| Network Working Group | D. King |
| Internet-Draft | Old Dog Consulting |
| Intended status: Informational | M. Boucadair |
| Expires: January 1, 2015 | France Telecom |
| S. Aldrin | |
| Huawei USA | |
| G. Mirsky | |
| Ericsson | |
| Q. Wu | |
| Huawei | |
| June 30, 2014 |
Use Cases for Transport Independent Multiple Layer OAM
draft-king-opsawg-time-multi-layer-oam-use-case-00
This document identifies and discusses use-cases for transport independent OAM that need to interface multi-layer or multi-domain transport networks to cover heterogeneous networking technologies. As providers face multi-layer networks and diverse transport technologies, generic and integrated OAM is desirable for simplifying network operations and maintenance.
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This document discusses use-cases for transport independent OAM that need to interface multi-layer or multi-domain transport networks to to cover heterogeneous networking technologies. As providers (e.g., network providers, data center providers, etc.) face multi-layer networks and diverse transport technology, generic and integrated OAM is desirable for keeping network complexity down and simplifying OAM.
This document is a part of the TIME effort, called Transport Independent OAM in Multi-Layer Environment. The goal of TIME is as follows
These objectives are not frozen; further discussion is required to target key issues and scope the work to be conducted within IETF accordingly.
The problem statement and architecture is discussed in [TIME-PS].
Domain A Domain B
---------- ----------
//-MPLS/IP -\\ //-MPLS/IP -\\
// \\ // \\
/ \ / \
|| || || ||
| | | |
+---+ +----+ +----+ +----+ +----+ +----+ +----+ +---+
|CE |--| PE |------| P +----| PE |-+ PE +---- | P |-----| PE |--|CE |
+-+-+ +--+-+ +--+-+ +-+--+ +--+-+ +--+-+ +-+--+ +-+-+
| | | | | | | | | | | |
| ||| | ||| ||| | ||| |
| | | | | | | |
| |\\ | //| |\\ | //| |
| | \\- | -// | | \\- | -// | |
| | ------+--- | | -----+---- | |
L1 | |Ethernet OAM(CC,CV,etc.) | | |
o-------D-----------+--------+-------+----------+---------D-------o
| | | | | | | |
L2| | |IP OAM(Ping, Tracerroute, etc.) | |
o-------o-----------D--------o-------o----------D---------o-------o
| | | | | | | |
L3| Transport Independent OAM(Integrated Ethernet with IP OAM |
o-------o-----------D--------o-------o----------D---------o-------o
| | | | | | | |
| | | | | | | |
o Maintenance Endpoint(MEP)
D Maintenance Intermediary point (MIP)
Figure 1 illustrates a multi-layer network in which IP traffic
between two customer edges is transported over an IP/MPLS provider
Figure 1 illustrates a multi-layer network in which IP traffic between two customer edges is transported over an IP/MPLS provider network and multiple layers OAMs are used. Ethernet OAM is used at the customer level for monitoring the end-to-end connection between the two customer edges, while IP OAM is used at the provider level for monitoring the connection between any two provider edges in each network. In addition to Ethernet OAM, transport independent OAM is also used for monitor end to end connection between the two customer edges at the abstract level.
With transport independent OAM in the data plane, a user who wishes to issue a IP Ping Command or use connectivity verification command can do so in the same manner regardless of the underlying protocol or transport technology. Consider a scenario where both Ethernet OAM and IP OAM can be decomposed into a set of various OAM functions and an Ethernet OAM can be integrated with IP OAM in one protocol. When one OAM function is invoked, it will be invoked in the same way as the other OAM function regardless of the underlying protocol.
Alternatively, when Ethernet OAM and IP OAM can be consolidated through uniformed interface at the management plane, A user who wishes to issue a IP Ping command or a IP Traceroute or initiate a session monitoring can also do so in the same manner regardless of the underlying protocol or technology.
Consider a scenario where an IP ping to PE B from CE A failed. Between CE A and PE B there are IEEE 802.1 bridges a,b and c. Let's assume a,b and c are using [8021Q] CFM. Upon detecting IP layer ping failure, the user may wish to "go down" to the Ethernet layer and issue the corresponding fault verification (LBM) and fault isolation (LTM) tools, using the same API.
