Internet DRAFT - draft-kumar-sfc-offloads
draft-kumar-sfc-offloads
Service Function Chaining S. Kumar
Internet-Draft J. Guichard
Intended status: Standards Track P. Quinn
Expires: April 23, 2017 Cisco Systems, Inc.
J. Halpern
Ericsson
S. Majee
F5 Networks
October 20, 2016
Service Function Simple Offloads
draft-kumar-sfc-offloads-03
Abstract
Service Function Chaining (SFC) enables services to be delivered by
selective traffic steering through an ordered set of service
functions. Once classified into an SFC, the traffic for a given flow
is steered through all the service functions of the SFC for the life
of the traffic flow even though this is often not necessary.
Steering traffic to service functions only while required and not
otherwise, leads to shorter SFC forwarding paths with improved
latencies, reduced resource consumption and better user experience.
This document describes the rationale, techniques and necessary
protocol extensions to achieve such optimization, with focus on one
such technique termed "simple offloads".
Status of This Memo
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provisions of BCP 78 and BCP 79.
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 23, 2017.
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Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Definition Of Terms . . . . . . . . . . . . . . . . . . . . . 3
3. Service Function Path Reduction . . . . . . . . . . . . . . . 4
3.1. Bypass . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.2. Simple Offload . . . . . . . . . . . . . . . . . . . . . 5
3.2.1. Stateful SFF . . . . . . . . . . . . . . . . . . . . 7
3.2.2. Packet Re-ordering . . . . . . . . . . . . . . . . . 7
3.2.3. Race Conditions . . . . . . . . . . . . . . . . . . . 8
3.2.4. Policy Implications . . . . . . . . . . . . . . . . . 8
3.2.5. Capabilities Exchange . . . . . . . . . . . . . . . . 8
4. Methods For SFP Reduction . . . . . . . . . . . . . . . . . . 9
4.1. SFP In-band Offload . . . . . . . . . . . . . . . . . . . 9
4.1.1. Progression Of SFP Reduction . . . . . . . . . . . . 11
4.2. Service Controller Offload . . . . . . . . . . . . . . . 12
5. Simple Offload Data-plane Signaling . . . . . . . . . . . . . 13
5.1. Offload Flags Definition . . . . . . . . . . . . . . . . 14
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 15
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
7.1. Standard Class Registry . . . . . . . . . . . . . . . . . 15
7.1.1. Simple Offloads TLV . . . . . . . . . . . . . . . . . 15
8. Security Considerations . . . . . . . . . . . . . . . . . . . 16
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 16
9.1. Normative References . . . . . . . . . . . . . . . . . . 16
9.2. Informative References . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16
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1. Introduction
Service function chaining involves steering traffic flows through a
set of service functions in a specific order. Such an ordered list
of service functions is called a Service Function Chain (SFC). The
actual forwarding path used to realize an SFC is called the Service
Function Path (SFP).
Service functions forming an SFC are hosted at different points in
the network, often co-located with different types of service
functions to form logical groupings. Applying a SFC thus requires
traffic steering by the SFC infrastructure from one service function
to the next until all the service functions of the SFC are applied.
Service functions know best what type of traffic they can service and
how much traffic needs to be delivered to them to achieve complete
delivery of service. As a consequence any service function may
potentially request, within its policy constraints, traffic no longer
be delivered to it or its function be performed by the SFC
infrastructure, if such a mechanism is available.
While there are several possible means to achieve this, one of the
most flexible, directly connected to functional semantics, is based
on allowing service functions themselves to evaluate a particular
flow and reflect the result of this evaluation back to the SFC
infrastructure.
This document outlines the "simple offloads" mechanism that avoids
steering traffic to service functions on flow boundary, on request
from the service functions, while still ensuring compliance to the
instantiated policy that mandates the SFC.
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
2. Definition Of Terms
This document uses the following terms. Additional terms are defined
in [RFC7498], [I-D.ietf-sfc-architecture] and [I-D.ietf-sfc-nsh].
Service Controller (SC): The entity responsible for managing the
service chains, including create/read/update/delete actions as
well as programming the service forwarding state in the network -
SFP distribution.
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Classifier (CF): The entity, responsible for selecting traffic as
well as SFP, based on policy, and forwarding the selected traffic
on the SFP after adding the necessary encapsulation. Classifier
is implicitly an SFF.
