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diff --git a/docs/design/specs/High-Priority-Traffic-Path.rst b/docs/design/specs/High-Priority-Traffic-Path.rst new file mode 100644 index 0000000..6243cbe --- /dev/null +++ b/docs/design/specs/High-Priority-Traffic-Path.rst @@ -0,0 +1,260 @@ +.. + This work is licensed under a Creative Commons Attribution 3.0 Unported + License. + + http://creativecommons.org/licenses/by/3.0/legalcode + +========================================== +High Priority Traffic Path +========================================== + +https://wiki.opnfv.org/display/ovsnfv/OVSFV+Requirement+-+High+Priority+Traffic+Path + +Problem description +=================== + +A network design may need to adequately accommodate multiple classes of traffic, each +class requiring different levels of service in critical network elements. + +As a concrete example, a network element managed by a service provider may be +handling voice and elastic data traffic. Voice traffic requires that the end-to-end +latency and jitter is bounded to some numerical limit (in msec) accuracy in order to ensure +sufficient quality-of-service (QoS) for the participants in the voice call. +Elastic data traffic does not impose the same demanding requirements on the network +(there will be essentially no requirement on jitter. For example, when downloading a +large file across the Internet, although the bandwidth requirements may be high there +is usually no requirement that the file arrives within a bounded time interval. + +Depending on the scheduling algorithms running on the network element, +frames belonging to the data traffic may get transmitted before frames +belonging to the voice traffic introducing unwanted latency or jitter. +Therefore, in order to ensure deterministic latency and jitter characteristics +end-to-end, each network element through which the voice traffic traverses +must ensure that voice traffic is handled deterministically. + +Hardware switches have typically been designed to ensure certain classes +of traffic can be scheduled ahead of other classes and are also +over-provisioned which further ensures deterministic behavior when +handling high priority traffic. However, software switches (which includes +virtual switches such as Open vSwitch) may require modification in order +to achieve this deterministic behavior. + +Use Cases +--------- + +1. Program classes of service + +The End User specifies a number of classes of service. Each class of service +will be represented by the value of a particular field in a frame. The class +of service determines the priority treatment which flows in the class will +receive, while maintaining a relative level of priority for other classes and +a default level of treatment for the lowest priority class of service. As +such, each class of service will be associated with a priority. The End User +will associate classes of service and priorities to ingress ports with the +expectation that frames that arrive on these ingress ports will get +scheduled following the specified priorities. + +Note: Priority treatment of the classes of service cannot cause any one of +the classes (even the default class) from being transferred at all. In other +words, a strict priority treatment would likely not be successful for serving +all classes eventually, and this is a key consideration. + +2. Forward high priority network traffic + +A remote network element sends traffic to Open vSwitch. The remote network +element, indicates the class of service to which this flow of traffic belongs +to by modifying a pre-determined but arbitrary field in the frame as specified +in Use Case 1. Some examples include the Differentiated Services Code Point +(DSCP) in an IP packet or the Priority Code Point (PCP) in an Ethernet frame. +The relative priority treatment that frames get processed by Open vSwitch can be guaranteed by the +values populated in these fields when the fields are different. If the fields +are the same, ordering is not deterministic. + +For example: Packet A is sent with a DSCP value of 0 and packet B is sent +with a value of 46; 0 has a lower priority than 46. Packet A arrives +before packet B. If Open vSwitch has been configured as such, Packet +B will be transmitted before Packet A. + +Proposed change +=============== + +TBD + +Alternatives +------------ + +TBD + +OVSDB schema impact +------------------- + +TBD + +User interface impact +--------------------- + +TBD + +Security impact +--------------- + +TBD + +Other end user impact +--------------------- + +TBD + +Performance Impact +------------------ + +TBD + +Other deployer impact +--------------------- + +TBD + +Developer impact +---------------- + +TBD + +Implementation +============== + +Assignee(s) +----------- + +Who is leading the writing of the code? Or is this a blueprint where you're +throwing it out there to see who picks it up? + +If more than one person is working on the implementation, please designate the +primary author and contact. + +Primary assignee: + <email address> + +Other contributors: + <email address> + +Work Items +---------- + +TBD + +Dependencies +============ + +TBD + +Testing +======= + +In order to test how effectively the virtual switch handles high priority traffic +types, the following scheme is suggested.:: + + +---------------------------+ Ingress Traffic Parameters + | | +-------------------------------------------+ + | | + | | Packet Size: The size of the Ethernet frames + | | + | | Tmax: RFC2544 Max. Throughput for traffic of + | PHY0 <-------+ "Packet Size" + | | + | | Total Offered Rate: The offered rate of both + | | traffic classes combined expressed as a % of + | | Tmax + | | + | | Ingress Rates are expressed as a percentage + | | of Total Offered Rate. + | | + | | Class A: + | OVS | Ethernet PCP = 0 (Background) + | (BR0) | Ingress Rate : rate_ingress_a(n) Mfps + | | + | | Class B: + | | Ethernet PCP = 7 (Highest) + | | Ingress