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Future-Net 2010
Verizon‘s Requirements for IP/MPLS-Based Carrier Ethernet Networks
Andrew G. Malis & Drew RexrodeVerizon Communications
[email protected]@verizon.com
2
Introduction
• Public Ethernet services are exploding in popularity
• External Ethernet interface to the customer does not necessarily
mean ―Ethernet inside‖– The Internet Engineering Task Force (IETF) has standardized
mechanisms for providing point-to-point and multipoint public Ethernet
services over IP/MPLS-based infrastructures
• This talk discusses Verizon‘s requirements for such solutions,
including functionality, conformance to Metro Ethernet forum (MEF)
service definitions, reliability, scalability, QoS, performance
monitoring, OAM, testing, and certification
3
Why Are Ethernet Services
Popular?
• Ubiquity and low cost of Ethernet interfaces in customer equipment,
universal experience with Ethernet in LANs, and perceived simplicity
• Successful marketing of the ―Ethernet‖ brand by vendors, IEEE,
MEF, and others– Little resemblance with original DIX Ethernet specifications, from
physical layer on up (e.g., today‘s Ethernet is mostly point-to-point or
ring-based rather than CSMA-CD at the physical layer)
– Most everything has changed except for the basic frame format – and
jumbograms (large frames up to 9K bytes) change even that
• Plenty of competition and favorable pricing by service providers
4
MEF Carrier Ethernet Service
Definitions
• Three service types based on the three Ethernet Virtual Connection (EVC) types
• Two ―UNI Types‖ determine whether services are ‗private‘ or ‗virtual‘– Port-based (All to One Bundling) single EVC (transparency, but uses an entire port per service)– VLAN-based ‗N‘ EVCs per UNI (not as transparent, but multiple services per port)
• Services are defined by combination of connectivity model and ‗UNI Type‘
• Also Ethernet-based access services to Layer 3 VPNs or dedicated Internet access
Connectivity ModelPort-Based
(All to One Bundling)
VLAN-Based
(EVC identified by VLAN ID)
E-Line
(point-to-point EVC)
Ethernet Private Line
(EPL)
Ethernet Virtual Private Line
(EVPL)
E-LAN
(multipoint-to-multipoint EVC)
Ethernet Private LAN
(EP-LAN)
Ethernet Virtual Private LAN
(EVP-LAN)
E-Tree
(rooted multipoint EVC)
Ethernet Private Tree
(EP-Tree)
Ethernet Virtual Private Tree
(EVP-Tree)
5
―Enterprise-Class‖ Ethernet
Limitations
• ―Enterprise-class‖ Ethernet switching has shortcomings as a basic
for public Ethernet services– Few features for high availability in protocols or equipment
– Scaling limits on MAC addresses, VLAN IDs, and spanning tree
topology limit the size of native Ethernet networks
– Spanning tree routing may take seconds to (occasionally) minutes to re-
converge
• Early Ethernet providers found that enterprise-class Ethernet cannot
naively be deployed for reliable carrier services
6
Evolving and Scaling Ethernet
Services
• A typical ―early‖ public Ethernet service provider probably uses
Ethernet switches and Q-in-Q for customer separation
• Typical end user services are– Ethernet Private LAN (EP-LAN)
– Ethernet Virtual Private LAN (EVP-LAN)
– Ethernet Private Line (EPL)
– Ethernet Virtual Private Line (EVPL)
– Each of these services requires the use of a provider VLAN tag
• As the service becomes successful, the provider will encounter the
usual Ethernet scaling limitations– MAC address scaling
– VLAN tag scaling (4K customer limit)
– Switching capacity limits
7
Typical ―Early‖ Ethernet Service
Network
• Characterized by organic
growth driven by customer
location
• All switches are ―edge
switches‖
• May be some number of
redundant links
• 802.3ad Link Aggregation may
also be used for resiliency or
for additional BW between
switches
• Flat network with spanning
tree routing– Network diameter is limited,
often to metro scope
PE – Provider Edge Switch
PE
PE
PE
PE
PE
PE
PE
PE
PE
PE
PE
PE
PE
PE
PE
PE
PE
GigE/LAG
8
Emergence of ―Carrier Ethernet‖
• Limitations in enterprise-class Ethernet have led to the development
of ―Carrier Ethernet‖
• Meant to address unique requirements for carrier Ethernet services,
including Verizon‘s services– Scaling to support a large number of customers
– Scaling to support large numbers of switches and customer interfaces
– Support both point-to-point (E-Line) and multipoint (E-LAN and E-Tree)
services
– Support for both port-based and VLAN-based services
– Support for QoS other than best-effort to support QoS-based SLAs
– Sub-second outage restoration and routing convergence to support
availability SLAs
– Policing and shaping to support sub-rate services (e.g., 200 Mbps
service on a physical GigE interface)
9
IETF Ethernet Services Support
• Point-to-point pseudowires (PWs) to carry layer two frames,
including Ethernet, over IP/MPLS networks
• Extends the MPLS LDP protocol to signal pseudowire establishment
• IETF extended PWs to a multipoint Ethernet service, VPLS (Virtual
Private LAN Service)
• PWs and VPLS extremely popular, implemented by most every
router vendor and in wide use by service providers world-wide
• Verizon uses both point-to-point PWs and VPLS to provide customer
Ethernet services
10
IP/MPLS Forum Ethernet Services
Support
• Extended IETF-defined PWs to support non-similar endpoint
interworking– Supports point-to-point Ethernet-to-Frame Relay, Ethernet-to-ATM, and
ATM-to-Frame Relay interworking over MPLS PWs
– Very useful for multiservice convergence, and to support customers with
a variety of access methods
– Can support applications such as hub location with GigE access, and
low-speed Frame Relay spokes
– Supports interworking of IP packets via ARP Mediation, and bridged
services by interworking native Ethernet with Ethernet frames
encapsulated by FR or ATM
– Can also support VPLS endpoints with FR or ATM-attached customer
equipment
11
H-VPLS vs. VPLS+PBB
• VPLS and H-VPLS as originally defined by the IETF cannot meet
Carrier Ethernet service scaling requirements:– 10s to 100s of thousands of EVCs
– Number of E-LAN bridging instances per edge switch/LER
– Up to millions of customer MAC addresses
• For these reasons, the IETF is now defining the combination of
VPLS in the core with Provider Backbone Bridges (PBB, 802.1ah) at
the edge
12
Scalable Network Architecture –
PBB + MPLS
• Metro Network Dedicated to Ethernet Service
• Investment Protection
• Hierarchy with PBB
• Administrative Traffic Eng.
