Internet DRAFT - draft-yizhou-detnet-ipv6-options-for-cqf-variant
draft-yizhou-detnet-ipv6-options-for-cqf-variant
DetNet Y. Li
Internet-Draft S. Ren
Intended status: Standards Track G. Li
Expires: 28 October 2023 F. Yang
Huawei Technologies
J. Ryoo
ETRI
P. Liu
China Mobile
26 April 2023
IPv6 Options for Cyclic Queuing and Forwarding Variants
draft-yizhou-detnet-ipv6-options-for-cqf-variant-02
Abstract
The fundamental Cyclic Queuing and Forwarding (CQF) defined by Time-
Sensitive Networking (TSN) requires no per-stream per-hop state
maintenance and at the same time its end-to-end bounded latency and
jitter can be easily computed. Such features are attractive and
therefore CQF is being considered in wider deployments. To
accommodate the different deployments, there are variants of CQF
enhancement. This document introduces a new IPv6 option to include
the cycle identification to help leverage CQF variants in DetNet
network to facilitate the deployments.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 28 October 2023.
Copyright Notice
Copyright (c) 2023 IETF Trust and the persons identified as the
document authors. All rights reserved.
Li, et al. Expires 28 October 2023 [Page 1]
Internet-Draft ipv6 for CQF variants April 2023
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminologies . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Features of CQF Variants . . . . . . . . . . . . . . . . . . 3
3.1. Desire to support higher speed links in DetNet . . . . . 4
3.2. Desire to support longer links in DetNet . . . . . . . . 5
4. CQF Variants . . . . . . . . . . . . . . . . . . . . . . . . 7
5. The CQF-Variant Option . . . . . . . . . . . . . . . . . . . 11
5.1. CQF-Variant Option Format . . . . . . . . . . . . . . . . 12
5.2. CQF-Variant Option Processing . . . . . . . . . . . . . . 13
6. Encapsulation of CQF-Variant Option . . . . . . . . . . . . . 13
7. Collaboration Considerations . . . . . . . . . . . . . . . . 14
8. Security Considerations . . . . . . . . . . . . . . . . . . . 15
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 16
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 16
11.1. Normative References . . . . . . . . . . . . . . . . . . 16
11.2. Informative References . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17
1. Introduction
The latency guarantee is the one of the most important features to be
provided by Deterministic Networking (DetNet).
[I-D.ietf-detnet-bounded-latency] presents some examples of queuing
mechanisms to show how each or the combination of them can be used to
achieve the different levels of end-to-end latency bound
requirements. Among them, Cyclic Queuing and Forwarding (CQF) shows
a great simplicity in calculation and configuration of latency
bounds.
Based on the two-buffer CQF specified in annex T of [IEEE8021Q], the
latency bound is between (h-1) * T_c + DT and (h+1) * T_c where h is
the number of hops, T_c is the cycle interval of buffer swapping and
DT, called dead time is a time interval at the end of a cycle, during
which no frames can be transmitted from the buffer to ensure the last
byte of the cycle to be received earlier than the end of the same
cycle by the next downstream node [I-D.ietf-detnet-bounded-latency].
Li, et al. Expires 28 October 2023 [Page 2]
Internet-Draft ipv6 for CQF variants April 2023
DT is usually the sum of output delay, link delay, frame preemption
delay, and processing delay. There can also be other factors
contributing to DT such as the time synchronization drifting.
Normally the DT is much lesser than cycle interval T_c so that it is
negligible. Hence the minimum latency becomes (h-1) * T_c
approximately. That is to say the end-to-end jitter is bounded by
2*T_c approximately for two-buffer CQF.
The latency and jitter bound of CQF is relatively intuitive and
almost fully depends on cycle interval T_c and number of hops. The
lesser T_c is, the smaller the end-to-end latency is. At the same
time, it requires no per-stream per-hop status at the intermediate
nodes as long as the cycle interval T_c is carefully selected to make
sure the overall bandwidth allowed in T_c is large enough to
accommodate all the traffic volume requiring CQF scheduling.