Rate : rate_ingress_b(n) Mfps + | | + | | Egress Traffic Measurements + | | +-------------------------------------------+ + | | Class A: + | | Egress Throughput : rate_egress_a(n) Mfps + | | Egress Latency : max_lat_egrees_a(n) ms + | | Egress Jitter : max_jit_egress_a(n) ms + | PHY1 +-------> + | | Class B: + | | Egress Throughput : rate_egress_b(n) Mfps + | | Egress Latency : max_lat_egrees_b(n) ms + +---------------------------+ Egress Jitter : max_jit_egress_b(n) ms + + +Open vSwitch is configured to forward traffic between two ports agnostic to the +traffic type. For example, using the following command: + +ovs-ofctl add-flow br0 in_port=0,actions=output:1 + +The test will be carried out with the functionality to enable high-priority +traffic enabled and disabled in order to guage the change in performance for +both cases. + +Two classes of traffic will be generated by a traffic generator. In the example +above, the classes are differentiated using the Ethernet PCP field. However, +another means for differentiating traffic could be used, depending the +prioritization scheme that is developed. + +Tests should be performed for each combination of: + +* Packet Sizes in (64, 512) +* Total Offered Rate in (80, 120, 150) +* rate_ingress_b(n) / rate_ingress_a(n) in (0.1, 0.2, 0.5) + +For each set, the following metrics should be collected for each traffic +class over a specified time period: + +Egress Throughput (Mfps) +Maximum Egress Latency (ms) +Maximum Egress Jitter (ms) + +Documentation Impact +==================== + +TBD + +References +========== + +Please add any useful references here. You are not required to have any +reference. Moreover, this specification should still make sense when your +references are unavailable. Examples of what you could include are: + +* Links to mailing list or IRC discussions + +- http://lists.opnfv.org/pipermail/opnfv-tech-discuss/2015-December/007193.html +- http://ircbot.wl.linuxfoundation.org/meetings/opnfv-ovsnfv/2016/opnfv-ovsnfv.2016-03-07-13.01.html + +* Links to relevant research, if appropriate + +- https://wiki.opnfv.org/download/attachments/5046510/qos_mechanisms.pdf?version=1&modificationDate=1459187636000&api=v2 + +* Related specifications as appropriate + +* Anything else you feel it is worthwhile to refer to + + +History +======= + +Optional section intended to be used each time the spec +is updated to describe new design, API or any database schema +updated. Useful to let reader understand what's happened along the +time. + +.. list-table:: Revisions + :header-rows: 1 + + * - Release Name + - Description + * - Colorado + - Introduced diff --git a/docs/design/specs/template.rst b/docs/design/specs/template.rst new file mode 100644 index 0000000..cc5dfd8 --- /dev/null +++ b/docs/design/specs/template.rst @@ -0,0 +1,272 @@ +.. + This work is licensed under a Creative Commons Attribution 3.0 Unported + License. + + http://creativecommons.org/licenses/by/3.0/legalcode + +========================================== +Example Spec - The title of your blueprint +========================================== + +Include the URL of OPNFV wiki page description: + +https://wiki.opnfv.org/display/ovsnfv/OVSFV+Requirement+-+Example + +Introduction paragraph -- why are we doing anything? A single paragraph of +prose that operators can understand. The title and this first paragraph +should be used as the subject line and body of the commit message +respectively. + +Some notes about the process: + +* The aim of this document is first to define the problem we need to solve, + and second agree the overall approach to solve that problem. + +* This is not intended to be extensive documentation for a new feature. + +* You should aim to get your spec approved before writing your code. + While you are free to write prototypes and code before getting your spec + approved, its possible that the outcome of the spec review process leads + you towards a fundamentally different solution than you first envisaged. + +* But, API changes are held to a much higher level of scrutiny. + As soon as an API change merges, we must assume it could be in production + somewhere, and as such, we then need to support that API change forever. + To avoid getting that wrong, we do want lots of details about API changes + upfront. + +Some notes about using this template: + +* Your spec should be in ReSTructured text, like this template. + +* Please wrap text at 79 columns. + +* Please do not delete any of the sections in this template. If you have + nothing to say for a whole section, just write: None + +* For help with syntax, see http://sphinx-doc.org/rest.html + +* To test out your formatting, build the docs using sphinx + +* If you would like to provide a diagram with your spec, ascii diagrams are + required. http://asciiflow.com/ is a very nice tool to assist with making + ascii diagrams. The reason for this is that the tool used to review specs is + based purely on plain text. Plain text will allow review to proceed without + having to look at additional files which can not be viewed in gerrit. It + will also allow inline feedback on the diagram itself. + +Problem description +=================== + +A detailed description of the problem. What problem is this blueprint +addressing? + +Use Cases +--------- + +What use cases does this address? What impact on actors does this change have? +Ensure you are clear about the actors in each use case: Developer, End User, +Deployer etc. + +Proposed change +=============== + +Here is where you cover the change you propose to make in detail. How do you +propose to solve this problem? + +If this is one part of a larger effort make it clear where this piece ends. In +other words, what's the scope of this effort? + +At this point, if you would like to just get feedback on the problem and +proposed change, you can stop here and post this for review to get +preliminary feedback. If so please say: +Posting