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Work done in the MEF Protocol and Transport Group –Protection Requirements Document Status is Straw Ballot –Protection Framework Document Status is Straw Ballot –MPLS Protection Implementation Agreement Status is Straw Ballot MEF Protection Work Items
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MEF ProtectionWork
Pascal MenezesTechnical Contributor
June 3rd 2003
• Agnostic to any transport and its related protection schemes.• Agnostic to any topology
– Does not rely on a certain topology for protection (ex: ring)– Can work with any topology (ring, mesh, mixed, etc)– Degree of protection is dependent on the richness of the redundancy of the topology
• Co-exist with any transport protection schemes (ex: SONET, RPR, 802.1d.
• Primarily designed for the protection of EVCs.– Based on MPLS based schemes because of the layer 2 service work in IETF for PPVPN
(ex: VPLS, VPWS, etc) and PWE3 WGs. This was the scheme chosen because of scalability and inter-MEN connectivity advantages.
– It is transparent to IEEE schemes (STP, Link Agg, etc) and it assumes IEEE protection schemes are part of the protection of an Ethernet transport mechanism (ie: it is part of the transport mechanism of the provider).
• Subscriber’s protection scheme is transparent (ie: STP, multi-homed)• Extensions to the PRMs for IEEE based technologies
– Looking into 802.1ad work and how to extend the framework interworking
Motivations
• Work done in the MEF Protocol and Transport Group– Protection Requirements Document
• Status is Straw Ballot– Protection Framework Document
• Status is Straw Ballot– MPLS Protection Implementation Agreement
• Status is Straw Ballot
MEF Protection Work Items
MEF Architecture External Reference Model
Subscriber
MEFUNI
EthernetInterworkingNNI
Metro EthernetNetwork (MEN)Autonomy X
OtherTransportNetworks
NetworkInterworkingNNI
Metro EthernetNetwork (MEN)Autonomy X
ServiceInterworkingNNI
Other Service Networks(Internet, PPP, FR, ATM)
Metro EthernetNetwork (MEN)Autonomy Y
NetworkInterworkingNNI
Subscriber
MEF UNI
Subscriber
OtherUNIs
Subscriber
MEFUNIs
802.3PHY
ATM VP
HOVC
STM-N
ATM VC
HOVC
STM-N
LOVC
HOVC
STM-N
MPLS
802.3PHY
OTUk
OCh
OTM-n
ODUk
othe
r
MPLS PDH OtherIP
MEN Applications (Voice, Video, Data, etc)
IP
HOVC
STM-N
MPLSMPLS VC
TransportLayer (s)
ApplicationServicesLayer (s)
IP
TCP/UDP OtherProtocolSuite(s)
Transport Layers
Application Layers
Ethernet Services
Medium (Fiber, Copper, Coax, wireless, etc.)
EthernetServiceLayer
Ethernet Layer
MEN Layered Model
MEF Ethernet Virtual Connection (EVC) Model
MetroEthernetNetwork
CustomerEdge(CE)
CustomerNetwork
NetworkElement
NetworkElement
NetworkElement
NetworkElement
CustomerNetwork
CustomerEdge(CE)
UserNetworkInterface
(UNI)
UserNetworkInterface
(UNI)
EthernetVirtual
Connection(EVC)
UNI = Service AttributesEVC = Service Attributes
• Protection switching times.• Failure detection requirements• Protection resource allocation requirements• Topology requirements• Failure notification requirements• Restoration and revertiveness requirements• Transparency for end user• Security requirements
MEF Protection Requirements
• Connectivity restoration time– Sub 50msec– Sub 200msec– Sub 2 sec– Sub 5 sec
• Protection type– 1+1– 1:1– 1:n– m:1– m:n
• Revertive or non-revertive mode• Reversion time• Degrade condition threshold (ex: packet loss)• QoS preservation
End to End Protection Service Level Specifications
OtherTransport
(Protection)
Ethernet(No Protection)CE
Metro Ethernet Network (MEN)
CE
End-to-End Protection Service Level Specification (SLS)
TransportSub-Network
TransportSub-Network
TransportSub-Network
OtherTransport
(Protection)
Transport & Protection SLS
BackboneRing
NENE
NE
NE
Access Ring NENE
NE
NE
Access Mesh
WAN 1Backbone
Ring
Access Ring
NE
NE
NENE
NE
NE
Access Mesh NENE
Metro Ethernet Network (MEN)
End-to-End Protection Service Level Specification (SLS)
WAN 2
Topology & Protection SLS
MEF Protection Reference Model (PRM)
End to End Path Protection
EEPP
Aggregated Line andNode Protection
ALNP
MEF Protection Mechanism
Topology
Transport
Ethernet Services Parameters(Protection EVC Service Attributes, Traffic Parameters, etc)
Service Level AgreementsSLA
Application Protection Constraint PolicyAPCP
End-to-End Path Protection
(EEPP)
Aggregated Line &Node Protection
ALNPTopology
Transport
• ALNP Backup LSPs• 1+1 EEPP Protection Type• 50 Msec Restoration Time• QoS Preserved
Protection Service Level SpecificationApplication Protection Constraint Policy
• 99.999 Availability• Packet loss • Delay• Jitter
Subscriber Service Level Agreement
Application Protection Constraint Policy (APCP)
• EVC Availability• EVC MTTR• etc..
