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Tutorial: MPLS based Metro Ethernet Networks
March 02, 2010 | By ALU
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Transcript
Barcelone---titre-pptjpg
Paresh Khatri
Jan, 2010
MPLS-based Metro Ethernet NetworksA Tutorial
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2| MPLS-based Metro Ethernet Networks, January 2010
Paresh Khatri
Director, Advanced Consulting Engineering
MPLS-based Metro Ethernet Networks
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3| MPLS-based Metro Ethernet Networks, January 2010
Agenda
Introduction to Metro Ethernet Services
Traditional Metro Ethernet networks
Delivering Ethernet over MPLS
Summary
Questions
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4| MPLS-based Metro Ethernet Networks, January 2010
1 Introduction
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5| MPLS-based Metro Ethernet Networks, January 2010
Paresh Khatri (pareshkhatri@alcatel-lucentcom)Director IP Competence Centre, APAC Solutions & Marketing, Alcatel-Lucent
Key focus areas:
Large-scale IP/MPLS networks
L2/L3 VPNs
Carrier Ethernet
Next-generation mobile backhaul networks
Acknowledgements:
Some figures and text are provided courtesy of the Metro Ethernet Forum (MEF)
Introduction
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6| MPLS-based Metro Ethernet Networks, January 2010
2 Introduction to Metro Ethernet Services
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7| MPLS-based Metro Ethernet Networks, January 2010
Agenda
2 Introduction to Metro Ethernet Services
21  Why Metro Ethernet ?
22  Attributes of Carrier Ethernet
23  Carrier Ethernet Services defined by the MEF
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8| MPLS-based Metro Ethernet Networks, January 2010
21 Why Metro Ethernet ?
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9| MPLS-based Metro Ethernet Networks, January 2010
What is Metro Ethernet ?“… generally defined as the network that bridges or connects geographically separated enterprise LANs while also connecting across the WAN or backbone networks that are generally owned by service providers  The Metro Ethernet Networks provide connectivity services across Metro geography utilising Ethernet as the core protocol and enabling broadband applications”
from “Metro Ethernet Networks A Technical Overview” from the Metro Ethernet Forum
Introduction to Metro Ethernet Services
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10| MPLS-based Metro Ethernet Networks, January 2010
Why Metro Ethernet ?Benefits both providers and customers in numerous ways …
Packet traffic has now overtaken all other traffic types
Need for rapid provisioning
Reduced CAPEX/OPEX
Increased and flexible bandwidth options
Well-known interfaces and technology
Introduction to Metro Ethernet Services
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11| MPLS-based Metro Ethernet Networks, January 2010
22 Attributes of Carrier Ethernet
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12| MPLS-based Metro Ethernet Networks, January 2010
Carrier Ethernet is a ubiquitous, standardized, carrier-class SERVICE defined by five attributes that distinguish Carrier Ethernet from familiar LAN based Ethernet
It brings the compelling business benefit of the Ethernet cost model to achieve significant savings
Carrier Ethernet
Scalability
Standardized Services
Service  Management
Quality of Service
Reliability
Carrier Ethernet Attributes
Sprite 71
The 5 Attributes of Carrier Ethernet
small MEF Logo
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13| MPLS-based Metro Ethernet Networks, January 2010
23 Carrier Ethernet Services defined by the MEF
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14| MPLS-based Metro Ethernet Networks, January 2010
What do we mean by Metro Ethernet services ?Use of Ethernet access tails
Provision of Ethernet-based services across the MAN/WAN
Point-to-point
Point-to-multipoint
Multipoint-to-multipoint
However, the underlying infrastructure used to deliver Ethernet services does NOT have to be Ethernet !!!
Referred to as Carrier Ethernet services by the Metro Ethernet Forum
The terms “Carrier Ethernet” and “Metro Ethernet” are used interchangeably in this presentation, but in the strict sense of the term, “Carrier Ethernet” refers to the carrier-grade evolution of “Metro Ethernet”
Introduction to Metro Ethernet Services
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15| MPLS-based Metro Ethernet Networks, January 2010
cloud2
Carrier Ethernet Network
UNI
Switch 1
dertified
The User Network Interface (UNI)The UNI is the physical interface or port that is the demarcation between the customer and the service provider/Cable Operator/Carrier/MSO
The UNI is always provided by the Service Provider
The UNI in a Carrier Ethernet Network is a standard physical Ethernet Interface at operating speeds 10Mbs, 100Mbps, 1Gbps or 10Gbps
dertified
CE: Customer Equipment, UNI:User Network Interface            MEF certified Carrier Ethernet products
Small Enterprise
Remote DSLAM
CE
MEF Carrier Ethernet Terminology
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16| MPLS-based Metro Ethernet Networks, January 2010
cloud2
Carrier Ethernet Network
UNI
Switch 1
dertified
MEF Carrier Ethernet Terminology
The User Network Interface (UNI):MEF has defined two types of UNIs:
MEF UNI Type I (MEF 13)
A UNI compliant with MEF 13
Manually configurable