Therefore, CQF offers very attractive features to users in terms of
simplicity and intuition and is getting wider acceptance in DetNet.
When employing CQF in networks to support higher speed long links,
there are variants to enhance CQF for those specific network
characteristics, including more buffers (greater than two buffers)
and cycle identification. The CQF variants do not change the basic
concept of fundamental CQF’s en-queue and de-queue logic, while a new
data plane option is required. This document introduces the new IPv6
[RFC8200] options to help such CQF variants unambiguously identify
the cycle in which the upstream node sends the data packet when the
large number of buffers is employed so that CQF variants can adapt to
the wider deterministic networking requirements.
2. Terminologies
CQF: Cyclic Queuing and Forwarding. A queuing mechanism defined by
annex T of [IEEE8021Q]. This document also uses CQF to refer to
the variants enhanced from it using time cycle based en-queuing
and draining.
3. Features of CQF Variants
The fundamental CQF uses two buffers to swap the packet receiving and
transmission. Swapping is executed every cycle interval T_c. Two
buffer generally maps to two traffic class queues.
When CQF is used in higher speed and/or longer links in wider area
networking, new features like larger number (>=3) of buffers and
cycle identification are introduced. Section 3 and Section 4
illustrate why these features are required and how they work.
Li, et al. Expires 28 October 2023 [Page 3]
Internet-Draft ipv6 for CQF variants April 2023
3.1. Desire to support higher speed links in DetNet
The fundamental CQF typically uses no less than hundreds of
microseconds as a cycle interval. In a network with a small
diameter, say less than 8 hops, it is sufficiently good to provide an
end-to-end latency bound in the order of several milliseconds.
With the increasing of link speed from 100Mbps to 1Gbps, 10Gbps or
even higher in larger networks, either more bytes can be transmitted
within the same cycle interval or the smaller cycle interval is
required to transmit the same amount of bytes in a cycle as that in
low speed networks.
Figure 1 shows a simple calculation on the number of bytes that can
be transmitted in a cycle with different cycle intervals and link
speeds. 1500 bytes is labeled with * as a baseline because a typical
maximum Ethernet frame is 1500 bytes and a selected cycle interval
should at least allow one such frame size to be transmitted unless
otherwise specified.
+----------+--------------------------------------+
| | Bytes Transmitted in a Cycle |
|Cycle Time+--------------------------------------+
| | Link Speed |
| (us) | 100Mbps | 1Gbps | 10Gbps |
+----------+------------+-------------+-----------+
| 1 | 12.5 | 125 | 1250 |
+----------+------------+-------------+-----------+
| 1.2 | 15 | 150 | 1500* |
+----------+------------+-------------+-----------+
| 2 | 25 | 250 | 2500 |
+----------+------------+-------------+-----------+
| 4 | 50 | 500 | 5000 |
+----------+------------+-------------+-----------+
| 10 | 125 | 1250 | 12500 |
+----------+------------+-------------+-----------+
| 12 | 150 | 1500* | 15000 |
+----------+------------+-------------+-----------+
| 120 | 1500* | 15000 | 150000 |
+----------+------------+-------------+-----------+
Figure 1: Bytes transmitted within one cycle interval
When the link speed is at 10Gbps, the cycle interval could be as
small as 1.2 us if a 1500 byte frame needs to be transmitted in one
cycle interval. It is not an accurate calculation because there are
certainly other factors to determine the cycle interval. However, it
shows that as the link speed increases, cycle interval can be greatly
Li, et al. Expires 28 October 2023 [Page 4]
Internet-Draft ipv6 for CQF variants April 2023
reduced in practice while satisfying the minimum amount of data
transmitted in a single cycle. The end-to-end latency bound when
applying CQF is determined by cycle interval and number of hops.
That is to say, CQFs with a smaller cycle interval have the potential
to meet more strict end-to-end latency requirements in higher link
speed networks or meet the same end-to-end latency requirement in
networks with much larger network diameter (number of hops).
