
• Multi-service ATM switch vendors add Ethernet services blades to their products that can
offer Ethernet-over-ATM Transparent LAN Service (TLS) with strict guaranteed QOS.
• Router vendors support a range of Ethernet VPNs over an IP backbone.
>
A lot is happening, and much of it could have a significant influence on the
telecom services.
look at the recent issue of the IEEE Communication Magazine :”Ethernet WAN Transport”
(March 2004)
• LightReading Webinar Sponsored by Cisco Systems, Fujitsu, Metrobility Optical Systems,
and RiverstoneNetworks, April 15, 2004: “Metro Ethernet Services, What Customers
Want?
•
Ethernet-Services-in-Provider-Networks
14 April 2004
— 7 —
What’s Going on…. in Standards?
>
Familiar Language
•
Enterprises are used to Frame Relay services:
–
committed information rate (CIR), Excess information rate (EIR), etc.
– SLA (Service Level Agreement).
•
Service Providers want to be able to talk to their customers in a familiar
language.
>
Interworking with other Layer 2 services, e.g., Frame Relay or ATM.
>
Different infrastructures are suited to different Ethernet service types:
–
The ITU-T is adapting Ethernet to SDH and MPLS transport networks.
– The IETF is emulating Ethernet links and LANs over a packet switched network.
– The IEEE is enhancing Ethernet capabilities such that services can be offered over
pure Ethernet networks.
– The MEF is defining the service attributes and service parameters that enable a
consistent set of features associated with various Ethernet services.
Standardizations are working on multiple combinations of protocols.
Ethernet-Services-in-Provider-Networks
14 April 2004
— 8 —
Ethernet Service Components
The MEF’s basic model of Ethernet services is
based on three key components:
>
The customer equipment (CE), either a
switch (IEEE 802.1Q bridge) or a router.
>
An Ethernet User Network Interface (UNI),
based on a standard IEEE 802.3 Ethernet
PHY and MAC, from 10 Mbit/s to 10 Gbit/s.
>
The Metro Ethernet Network (MEN), which
may use different transport and service
delivery technologies, such as SONET/SDH,
WDM, RPR, MAC-in-MAC, Q-in-Q (VLAN
stacking), or MPLS.
Metro Ethernet Forum (MEF)
http://www.metroethernetforum.org
The MEN should be scalable and flexible
enough to support a wide range of services in
cost-effectIve manner (comparable to TDM,
Frame Relay, or ATM)
Ethernet-Services-in-Provider-Networks
14 April 2004
— 9 —
Ethernet Service Types
Ethernet Line (E-Line)
Ethernet LAN (E-LAN)
>
point-to-point connectivity
>
E-line services can be used to create
Ethernet private line services, Ethernetbased Internet access services, and
point-to-point Ethernet VPNs.
>
multipoint-to-multipoint (any-to-any)
connectivity.
>
E-LAN Services can be used to create
multipoint Ethernet VPNs, and Ethernet
Transparent LAN services.
UNI
Customer
Equipment
UNI
PE
Metro Ethernet
Network
PE
PE
EVC1
PE
Customer
UNI Equipment
Customer
Equipment
EVC3
Point-to-Point EVC
UNI
PE
Customer
Equipment
Metro Ethernet Forum (MEF): http://www.metroethernetforum.org
Ethernet-Services-in-Provider-Networks
Carrier
Networks
14 April 2004
— 10 —
EVC2
Ethernet
Learning
Bridge
UNI
Customer
Equipment
Ethernet Services Examples
Ethernet Private Line to ASP for storage application
Intranet/Extranet application using E-Line service type
Ethernet-Services-in-Provider-Networks
14 April 2004
[from Metro Ethernet Forum]
EtherRelay service using E-Line Service type
LAN Extension application using E-LAN service type
— 11 —
Outline
>
Introduction
•
•
>
Metro Ethernet Network Solutions
•
•
•
>
Infrastructure
Ethernet Services
Provider Bridged Networks
GMPLS-Enabled Metro Networks
MPLS-Enabled Metro Networks
VPLS, Providing Ethernet Connectivity over Provider Networks
•
•
VPLS Model
Scaling VPLS
Ethernet-Services-in-Provider-Networks
14 April 2004
— 12 —
Solution 1: Provider Bridged Network
Frame Format
MAC
DA
MAC
SA
VLAn ID
(12 bits)
.1p
(3 bits)
CFI
(1 bit)
Eth Type
0x8100
.1Q PVLAN tag
VLAN
Tag
.1Q Eth
Type
Orig.