Specified for existing Ethernet devices
Provides bare minimum data-plane connectivity services with no control-plane or management-plane capabilities
MEF UNI Type II (MEF 20)
Automatically configurable via E-LMI (allowing UNI-C to retrieve EVC status and configuration information from UNI-N)
Manageable via OAM
dertified
CE: Customer Equipment, UNI:User Network Interface            MEF certified Carrier Ethernet products
Small Enterprise
Remote DSLAM
CE
UNI
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17| MPLS-based Metro Ethernet Networks, January 2010
MetroMetroEthernetEthernetNetworkNetworkCustomerCustomerEdgeEdge(CE)(CE)User NetworkUser NetworkInterfaceInterface(UNI)(UNI)User NetworkUser NetworkInterfaceInterface(UNI)(UNI)CustomerCustomerEdgeEdge(CE)(CE)MEF Carrier Ethernet Terminology
Customer Equipment (CE) attaches to the Metro Ethernet Network (MEN) at the UNI
Using standard Ethernet frames
CE can be
Router or bridge/switch -IEEE 8021 bridge
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18| MPLS-based Metro Ethernet Networks, January 2010
Ethernet Services “Eth” Layer
rectangle
Subscriber Site
oval
Service Provider 1
Metro Ethernet  Network
oval
Service Provider 2Metro Ethernet  Network
rectangle
Subscriber Site
ETHUNI-C
ETHUNI-N
ETHUNI-N
ETHUNI-N
ETHUNI-N
ETHUNI-C
uni
enni
inni
inni
uni
UNI: User Network Interface, UNI-C: UNI-customer side, UNI-N network sideNNI: Network to Network Interface, E-NNI: External NNI; I-NNI Internal NNI
MEF Ethernet Services Model
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19| MPLS-based Metro Ethernet Networks, January 2010
MEF Carrier Ethernet Terminology
Ethernet Virtual Connection (EVC)An Ethernet Service Instantiation
Most commonly (but not necessarily) identified via a VLAN-ID
Like Frame Relay and ATM PVCs or SVCs
Connects two or more subscriber sites (UNI’s)
Can multiplex multiple EVCs on the same UNI
An association of two or more UNIs
Prevents data transfer between sites that are not part of the same EVC
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20| MPLS-based Metro Ethernet Networks, January 2010
MEF Carrier Ethernet Terminology
Ethernet Virtual Connection (EVC)Three types of EVC:
UNI
MEN
UNI
Point-to-Point EVC
MEN
Multipoint-to-Multipoint EVC
MEN
Rooted-Multipoint EVC
Leaf
Leaf
Leaf
Root
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21| MPLS-based Metro Ethernet Networks, January 2010
Large Enterprise
ServiceProvider Central Office
ServiceProvider Central Office
Large Enterprise
E-LINE
E-LAN
Point to PointService Type used to createEthernet Private Lines
Virtual Private Lines
Ethernet Internet Access
E-TREE
Point to Multi-PointEfficient use of Service Provider ports
Foundation for Multicast networks eg IPTV
Multi-Point to Multi-PointService Type used to createMultipoint Layer 2 VPNs
Transparent LAN Service
cloud2
Router2
Router2
Point-to-Point EVC
Remote DSLAM
CE
UNI
UNI
CE
Remote DSLAM
cloud2
Medium Enterprise
Remote DSLAM
CE
UNI
Remote DSLAM
CE
Router2
Router2
Router2
Router2
UNI
Multipoint EVC
Flat screen
pic
Flat screen
pic
Large Enterprise
cloud2
Rooted Multipoint EVC
Remote DSLAM
Remote DSLAM
CE
UNI
Remote DSLAM
CE
Router2
Router2
Router2
UNI
CE
UNI
Residential
Basic Carrier Ethernet Services
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22| MPLS-based Metro Ethernet Networks, January 2010
cloud2
EVCs and Services
In a Carrier Ethernet network, data is transported across Point-to-Point, Multipoint-to-Multipoint and Point-to-Multipoint EVCs according to the attributes and definitions of the E-Line, E-LAN and E-Tree services respectively
Router2
Router2
Point-to-Point EVC
Carrier Ethernet Network
dertified
UNI
UNI
dertified
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23| MPLS-based Metro Ethernet Networks, January 2010
Services Using E-Line Service Type
Ethernet Private Line (EPL)Replaces a TDM Private line
Dedicated UNIs for Point-to-Point connections
Single Ethernet Virtual Connection (EVC) per UNI
ServiceProvider Central Office
bildin
Servers A
cloud2
Point-to-Point EVC
Medium Enterprise
Remote DSLAM
Carrier Ethernet Network
Remote DSLAM
CE
UNI
Remote DSLAM
CE
Router2
Router2
dertified
Router2
dertified
UNI
CE
UNI
ISPPOP
Router2
dertified
UNI
Storage Service Provider
Internet
Internet
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24| MPLS-based Metro Ethernet Networks, January 2010
Services Using E-Line Service Type
Ethernet Virtual Private Line (EVPL)Replaces Frame Relay or ATM services
Supports Service Multiplexed UNI (ie multiple EVCs per UNI)
Allows single physical connection (UNI) to customer premise equipment for multiple virtual connections
This is a UNI that must be configurable to support Multiple EVCs per UNI
store
Large Enterprise
Service Multiplexed Ethernet UNI
cloud2
Multipoint-to-Multipoint EVC
Medium Enterprise
Remote DSLAM
Carrier Ethernet Network
Remote DSLAM
CE
UNI
Remote DSLAM
CE
Router2
Router2
dertified
dertified
Router2
dertified
UNI
CE
UNI
Flat screen
pic
Desktop
Laptop
Office Phone
Flat screen
pic
Desktop
Laptop
Office Phone
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25| MPLS-based Metro Ethernet Networks, January 2010
Services Using E-LAN Service Type
Ethernet Private LAN and Ethernet Virtual Private LAN ServicesSupports dedicated or service-multiplexed UNIs
Supports transparent LAN services and multipoint VPNs
Large Enterprise
Service Multiplexed Ethernet UNI
cloud2
Point-to-Multipoint EVC
Carrier Ethernet Network