Offload: A request or a directive from the SF to alter the SFP so as
to remove the requesting SF from the SFP while maintaining the
effect of the removed SF on the offloaded flow.
3. Service Function Path Reduction
The packet forwarding path of a SFP involves the classifier, one or
more SFFs and all the SFs that are part of the SFP. Packets of a
flow are forwarded along this path to each of the SFs, for the life
of the flow, whether SFs perform the full function in treating the
packet or reapply the cached result, from the last application of the
function, on the residual packets of the flow. In other words, every
packet on the flow incurs the same latency and the end-to-end SFP
latency remains more or less constant subject to the nature of the
SFs involved. If an SF can be removed from the SFP, for a specific
flow, traffic steering to the SF is avoided for that flow; thus
leading to a shorter SFP for the flow. When multiple SFs in a SFP
are removed, the SFP starts to converge towards the optimum path,
incurring a fraction of the latency associated with traversing the
SFP.
Although SFs are removed from the SFP, the corresponding SFC is not
changed - this is subtle but an important characteristic of this
mechanism. In other words, this mechanism does not alter the SFC and
still uses the SFP associated with the SFC.
There are two primary approaches to removing an SF from the SFP.
Namely,
o Bypass: Mechanism that alters the SFC. Described in this draft
for completeness.
o Simple Offload: Mechanism that alters the SFP alone, does not
affect the SFC. This is the primary focus of this draft.
3.1. Bypass
Many service functions do not deliver service to certain types of
traffic. For instance, typical WAN optimization service functions
are geared towards optimizing TCP traffic and add no value to non-TCP
traffic. Non-TCP traffic thus can bypass such a service function.
Even in the case of TCP, a WAN optimization SF may not be able to
service the traffic if the corresponding TCP flow is not seen by it
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from inception. In such a situation a WAN optimization SF can avoid
the overhead of processing such a flow or reserving resources for it,
if it had the ability to request such flows not be steered to it. In
other words such service functions need the ability to request they
be bypassed for a specified flow from a certain time in the life of
that flow.
A seemingly simple alternative is to require service functions pre
specify the traffic flow types they add value to, such as the one-
tuple: IP protocol-type described above. A classifier built to use
such data exposed by SFs, may thus enable bypassing such SFs for
specific flows by way of selecting a different SFC that does not
contain the SF being removed.
Although knowledge of detailed SF profiles helps SFC selection at the
classifier starting the SFC, it leads to shortcomings.
o It adds to the overhead of classification at that classifier as
all SF classification requirements have to be met by the
classifier.
o It leads to conflicts in classification requirements between the
classifier and the SFs. Classification needs of different SFs in
the same SFC may vary. A classifier thus cannot classify traffic
based on the classification of one of the SFs in the chain. For
instance, even though a flow is uninteresting to one SF on an SFC,
it may be interesting to another SF in the same SFC.
o The trigger for bypassing an SF may be dynamic as opposed to the
static classification at the classifier - it may originate at the
SFs themselves and involve the control and policy planes. The
policy and control planes may react to such a trigger by
instructing the classifier to select a different SFC for the flow,
thereby achieving SF bypass.
3.2. Simple Offload
Service delivery by a class of service functions involves inspecting
the initial portion of the traffic and determining whether traffic
should be permitted or dropped. In some service functions, such an
inspection may be limited to just the five tuple, in some others it
may involve protocol headers, and in yet others it may involve
inspection of the byte stream or application content based on the
policy specified. Firewall service functions fall into such a class,
for example. In all such instances, servicing involves determining
whether to permit the traffic to proceed onwards or to deny the
traffic from proceeding onwards and drop the traffic. In some cases,
dropping of the traffic may be accompanied with the generation of a
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response to the originator of traffic or to the destination or both.
Once the service function determines the result - permit or deny (or
drop), it simply applies the same result to the residual packets of
the flow by caching the result in the flow state.
In essence, the effect of service delivery is a PERMIT or a DENY
action on the traffic of a flow. This class of service functions can
avoid all the overhead of processing such traffic at the SF, by
simply requesting another entity in the SFP, to assume the function
of performing the action determined by the service function. Since
PERMIT and DENY are very simple actions, other entities in the SFP
are very likely to be able to perform them on behalf of the
requesting SF. A service function can thus offload simple functions
to other entities in the SFP.