+--------+
|Unified |
+---------------------------+OSS/NMS +---------------------------+
| +--------+ |
| Domain A Domain B |
| ---------- ---------- |
| // MPLS/IP -\\ //- MPLS/IP -\\ |
+----+ // \\ // \\ |
|SF- | SN1 SN2 SN3 SN4 SN5 SN6 +-+--+
| |+++--+ +----| +--+++ +++--+ +----+ +--+++-|SF- |
|Ingr||SF1 | | | |SF4|| || | |SF7 | | || |Egr |
| ++ +------| +----+ +-+ +-----| +-----| +-+ |
|ess ||SF2 | | SF3| |SF5 | |SF6 | |SF8 | |SF9 | |ess |
+-+-+|+--+-+ +--+-+ +-+--+ +--+-+ +--+-+ +-+--+ |+-+-+
| | | | | | | | | | | |
| ||| | ||| ||| | ||| |
| | | | | | | |
| |\\ | //| |\\ | //| |
| | \\- | -// | | \\- | -// | |
| | ------+--- | | -----+---- | |
L1 | |Ethernet OAM(CC,CV, etc.) | | |
o-------D-----------+--------+-------+----------+---------D-------o
| | | | | | | |
L2 | |IP OAM(Ping, Tracerroute, etc.) | |
o-------o-----------D--------o-------o----------D---------o-------o
| | | | | | | |
L3 Transport Independent OAM(Integrated Ethernet with IP OAM |
o-------o-----------D--------o-------o----------D---------o-------o
| | | | | | | |
| | | | | | | |
o Maintenance Endpoint(MEP)
D Maintenance Intermediary point (MIP)
Layer7- SF1 --------------------- SF6 ------- SF7-------------
Layer6------------------------F4 --------------------------------
Layer5------------ SF3-------SF5------------------------- SF9----
Layer4---SF2 ---------------------------------- SF8--------------
In Service Function Chain, the service packets are steered through a set of Service Function Nodes distributed in the network. Overlay technologies (or tunneling techniques in general) can be used to stitch these Service Function Nodes in order to form end to end path.
When the service packet enters into the network, OAM information needs to be imposed by ingress node of the network into the packet(e.g., packet header extension or TLV extension in the overlay header) and pass through the network in the same path as the service traffic and processed by a set of Service Functions that are hosted in Service Function Nodes and located in different layers at the top of layer 3.
When any Service Function Nodes or any service segment between two service nodes fails to deliver user traffic, there is a need to provide a tool that would enable users to detect such failures, and a mechanism to isolate faults.
In case of several SFs co-located in the same Service Function Node, the packet is processed by all SFs in the Service Function Node, Once the packet is successfully handled by one SF, the packet is forwarded to the next SF that is in the same Service Function Node.
When the packet leave the network, the OAM information needs to stripped out from the packet.
To provide unified view of OAM information common to different layers, different domains, different operators, these OAM information needs to gathered from various layer using different encapsulation and tunneling techniques and abstracted and provided to the management application via the unified management interface.
As indicated in [I-D.boucadair-sfc-requirments], the following OAM functions are to be supported:
Other service diagnosis and troubleshooting requirements are discussed in [I-D.boucadair-sfc-requirments].
Domain A Domain B
---------- ----------
//-MPLS/IP -\\ //-MPLS/IP -\\
// \\ // \\
/ \ / \
|| || || ||
| | | |
+---+ +----+ +----+ +----+ +----+ +----+ +----+ +---+
|CE |--| PE +------| P +----| PE +-+ PE +-----+ P +-----+ PE +--|CE |
+-+-+ +--+-+ +--+-+ +-+--+ +--+-+ +--+-+ +-+--+ +-+-+
| | | | | | | | | | | |
| ||| | ||| ||| | ||| |
| | | | | | | |
| |\\ | //| |\\ | //| |
| | \\- | -// | | \\- | -// | |
| | ------+--- | | -----+---- | |
L1 | |Ethernet OAM(CC,CV,etc) | | |
o-------D-----------+--------+-------+----------+---------D-------o
| | | | | | | |
| L2 | |IP OAM(Ping, Tracerroute, etc.) |
o-----------D--------o-------o----------D---------o-
| | | | | |
o Maintenance Endpoint(MEP)
D Maintenance Intermediary point (MIP)
Overlay network is referred to a network that is built on top of another underlying network and provides various services to tenant system. With the growth of network virtualization technology, the needs for inter-connection between various overlay technologies/ networks (e.g., VXLAN or NVGRE) in the Wide Area Network (WAN) become important since it can provide end to end connectivity.
When a packet traverses a set of overlay networks in the data path, each overlay network will comprise an overlay segment used to connect overlay nodes in the same network and these overlay segment are stitched together to form end to end data path.
When any Overlay Segment fails to deliver user traffic, there is a need to provide a tool that would enable users to detect such failures, and a mechanism to isolate faults. It may also be desirable to test the data path before mapping user traffic to the Overlay Segment.
This section provides high-level requirements to fulfill transport independent OAM in Multi-layer Environment to support various use cases discussed in the previous sections.
This memo includes no request to IANA.
TBD.
| [I.D-quinn-sfc-problem-statement] | Quinn, P., "Network Service Chaining Problem Statement", ID draft-quinn-nsc-problem-statement-03, August 2013. |
| [TIME-PS] | Wu, Q., "Problem Statement and Architecture for Transport-Independent Multiple Layer OAM", ID draft-ww-opsawg-multi-layer-oam-01, June 2014. |