Remote DSLAM
CE
UNI
Remote DSLAM
Router2
Router2
dertified
dertified
Router2
dertified
UNI
UNI
store
Medium Enterprise
Remote DSLAM
Remote DSLAM
CE
dertified
UNI
CE
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26| MPLS-based Metro Ethernet Networks, January 2010
Services Using E-Tree Service Type
Ethernet Private Tree (EP-Tree) and Ethernet Virtual Private Tree (EVP-Tree) ServicesEnables Point-to-Multipoint Services with less provisioning than typical hub and spoke configuration using E-Lines
Provides traffic separation between users with traffic from one “leaf” being allowed to arrive at one of more “roots” but never being transmitted to other “leaves”
Large Enterprise
Root
cloud2
Carrier Ethernet Network
Remote DSLAM
CE
UNI
Router2
Router2
dertified
dertified
Router2
dertified
UNI
UNI
store
Medium Enterprise
Remote DSLAM
Remote DSLAM
CE
CE
Leaf
Leaf
Router2
dertified
UNI
Medium Enterprise
Remote DSLAM
CE
Leaf
Rooted-Multipoint EVC
Ethernet Private Tree example
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27| MPLS-based Metro Ethernet Networks, January 2010
Name any two of the five attributes of Carrier Ethernet as defined by the Metro Ethernet Forum
Audience Question 1
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28| MPLS-based Metro Ethernet Networks, January 2010
3 Traditional Metro Ethernet networks
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29| MPLS-based Metro Ethernet Networks, January 2010
Agenda
3 Traditional Metro Ethernet Networks
31  Service Identification
32  Forwarding Mechanism
33  Resiliency and Redundancy
34  Recent Developments
35  Summary
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30| MPLS-based Metro Ethernet Networks, January 2010
Traditional methods of Ethernet delivery:Ethernet switching/bridging networks (8021d/8021q)
Services identified by VLAN IDs/physical ports
VLAN IDs globally significant
Resiliency provided using variants of the Spanning Tree Protocol
Traditional Metro Ethernet Networks
Agg
Agg
Core
Core
Access
Access
Access
Access
Agg
Agg
Access
Access
Access
Access
Core
Core
CPE
CPE
CPE
CPE
CPE
CPE
CPE
CPE
CPE
CPE
CPE
CPE
CPE
CPE
CPE
CPE
Ethernet Switches
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31| MPLS-based Metro Ethernet Networks, January 2010
31 Service Identification
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32| MPLS-based Metro Ethernet Networks, January 2010
Service Identification:Ethernet switching/bridging networks
First generation was based on IEEE 8021q switches
One obvious limitation was the VLAN ID space the 12-bit VLAN ID allows a maximum of 4094 VLANs (VLANs 0 and 4095 are reserved) This limited the total number of services in any one switching/bridging domain
The other problem was that of customer VLAN usage customers could not carry tagged traffic transparently across the network
Traditional Metro Ethernet Networks
C-DA
C-SA
Payload
C-VID
Ethertype
Ethertype
VLAN ID
(12 bits)
PCP(3 bits)
0x8100(16 bits)
CFI (1 bit)
Tag
Protocol
Identifer (TPID)
Tag
Control
Information (TCI)
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33| MPLS-based Metro Ethernet Networks, January 2010
Service Identification :Q-in-Q (aka VLAN stacking, aka 8021ad) comes to the rescue !
Q-in-Q technology, which has now been standardised by the IEEE as 8021ad (Provider Bridging), allowed the addition of an additional tag to customer Ethernet frames the S-tag  The S-tag (Service Tag) was imposed by the Service Provider and therefore, it became possible to carry customer tags (C-tags) transparently through the network
Traditional Metro Ethernet Networks
Provider
Bridge
Customer
Device
C-DA
C-SA
Payload
C-VID
Ethertype
Ethertype
C-DA
C-SA
Payload
S-VID
C-VID
Ethertype
Ethertype
Ethertype
VLAN ID
(12 bits)
PCP(3 bits)
0x88a8
(16 bits)
DEI (1 bit)
Tag
Protocol
Identifer (TPID)
Tag
Control
Information (TCI)
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34| MPLS-based Metro Ethernet Networks, January 2010
Service Identification:Some important observations about Q-in-Q:
This is not a new encapsulation format; it simply results in the addition of a second tag to the customer Ethernet frame, allowing any customer VLAN tags to be preserved across the network
There is no change to the customer destination or source MAC addresses
The number of distinct service instances within each Provider Bridging domain is still limited by the S-VLAN ID space ie 4094 S-VLANs  The difference is that customer VLANs can now be preserved and carried transparently across the provider network
Traditional Metro Ethernet Networks
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35| MPLS-based Metro Ethernet Networks, January 2010
32 Forwarding Mechanism
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36| MPLS-based Metro Ethernet Networks, January 2010
Forwarding Mechanism:Dynamic learning methods used to build forwarding databases
Traditional Metro Ethernet Networks
Agg
Agg
Core
Core
Access
Access
Access
Access
Agg
Agg
Access
Access
Access
Access
Core
Core
CPE
CPE
CPE
CPE
CPE
CPE
CPE
CPE
CPE
CPE
CPE
CPE
CPE
CPE
CPE
CPE
MAC Learning Points
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37| MPLS-based Metro Ethernet Networks, January 2010
Traditional Metro Ethernet Networks
Forwarding Mechanism:Dynamic learning methods used to build forwarding databases
Provider
Switch
E1
CPE
(MAC A)
Provider
Switch
E2
Provider
Switch
C
Provider
Switch
E3
CPE
(MAC C)
CPE
(MAC B)
Forwarding Database E1

