Internet DRAFT - draft-song-opsawg-dnp4iq
draft-song-opsawg-dnp4iq
OPSAWG H. Song, Ed.
Internet-Draft J. Gong
Intended status: Informational Huawei Technologies Co., Ltd
Expires: December 21, 2017 June 19, 2017
Requirements for Interactive Query with Dynamic Network Probes
draft-song-opsawg-dnp4iq-01
Abstract
This document discusses the motivation and requirements for
supporting interactive network queries and data collection through a
mechanism called Dynamic Network Probes (DNP). Network applications
and OAM have various data requirements from the data plane. The
unpredictable and interactive nature of the query for network data
analytics asks for dynamic and on-demand data collection
capabilities. As user programmable and configurable data plane is
becoming a reality, it can be extended to support interactive query
through DNPs. DNP supports node, path, and flow-based data
preprocessing and collection. For example, in-situ OAM (iOAM) with
user-defined flow-based data collection can be programmed and
configured through DNP. DNPs serve as a building block of an
integrated network data telemetry and analytics platform which
involves the network data plane as an active component for user-
defined data collection and preparation.
Status of This Memo
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This Internet-Draft will expire on December 21, 2017.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Motivation for Interactive Query with DNP . . . . . . . . . . 3
3. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1. In-Situ OAM with User Defined Data Collection . . . . . . 6
3.2. DDoS Detection . . . . . . . . . . . . . . . . . . . . . 6
3.3. Elephant Flow Identification . . . . . . . . . . . . . . 6
3.4. Network Congestion Monitoring . . . . . . . . . . . . . . 7
4. Enabling Technologies for DNP . . . . . . . . . . . . . . . . 7
5. Dynamic Network Probes . . . . . . . . . . . . . . . . . . . 9
5.1. DNP Types . . . . . . . . . . . . . . . . . . . . . . . . 11
5.1.1. Node Based . . . . . . . . . . . . . . . . . . . . . 11
5.1.2. Path Based . . . . . . . . . . . . . . . . . . . . . 12
5.1.3. Flow Based . . . . . . . . . . . . . . . . . . . . . 13
6. Interactive Query Architecture . . . . . . . . . . . . . . . 13
7. Requirements for IQ with DNP . . . . . . . . . . . . . . . . 14
8. Considerations for IQ with DNP . . . . . . . . . . . . . . . 15
8.1. Technical Challenges . . . . . . . . . . . . . . . . . . 15
8.2. Standard Consideration . . . . . . . . . . . . . . . . . 16
9. Security Considerations . . . . . . . . . . . . . . . . . . . 16
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16
11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 16
12. Informative References . . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 18
1. Introduction
Network service provider's pain points are often due to the lack of
network visibility. For example, network congestion collapse could
be avoided in many cases if it were known exactly when and where
congestion is happening or even better, if it could be precisely
predicted well before any impact is made; sophisticated network
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attacks could be prevented through stateful and distributed network
behavior analysis.
In order to provide better application-centric services, user flows
and their interaction with networks need to be tracked and
understood.
The emerging trend of network automation aims to keep people out of
the OAM and control loop to the greatest extent for automated health
prediction, fault recovery, demand planning, network optimization,
and intrusion prevention, based on big data analytics and machine
learning technologies.
These applications need all kinds of network data, either passing
through networks or generated by network devices. For such
applications to be effective, the data of interest needs to be
retrieved in real time and on demand in an interactive and iterative
fashion. Continuous streaming data is often required. Therefore, it
is valuable to build a unified and general-purpose network telemetry
and analytics platform with integrated data plane support to provide
the complete network visibility at the minimum data bandwidth. This
is in contrast to the piecemeal solutions which only deal with one
single problem at a time.
We propose two ideas to enable such a vision. First, we devise the
Dynamic Network Probe (DNP) as a flexible and dynamic means for data
plane data collection and preprocessing, which can prepare data for
data analytics applications (Note that most of the DNPs are so common
that it makes perfect sense to predefine the standard data models for
them such that the conventional data plane devices can still be
designed and configured to support them). Second, we show the
possibility to build a universal network telemetry and analytics
platform with an Interactive Query (IQ) interface to the data plane
which can compile and deploy DNPs at runtime (or configure DNPs
dynamically based on standard data models). In such a system,
network devices play an integral and active role. We show a layered
architecture based on a programmable data plane which supports
interactive queries on network data.