to get preliminary feedback on the scope of this spec. + +Alternatives +------------ + +What other ways could we do this thing? Why aren't we using those? This doesn't +have to be a full literature review, but it should demonstrate that thought has +been put into why the proposed solution is an appropriate one. + +OVSDB schema impact +------------------- + +Changes which require modifications to the data model often have a wider impact +on the system. The community often has strong opinions on how the data model +should be evolved, from both a functional and performance perspective. It is +therefore important to capture and gain agreement as early as possible on any +proposed changes to the data model. + +Questions which need to be addressed by this section include: + +* What new data objects and/or database schema changes is this going to + require? + +User interface impact +--------------------- + +Each user interface that is either added, changed or removed should have the +following: + +* Specification for the user interface + +* Example use case including typical examples for both data supplied + by the caller and the response + +Security impact +--------------- + +Describe any potential security impact on the system. Some of the items to +consider include: + +* Does this change touch sensitive data such as tokens, keys, or user data? + +* Does this change alter the interface in a way that may impact security, such as + a new way to access sensitive information? + +* Does this change involve cryptography or hashing? + +* Does this change require the use of sudo or any elevated privileges? + +* Does this change involve using or parsing user-provided data? This could + be directly at the API level or indirectly such as changes to a cache layer. + +* Can this change enable a resource exhaustion attack, such as allowing a + single interaction to consume significant server resources? + +Other end user impact +--------------------- + +Aside from the user interfaces, are there other ways a user will interact with this +feature? + +Performance Impact +------------------ + +Describe any potential performance impact on the system, for example +how often will new code be called, and is there a major change to the calling +pattern of existing code. + +Examples of things to consider here include: + +* Will the change include any locking, and if so what considerations are there + on holding the lock? + +Other deployer impact +--------------------- + +Discuss things that will affect how you deploy and configure Open vSwitch +that have not already been mentioned, such as: + +* What config options are being added? Should they be more generic than + proposed? Are the default values ones which will work well in + real deployments? + +* Is this a change that takes immediate effect after its merged, or is it + something that has to be explicitly enabled? + +* If this change is a new binary, how would it be deployed? + +* Please state anything that those doing continuous deployment, or those + upgrading from the previous release, need to be aware of. Also describe + any plans to deprecate configuration values or features. + +Developer impact +---------------- + +Discuss things that will affect other developers working on Open vSwitch, +such as: + +Implementation +============== + +Assignee(s) +----------- + +Who is leading the writing of the code? Or is this a blueprint where you're +throwing it out there to see who picks it up? + +If more than one person is working on the implementation, please designate the +primary author and contact. + +Primary assignee: + <email address> + +Other contributors: + <email address> + +Work Items +---------- + +Work items or tasks -- break the feature up into the things that need to be +done to implement it. Those parts might end up being done by different people, +but we're mostly trying to understand the timeline for implementation. + + +Dependencies +============ + +* If this requires functionality of another project that is not currently used + document that fact. + +* Does this feature require any new library dependencies or code otherwise not + included in Open vSwitch? Or does it depend on a specific version of library? + + +Testing +======= + +Please discuss the important scenarios needed to test here, as well as +specific edge cases we should be ensuring work correctly. For each +scenario please specify if this requires specialized hardware. + +Please discuss how the change will be tested: Open vSwitch unit tests, VSPERF +performance tests, Yardstick tests, etc. + +Is this untestable in gate given current limitations (specific hardware / +software configurations available)? If so, are there mitigation plans (3rd +party testing, gate enhancements, etc). + + +Documentation Impact +==================== + +Which audiences are affected most by this change, and which documentation +should be updated because of this change? Don't +repeat details discussed above, but reference them here in the context of +documentation for multiple audiences. If a config option +changes or is deprecated, note here that the documentation needs to be updated +to reflect this specification's change. + +References +========== + +Please add any useful references here. You are not required to have any +reference. Moreover, this specification should still make sense when your +references are unavailable. Examples of what you could include are: + +* Links to mailing list or IRC discussions + +* Links to relevant research, if appropriate + +* Related specifications as appropriate + +* Anything else you feel it is worthwhile to refer to + + +History +======= + +Optional section intended to be used each time the spec +is updated to describe new design, API or any database schema +updated. Useful to let reader understand what's happened along the +time. + +.. list-table:: Revisions + :header-rows: 1 + + * - Release Name + - Description + * - 2.x + - Introduced |