EthTyp
Data
Metro Ethernet
Network
CES
CES
UNI-A PE-A
PE-B
UNI-B
CE-A
CE-B
CES
CE : Customer Equipment
PE : Provider Edge Bridge/Router
UNI: User to Network Interface
CES: Core Ethernet Switch/Bridge
PE-C
Spanning Tree
UNI-C
CE-C
Ethernet-Services-in-Provider-Networks
14 April 2004
— 13 —
CRC
Ethernet is Evolving…..Carrier Class Ethernet
>
Challenges with a Pure Ethernet Solution?
•
•
•
•
•
•
>
Ethernet was originally developed for the LAN applications (shared medium), providing best effort
access.
It uses flat addressing (scalability).
It lacks traffic engineering (load balancing)
It lacks rich OAM (Operation, Administration, Maintenance) features.
Its spanning tree protocol converges slowly.
It lacks Quality of Service (QoS).
Solution in Progress…
•
•
•
•
•
•
Scalability: IEEE 802.1ad work on Q-in-Q
Fast Convergence of Spanning Tree: IEEE 802.1w work on Rapid Spanning Tree
OAM is being standardized (IEEE Ethernet in the First Mile) to monitor link operation, and improve fault
isolation
MEF is specifying architecture, protocols and management for metro Ethernet. This will result in
specifications for EVC protection, QOS, an Ethernet NNI, and OAM&P for end-to-end management of
Ethernet services, regardless of the underlying transport technology.
Class of Service: Various solutions are being proposed for this shortcoming. Ethernet classes of service
(COS) can be identified via IEEE 802.1Q, user priority bits (802.1p), MPLS EXP bits, or DiffServ
Codepoints,
IEEE 802.3ad (Link Aggregation): Faster connections between switches managed as a single
connection, load balancing among the individual links within a logical connection For the service
providers, a final value is the ability to add or subtract bandwidth to a connection in whatever
combination of bandwidths (10 Mbit/s, 100 Mbit/s, 1 Gbit/s) is available on that switch.
Ethernet-Services-in-Provider-Networks
14 April 2004
— 14 —
Ethernet Bridging Technology is Evolving…But is it
Enough?
1997
Enterprise Bridging
2000
Metro-Oriented Extensions
2004
Bridging Technology Futures
>
VLANs
>
VLANs
>
VLANs
>
802.1D Spanning Tree
>
802.1D Spanning Tree
>
802.1D Spanning Tree
>
Per-port RMON statistics
>
Per-port RMON statistics
>
Per-port RMON statistics
>
Ping and Traceroute
>
Ping and Traceroute
>
Ping and Traceroute
>
802.3ad link aggregation
>
802.3ad link aggregation
>
802.1P/DiffServ
>
802.1P/DiffServ
>
802.1w RSTP
>
802.1w RSTP
>
802.1s MIST
>
802.1s MIST
>
VLAN stacking
>
VLAN stacking
Ring Spanning Tree
>
Ring Spanning Tree
>
EFM
>
802.1ad provider bridges
Ethernet
>
Bridging
is trying to adapt….
Ethernet-Services-in-Provider-Networks
14 April 2004
— 15 —
Solution 2: GMPLS-Enabled Metro Network
Just a potential solution.
Not all the details are worked out yet.
P-MAC
DA
How it works
• Core nodes are simple Ethernet switches
(Electrical counterpart of Optical switch)
• No need to run a spanning tree protocol.
• A new label (such as MAC address) is added to
the packet at Ingress.
• A forwarding table is maintained at each core
switch.
• Packets are forwarded in the MEN based on the
outer label.
• This network solution is capable of providing
many features such as traffic engineering,
Quality of service, path protection, fault
recovery, and OAM functionalities.
Challenges
• A complete standard solution not available yet.
• Perceived as a costly solution.
Ethernet-Services-in-Provider-Networks
14 April 2004
P-MAC
SA
MAC
DA
MAC
SA
.1Q Eth
Type
VLAN
Tag
Orig.