In this document We discuss requirements, use cases, working items,
and challenges, with the hope to trigger community interests to
develop corresponding technologies and standards.
2. Motivation for Interactive Query with DNP
Network applications, such as traffic engineering, network security,
network health monitoring, trouble shooting, and fault diagnosis,
require different types of data collection. The data are either
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normal traffic packets that are filtered, sampled, or digested, or
metadata generated by network devices to convey network states and
status. Broadly speaking, there are three types of data to be
collected from network data plane: path-based, flow-based, and node-
based. Path-based data is usually collected through dedicated
probing packets (e.g., ping and traceroute); Flow-based data
collection designates user flows to carry data of interest (e.g., in-
situ OAM [I-D.brockners-inband-oam-requirements]); Node-based data is
directly retrieved from selected network devices (e.g., ipfix
[RFC7011]).
Some data is considered atomic or primitive. For example, a packet's
arrival timestamp at a particular node cannot be further
disintegrated. The atomic data can be used to generate synthetic and
combinational data. For example, a packet's latency on a path can be
calculated through the packet timestamps at the end of the path.
Depending on the application, either data may be required. If the
application's real intent is the latter, it makes sense to directly
provide such data to reduce the data transfer bandwidth, at the cost
of a small processing overhead in the data plane and/or control
plane. Some synthetic and combinational data can be acquired through
multiple data types, but the most efficient way is preferred for a
specific network. For the similar purpose of data traffic reduction,
applications may not need the "raw" data all the time. Instead, they
may want data that is sampled and filtered, or only when some
predefined condition is met. Anyway, application's requirements on
data are diversified and unpredictable. Applications may need some
data which is not readily available at the time of request.
Some applications are interactive or iterative. After analyzing the
initial data, these applications may quickly shift interests to new
data or need to keep refining the data to be collected based on
previous observations (e.g., an elephant flow detector continues to
narrow down the flow granularity and gather statistics). The control
loop algorithms of these applications continuously interact with the
data plane and modify the data source and content in a highly dynamic
manner.
Ideally, to support all potential applications, we need full
visibility to know any states anytime anywhere in the entire network
data plane. In reality, this is extremely difficult if not
impossible. A strawman option is to mirror all the raw traffic to
servers where data analytics engine is running. This brute-force
method requires to double the device port count and the traffic
bandwidth, and poses enormous computing and storage cost. As a
tradeoff, Test Access Port (TAP) or Switch Port Analyzer (SPAN) is
used to selectively mirror only a portion of the overall traffic.
Network Packet Broker (NPB) is deployed along with TAP or SPAN to
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process and distribute the raw data to various data analytics tools.
There are some other solutions (e.g., sflow [RFC3176] and ipfix
[RFC7011]) which can provide sampled and digested packet data and
some traffic statistics. Meanwhile, network devices also generate
various log files to record miscellaneous events in the system.
When aggregating all these solutions together, we can gain a
relatively comprehensive view of the network. However, the main
problem is the lack of a unified platform to deal with the general
network telemetry problem and the highly dynamic and unpredictable
data requirements. Moreover, each piecemeal solution inevitably
loses information due to data plane resource limitations which makes
the data analytical results suboptimal.
Trying to design an omnipotent system to support all possible runtime
data requests is also unviable because the resources required are
prohibitive (e.g., even a simple counter per flow is impossible in
practice). An alternative is to reprogram or reconfigure the data
plane device whenever an unsupported data request appears. This is
possible thanks to the recently available programmable chips and the
trend to open the programmability to service providers.
Unfortunately, the static programming approach cannot meet the real
time requirements due to the latency incurred by the programming and
compiling process. The reprogramming process also risks breaking the
normal operation of network devices.
Then a viable solution left to us is: whenever applications request
data which is yet unavailable in the data plane, the data plane can
be configured in real time to return the requested data. That is, we
do not attempt to make the network data plane provide all data all
the time. Instead, we only need to ensure that any application can
acquire necessary data instantly whenever it actually needs it. This
data-on-demand model can support effectively omni network visibility,
Note that data collection is meant to be passive and should not
change the network forwarding behavior. The active forwarding
behavior modification is out of the scope of this draft.