Industry automation has some typical application period requirement,
e.g. 100 us to 2 ms for isochronous traffic, 500 us to 1 ms for
cyclic-synchronous and 2 to 20 ms for cyclic-asynchronous traffic.
The network cycle interval is usually a fraction of the application
period. When the cycle interval is in the order of tens of
microseconds, CQF can be used to meet the most strict end-to-end
latency requirements. For instance, if we assume the number of hops
is 24, when cycle interval is set to 10us, the end-to-end latency
bound can be around (24+1)*10 = 250 us which has the potential to
meet the latency bound requirement for isochronous traffic.
In summary a higher speed network makes the shorter cycle interval
feasible because sufficiently large traffic volume can be transmitted
within one cycle interval. A shorter cycle interval further offers
shorter end-to-end latency and jitter bounds which provide CQF with
the potentials to meet more strict latency requirements in wider
deployments while preserving its simplicity of latency calculation
and provisioning. Therefore there is a strong motivation to leverage
CQF and at the same time to make cycle interval as short as possible.
3.2. Desire to support longer links in DetNet
As shown in Figure 2 for fundamental two buffer CQF, the last byte
sent by node A in cycle (i-1) has to be ready for sending at node B
before the start of cycle i. To realize it, DT or dead time is
imposed. It is a time interval usually at the end of a cycle so that
a node should not send the scheduled CQF packets.
Dead time is at least the sum of the maximum propagation delay to the
next node, the maximum processing delay at the next node and the
maximum other time variations. Therefore either the longer
propagation or longer processing delay makes dead time larger.
Packets from DetNet service is likely to be propagated over long
links in the wider area. It takes around 5us per kilometer to
propagate, i.e. 0.5ms every hundred kilometers. Hence the dead time
can be as large as milliseconds or tens of milliseconds in case of
hundred kilometers of longer links and larger processing delays.
That would make the dead time eat up most of the cycle interval when
cycle interval is short (e.g., at the same order or one order higher
of magnitude in time as dead time). Then the useful time in a cycle
Li, et al. Expires 28 October 2023 [Page 5]
Internet-Draft ipv6 for CQF variants April 2023
will be much reduced. In some extreme cases, when the link is long
and the cycle interval is set to extremely short, the first packet
sent in a cycle by a node will not be possibly received in the same
cycle interval at the next node. That makes the useful time in a
cycle reaches zero in two buffer CQF. Then two buffer CQF will be no
longer suitable.
--------------------------------------------------------> Time
| | | |
Node A | cycle i-1 | cycle i | cycle i+1 |
| | | |
Sending ---------------+----------------------------------
|+------+ |+------+ |+------+ |
||//////| ||//////| ||//////| |
|+------+ |+------+ |+------+ |
| buf_1 | buf_2 | buf_1 |
| | | | | | |
| | DT | | DT | | DT |
Node B | |<--->| |<--->| |<--->|
| | | |
Receiving--------------------------------------------------
| +------+| +------+| +------+|
| |//////|| |//////|| |//////||
| +------+| +------+| +------+|
| buf_1 | buf_2 | buf_1 |
| | | |
| | | |
Node B | | | |
| | | |
Sending --------------------------------------------------
| |+------+ |+------+ |
| ||//////| ||//////| |
| |+------+ |+------+ |
| | buf_1 | buf_2
DT=Dead Time
Figure 2: Fundamental Two Buffer CQF
In summary it is hard to achieve the followings at the same time in
the fundamental two buffer CQF.
1. Shorter cycle interval to support lower end to end latency as
shown in Section 3.1.
Li, et al. Expires 28 October 2023 [Page 6]
Internet-Draft ipv6 for CQF variants April 2023
2. Larger dead time to support longer link between neighbours.
3. Smaller ratio of dead time to cycle interval to improve
utilization.
4. CQF Variants
CQF variants are used to solve the dilemma aforementioned with minor
changes to the fundamental two buffer CQF. This section introduces
the large number of buffers and cycle identification variants to CQF.