Ethernet Service AttributesEthernet Services Parameters
NE
NE
IngressNE NE NE Egress
NE
BackupLSP
BackupLSP
PrimaryLSP
Aggregated Line and Node Protection (ALNP)
Aggregated Node and Line Protection (ALNP)
CEA
NE3
NE8
NE4
NE9
CEZ
NE10
NE2
NE5
NE7
NE1
NE6
EVC
NE
NE
NE
IngressNE NE NE Egress
NE
BackupLSP
BackupLSP
PrimaryLSP
NESecondary
LSP
End-to-End Path Protection (EEPP)
Redundant Network
PrimaryNetwork
End-to-End Path Protection (EEPP)
CEA
NE3
NE8
NE4
NE9
CEZ
NE10
NE2
NE5
NE7
NE1
NE6
EVC
BackboneRing
NENE
NE
NE
Access Ring NENE
NE
NE
Access Mesh
WAN 1Backbone
Ring
Access Ring
NE
NE
NENE
NE
NE
Access Mesh NE
NE
Metro Ethernet Network (MEN)
WAN 2
NE
NE NE
NE
NE
NE
Primary LSP
Backup LSP
Secondary LSP
PRM Example
Protection And ProtectedTransport Sub-Networks
• Generic approach – PRM interoperability with any kind of transport / topology / protected MPLS-subnetwork / logical-link.
• Failures within the protected-transport/subnetwork are provided by itself.
• PRM is required for completing the solution in the border between the protected transport/subnetwork and other subnetworks.
• Requires indications from the lower layer.• Indications achieved either by the lower-layer or by an
OA&M procedure that operates above it.• PRM does not require knowledge of internal structure of
the protected subnetwork.
PRM and Protected Transport Sub-Networks
NE NE
NE NE
CE NE
NE NE
NE CE
NE NENE NE
PRM and RPR
RPRSub-Network
No protection needed
GELinks
RPRSub-Network
Protection needed
• Two rings, each protected by technology-specific means, interconnected with point-to-point links.
• PRM is required for protecting the P2P links and the border nodes (for example, protection tunnel for node A in blue).
A
PRM and SONET
SONETSub-Network
SONETSub-Network
• A topology containing protected-transport subnetwork as well as unprotected P2P links.
Protected Transport / Subnetwork
A
DB
CE
F
G
H
Example Network
Unprotected link
• Failures within the protected subnetwork are protected by its native capabilities.
• Failure of border nodes like node A are not protected by the transport/subnetwork.
Protected Transport /Subnetwork
A
DB
CE
F
G
H
Where is PRM Needed?
• Protection-tunnels are required only for protection of border nodes (unprotected links/nodes).
• Failure of a link leading to the border node activates the operation of PRM – switch to the protection tunnel.
Protected Transport / Subnetwork
A
DB
CE
F
G
H
PRM Operation in Protected Transport Sub-Networks
• When the failed node is at the exit of an LSP from the protected subnetwork, the entry node is the one to activate the PRM – switch to the protection tunnel.
• This requires receipt of indication about the failure from the protected transport subnetwork or MPLS OAM/Hello.
Protected Transport / Subnetwork
A
DB
CE
F
G
H
PRM and Egress Border Failure Case
• Some transports have means for indicating about failures and about their type and place.
• OAM procedures on LSPs• Heartbeat on links: ex: RSVP Hello Ext.
Node Failure Indications in Protected Transport Subnetworks
• The PRM scheme is generalized to interoperate with protected-transports / unprotected-transports / protected-subnetworks / logical-links.
• PRM does not have knowledge of internal structure of the protected subnetwork.
• Protected subnetworks can use any kind of protection mechanism.
• Subscribers protection mechanisms are transparent• The PRM is a multi-layers protection model that
co-exist together.
Summary
Thank You