MAC
Interface

MAC-A
i1

MAC-B
i2

MAC-C
i2

i1
i2
i3
i4
i5
i6
i7
i8
i9
Forwarding Database E2

MAC
Interface

MAC-A
i6

MAC-B
i7

MAC-C
i6

Forwarding Database E3

MAC
Interface

MAC-A
i8

MAC-B
i8

MAC-C
i9

Forwarding Database C

MAC
Interface

MAC-A
i3

MAC-B
i5

MAC-C
i4

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38| MPLS-based Metro Ethernet Networks, January 2010
Forwarding Mechanism:Dynamic learning methods used to build forwarding databases
Data-plane process there are no control-plane processes for discovering endpoint information
In the worst case, ALL switches have forwarding databases that include ALL MAC addresses  This is true even for switches in the core of the network (Switch C in preceding example)
Switches have limited resources for storing MAC addresses  This poses severe scaling issues in all parts of the network  VLAN-stacking does not help with this problem
On topology changes, forwarding databases are flushed and addresses need to be re-learned  While these addresses are re-learned, traffic to unknown destinations is flooded through the network, resulting in wasted bandwidth
Traditional Metro Ethernet Networks
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39| MPLS-based Metro Ethernet Networks, January 2010
33 Resiliency and Redundancy
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40| MPLS-based Metro Ethernet Networks, January 2010
Resiliency and RedundancyRedundancy is needed in any network offering Carrier-grade Ethernet BUT loops are bad !!
The Spanning Tree Protocol (STP) is used to break loops in bridged Ethernet networks
There have been many generations of the STP over the years
All of these variants work by removing redundant links so that there is one, and only one, active path from each switch to every other switch ie all loops are eliminated  In effect, a minimum cost tree is created by the election of a root bridge and the subsequent determination of shortest-path links to the root bridge from every other bridge
Bridges transmit special frames called Bridge Protocol Data Units (BPDUs) to exchange information about bridge priority, path costs etc
High Availability is difficult to achieve in traditional Metro Ethernet networks
Traditional Metro Ethernet Networks
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41| MPLS-based Metro Ethernet Networks, January 2010
Building the Spanning Tree …
Traditional Metro Ethernet Networks
Switch
A
Switch
B
Switch
C
Switch
D
10
10
20
10
Switch
A
Switch
B
Switch
C
Switch
D
Root Bridge
Rudimentary Traffic-Engineering Capabilities
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42| MPLS-based Metro Ethernet Networks, January 2010
First generation of STP (IEEE8021d-1998):Had a number of significant shortcomings:
Convergence times the protocol is timer-based with times in the order of 10s of seconds  After network topology changes (failure or addition of links), it could take up to 50s for the network to re-converge
The protocol was VLAN-unaware, which meant that in an IEEE 8021q network, all VLANs had to share the same spanning tree  This meant that there were network links that would not be utilised at all since they were placed into a blocked state
Many vendors implemented their own, proprietary extensions to the protocol to allow the use of a separate STP instance per VLAN, allowing better link utilisation within the network
There were many conditions which resulted in the inadvertent formation of loops in the network  Given the flooding nature of bridged Ethernet, and the lack of a TTL-like field in Ethernet frames, looping frames could loop forever
There are numerous well-publicised instances of network meltdowns in Enterprise and Service Provider networks
A lot of service providers have been permanently scarred by the catastrophic effects of STP loops !
Traditional Metro Ethernet Networks
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43| MPLS-based Metro Ethernet Networks, January 2010
Newer generations of STP (IEEE8021d-2004 Rapid STP aka 8021w):Some major improvements:
Dependence on timers is reduced  Negotiation protocols have been introduced to allow rapid transitioning of links to a forwarding state
The Topology Change process has been re-designed to allow faster recovery from topology changes
Optimisations for certain types of direct and indirect link failures
Convergence times are now down to sub-second in certain special cases but a lot of failure cases still require seconds to converge !
But…
The protocol was still VLAN-unaware, which meant that the issue of under-utilised links was still present
Traditional Metro Ethernet Networks
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44| MPLS-based Metro Ethernet Networks, January 2010
Newer generations of STP (IEEE8021q-2003 Multiple STP aka 8021s):Built on top of RSTP
Added VLAN awareness:
Introduces the capability for the existence of multiple STP instances within the same bridged network
Allows the association of VLANs to STP instances, in order to provide a (relatively) small number of STP instances, instead of using an instance per VLAN
Different STP instances can have different topologies, which allows much better link utilisation
BUT
The stigma associated with past failures is hard to remove…
The protocol is fairly complicated, compared to its much simpler predecessors
Traditional Metro Ethernet Networks
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45| MPLS-based Metro Ethernet Networks, January 2010
34 Recent Developments
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46| MPLS-based Metro Ethernet Networks, January 2010
Provider Backbone BridgingTakes IEEE 8021ad to the next level
MAC-in-MAC technology:
Customer Ethernet frames are encapsulated in a provider Ethernet frame
Alleviates the MAC explosion problem
Core switches no longer need to learn customer MAC addresses
Does not address the STP issue, however
Traditional Metro Ethernet Networks
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47| MPLS-based Metro Ethernet Networks, January 2010
Provider Backbone Bridging (PBB)
Ethernet Technology being standardized in IEEE 8021ah Task GroupDesigned to interconnect Provider Bridge Networks (PBN -IEEE 8021ad)
Adds a Backbone Header to a Customer/QinQ Ethernet Frame
Provider Addressing for Backbone Forwarding
New extended tag for Service Virtualization
Standardization ongoing
PBBN is Ethernet based:
Connectionless Forwarding based on MAC Learning & Forwarding,
Loop Avoidance based on STP,
VLAN ID for Broadcast Containment
PBN
PBN
PBBN
PBB BEB
7450_blue
7450_blue
PBB BEB
BEB:Backbone Edge BridgeForward frames based on backbone MAC addresses
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48| MPLS-based Metro Ethernet Networks, January 2010
C-DA
C-SA
Payload
B-DA
B-SA
B-VID
I-SID
S-VID
C-VID
Ethertype
Ethertype
Ethertype
Ethertype
Ethertype
PBN (QinQ)
PBN (QinQ)
PBBN
PBB PE2
C-DA
C-SA
Payload
S-VID
C-VID
Ethertype
Ethertype
Ethertype
C-DA
C-SA
Payload
S-VID
C-VID
Ethertype
Ethertype
Ethertype
QinQ frame
QinQ frame
PBB frame
B2
PBB PE1
B1
B4
B6
B5
B3
A1
CMAC=X
Backbone FIBsA1->Port
Customer FIBX->A1
Customer FIBX->Port
CMAC=Y
MAC-based, Connectionless Forwarding
Broadcast Containment
Extended Service Tag
Identifies the service instance inside PE
I1
I2
I1
I1
I2
IEEE 8021ah Model for PBB I and B Components
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49| MPLS-based Metro Ethernet Networks, January 2010
8021ah Provider Backbone Bridge Encapsulation
Payload