CQF can use more than two buffers to minimize the dead time and
increase the useful time in a cycle so as to support long link delay.
Figure 3 shows how a three buffer CQF works in a rotating manner in
general. Node A sends packets in cycle (i-1). The time interval
over which node B receives these packet spans two cycles, cycle (i-1)
and cycle i. Hence a method is needed to make node B send them all
at once in cycle (i+1) in order to ensure packets in a single cycle
from the previous node always being sent out in one cycle at the
current node.
Li, et al. Expires 28 October 2023 [Page 7]
Internet-Draft ipv6 for CQF variants April 2023
--------------------------------------------------------> Time
| | | |
Node A | cycle i-1 | cycle i | cycle i+1 |
| | | |
Sending ---------------+----------------------------------
|+----------+ |+----------+ |+----------+ |
||//////////| ||//////////| ||//////////| |
|+----------+ |+----------+ |+----------+ |
| buf_1 | buf_2 buf_3 |
| | | | | | |
| ->| |<- ->| |<- ->| |<-
| DT DT DT
|
-------------------------------------------------
Node B | +-----------+ +-----------+ +-----------+
| |///////////| |///////////| |///////////|
Receiving | +-----------+ +-----------+ +-----------+
| buf_1 | buf_2 | buf_3 |
| | | |
| | | |
| | | |
| | | |
---------------|----------------------------------
Node B | | |+----------+ |+----------+
| | ||//////////| ||//////////|
Sending | | |+----------+ |+----------+
| | buf_1 buf_2
DT=Dead Time
Figure 3: Three Buffer CQF
More than three buffers will be required when the receiving interval
at node B for packets sent in a single cycle interval from node A
spans over more than two cycle interval boundaries. This can happen
when the time variance including propagation, processing, regulation
and other factors between two neighbouring DetNet nodes is large.
Note that due to the variance in time, the receiving interval at the
downstream node can be much larger than one cycle interval in which
the upstream node transmits. When time variance is large and cycle
interval and dead time are set small, the possible receiving time of
the last few packets from node A’s cycle (i-1) at node B can overlap
with the possible receiving time of the first few packets from node
A’s cycle i in different rounds of buffer rotations. Hence, when the
buffer number is larger than two, if the receiving side still uses
Li, et al. Expires 28 October 2023 [Page 8]
Internet-Draft ipv6 for CQF variants April 2023
the traditional CQF implicit time borderline to demarcate the
receiving packets from the consecutive cycles of the upstream node,
it may cause the ambiguity in identifying the right sending cycle at
the upstream node and further affect the correctness of the decision
of which output buffer to put the received packets at the current
node.
Figure 4 shows such an ambiguity when time based cycle demarcation is
used. The packet sent by node A in its cycle (i-1) can be received
at any time in the receiving interval indicated as “receiving window
for A’s buf_1” in Figure 4. The receiving window refers to the time
interval between the earliest time that the first packet sent in a
given cycle from an upstream node is processed and enqueued in an
output buffer and the latest time that the last packet of the cycle
is processed and enqueued in an output buffer. Network operators may
configure the size of the receiving window, taking the time variance
of their networks into account. It can be seen that the spanning
time period of receiving window is longer than the cycle interval.
This is because there is a large time variance experienced between A
and B, e.g. varying processing time for different packets in
different cycles. It does not mean the receiving interval for every
cycle always constantly span over such a large receiving window. The
receiving window time interval indeed is determined by the worst case
time variance value and that should be used for regular time cycle
demarcation.