Data can be customized dynamically and polled or pushed based on
application's request. Moderate data preprocessing and preparation
by data plane devices may be needed. Such "in-network" processing
capability can be realized through DNP.
3. Use Cases
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3.1. In-Situ OAM with User Defined Data Collection
In-situ OAM [I-D.brockners-inband-oam-requirements] collects data on
user traffic's forwarding path. From the control and management
plane point of view, each data collection task is a query from the
OAM application. In case the data collection function is not hard
coded in network devices, DNP can be dynamically deployed to support
the in-situ OAM.
While the current in-situ OAM drafts only concern the data plane
packet format and use cases, the applications still need a control
and management interface to dynamically enable and disable the in-
situ OAM functions, which involves the tasks such as choosing the
source and destination nodes on the path, the flow to carry the OAM
data, and the way to handle the data at the path end. These
configuration tasks can be done through DNP.
More importantly, in-situ OAM [I-D.brockners-inband-oam-data] may
collect user-defined data which are not available at device
configuration time. In this case, the data can be defined by DNP.
DNP can further help to preproess the data before sending the data to
the subscribing application. This can help to reduce the OAM header
size and the application's work load.
3.2. DDoS Detection
In a data center the security application wants to find the servers
under possible DDoS attack with a suspiciously large number of
connections. It can deploy DNPs on all the portal switches to
periodically report the number of unique flows targeting the set of
the protected servers. Once the queried data are collected, it is
easy to aggregate the data to find the potential DDoS attacks.
3.3. Elephant Flow Identification
An application wants to query the network-wide top-n flows. Various
algorithms have been developed at each network device to detect local
elephant flows. These algorithms can be defined as DNPs. A set of
network devices are chosen to deploy the DNPs so each will
periodically report the local elephant flows. The application will
aggregate the data to find the global elephant flows. The elephant
flow identification can be an interactive process. The application
may need to adjust the existing DNPs or deploy new DNPs to refine the
detection results.
In some cases, the local resource in a network device is not
sufficient to monitor the entire flow space. We can partition the
flow space and configure one network device in a group with a DNP to
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track only a subset of flows, given the assumption that each device
can see all the flows.
3.4. Network Congestion Monitoring
Network congestion is reflected by packet drops at routers or
switches. While it is easy to get the packet drop count at each
network device, it is difficult to gain insights on the victims, hot
spots, and lossy paths. We can deploy DNPs to acquire such
information. DNPs are deployed on all network devices to collect the
detailed information about the dropped packet such as its signature
and the port it is dropped. Based on the collected data, the
application can generate the report on the top victims, hot spots,
and the most lossy paths.
4. Enabling Technologies for DNP
Network data plane is becoming user programmable. It means the
network operators are in control of customizing the network device's
function and forwarding behavior. Figure 1 shows the industry trend,
which shapes new forms of network devices and inspires innovative
ways to use them.
+-------+ +-------+ +-------+
| | | | | |
| NOS | | APP | | APP |
| | | | | |
+-------+ +-------+ +-------+
^ ^ ^
| | | runtime
decouple | ------> | config time ---> | interactive
| | programming | programming
V V V
+----------+ +-------------+ +-------------+
| box with | | box with | | box with |
| fixed | | programmable| | interactive |
| function | | chip | | programmable|
| ASIC | | | | chip |
+----------+ +-------------+ +-------------+
Figure 1: Towards User Programmable Data Plane
The first trend is led by the OCP networking project, which advocates
the decoupling of the network operating system and the network device
hardware. A common Switch Abstract Interface (SAI) allows
applications to run on heterogeneous substrate devices. However,
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such devices are built with fixed function ASICs, which provide
limited flexibility for application customization.
The second trend is built upon the first one yet makes a big leap.
Chip and device vendors are working on opening the programmability of
the NPU, CPU, and FPGA-based network devices to network operators.
Most recently, programmable ASIC has been proven feasible. High
level languages such as P4 [DOI_10.1145_2656877.2656890] have been
developed to make the network device programming easy and fast. Now
a network device can be programmed into different functioning boxes
depending on the program installed.
However, such programming process is considered static. Even a minor
modification to the existing application requires to recompile the
updated source code and reinstall the application. This incurs long
deployment latency and may also temporarily break the normal data
plane operation.