• Operations skill set / OSS Leverage
• MPLS core leveraged across multiple services (e.g., Ethernet, L3 VPNs)
• Scalable and mature control plane
• Leverage control plane to ease administration (BGP-Auto Discovery, TE)
• Less touch points for cross-metro services
• PBB (B-VID) VPLS instance (reduce PW Meshiness)
• Broadcast containment per service across core (via MMRP/BGP-AD)
• PBB MAC hiding
BEB
BEB
PB
PB
PB
PB
PB
PB
BEB
BEB
BEB
PP
BCB
BEB
/PE
N-PE
PBEB
PB
N-PE
PBEB
N-PE
PBEB
BCB
13
PBB-VPLS— MAC Scaling and
Customer-Addressing Awareness
• ―Hub‖ PE-rs get visibility of 100,000s of MACs
• High customer-addressing awareness
• MAC tables reduced: one B-MAC per
node
• No customer-addressing awareness
MTU-s
MTU-s
PE-rs
No. of MAC addresses/node
0MTU-s
1000s
100,000s
PE-rs
Customer MACs
Backbone MACs
MTU-s
MTU-s PE-rs
No. of MAC addresses/node
0MTU-s
1000s
100,000s
PE-rs
PBB-VPLS
MPLSMPLS
H-VPLS
14
PBB-VPLS Benefits — Service/Pseudowire
Scaling and Customer-Service Awareness
Customer services
Customer PWs
Backbone services
Backbone PWs
MTU-sMTU-s
PE-rsB
B
B
B
B
B
BB
B
B
MTU-s
PE-rs
0
1000s
100,000s
10,000s
No. of services-PW/node No. of services-PW/node
0
1000s
100,000s
10,000s
MTU-S MTU-S PE-rs PE-rs MTU-S MTU-S PE-rs PE-rs
VPLS + PBBH-VPLS
100s
15
OAM Specifications
• The IEEE, ITU-T, and MEF have defined Ethernet OAM (Operations,
Administration and Maintenance) specifications to allow fault
detection and correction. These include:– Link OAM: IEEE 802.3-2005, Clause 57
• Enables monitoring and troubleshooting of native Ethernet links
– Ethernet Local Management Interface (E-LMI): MEF 16
• Provides EVC status
• Enables automatic configuration of Customer Equipment (CE)
– Connectivity Fault Management (CFM): IEEE 802.1ag
• Enables monitoring and troubleshooting of VLANs within a network
• Supports multiple views (Customer, Service Provider, Operator)
– Service OAM: ITU-T Y.1731
• Extends CFM to include additional FM capabilities
• Performance Monitoring (PM)
16
Carrier Ethernet over MPLS
Testing
• Requires documentation and references– MEF, BBF, IETF, IEEE
• Automation– Definitive Parameters
17
802.1 q-in-q/ad and 802.1ah - Service
Tunneling Testing Scenario (Example)
CEs
PBBN
Q-in-Q /82.1adISIDISIDISID
ISIDISIDISID ISIDISID
ISIDISID
ISID
G.8031
Tunnel protection group
BCB1 BCB2
BEB1 BEB2 BEB3 BEB4BEB5 BEB6
VLAN 100VLAN 100 VLAN 100VLAN 100
0000.c004.0102
0000.c004.0103
0000.c004.0104
0000.c004.01050000.c004.0106
0000.c004.0107
0000.c004.0108
0000.c004.0109
18
Carrier Ethernet over MPLS
Certification
• ROI
• Time to Market
• Man Hours
• Resources
19
Conclusions
• Verizon‘s Carrier Ethernet services must meet stringent
requirements for:
– Conformance to Metro Ethernet forum (MEF) service definitions
– Scalability to support customer growth
– Reliability, resilience, OAM for troubleshooting and performance
monitoring, to support high service availability
– Standards-based certification
– Pre-deployment and post-deployment testing