As with PERMIT and DENY actions, there are others which are simple
enough to be supported. Some are listed here for illustration.
Unidirectional Offload: Client-Server communication, typical of HTTP
request-response transactions, imposes higher cost on SFs in one
direction. Reponses often carry more bytes, sometimes orders of
mangnitude more, as compared to requests. SFs could avoid the
cost of moving the bits in the response direction to which it may
add no value, once the policy is satisfied, if the response flow
can be offloaded. Hence Offloads must be requestable on a
unidirectional flow boundary.
TCP Control Exception Offload: Most SFs maintain flow state and
would like to know when a flow terminates, so SFs can cleanup the
flow state and associated resources. Such SFs need to receive
the TCP control packets, the ones with control flags [RFC0793]
set, on the flow even when the flow itself is offloaded, in order
to perform such activity. Hence Offloads must be predicatable to
offload all but the TCP control packets of a flow.
Time Limited Offload: SF policy may dictate flows be limited to
certain period of time among other reasons to optimize SF load.
SFs can request a flow be offloaded for a specific time duration
after which, all traffic on that flow gets redirected to the SF
as was done before the offload was initiated. Hence Offloads
must be requestable on a time limit.
Volume Limited Offload: As with time limited offlaods, SF policy may
dictate flows be limited to certain volume of data. SFs can
request a flow be offloaded until a specified number of bytes
traverse the flow. Hence Offloads must be requestable on a
volume limit.
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Since SFF is the one steering traffic to the SFs and hence is on the
SFP, it is a natural entity to assume the offload function. A SF not
interested in traffic being steered to it can simply perform a simple
offload by indicating a PERMIT action along with an OFFLOAD request.
The SFF responsible for steering the traffic to the SF takes note of
the ACTION and offload request. The OFFLOAD directive and the ACTION
received from the requesting SF are cached against the SF for that
flow. Once cached, residual packets on the flow are serviced by the
cached directive and action as if being serviced by the corresponding
SF.
3.2.1. Stateful SFF
SFFs are the closest SFC infrastructure entities to the service
functions. SFFs may be state-full and hence can cache the offload
and action in both of the unidirectional flows of a connection. As a
consequence, action and offload become effective on both the flows
simultaneously and remain so until cancelled or the flow terminates.
SFFs may not always honor the offload requests received from SFs.
This does not affect the correctness of the SFP in any way. It
implies that the SFs can expect traffic to arrive on a flow, which it
offloaded, and hence must service them, which may involve requesting
an offload again. It is natural to think of an acknowledgement
mechanism to provide offload guarantees to the SFs but such a
mechanism just adds to the overhead while not providing significant
benefit. Offload serves as a best effort mechanism.
3.2.2. Packet Re-ordering
The simple offload mechanism creates short time-windows where packet
re-ordering may occur. While SFs request flows be offloaded to SFFs,
packets may still be in flight at various points along the SFP,
including some between the SFF and the SF. Once the offload decision
is received and committed into the flow entry at the SFF, any packets
arriving after and destined to the offloading SF are treated to the
offload decision and forwarded along (if it is a PERMIT action).
Inflight packets to the offloading SF may arrive at the SFF after one
or more packets are already treated to the offload decision and
forwarded along.
This is a transitional effect and may not occur in all cases. For
instance, if the decision to offload a flow by an SF is based on the
first packet of TCP flow, a reasonable time window exists between the
offload action being committed into the SFF and arrival of subsequent
packet of the same flow at that SFF. Likewise, request/response
based protocols such as HTTP may not always be subject to the re-
ordering effects.
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3.2.3. Race Conditions
The tuple that make up an end-to-end flow or connection, such as a
five tuple TCP connection, may be reused in a very short span of time
when very high performing end points are involved. A very remote
manifestation of this behavior may involve the wrong incarnation of a
flow at the SFF receiving the flow offload request from a SF.
Implementations of simple offloads must thus be aware of such a
possibility and include appropriate measures to address it. It is
important to note that a SFF must maintain correctness and hence it
is acceptable to not honor a simple offloads request to resolve such
an occurrence. After all SFs exist with right security posture to
protect against malicious traffic.