User programmable data plane should be stretched further to support
runtime interactive programming in order to extend its scope of
usability, as proposed in POF [DOI_10.1145_2491185.2491190] Dynamic
application requirements cannot be foreseen at design time, and
runtime data plane modifications are required to be done in real time
(for agile control loop) and on demand (to meet data plane resource
constraints). Meanwhile, the data plane devices are capable of doing
more complex things such as stateful processing without always
resorting to a controller for state tracking. This allows network
devices to offload a significant portion of the data processing task
and only hand off the preprocessed data to the data-requesting
applications.
We can still use static programming with high level languages such as
P4 to define the main data plane processing and forwarding function.
But at runtime, whenever an application requires to make some
modification to the data plane, we deploy the incremental
modification directly through the runtime control channel. The key
to make this dynamic and interactive programming work is to maintain
a unified interface to devices for both configuration and runtime
control, because both programming paths share the same data plane
abstraction and use the same back-end adapting and mapping method.
NPU-based network devices and virtual network devices running on CPU/
GPU can easily support the static and runtime in-service data plane
programmability. ASIC and FPGA-based network devices may be
difficult to support runtime programming and update natively.
However, for telemetry data collection tasks, the device local
controller (or even remote servers) can be used in conjunction with
the forwarding chip to complete the data preprocessing and
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preparation. After all, applications do not care how the data probes
are implemented as long as the same API is maintained.
5. Dynamic Network Probes
Network probes are passive monitors which are installed at specific
forwarding data path locations to process and collect specific data.
DNPs are dynamically deployed and revoked probes by applications at
runtime. The customizable DNPs can collect simple statistics or
conduct more complex data preprocessing. Since DNPs may require
actively modifying the existing data path pipeline beyond simple flow
entry manipulation, these operations need to be done through
interactive programming process. When a DNP is revoked, the involved
shared resources are automatically recycled and returned back to the
global resource pool.
DNPs can be deployed at various data path locations including port,
queue, buffer, table, and table entry. When the data plane
programmability is extended to cover other components (e.g., CPU
load, fan speed, GPS coordination, etc.), DNPs can be deployed to
collect corresponding data as well. A few data plane objectives can
be composed to form probes. These objectives are counter, meter,
timer, timestamp, register, and table. Combining these with the
packet filter through flow table entry configuration, one can easily
monitor and catch arbitrary states on the data plane.
In practice, DNP can be considered a virtual concept. Its deployment
can be done through either configuration or programming. For less
flexible platforms, probes can be predefined but support on-demand
runtime activation. Complex DNP functions can also be achieved
through collaboration between data plane and control plane. Most
common DNPs can be modeled for easy implementation. The goal is to
make DNP implementation transparent to upper layer applications.
The simplest probe is just a counter. The counter can be configured
to count bytes or packets and the counting can be conditional. The
more complex probes can be considered as Finite State Machines (FSM)
which are configured to capture specific events. FSMs essentially
preprocess the raw stream data and only report the necessary data to
subscribing applications.
Applications can use poll mode or push mode to access probes and
collect data. The normal counter probes are often accessed via poll
mode. Applications decide what time and how often the counter value
is read. On the other hand, the complex FSM probes are usually
accessed in push mode. When the target event is triggered, a report
is generated and pushed to the application.
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Timer is a special global resource. A timer can be configured to
link to some action. When the time is up, the corresponding action
is executed. For example, to get notification when a port load
exceeds some threshold, we can set a timer with a fixed time-out
interval, and link the timer to an action which reads the counter and
generates the report packet if the condition is triggered. This way,
the application avoids the need to keep polling statistics from the
data plane.
With the use of global registers and state tables, more complex FSM
probes can be implemented. For example, to monitor the half-open TCP
connections, for each SYN request, we store the flow signature to a
state table. Then for each ACK packet, the state table is checked
and the matched entry is removed. The state table can be
periodically polled to acquire the list of half-open connections.
The application can also choose to only retrieve the counter of half-
open connections. When the counter exceeds some threshold, further
measures can be taken to examine if a SYN flood attack is going on.
Registers can be considered mini state tables which are good to track
a single flow and a few state transitions. For example, to get the
duration of a particular flow, when the flow is established, the
state and the timestamp are recorded in a register; when the flow is
torn down, the flow duration can be calculated with the old timestamp
and the new timestamp. In another example, we want to monitor a
queue by setting a low water mark and a high water mark for the fill
level. Every time when an enqueue or a dequeue event happens, the
queue depth is compared with the marks and a report packet is
generated when a mark is crossed.