Li, et al. Expires 28 October 2023 [Page 9]
Internet-Draft ipv6 for CQF variants April 2023
--------------------------------------------------------> Time
| | | | |
Node A | cycle | cycle | cycle | cycle |
| i-1 | i | i+1 | i+2 |
Sending ----------+--------+--------+--------+
|+-----+ |+-----+ |+-----+ |+-----+ |
||/////| ||/////| ||/////| ||/////| |
|+-----+ |+-----+ |+-----+ |+-----+ |
| buf_1 | buf_2 | buf_3 | buf_4 |
| | | | | | | | |
| ->| |<- ->| | ->| | ->| |
| DT DT DT DT
|
--------------------------------------
| +-----------+receiving window
Node B | |///////////|for A's buf_1
| +-----------+
Receiving | put to B's buf_1
|
| ->| |<- ambiguity window 1
|
| +-----------+receiving window
| |///////////|for A's buf_2
| | +-----------+
| | put to B's buf_2
| |
| | ->| |<- ambiguity window 2
| | |
| | | +-----------+receiving window
| | | |///////////|for A's buf_3
| | | +-----------+
| | | put to B's buf_3
| | |
| | | ..........
| | |
-|--------|--------|--------|---------------
Node B | | | | | |
| | | +-----+|+-----+ |+-----+ |+-----+
Sending | | | |/////|||/////| ||/////| ||/////|
| | | +-----+|+-----+ |+-----+ |+-----+
| | | buf_4 | buf_1 | buf_2 | buf_3
DT=Dead Time
Figure 4: Ambiguity of time based cycle demarcation in CQF
Li, et al. Expires 28 October 2023 [Page 10]
Internet-Draft ipv6 for CQF variants April 2023
When a packet is received in ambiguity window 1 in Figure 4, node B
is not able to use the receiving time to determine which buffer is
the correct one to put the packet in because it cannot tell if the
packet is sent from cycle (i-1) or cycle i on node A. If node B puts
the packet to the wrong output buffer, the packet may experience the
unexpected delay. At the same time, the packet occupying the non-
designated buffer may break the contracts between the end hosts and
DetNet networks and then cause the unpredictable consequences.
It has been noted that the DT can be greatly increased to beat the
time variance in order to make the receiving windows do not overlap
so as to remove such ambiguity. However, it is not always practical
and usually not desired because large DT will eat useful cycle time
and bring the low utilization issue as illustrated in Section 3.
Therefore, it would be desired to keep DT as small as possible and at
the same time identify the cycle interval correctly.
CQF variant carries the cycle identification in the data plane to
help determine the correct output port buffer to place the data
packets. It requires the IPv6 data plane enhancement which is
introduced in next section. The configuration and forwarding logic
makes no change from the fundamental CQF. The mapping relation from
the upstream node A’s output port cycle to the downstream node B’s
output port cycle should be determined in advance and stored on node
B. Such CQF variants can be deployed in networks supporting
frequency synchronization only, which alleviate the dependency on
network-wide strict time synchronization. When calculating and
determining the mapping relation, the time phase difference between
neighboring nodes should be taken into consideration if only
frequency synchronization is in use. Optionally the mapping relation
can be dynamically changed when the network condition changes.
This document does not specify the mechanisms to determine the
mapping relation since it can be easily deduced from fundamental CQF
and does not require additional standardization. Some example can be
found in section 5.1 in [multipleCQF].
5. The CQF-Variant Option
This document defines a new IPv6 option for DetNet to leverage the
CQF variant queuing mechanism. This option is to be placed in the
IPv6 HbH (Hop-by-Hop) Options or DOH (Destination Option Header)
header.
Li, et al. Expires 28 October 2023 [Page 11]
Internet-Draft ipv6 for CQF variants April 2023
5.1. CQF-Variant Option Format
The CQF-Variant Option helps the receiving port to identify in which
time cycle interval the packet is sent from the upstream node. It
can be used to determine the output port buffer to enqueue the
packet.
0 1 2 3
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option Type | Opt Data Len |E| Flags | Cycle Id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
~ (64-bit extension if flag E-bit is 1) ~
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: CQF-Variant Option Format Example
CQF-Variant Option fields:
* Option Type: 8-bit identifier of the type of option. Value TBD by
IANA. If the processing IPv6 node does not recognize the Option
Type it must discard the packet and return an ICMP message (the
highest-order 2 bits = 10). The Option Data of this option may
change en route to the packet's final destination (the third-
highest-order bit=1).