C-TAG TCI

q Etype = 81-00

S TAG TCI

ad Etype = 88-a8

C SA

C DA

I TAG TCI

ah Etype = 88-e7

B TAG TCI

ad Etype = 88-a8

B SA

B DA

6+6
22 (w/o FCS)
2+2
2+4
I-TAG
B-TAG
S-TAG
C-TAG
DEI
p bits
VLAN-ID

I-PCP
IDEI
UCA
Res
I-SID

24
3
1
3
1
Bits
I-PCP = Customer Priority
I-DEI = Drop Elegibility
UCA = Use Customer Addresses
I-SID = Service Instance ID
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35 Summary
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Summary of Issues:High Availability is difficult to achieve in networks running the Spanning Tree Protocol
Scalability IEEE 8021q/8021ad networks run into scalability limitations in terms of the number of supported services
Customer Ethernet frames are encapsulated in a provider Ethernet frame
QoS only very rudimentary traffic-engineering can be achieved in bridged Ethernet networks
A lot of deployed Ethernet switching platforms lack carrier-class capabilities required for the delivery of Carrier Ethernet services
New extensions in IEEE 8021ah address some limitations such as the number of service instances and MAC explosion problems
Traditional Metro Ethernet Networks
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Which IEEE standard defines Provider Bridging (Q-in-Q) ?
Audience Question 2
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What is the size of the I-SID field in IEEE 8021ah?
Audience Question 3
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4 Delivering Ethernet over MPLS
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Agenda
4 Delivering Ethernet over MPLS
41 Introduction to MPLS
42  The Pseudowire Reference Model
43  Ethernet Virtual Private Wire Service
44  Ethernet Virtual Private LAN Service
45  Scaling VPLS
46  VPLS Topologies
47 Resiliency Mechanisms
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41 Introduction to MPLS
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MPLS AttributesConvergence: From “MPLS over everything” to “Everything over MPLS” !
One network, multiple services
Excellent virtualisation capabilities
Today’s MPLS network can transport IP, ATM, Frame Relay and even TDM !
Scalability
MPLS is used in some of the largest service provider networks in the world
Advanced Traffic Engineering capabilities using RSVP-TE
Rapid recovery based on MPLS Fast ReRoute (FRR)
Rapid restoration around failures by local action at the Points of Local Repair (PLRs)
Sub-50ms restoration on link/node failures is a key requirement for carriers who are used to such performance in their SONET/SDH networks
Feature-richness
MPLS has 10 years of development behind it and continues to evolve today
Layer 3 VPNs have already proven themselves as the killer app for MPLS there is no reason why this success cannot be emulated by Layer 2 VPNs
Delivering Ethernet over MPLS
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The “Multiprotocol” nature of MPLS:MPLS is multiprotocol in terms of both the layers above and below it !
The ultimate technology for convergence
MPLS is truly Multi-Protocol
MPLS
Ethernet
Frame
Relay
ATM
PoS
PPP
Etc
Physical
Ethernet
Frame
Relay
ATM
TDM
IP
Etc
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The virtualisation capabilities of MPLS:One common network supports multiple, different overlaid services
MPLS Virtualisation
PE
PE
MPLS
PE
PE
PE
P
P
P
P
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The virtualisation capabilities of MPLS:One common network supports multiple, different overlaid services
MPLS Virtualisation
VPLS
VPWS
L3VPN
MPLS
PE
PE
PE
PE
PE
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MPLS Scalability:Service state is kept only on the Provider Edge devices
The Provider (P) devices simply contain reachability information to each other and all PEs in the network
The Provider Edge (PE) devices contain customer and service-specific state
MPLS Scalability
PE
PE
MPLS
PE
PE
PE
P
P
P
P
No customer or service state in the core
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Traffic-Engineering capabilitiesThe Problem: consider example below all mission-critical traffic between nodes A and Z has to use the path A-D-E-F-Z, while all other traffic uses the path A-B-C-Z  
MPLS Traffic-Engineering
A
Z
D
E
F
B
C
Other traffic
Mission-critical traffic
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The IGP-based solutionUse link metrics to influence traffic path
MPLS Traffic-Engineering
A
Z
D
E
F
B
C
10
10
10
10
30
10
10
Other traffic
Mission-critical traffic
It’s all or nothing Traffic cannot be routed selectively
Other solutionsPolicy-based routing will work but is cumbersone to manage and has to be carefully crafted to avoid routing loops
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The MPLS solutionUse constrained path routing to build Label Switched Paths (LSPs)
MPLS Traffic-Engineering
Constrain LSP1 to use only the “orange” physical links
A
Z
D
E
F
B
C
Mission-critical traffic
LSP 2
LSP 1
Other traffic
Constrain LSP2 to use only the “blue” physical links
At the PEs, map the mission-critical traffic to LSP2 and…
…all other traffic to LSP1
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Recovery from failures typical IGPStep 1 Detection of the failure
One or more routers detect that a failure (link or node) has occurred
Step 2 Propagation of failure notification
The router(s) detecting the failure inform other routers in the domain about the failure
Step 3 Recomputation of Paths/Routes
All routers which receive the failure notification now have to recalculate new routes/paths by running SPF algorithms etc
Step 4 Updating of the Forwarding Table
Once new routes are computed, they are downloaded to the routers’ forwarding table, in order to allow them to be used
All of this takes time…
MPLS Traffic-Engineering
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Failure and Recovery Example IGP-basedWhat happens immediately after the link between C and Z fails ?  
MPLS Traffic-Engineering
B
Z
Direction of traffic flow
Step 1 -Assuming a loss of signal (or similar physical indication) nodes C and Z immediately detect that the link is down
Node A does not know that the link is down yet and keeps sending traffic destined to node Z to Node C Assuming that node C has not completed step 4 yet, this traffic is dropped
C
A
10
10
20
10
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Failure and Recovery Example (continued) IGP-basedNode C (and node Z) will be the first to recalculate its routing table and update its forwarding table (step 4)
MPLS Traffic-Engineering
In the meantime, Node A does not know that the link is down yet and keeps sending traffic destined to node Z to Node C  Given that node C has completed step 4, it now believes (quite correctly) that the best path to Z is via node A  BUT node A still believes that the best path to node Z is via node C so it sends the traffic right back to node C  We have a transient loop (micro-loop) …
The loop resolves itself as soon as node A updates its forwarding table but in the meantime, valuable packets have been dropped
B
Z
Direction of traffic flow
C
A
10
10
20
10
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Failure and Recovery Example (continued)Node A and all other nodes eventually update their forwarding tables and all is well again
But the damage is already done  
MPLS Traffic-Engineering
B
Z
Direction of traffic flow
C
A
10
10
20
10