Some probes are essentially packet filters which are used to filter
out a portion of the traffic and mirrored the traffic to the
application or some other target port for further processing. There
are two ways to implement a packet filter: use a flow table that
matches on the filtering criteria and specify the associated action;
or directly make a decision in the action. An example of the former
case is to filter all packets with a particular source IP address.
An example of the latter case is to filter all TCP FIN packets at the
edge. Although we can always use a flow table to filter traffic,
sometimes it is more efficient and convenient to directly work on the
action. As being programmed by the application, the filtered traffic
can be further processed before being sent. Two most common
processes are digest and sample, both aiming to reduce the quantity
of raw data. The digest process prunes the unnecessary data from the
original packet and only packs the useful information in the digest
packet. The sample process picks a subset of filtered traffic to
send based on some predefined sampling criteria. The two processes
can be used jointly to maximize the data reduction effect.
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An application may need to install multiple DNPs in one device or
across multiple devices to finish one data analytical task. For
example, to measure the latency of any link in a network. We install
a DNP on the source node to generate probe packets with timestamp.
We install another DNP at the sink node to capture the probe packets
and report both the source timestamp and the sink timestamp to the
application for link latency calculation. The probe packets are also
dropped by the sink DNP. The source DNP can be configured to
generate probe packets at any rate. It can also generate just one
probe packet per application request.
Using the similar idea, we can deploy DNPs to measure the end-to-end
flow latency or trace exact flow paths. In this case, the DNPs can
be deployed to enable the corresponding iOAM in-situ data collection
service. At the path end, the DNP calculates the desired output
based on the collected data.
Applications could have many such custom data requests. Each request
lasts various time and consumes various network resources. Dynamic
probe configuration or programming is not only efficient but also
necessary. In summary, DNP is a versatile tool to prepare and
generate just-in-time telemetry data for data analytical
applications.
5.1. DNP Types
DNP can be roughly grouped into three types: node-based, path-based,
and flow-based. Following is the list of DNPs. Some are atomic and
the others can be derived from the atomic ones. Note that the list
is by no means comprehensive. The list does not include the device
state and status data that is steadily available. Depending on the
device capability, more complex DNPs can be implemented.
Applications can subscribe data from multiple DNPs to meet their
needs. The flow-based data can be directly provided by iOAM data or
derived from iOAM data.
5.1.1. Node Based
o Streaming Packets
* Filter flow by user-defined flow definition.
* Sample with user-defined sample rate. The sample can be based
on interval or probability.
* Generate packet digest with user defined format.
o Flow Counter
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* Associate poll-mode counter for user-defined flow.
* Associate push-mode counter for user-defined flow. The counter
value is pushed at user-defined threshold or interval.
o Flow Meter
* Associate poll-mode meter for user-defined flow.
* Associate push-mode meter for user-defined flow. The meter
value is pushed at user-defined threshold or interval.
o Queue
* Queue depth for designated queue is polled or pushed at user-
defined threshold or interval.
* Designated buffer depth is polled or pushed at user-defined
threshold or interval.
o Time
* Time gap between user-defined flow packets is polled or pushed
in streaming data or at user-defined threshold.
* Arrival/Departure/Sojourn time of user-defined flow packets is
polled or pushed streaming data or at user defined threshold.
o Statistics
* Number of active flows, elephant flows, and mice flows.
5.1.2. Path Based
o Number of active flows per node on the path.
o Path latency.
o Round trip time of the path.
o Node ID and ingress/egress port of the path.
o Hop count of the path.
o Buffer/queue depth of the nodes on the path.
o Workload of the nodes on the path.
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5.1.3. Flow Based
o Flow Latency: Latency at each hop or cumulative E2E latency for
user-defined flow.
o Flow Jitter: Jitter at each hop or on the entire path for user-
defined flow.
o Flow Bandwidth: Bandwidth at each hop or the bottleneck bandwidth
on the entire path for user-defined flow.
o Flow Path Trace: Port and Node ID, and other data of the path for
user-defined flow.
o Proof of Transit (PoT) for particular set of nodes.