A simple and widely used method to serialize reuse of tuples is to
use an incarnation number in addition to the five-tuple. The
steering SFF can pass an opaque cookie, which in its simplest form
could be the incarnation number, that is preserved by the SF and
passed along with the simple offload request. SFF can thus correctly
identify the right incarnation of the flow. SYN detection at the SFF
to take corrective action is another option. The SFF implementations
may employ any technique deemed appropriate.
3.2.4. Policy Implications
Offload mechanism may be controlled by the policy layer. The SFs
themselves may have a static policy to utilize the capability offered
by the SFC infrastructure. They could also be dynamic and controlled
by the specific policy layer under which the SFs operate.
Similarly, the SFC infrastructure, specifically the classifiers and
the SFFs, may be under the SFC infrastructure control plane policy
controlling the decision to honor offloads from an SF. This policy
in turn may be coarse-grain, at the SF level, and hence static. It
can also be fine grain and hence dynamic but it adds to the overhead
of policy distribution.
Policy model related to offloads is out of scope of this document.
3.2.5. Capabilities Exchange
Simple offloads can be exposed and negotiated a priori as a
capability between the SFFs and the SFs or the corresponding control
layers. In the simplest of the implementations, this is provided by
the SFC infrastructure and the SFs are statically configured to
utilize them without capabilities negotiation, within the constraints
of the SF specific policies.
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Capabilities exchange is outside the scope of this document.
4. Methods For SFP Reduction
There are a number of different models that may be used to facilitate
SFP shortening.
The methods discussed in the following sections require signaling
among the participant components to communicate offload and permit/
deny actions. The signaling may be performed in the data-plane or in
the control plane.
a. Data-plane: A SFC specific communication channel is needed for
SFs to communicate the offload request along with the SF treated
packet. [NSH] defines a header specifically for carrying SFP
along with metadata and provides such a channel for use with
offloads. Necessary bits need to be allocated in NSH to convey
the action as well as the offload directive. This signaling may
be limited to SF and SFF or may continue from one SFF to another
SFF or the classifier. It may also involve signaling directly
from the SF to the classifier.
b. Control-plane: Messages are required between the SF and the
service controller as well as between the SFF and the service
controller. Service controller messaging is out of scope of this
document and it is assumed to be service controller specific,
which may include open or standard interfaces.
4.1. SFP In-band Offload
SFs receive traffic on an overlay from the SFF. SFs service the
traffic and turn them back to the SFF on an overlay or forward the
traffic on the underlay. In the former case, along with returning
the traffic to SFF, they can perform simple offload by signaling
OFFLOAD and ACTION to the SFF. SFF caches the OFFLOAD and ACTION
while forwarding the serviced packet onwards to the next service hop
on the SFP or dropping it as per the ACTION. This may continue from
one hop to the next on the SFP. SFF can now enforce the OFFLOAD and
ACTION on the residual packets of the flow.
By performing such hop-by-hop offloads, SFP can be reduced from its
original length, steering traffic to only the SFFs and the SFs that
really need to see the traffic.
Figure 1 to Figure 3 show an example of SF and SFF performing offload
operations, with PERMIT action, and the effect thereafter on the SFP.
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SFID(1) SFID(2) SFID(3)
+------+ +------+ +------+
....| SF1 |.... ....| SF2 |.... ....| SF3 |....
. +------+ . . +------+ . . +------+ .
. | . . | . . | .
. | . . | . . | .
. | . . | . . | .
. | . . | . . | .
. | . . | . . | .
+----+ . +------+ . . +------+ . . +------+ .
| CF |------| SFF1 |-----------| SFF2 |-----------| SFF3 |------ Net
+----+ . +------+ . . +------+ . . +------+ .
. . . . . .
SFP1 ... ..... ..... ... >
SFC1 = {SF1, SF2, SF3}
SFC1 -> SFP1
Where,
SFC1 is a service function chain
SF1, SF2 and SF3 are three service functions
SFP1 is the servcie function path for SFC1
CF is the classifier starting SFP1 based on policy
Note: Network forwarders are omitted from the figure for simplicity
Figure 1: SFC1 with corresponding SFP1
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O
f
SFID(1) f +- SFID(2) SFID(3)
+------+ l | +------+ +------+
....| SF1 |.... o | | SF2 | ....| SF3 |....
. +------+ . a | +------+ . +------+ .
. | . d | | . | .
. | . | | . | .
. | . | | . | .
. | . v | . | .
. | . | . | .