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Recovery from failures how can MPLS help ?RSVP-TE Fast Re-Route (FRR) pre-computes detours around potential failure points such as next-hop nodes and links
When link or node failures occur, the routers (Points of Local Repair) directly connected to the failed link rapidly (sub-50ms) switch all traffic onto the detour paths  
The network eventually converges and the head-end router (source of the traffic) switches traffic onto the most optimal path  Until that is done, traffic flows over the potentially sub-optimal detour path BUT the packet loss is kept to a minimum
MPLS Traffic-Engineering
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Failure and Recovery Example with MPLS FRRNode C pre-computes and builds a detour around link C-Z  
MPLS Traffic-Engineering
B
Z
Direction of traffic flow
C
A
10
10
20
10
Bypass tunnel
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Failure and Recovery Example with MPLS FRRWhen link C-Z  fails, node C reroutes traffic onto the detour tunnel
Traffic does a U-turn but still makes it to the destination
MPLS Traffic-Engineering
B
Z
Direction of traffic flow
C
A
10
10
20
10
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What is the size of the MPLS label stack entry ?
And the MPLS label itself ?
Audience Question 4
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42 The Pseudowire Reference Model
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Pseudowires:Key enabling technology for delivering Ethernet services over MPLS
Specified by the pwe3working group of the IETF
Originally designed for Ethernet over MPLS (EoMPLS) initially called Martini tunnels
Now extended to many other services ATM, FR, Ethernet, TDM
Encapsulates and transports service-specific PDUs/Frames across a Packet Switched Network (PSN) tunnel
The use of pseudowires for the emulation of point-to-point services is referred to as Virtual Private Wire Service (VPWS)
IETF definition (RFC3985):
“a mechanism that emulates the essential attributes of a
telecommunications service (such as a T1 leased line or Frame Relay)
over a PSN  PWE3 is intended to provide only the minimum necessary
functionality to emulate the wire with the required degree of
faithfulness for the given service definition”
The Pseudowire Reference Model
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Generic PWE3 Architectural Reference Model:
PWE3 Reference Model
PSN
CE 1
CE 2
Emulated Service
Pseudowire
PSN Tunnel
Attachment Circuit
Attachment Circuit
PE 1
PE 2
Payload
Payload
PW Demultiplexer
Physical
Data Link
PSN
Payload
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Pseudowire TerminologyAttachment circuit (AC)
The physical or virtual circuit attaching a CE to a PE
Customer Edge (CE)
A device where one end of a service originates and/or terminates
Forwarder (FWRD)    
A PE subsystem that selects the PW to use in order to transmit a payload received on an AC
Packet Switched Network (PSN)
Within the context of PWE3, this is a network using IP or MPLS as the mechanism for packet forwarding
Provider Edge (PE)
A device that provides PWE3 to a CE
Pseudo Wire (PW)
A mechanism that carries the essential elements of an emulated service from one PE to one or more other PEs over a PSN
PSN Tunnel
A tunnel across a PSN, inside which one or more PWs can be carried
PW Demultiplexer
Data-plane method of identifying a PW terminating at a PE
PWE3 Terminology
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Pseudowire Protocol Layering:The PW demultiplexing layer provides the ability to deliver multiple PWs over a single PSN tunnel
Pseudowire Protocol Layering
Payload
PW Label
Physical
Data Link
PSN Label
Ethernet over MPLS PSN
Ethernet Frame
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43 Ethernet Virtual Private Wire Service (VPWS)
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Ethernet Pseudowires:Encapsulation specified in RFC4448 “Encapsulation Methods for Transport of Ethernet over MPLS Networks”
Ethernet pseudowires carry Ethernet/8023 Protocol Data Units (PDUs) over an MPLS network
Enables service providers to offer “emulated” Ethernet services over existing MPLS networks
RFC4448 defines a point-to-point Ethernet pseudowire service
Operates in one of two modes:
Tagged mode -In tagged mode, each frame MUST contain at least one 8021Q VLAN tag, and the tag value is meaningful to the two PW termination points
Raw mode -On a raw mode PW, a frame MAY contain an 8021Q VLAN tag, but if it does, the tag is not meaningful to the PW termination points, and passes transparently through them
Ethernet Virtual Private Wire Service
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Ethernet Pseudowires (continued):Two types of services:
“port-to-port” all traffic ingressing each attachment circuit is transparently conveyed to the other attachment circuit, where each attachment circuit is an entire Ethernet port
“Ethernet VLAN to VLAN” all traffic ingressing each attachment circuit is transparently conveyed to the other attachment circuit, where each attachment circuit is a VLAN on an Ethernet port
In this service instance, the VLAN tag may be stripped on ingress and then re-imposed on egress
Alternatively, the VLAN tag may be stripped on ingress and a completely different VLAN ID imposed on egress, allowing VLAN re-write
The VLAN ID is locally significant to the Ethernet port
Ethernet Virtual Private Wire Service
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PWE3 Architectural Reference Model for Ethernet Pseudowires
PWE3 Reference Model for Ethernet VPWS
PSN
CE 1
CE 2
Emulated Service
Pseudowire
PSN Tunnel
Attachment Circuit
Attachment Circuit
PE 1
PE 2
Payload
Payload
PW Demultiplexer
Physical
Data Link
PSN
Payload
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Ethernet PWE3 Protocol Stack Reference Model:
Ethernet Virtual Private Wire Service
Emulated
Ethernet
PW Demultiplexer
Physical
Data Link
PSN MPLS
Emulated Service
Emulated
Ethernet
PW Demultiplexer
Physical
Data Link
PSN MPLS
Pseudowire
PSN Tunnel
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Example 1: Ethernet VPWS port-to-port (traffic flow from CE1 to CE2)
Ethernet VPWS Example 1
PSN
CE 1
CE 2
Port 1/2/1
Port 3/2/0
PE 1
PE 2
Payload
Payload
6775
Physical
Data Link
1029
PE1 Config:
Service ID: 1000
Service Type: Ethernet VPWS
(port-to-port)
PSN Label for PE2: 1029
PW Label from PE2: 6775
Port: 1/2/1
PE2 Config:
Service ID: 1000
Service Type: Ethernet VPWS
(port-to-port)
PSN Label for PE1: 4567
PW Label from PE1: 10978
Port: 3/2/0
Traffic Flow
DA
SA
VLAN tag
DA
SA
VLAN tag
Payload
DA
SA
VLAN tag
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Example 1: Ethernet VPWS port-to-port (traffic flow from CE2 to CE1)
Ethernet VPWS Example 1
PSN
CE 1
CE 2
Port 1/2/1
Port 3/2/0
PE 1
PE 2
Payload
Payload
10978
Physical
Data Link
4567
PE1 Config:
Service ID: 1000
Service Type: Ethernet VPWS
(port-to-port)
PSN Label for PE2: 1029
PW Label from PE2: 6775
Port: 1/2/1
PE2 Config:
Service ID: 1000
Service Type: Ethernet VPWS
(port-to-port)
PSN Label for PE1: 4567
PW Label from PE1: 10978
Port: 3/2/0
Traffic Flow
DA
SA
VLAN tag
DA
SA
VLAN tag
Payload
DA
SA
VLAN tag
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Example 2: Ethernet VPWS VLAN-based (traffic flow from CE1 to CE2)
Ethernet VPWS Example 2
PSN
CE 1
CE 2
Port 1/2/1
Port 3/2/0
PE 1
PE 2
Payload
Payload
5879
Physical
Data Link
1029
PE1 Config:
Service ID: 2000
Service Type: Ethernet VPWS
(VLAN-100)
PSN Label for PE2: 1029
PW Label from PE2: 5879
Port: 1/2/1 VLAN 100