6. Interactive Query Architecture
In the past, network data analytics is considered a separate function
from networks. They consume raw data extracted from networks through
piecemeal protocols and interfaces. With the advent of user
programmable data plane, we expect a paradigm shift that makes the
data plane be an active component of the data analytics solution.
The programmable in-network data preprocessing is efficient and
flexible to offload some light-weight data processing through dynamic
data plane programming or configuration. A universal network data
analytics platform built on top of this enables a tight and agile
network control and OAM feedback loop.
While DNP is a passive data plane data collection mechanism, we need
to provide a query interface for applications to use the DNPs for
data analytics. A proposed dynamic networking data analytical system
architecture is illustrated in Figure 2. An application translates
its data requirements into some dynamic transactional queries. The
queries are then compiled into a set of DNPs targeting a subset of
data plane devices (Note that in a less flexible target with
predefined models, DNPs are configured). After the DNPs are
deployed, each DNP conducts in-network data preprocessing and feeds
the preprocessed data to the collector. The collector finishes the
data post-processing and presents the results to the data-requesting
application.
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+------------------------------------+
|network data analytics applications |
+----------- ------------------------+
^
V
+------------------------------------+
|dynamic and interactive query |
+------------------------------------+
^ |
| V
+---------------+ +------------------+
|post process | |DNP compile/config|
+---------------+ +------------------+
^ |
| V
+---------------+ +---------------+
|data collection| |DNP deployment |
+---------------+ +---------------+
^ ^ ^ | | |
| | | V V V
+------------------------------------+
|network data plane |
|(in-network data preprocessing) |
+------------------------------------+
Figure 2: Architecture of IQ with DNP
A query can be either continuous or one-shot. The continuous query
may require the application to refine the existing DNPs or deploy new
DNPs. When an application revokes its queries, the idle DNP resource
is released. Since one DNP may be subscribed by multiple
applications, the runtime system needs to keep track of the active
DNPs.
7. Requirements for IQ with DNP
This section lists the requirements for interactive query with DNP:
o Applications should conduct interactive query through a standard
interface (i.e., API). The system is responsible to compile the
IQ into DNPs and deploy the DNPs to the corresponding network
nodes.
o DNPs can be deployed through some standard south bound interface
and protocols such as gRPC, NETCONF, etc.
o The interactive query should not modify the forwarding behavior.
The API should provide the necessary isolation.
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o The deployed DNP should not lower the forwarding performance of
the data plane devices. If the DNP would affect the forwarding
performance, the query should be denied.
o The system should support multiple parallel queries from multiple
applications.
o One application can deploy different DNPs to a set of network
nodes and these DNPs work jointly to finish a function.
o DNP may be revoked and preempted by the controller due to resource
conflict and application priority.
8. Considerations for IQ with DNP
8.1. Technical Challenges
Some technical issues need to be addressed to realize interactive
query with DNP on general network data plane:
o Allowing applications to modify the data plane has security and
safety risks (e.g., DoS attack). The counter measure is to supply
a standard and safe API to segregate applications from the runtime
system and provide applications limited accessibility to the data
plane. Each API can be easily compiled and mapped to standard
DNPs. An SQL-like query language which adapts to the stream
processing system might be feasible for the applications.
o When multiple correlated DNPs are deployed across multiple network
devices or function blocks, or when multiple applications request
the same DNPs, the deployment consistency needs to be guaranteed
for correctness. This requires a robust runtime compiling and
management system which keeps track of the subscription to DNPs
and controls the DNP execution time and order.
o The performance impact of DNPs must be evaluated before deployment
to avoid unintentionally reducing the forwarding throughput.
Fortunately, the resource consumption and performance impact of
standard DNPs can be accurately profiled in advance. A device is
usually over provisioned and is capable of absorbing extra
functions up to a limit. Moreover, programmable data plane allows
users to tailor their forwarding application to the bare bones so
more resources can be reserved for probes. The runtime system
needs to evaluate the resulting throughput performance before
committing a DNP. If it is unacceptable, either some old DNPs
need to be revoked or the new request must be denied.
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o While DNP is relatively easy to be implemented in software-based
platform (e.g., NPU and CPU), it is harder in ASIC-based
programmable chips. Architectural and algorithmic innovations are
needed to support a more flexible pipeline which allows new
pipeline stage, new tables, and new custom actions to be inserted
at runtime through hitless in-service updates. An architecture
with shared memory and flexible processor cores might be viable to
meet these requirements. Alternatively, DNPs can be implemented
using an "out-of-band" fashion. That is, the slow path processor
is engaged in conjunction with the forwarding chip to complete the
DNP function.