+----+ . +------+ . +------+ . +------+ .
| CF |------| SFF1 |-----------| SFF2 |-----------| SFF3 |----- Net
+----+ . +------+ . +------+ . +------+ .
. . . .
SFP1 ... ........................ ... >
Figure 2: SFP1 after SFID(2) performs an Offload
O O
f f
f +- SFID(1) SFID(2) f +- SFID(3)
l | +------+ +------+ l | +------+
o | | SF1 | | SF2 | o | | SF3 |
a | +------+ +------+ a | +------+
d | | | d | |
| | | | |
| | | | |
v | | v |
| | |
+----+ +------+ +------+ +------+
| CF |------| SFF1 |-----------| SFF2 |-----------| SFF3 |----- Net
+----+ +------+ +------+ +------+
SFP1 .......................................................... >
Figure 3: SFP1 after SFID(1) and SFID(3) perform Offloads
4.1.1. Progression Of SFP Reduction
SFP reduction happens one SFF at a time: by collapsing the SFF-to-SF
hops into the SFF or the SFC infrastructure.
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Figure 1 to Figure 3 show one sequence of offload events that lead to
a shorter SFP.
Corresponding transformation of the actual forwarding path is
captured by the states below.
Stage-1: Prior to any offloads, service function path SFP1
(corresponding to SFC1) has the following actual forwarding path
as shown in Figure 1:
CF ->
SFF1 -> SF1 -> SFF1 ->
SFF2 -> SF2 -> SFF2 ->
SFF3 -> SF3 -> SFF3 ->
Stage-2: After SF2 performs a simple offload, service function path
SFP1 changes to the one represented below, as also shown in
Figure 2:
CF ->
SFF1 -> SF1 -> SFF1 ->
SFF2 ->
SFF3 -> SF3 -> SFF3 ->
Stage-3: After SF1 and SF3 both perform simple offloads, service
function path SFP1 changes to the one represented below, as also
show in Figure 3:
CF ->
SFF1 ->
SFF2 ->
SFF3 ->
When all the SFs in a SFP perform offloads the forwarding path is
reduced to pass through just the SFFs.
4.2. Service Controller Offload
Each SF signals the service controller of the OFFLOAD and ACTION via
control plane messaging for a specific flow. The service controller
then signals the appropriate SFFs to offload the requested SFs, there
by achieving the hop-by-hop offload behavior.
The service controller has full knowledge of all the SFs of the SFP
offloading the flow and hence can determine the optimum SFP within
the Service Controller and program the appropriate SFFs to achieve
SFP optimization.
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5. Simple Offload Data-plane Signaling
Since Offload and action are signaled at the time of returning the
traffic to SFF, post servicing the traffic, such signaling can be
integrated into the SFC service header of the packet.
Figure 4 and Figure 5 show the bits necessary to achieve the
signaling using the SFC encapsulation as described in
[I-D.ietf-sfc-nsh]. In particular, for NSH MD-Type1 header format,
the offload bits are communicated via the flags field in the very
first byte of the fixed context headers. For NSH MD-Type2 header
format, the offload bits are communicated via a new standard TLV -
Simple Offload TLV. The standard TLV is requested to be allocated
from the TLV Class, "Standard Class", from the IANA.
By integrating the signaling with the packets, the simple offloads
scale with the traffic in the data plane.
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|D| F |X| Context Header 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|B|U|T|D|R|R|R|R| Context Header 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Context Header 3 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Context Header 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
X : Extend flags into first byte of "Context Header 2"
B : Bidirectional Offload
U : Unidirectional Offload
T : TCP-control Exception Offload
D : Drop Offload
Figure 4: NSH Type-1 Offload Bits shown for DC Allocation
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0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| STANDARD CLASS | SimpleOffload |0|0|0| 0x2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|B|U|T|D|S|V|R|R|R|R|R|R| Offload-data |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
B : Bidirectional Offload
U : Unidirectional Offload
T : TCP-control Exception Offload
D : Drop Offload
S : Time Limited Offload
V : Volume Limited Offload
Figure 5: NSH Type-2 Offload Bits
5.1. Offload Flags Definition
Offload Control Flags:
B, Bidirectional Offload: SF requests both flows in the connection,
described by the payload, be offloaded, by setting B=1. B=0
otherwise.
