Hi, again: Regarding Issue of OAM information Gathering from Service Function described in section 4.6, “ When the service packets is steered through a set of service nodes distributed in the network, each service node work at different layers above layer 3 and may have several SFs collocated with itself. When OAM mechanism is applied, it is necessary to allow OAM packet exchanged between these service nodes or service function at different layers. when Service function involved in the SFC doesn't support OAM capability(e.g., SF is SFC-unaware service function), Service node should be responsible for monitor and diagnose the Service function and check service availability to these service function. It is more desirable to allow service function register to service node. Either service function report status to service node or service node perform live check to these service function.
In addition, service functions usually don't have Layer 2-3 switching/ routing capability and therefore are not aware of any OAM function at layer 2-3. Also when there is no OAM functions at service layers at top of layer 3, it is hard to identify layer that can be used to gather OAM information when it comes to a fault situation or degradation of performance. For example, when a data packet is transmitted from one service function to another service function and the data packet may be lost between two service functions or discarded by either of service function, assume two service functions are embedded in two different service nodes, how to detect the fault between them and how to isolate problem to that layer? ” As you said, The above text can be presented as an example to illustrate a problem not a problem per section. I agree it is too much specific to SFC case. I am expecting to cover overlay OAM case as well. In the overlay OAM, 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. I will see how to abstract common issue from both SFC case and Overlay OAM case. Yes, we really need a use case draft to discuss what these use case look like and provide high-level requirements To support various use cases. Regards! -Qin 发件人: [email protected]<mailto:[email protected]> [mailto:[email protected]] 发送时间: 2014年6月24日 22:13 收件人: Qin Wu 主题: RE: Unified oam BOF proposal request in IETF 90 Hi Qin, Please find attached a first set of comments. Cheers, Med
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