8.2. Standard Consideration
The query API can be potentially standardized. The actually DNP
deployment interface may consider to reuse or extend the IETF
standards and drafts such as gRPC [I-D.talwar-rtgwg-grpc-use-cases]
and NETCONF [RFC6241]. We may also define standard telemetry YANG
[RFC6020] models for common DNPs so these DNPs can be used in a
configurable way.
9. Security Considerations
Allowing applications to modify the data plane has security and
safety risks (e.g., DoS attack). The counter measure is to supply
standard and safe API to segregate applications from the runtime
system and provide applications limited accessibility to the data
plane. Each API can be easily compiled and mapped to standard DNPs.
An SQL-like query language which adapts to the stream processing
system might be feasible and secure for the applications.
10. IANA Considerations
This memo includes no request to IANA.
11. Acknowledgments
The authors would like to thank Frank Brockners, Carlos Pignataro,
Tom Tofigh, Bert Wijnen, Stewart Bryant, James Guichard, and Tianran
Zhou for the valuable comments and advice.
12. Informative References
[DOI_10.1145_2491185.2491190]
Song, H., "Protocol-oblivious forwarding", Proceedings of
the second ACM SIGCOMM workshop on Hot topics in software
defined networking - HotSDN '13 ,
DOI 10.1145/2491185.2491190, 2013.
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[DOI_10.1145_2656877.2656890]
Bosshart, P., Varghese, G., Walker, D., Daly, D., Gibb,
G., Izzard, M., McKeown, N., Rexford, J., Schlesinger, C.,
Talayco, D., and A. Vahdat, "P4", ACM SIGCOMM Computer
Communication Review Vol. 44, pp. 87-95,
DOI 10.1145/2656877.2656890, July 2014.
[I-D.brockners-inband-oam-data]
Brockners, F., Bhandari, S., Pignataro, C., Gredler, H.,
Leddy, J., Youell, S., Mizrahi, T., Mozes, D., Lapukhov,
P., and R. <>, "Data Formats for In-situ OAM", draft-
brockners-inband-oam-data-02 (work in progress), October
2016.
[I-D.brockners-inband-oam-requirements]
Brockners, F., Bhandari, S., Dara, S., Pignataro, C.,
Gredler, H., Leddy, J., Youell, S., Mozes, D., Mizrahi,
T., <>, P., and r. remy@barefootnetworks.com,
"Requirements for In-situ OAM", draft-brockners-inband-
oam-requirements-02 (work in progress), October 2016.
[I-D.talwar-rtgwg-grpc-use-cases]
Specification, g., Kolhe, J., Shaikh, A., and J. George,
"Use cases for gRPC in network management", draft-talwar-
rtgwg-grpc-use-cases-01 (work in progress), January 2017.
[RFC3176] Phaal, P., Panchen, S., and N. McKee, "InMon Corporation's
sFlow: A Method for Monitoring Traffic in Switched and
Routed Networks", RFC 3176, DOI 10.17487/RFC3176,
September 2001, <http://www.rfc-editor.org/info/rfc3176>.
[RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for
the Network Configuration Protocol (NETCONF)", RFC 6020,
DOI 10.17487/RFC6020, October 2010,
<http://www.rfc-editor.org/info/rfc6020>.
[RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
and A. Bierman, Ed., "Network Configuration Protocol
(NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
<http://www.rfc-editor.org/info/rfc6241>.
[RFC7011] Claise, B., Ed., Trammell, B., Ed., and P. Aitken,
"Specification of the IP Flow Information Export (IPFIX)
Protocol for the Exchange of Flow Information", STD 77,
RFC 7011, DOI 10.17487/RFC7011, September 2013,
<http://www.rfc-editor.org/info/rfc7011>.
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Authors' Addresses
Haoyu Song (editor)
Huawei Technologies Co., Ltd
2330 Central Expressway
Santa Clara, 95050
USA
Email: haoyu.song@huawei.com
Jun Gong
Huawei Technologies Co., Ltd
156 Beiqing Road
Beijing, 100095
P.R. China
Email: gongjun@huawei.com
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