EthTyp
CRC
Data
Frame Format
GMPLS
Control Plane
CES
CES
UNI-A PE-A
PE-B
CE-A
UNI-B
CE-B
CES
CE : Customer Equipment
PE : Provider Edge Bridge/Router
UNI: User to Network Interface
CES: Core Ethernet Switch/Bridge
PE-C
UNI-C
CE-C
— 16 —
Solution 3: MPLS-Enabled Metro Network
Tunnel
Label
VC
Label
MAC
DA
MAC
SA
VLAN
Tag
Eth
Type
Data
CRC
Frame Format (Martini Encap)
Metro Ethernet
Network
LSR
UNI-A PE-A
CE-A
PE-B
UNI-B
LSP1
LSP2
CE-B
LSP3
PE-C
CE : Customer Equipment
PE : Provider Edge
UNI: User to Network Interface
LSP: Label Switched Path
LSR: Label Switch Router
UNI-C
CE-C
Ethernet-Services-in-Provider-Networks
14 April 2004
— 17 —
The Advantages of an MPLS-Enabled Metro Ethernet:
Deterministic, Scalable, Resilient Networks and Services
>
Support for tens of 1000s of
subscribers
>
Robust, manageable control plane
protocols
End-to-end OA&M tools
>
Enables inter-metro services
Traffic Engineering for efficient use of
network resources
>
Fast failover for services
>
Per-service QoS
Sophisticated SLAs
>
Sophisticated billing models
>
Leverages MPLS switching
>
No Spanning Tree Protocol
>
No VLANs or Q-tag management
>
>
>
Ethernet-Services-in-Provider-Networks
14 April 2004
— 18 —
Outline
>
Introduction
•
•
>
Metro Ethernet Network Solutions
•
•
•
>
Infrastructure
Ethernet Services
Provider Bridged Networks
GMPLS-Enabled Metro Networks
MPLS-Enabled Metro Networks
VPLS, Providing Ethernet Connectivity over Provider Networks
•
•
VPLS Model
Scaling VPLS
Ethernet-Services-in-Provider-Networks
14 April 2004
— 19 —
VPLS
>
VPLS is a network service that offers layer 2 multipoint connectivity
between edge devices in a single bridge domain.
>
VPLS transforms the packet network into a switched LAN. To the enterprise,
the VPLS service makes the service provider network operate as a single
VLAN, with a unique SLA, protection attributes, availability attributes and
MAC address learning and forwarding for scalable multipoint configurations.
All customer sites using VPLS appear to be on the same LAN, regardless of their
locations. Customer edge devices appear to each other as connected via single
logical learning bridge with fully meshed ports.
Ethernet-Services-in-Provider-Networks
14 April 2004
— 20 —
VPLS Model
• CE may be a router, a switch, or a host.
• PE is a router which includes a "bridge" module. At minimum, the "bridge" module
must perform MAC addresses learning, and aging.
• Attachment Circuit may be a Frame Relay DLCI, an ATM VPI/VCI, an Ethernet
port, a VLAN, a PPP connection, an MPLS LSP, etc.
• A Pseudo Wire is a connection between two PE devices.
• MTUs are typically located in large buildings, serving different customers.
• In the IETF PPVPN terminology, an MTU is called a Layer2 PE (L2PE).
Site A
CE
Site B
PE
Service Provider
Network
PE
P
CE
P
Attachment Circuit
Site C
PE
Layer 2 Link
CE
LSP Tunnel
Pseudo Wire
MTU/L2PE
VPLS A
Site D
CE : Customer Edge Device
PE : Provider Edge Device
P : Provider Router
MTU: Multi Tenant Unit
Ethernet-Services-in-Provider-Networks
CE
14 April 2004
— 21 —
VPLS Building Blocks
>
Network Elements
the transport layer, as well as switches and routers.
>
Tunneling
encapsulation of a data packet into payload of another data packet.
>
Signaling
(also called auto-configuration); the mechanism by which tunnels are established, and routing
information are exchanged.
>
VPLS edge device discovery
(also called Auto-discovery function); the process by which one PE router learns which other PE
routers are participating in the VPLS.
>
MAC address learning
the PE learns the source MAC addresses of the devices in the network and keeps them in a
separate forwarding information base (FIB) for every VPLS.
>
Flooding
this function is used by the routers to learn unknown MAC addresses.
>
Loop avoidance
Ethernet-Services-in-Provider-Networks
14 April 2004
— 22 —
VPLS Options:
Lasserre-V.Kompella (LDP) vs. K.Kompella (BGP)
>
The Lassere-V.Kompella draft uses LDP for pseudowire signaling; a point-to-point signaling
already used in Draft Martini.
>
LDP is point-to-point signaling protocol. It establishes the connections one by one.
>
The Lassere-V.Kompella draft does not define an auto-discovery method (so there is a need
for extension of LDP, or to do it manually, or to develop proprietary solutions)
>
The Lassere-V.Kompella draft is supported by many vendors including Alcatel.
>
The K.Kompella draft uses BGP protocol for both signaling and auto-discovery.
>
BGP is a broadcast signaling protocol. Every time it sets up a new connection, it uses route
reflector to broadcast messages to every PE router.
>
Since BGP is already being used for signaling and discovery in Layer 3 VPN, it can be re-used
for VPLS as well.
>
However, since BGP is a broadcast protocol, it may not be bandwidth efficient.