PE2 Config:
Service ID: 1000
Service Type: Ethernet VPWS
(VLAN-200)
PSN Label for PE1: 4567
PW Label from PE1: 21378
Port: 3/2/0 VLAN 200
Traffic Flow
DA
SA
VLAN tag -100
DA
SA
Payload
DA
SA
VLAN tag -200
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Example 2: Ethernet VPWS VLAN-based (traffic flow from CE2 to CE1)
Ethernet VPWS Example 2
PSN
CE 1
CE 2
Port 1/2/1
Port 3/2/0
PE 1
PE 2
Payload
Payload
21378
Physical
Data Link
4567
PE1 Config:
Service ID: 2000
Service Type: Ethernet VPWS
(VLAN-100)
PSN Label for PE2: 1029
PW Label from PE2: 5879
Port: 1/2/1 VLAN 100
PE2 Config:
Service ID: 1000
Service Type: Ethernet VPWS
(VLAN-200)
PSN Label for PE1: 4567
PW Label from PE1: 21378
Port: 3/2/0 VLAN 200
Traffic Flow
DA
SA
VLAN tag -100
DA
SA
Payload
DA
SA
VLAN tag -200
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Ethernet Pseudowires Setup and Maintenance:Signalling specified in RFC4447 “Pseudowire Setup and Maintenance Using the Label Distribution Protocol (LDP)”
The MPLS Label Distribution Protocol, LDP [RFC5036], is used for setting up and maintaining the pseudowires
PW label bindings are distributed using the LDP downstream unsolicited mode
PEs establish an LDP session using the LDP Extended Discovery mechanism aka Targeted LDP or tLDP
The PSN tunnels are established and maintained separately by using any of the following:
The Label Distribution Protocol (LDP)
The Resource Reservation Protocol with Traffic Engineering (RSVP-TE)
Static labels
Ethernet Virtual Private Wire Service
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Ethernet Pseudowires Setup and Maintenance:LDP distributes FEC to label mappings using the PWid FEC Element (popularly known as FEC Type 128)
Both pseudowire endpoints have to be provisioned with the same 32-bit identifier for the pseudowire to allow them to obtain a common understanding of which service a given pseudowire belongs to
Ethernet Virtual Private Wire Service
0                   1                   2                   30 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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+|  PWid (0x80)  |C|         PW type             |PW info Length |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+|                          Group ID                             |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+|                           PW ID                               |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+|                Interface Parameter  Sub-TLV                   ||                              \"                                ||                              \"                                |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Ethernet Pseudowires Setup and Maintenance:A new TLV, the Generalized PWid FEC Element (popularly known as FEC Type 129) has also been developed but is not widely deployed as yet
The Generalized PWid FEC element requires that the PW endpoints be uniquely identified; the PW itself is identified as a pair of endpoints  In addition, the endpoint identifiers are structured to support applications where the identity of the remote endpoints needs to be auto-discovered rather than statically configured
Ethernet Virtual Private Wire Service
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Ethernet Pseudowires Setup and Maintenance:The Generalized PWid FEC Element (popularly known as FEC Type 129)
Ethernet Virtual Private Wire Service
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Gen PWid (0x81)|C|         PW Type             |PW info Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|   AGI Type    |    Length     |      Value                    |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~                    AGI  Value (contd)                        ~
|                                                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|   AII Type    |    Length     |      Value                    |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~                   SAII  Value (contd)                        ~
|                                                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|   AII Type    |    Length     |      Value                    |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~                   TAII Value (contd)                         ~
|                                                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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What protocol is used to exchange pseudowire labels between provider edge routers ?
Audience Question 5
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44 Ethernet Virtual Private LAN Service (VPLS)
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Ethernet VPLS:Two variants
RFC4762 -Virtual Private LAN Service (VPLS) Using Label Distribution Protocol (LDP) Signaling  We will concentrate on this variant in the rest of this tutorial
RFC4761 -Virtual Private LAN Service (VPLS) Using BGP for Auto-Discovery and Signaling
Ethernet Virtual Private LAN Service
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Definition:A VPLS creates an emulated privateLAN segment for a given set of users  
It creates a Layer 2 broadcast domain that is fully capable of learning and forwarding on Ethernet MAC addresses and that is closed to a given set of users  Multiple VPLS services can be supported from a single Provider Edge (PE) node
The primary motivation behind VPLS is to provide connectivity between geographically dispersed customer sites across MANs and WANs, as if they were connected using a LAN
The main intended application for the end-user can be divided into the following two categories:
Connectivity between customer routers: LAN routing application
Connectivity between customer Ethernet switches: LAN switching application
Ethernet Virtual Private LAN Service
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Benefits for the customer:Simplicity
Behaves like an “ethernet switch in the sky”
No routing interaction with the provider
Clear demarcation between subscriber and provider
Layer 3 agnostic
Scalable
Provider configures site connectivity only
Hierarchy reduces number of sites touched
Multi-site connectivity
On the fly connectivity via Ethernet bridging
VPLS Benefits
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Topological Model for VPLS (customer view)
VPLS Topological Model
PSN
CE 1
CE 2
CE 3
Ethernet Switch
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Topological Model for VPLS (provider view)
VPLS Topological Model
PSN
CE 1
CE 2
Emulated LAN
Attachment Circuit
Attachment Circuit
PE 1
PE 2
CE 3
PE 3
Attachment Circuit
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PSN Tunnels and Pseudowire Constructs for VPLS:
Constructing VPLS Services
PSN
CE 1
CE 2
Attachment Circuit
Attachment Circuit
CE 3
Attachment Circuit
PSN (LSP) tunnel
VB
VB
PE 1
PE 2
PE 3
VB
VB
Virtual Bridge Instance
Pseudowire
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Provider Edge Functions:PE interfaces participating in a VPLS instance are able to flood, forward, and filter Ethernet frames, like a standard Ethernet bridged port
Many forms of Attachment Circuits are acceptable, as long as they carry Ethernet frames:
Physical Ethernet ports
Logical (tagged) Ethernet ports
ATM PVCs carrying Ethernet frames
Ethernet Pseudowire
Frames sent to broadcast addresses and to unknown destination MAC addresses are flooded to all ports:
Attachment Circuits
Pseudowires to all other PE nodes participating in the VPLS service
PEs have the capability to associate MAC addresses with Pseudowires
VPLS PE Functions
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Provider Edge Functions (continued):Address learning:
Unlike BGP VPNs [RFC4364], reachability information is not advertised and distributed via a control plane
Reachability is obtained by standard learning bridge functions in the data plane
When a packet arrives on a PW, if the source MAC address is unknown, it is associated with the PW, so that outbound packets to that MAC address can be delivered over the associated PW
When a packet arrives on an AC, if the source MAC address is unknown, it is associated with the AC, so that outbound packets to that MAC address can be delivered over the associated AC
VPLS PE Functions
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VPLS Signalling
VPLS Mechanics:Bridging capable PE routers are connected with a full mesh of MPLS LSP tunnels
Per-Service pseudowire labels are negotiated using RFC 4447 techniques
Replicates unknown/broadcast traffic in a service domain
MAC learning over tunnel & access ports
Separate FIB per VPLS for private communication
PSN
CE 1
CE 2
VPLS Service
Attachment Circuit
Attachment Circuit
PE 1
PE 2
CE 3
PE 3
Attachment Circuit
Full mesh of LSP tunnels
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VPLS Signalling
Tunnel establishmentLDP:
MPLS paths based on IGP reachability
RSVP: traffic engineered MPLS paths with bandwidth & link constraints, and fast reroute alternatives
Pseudowire establishmentLDP: point-to-point exchange of PW ID, labels, MTU
PSN
CE 1
CE 2
VPLS Service
Attachment Circuit
Attachment Circuit
PE 1
PE 2
CE 3
PE 3
Attachment Circuit
Full mesh of LSP tunnels
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VPLS Signalling
A full mesh of pseudowires is established between all PEs participating in the VPLS service:Each PE initiates a targeted LDP session to the far-end System IP (loopback) address
Tells far-end what PW label to use when sending packets for each service
PSN
CE 1
CE 2
Attachment Circuit
Attachment Circuit
CE 3
Attachment Circuit
PSN (LSP) tunnel
VB
VB
PE 1
PE 2
PE 3
VB
VB
Virtual Bridge Instance
Pseudowire
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VPLS Signalling
Why a full mesh of pseudowires?If the topology of the VPLS is not restricted to a full mesh, then it may be that for two PEs not directly connected via PWs, they would have to use an intermediary PE to relay packets
A loop-breaking protocol, such as the Spanning Tree Protocol, would be required
With a full-mesh of PWs, every PE is now directly connected to every other PE in the VPLS via a PW; there is no longer any need to relay packets
The loop-breaking rule now becomes the \"split horizon\" rule, whereby a PE MUST NOT forward traffic received from one PW to another in the same VPLS mesh
Does this remind you of a similar mechanism used in IP networks ?  The ibgp full-mesh !
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105| MPLS-based Metro Ethernet Networks, January 2010
Ethernet Pseudowires Setup and Maintenance:Signalling specified in RFC4447 “Pseudowire Setup and Maintenance Using the Label Distribution Protocol (LDP)”
The MPLS Label Distribution Protocol, LDP [RFC5036], is used for setting up and maintaining the pseudowires
PW label bindings are distributed using the LDP downstream unsolicited mode
PEs establish an LDP session using the LDP Extended Discovery mechanism aka Targeted LDP or tLDP
The PSN tunnels are established and maintained separately by using any of the following:
The Label Distribution Protocol (LDP)
The Resource Reservation Protocol with Traffic Engineering (RSVP-TE)
Static labels
VPLS Pseudowire Signalling
Barcelone---suitepptjpg
106| MPLS-based Metro Ethernet Networks, January 2010
Ethernet Pseudowires Setup and Maintenance:LDP distributes FEC to label mappings using the PWid FEC Element (popularly known as FEC Type 128)
Both pseudowire endpoints have to be provisioned with the same 32-bit identifier for the pseudowire to allow them to obtain a common understanding of which service a given pseudowire belongs to
VPLS Pseudowire Signalling
0                   1                   2                   30 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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+|  PWid (0x80)  |C|         PW type             |PW info Length |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+|                          Group ID                             |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+|                           PW ID                               |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+|                Interface Parameter  Sub-TLV                   ||                              \"                                ||                              \"                                |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Barcelone---suitepptjpg
107| MPLS-based Metro Ethernet Networks, January 2010
Ethernet Pseudowires Setup and Maintenance:A new TLV, the Generalized PWid FEC Element (popularly known as FEC Type 129) has also been developed but is not widely deployed as yet
The Generalized PWid FEC element requires that the PW endpoints be uniquely identified; the PW itself is identified as a pair of endpoints  In addition, the endpoint identifiers are structured to support applications where the identity of the remote endpoints needs to be auto-discovered rather than statically configured
VPLS Pseudowire Signalling
Barcelone---suitepptjpg
108| MPLS-based Metro Ethernet Networks, January 2010
Ethernet Pseudowires Setup and Maintenance:The Generalized PWid FEC Element (popularly known as FEC Type 129)
VPLS Pseudowire Signalling
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Gen PWid (0x81)|C|         PW Type             |PW info Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|   AGI Type    |    Length     |      Value                    |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~                    AGI  Value (contd)                        ~
|                                                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|   AII Type    |    Length     |      Value                    |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~                   SAII  Value (contd)                        ~
|                                                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|   AII Type    |    Length     |      Value                    |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~                   TAII Value (contd)                         ~
|                                                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Barcelone---suitepptjpg
109| MPLS-based Metro Ethernet Networks, January 2010
Ethernet VPLS Signalling Example
PE1 Config:
Service ID: 1001
Service Type: Ethernet VPLS
PSN Label for PE2: 1029
PSN Label for PE3: 9178
PW Label from PE2: 6775
PW Label from PE3: 10127
Port: 1/2/1
PE2 Config:
Service ID: 1001
Service Type: Ethernet VPLS
PSN Label for PE1: 4567
PSN Label for PE3: 11786
PW Label from PE1: 10978
PW Label from PE3: 4757
Port: 3/2/0
Port 1/2/1
Port 3/2/0
PSN
M1
M2
M3
VB
PE 1
PE 2
PE 3
VB
VB
PE3 Config:
Service ID: 1001
Service Type: Ethernet VPLS
View All (861)
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