* Opt Data Len: 8-bit length of the option data.
* Flags: 8-bit field to indicate what CQF-Variant information
followed. The leftmost bit is called E-bit. When E-bit set to 1,
there is a 64-bit extension in length after Cycle Id.
* Cycle Id: 8-bit field to indicate the time cycle ID at output port
of the upstream node when the packet is sent out.
* 64-bit extension: This field contains values required for a
particular CQF variant, such as timestamp. This field exists only
when E-bit in Flags field is set to one. [Editor's Note: Text
will be modified or added as specific uses for this field are
identified]
Li, et al. Expires 28 October 2023 [Page 12]
Internet-Draft ipv6 for CQF variants April 2023
5.2. CQF-Variant Option Processing
A packet carrying CQF-Variant Option with Cycle Id does not change
the fundamental cyclic queuing and forwarding behaviors of CQF. At
the data plane, the packet transmitted from an output port carries an
unambiguous cycle Id. There are different ways to manage the cycle
id and output buffer. The simplest one is to map a buffer to a cycle
id in a rotating manner. When the buffers rotate for transmission,
cycle id also rotates. Packets in one buffer are sent all at once
within a cycle interval and carry the same cycle id.
When a router receives a data packet with Cycle Id, it uses the cycle
id to enqueue the packet to the correct output buffer that implicitly
maps to a local cycle id for output transmission. Therefore the
cycle id changes every hop.
Each node has the pre-computed and maintained mapping relation
between the incoming cycle id of each input port and the output
buffer number of the outgoing port. Such relation is determined in
advance by measuring and/or configure the various delay components of
the serviced DetNet flows as indicated in Figure 1 in
[I-D.ietf-detnet-bounded-latency]. Once the output buffer to place
an incoming packet is determined, the cycle id value carried in later
packet transmission is decided implicitly.
Cycle Id can be used as an implicit aggregated flow id and also is a
quick way to identify the streams requiring DetNet service which
provides an alternative to use 6-tuple to identify an IPv6 flow shown
in [RFC8938].
6. Encapsulation of CQF-Variant Option
When used in IPv6 networks, the CQF-Variant option can be placed in
an HbH extension header or DOH.
Figure 6 shows the encapsulation of CQF-Variant option in HbH
extension header. When every DetNet forwarding node along the path
is provisioned to use CQF variants as the queuing mechanism, this
option should be placed here. If a router does not support this
option, it discards the packet and returns an ICMP message.
Li, et al. Expires 28 October 2023 [Page 13]
Internet-Draft ipv6 for CQF variants April 2023
+-----------------------------------+
| DetNet IP Packet |
+-----------------------------------+
| other EHs |
+-----------------------------------+
| IPv6 Hop-by-Hop Ex Hdr |
| (CQF-Variant Option) |
+-----------------------------------+
| IPv6 Header |
+-----------------------------------+
| Data-Link |
+-----------------------------------+
| Physical |
+-----------------------------------+
Figure 6: Example 1: CQF-Variant Option Encapsulated in HbH
In some deployments the path selection is indicated using IPv6
routing header (RH) by specifying a set of nodes that must be
traversed by the packet along its path to the destination. When such
a source routing mechanism is used, CQF-Variant Option is placed in
DOH (Destination Option Header) as shown in Figure 7. Then CQF-
Variant Option will be processed by the specified in-path routers.
+-----------------------------------+
| DetNet IP Packet |
+-----------------------------------+
| other EHs including RH |
+-----------------------------------+
| IPv6 Destination Ex Hdr |
| (CQF-Variant Option) |
+-----------------------------------+
| IPv6 Header |
+-----------------------------------+
| Data-Link |
+-----------------------------------+
| Physical |
+-----------------------------------+
Figure 7: Example 2: CQF-Variant Option Encapsulated in DOH
(To be discussed: Should and how CQF-Variant Option to be placed in
SRv6.)