>
The K.Kompella draft is mainly supported by Juniper.
Ethernet-Services-in-Provider-Networks
14 April 2004
— 23 —
Scaling VPLS
If all MTU devices are full-blown VPLS PE devices, then as the number of customer grows, there will be a
significant increase in:
-
The number of tunnels (every PE needs to maintain one tunnel to every peer PE)
The number of Pseudo Wires (every PE needs to maintain one PW per VPLS per every peer PE)
The total number of MAC addresses per PE
The number of signaling connections
PE
PE
PE
PE
PE
Ethernet-Services-in-Provider-Networks
14 April 2004
— 24 —
Hierarchical VPLS (Hub-and-Spoke)
Hierarchical VPLS distributes the VPLS functions between PE devices and MTUs.
It reduces the replication requirement (data plane) and the number of signaling connections (control plane).
However, it does not reduce the number of MAC addresses that need to be maintained. PE still does the
Ethernet bridging.
Spoke VC
Can be MPLS (draft Martini) or
VLAN Tag (Q-in-Q)
MTU
MTU
PE
PE
MTU
PE
MTU
MTU
Hub
Ethernet-Services-in-Provider-Networks
14 April 2004
— 25 —
H-VPLS Reduces Replication
Hierarchical VPLS reduces the replication requirement when the full mesh of
pseudo wires grows.
Basic VPLS
Hierarchal VPLS
MTU
PE
MTU
PE
PE
PE
PE
MTU
PE
MTU
PE
PE
Ethernet-Services-in-Provider-Networks
14 April 2004
— 26 —
MTU
H-VPLS Facilitates Provisioning & Signaling
Hierarchical VPLS facilitates provisioning and signaling when a new site is added to
the network.
Basic VPLS
Hierarchal VPLS
New site
New site
MTU
PE
MTU
PE
MTU
PE
PE
PE
PE
MTU
PE
MTU
PE
PE
Ethernet-Services-in-Provider-Networks
14 April 2004
— 27 —
MTU
De-Coupled VPLS
>
De-coupled VPLS distributes the VPLS functions between PEs and
MTUs.
>
De-coupled VPLS reduces the number of MAC addresses to
maintain, and the number of signaling connections, but does not limit
the number of Pseudo-Wires as the Hierarchal VPLS does.
>
All Ethernet MAC functions (MAC switching, learning, aging,
flooding, STP, etc) and Pseudo-Wire termination functions are
performed in the MTU, while the auto-discovery and the LSR (MPLS)
functions are performed in the PE.
Ethernet-Services-in-Provider-Networks
14 April 2004
— 28 —
De-coupled VPLS, how it works?
•
•
•
•
All sites attached to MTU A, B, and C belong to one VPLS (orange).
The link between MTU and PE is able to maintain multiple virtual circuits,
implemented using MPLS labels or VLAN tags.
PE acts as an LSR/LER. It does not implement Ethernet bridging functions.
Each MTU needs to establish and maintain one Pseudo-Wire to every other MTU
associated with that particular VPLS.
De-coupled VPLS
MTU B
CE
CE
MTU A
PE
CE
PE
MTU C
CE
PE
CE
CE
Signaling
Ethernet-Services-in-Provider-Networks
14 April 2004
Signaling
— 29 —
De-coupled VPLS: how it addresses scalability?
>
MTUs (L2PEs) have only one signaling connection.
>
PEs are MPLS routers, and act as forwarding engine. They do not provide
Ethernet bridging functions.
>
Number of core signaling connections for PE devices does not depend on
the number of L2PE (MTU) devices. It depends only on the number of PEs.
>
However, the number of Pseudo-Wires is highly dependent on the number
of L2PEs participating in a particular VPLS.
>
Also, addition of a new L2PE (MTU) into an existing VPLS will trigger the
provisioning of a new Pseudo-Wire in every MTU that belongs to that VPLS.
>
When an MTU receives an unknown unicast or a multicast frame from a
CE, it needs to broadcast the frame on every Pseudo-Wire to every peer
MTU.
Ethernet-Services-in-Provider-Networks
14 April 2004
— 30 —
Summary
>
There is a lot going on both in industry and in standardization to
define and support Ethernet services in the MAN.
>
Ethernet is evolving into a reliable, scalable, and manageable
transport technology (opportunities for innovation and new
solutions)
>
Presented different solutions to support Carrier Class Ethernet
Services in the MAN.
>
MPLS-Enabled Metro Ethernet is the feasible solution available
today.
Ethernet-Services-in-Provider-Networks
14 April 2004
— 31 —
Thank You
www.alcatel.com
Ethernet-Services-in-Provider-Networks
14 April 2004
— 32 —