U, Unidirectional Offload: SF requests only the current flow in the
connection, described by the payload, be offloaded, by setting
U=1. U=0 otherwise.
One and only one of 'B' and 'U' MUST be specified to indicate
offload. In the event a NSH encapsulated packet is received with
both 'B' and 'U' offload flags set to 1, 'B' MUST take precedence.
Offload Function Flags:
B|U, Permit Offload: When either B=1 or U=1, the implicit function
is to PERMIT or allow all packets on the flow(s) to traverse
along the SFP, unless over-ridden by other functional flags.
D, Drop Offload: Setting D=1, requests packets on the offloaded
flow(s) be dropped; D MUST be set to 0 otherwise. D=1 modifies
the default PERMIT behavior of 'B' and 'U' flags.
T, TCP-control Exception Offload: Setting T=1 requests TCP control
packets to be exempted from Offload behavior. TCP control
packets MUST continue to be forwarded to the SF while the rest of
the packets must be allowed to bypass the SF contingent upon the
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application of other offload flags. T MUST be set to 0
otherwise.
S, Time Limited Offload: Setting S=1 requests the flow(s) to be
offloaded for the duration specified, in seconds, in offload-data
field. After that duration, offload behavior must be cancelled
and affected flow(s) MUST be redirected to the SF. S MUST be set
to 0 otherwise.
V, Volume Limited Offload: Setting V=1 requests the flow(s) to be
offloaded until the volume of data specified, in Kilo Bytes, in
offload-data field has traversed the flow(s). After that volume
of data has traversed, offload behavior must be cancelled and
affected flow(s) MUST be redirected to the SF. V MUST be set to
0 otherwise.
6. Acknowledgements
The authors would like to thank Abhjit Patra, Nagaraj Bagepalli, Kent
Leung, Erik Nordmark, Diego Lopez for their comments, thoughtful
questions and suggestions, review, etc.
7. IANA Considerations
7.1. Standard Class Registry
IANA is requested to allocate a "STANDARD" class from the TLV Class
registry. Allocation of the registry values under this class shall
follow the "IETF Review" policy defined in RFC 5226 [RFC5226].
7.1.1. Simple Offloads TLV
IANA is requested to allocate TLV type with value 0x1 from the
STANDARD TLV class registry. The format of the "Simple Offloads" TLV
is as defined in this draft.
+------+-----------------+------------------------+---------------+
| TLV# | Name | Description | Reference |
+------+-----------------+------------------------+---------------+
| 1 | Simple Offloads | SF Flow Offload to SFF | This document |
+------+-----------------+------------------------+---------------+
Table 1: Standard Class Registry
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8. Security Considerations
Security of the offload signaling mechanism is very important. This
document does not advocate any additional security mechanisms beyond
the data plane and control plane signaling security mechanisms.
9. References
9.1. Normative References
[I-D.ietf-sfc-architecture]
Halpern, J. and C. Pignataro, "Service Function Chaining
(SFC) Architecture", draft-ietf-sfc-architecture-11 (work
in progress), July 2015.
[I-D.ietf-sfc-nsh]
Quinn, P. and U. Elzur, "Network Service Header", draft-
ietf-sfc-nsh-10 (work in progress), September 2016.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
9.2. Informative References
[RFC0793] Postel, J., "Transmission Control Protocol", STD 7,
RFC 793, DOI 10.17487/RFC0793, September 1981,
<http://www.rfc-editor.org/info/rfc793>.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
DOI 10.17487/RFC5226, May 2008,
<http://www.rfc-editor.org/info/rfc5226>.
[RFC7498] Quinn, P., Ed. and T. Nadeau, Ed., "Problem Statement for
Service Function Chaining", RFC 7498,
DOI 10.17487/RFC7498, April 2015,
<http://www.rfc-editor.org/info/rfc7498>.
Authors' Addresses
Surendra Kumar
Cisco Systems, Inc.
170 W. Tasman Dr.
San Jose, CA 95134
Email: smkumar@cisco.com
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Jim Guichard
Cisco Systems, Inc.
Email: jguichar@cisco.com
Paul Quinn
Cisco Systems, Inc.
Email: paulq@cisco.com
Joel Halpern
Ericsson
Email: joel.halpern@ericsson.com
Sumandra Majee
F5 Networks
90 Rio Robles
San Jose, CA
US
Email: S.Majee@F5.com
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