7. Collaboration Considerations
[Editor’s Note: This chapter will be deleted when the WG forms
consent on final solution.]
Li, et al. Expires 28 October 2023 [Page 14]
Internet-Draft ipv6 for CQF variants April 2023
From the comments and presentations in detnet session of IETF 114,
the authors paid much attention on related solutions, e.g.,
[I-D.yzz-detnet-enhanced-data-plane] and [I-D.eckert-detnet-tcqf].
The former document introduced a general IPv6 Option of BLI(Bounded
Latency Information) that can be carried in IPv6 extension header.
introduced a general IPv6 Option of BLI(Bounded Latency Information)
that can be carried in IPv6 extension header. To encapsulate cycle
id and potential timestamp information by the way introduced in BLI,
it will takes 5 Bytes and 12 Bytes correspectively see Figure 8. In
this document, it will takes 2 Bytes and 10 Bytes for the option
data. From the latter TCQF document, it will reuse DSCP code points
in a single administrative domain. Only 4 bits of DSCP is available,
it is unable to acommodate cycle id or timestamp information. Full
discussion should be taken in detnet WG and final decision is
significant to future proposal of solution of detnet.
+---------------+-------------+-------------+-------------+
| BLI Type = 1 | Format = 3 | Flag | Reserved |
+---------------+-------------+---------------------------+
| BLI=cycle id |
+---------------+
+---------------+-------------+-------------+-------------+
| BLI Type = 1 | Format = 5 | Flag | Reserved |
+---------------+-------------+---------------------------+
| Bounded Latency Information |
| (PTP 64-bit Timestamp ) |
+---------------------------------------------------------+
Figure 8: CQF-Variant Information in Format of BLI Options
8. Security Considerations
9. IANA Considerations
This document defines a new CQF-Variant Option for the “Destination
Options and Hop-by-Hop Options” under the “Internet Protocol Version
6 (IPv6) Parameters” registry [IPV6-PARMS] with the suggested values
in Figure 9.
+------+-----+-----+-------+--------------------+-------------+
| Hexa | act | chg | rest | Description | Reference |
+------+-----+-----+-------+--------------------+-------------+
| 0xB1 | 10 | 1 | 10001 | CQF-Variant Option |this document|
+------+-----+-----+-------+--------------------+-------------+
Figure 9: CQF-Variant Option Code in Destination Options and Hop-
by-Hop Options
Li, et al. Expires 28 October 2023 [Page 15]
Internet-Draft ipv6 for CQF variants April 2023
10. Contributors
The following co-authors have contributed to this document:
Xiaoliang Zheng Huawei Email: zhengxiaoliang@huawei.com
11. References
11.1. Normative References
[RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", STD 86, RFC 8200,
DOI 10.17487/RFC8200, July 2017,
<https://www.rfc-editor.org/info/rfc8200>.
11.2. Informative References
[RFC8938] Varga, B., Ed., Farkas, J., Berger, L., Malis, A., and S.
Bryant, "Deterministic Networking (DetNet) Data Plane
Framework", RFC 8938, DOI 10.17487/RFC8938, November 2020,
<https://www.rfc-editor.org/info/rfc8938>.
[I-D.ietf-detnet-bounded-latency]
Finn, N., Le Boudec, J., Mohammadpour, E., Zhang, J., and
B. Varga, "Deterministic Networking (DetNet) Bounded
Latency", Work in Progress, Internet-Draft, draft-ietf-
detnet-bounded-latency-10, 8 April 2022,
<https://datatracker.ietf.org/doc/html/draft-ietf-detnet-
bounded-latency-10>.
[I-D.yzz-detnet-enhanced-data-plane]
Geng, X., Zhou, T., Zhang, L., and Z. Du, "DetNet Enhanced
Data Plane", Work in Progress, Internet-Draft, draft-yzz-
detnet-enhanced-data-plane-02, 24 December 2022,
<https://datatracker.ietf.org/doc/html/draft-yzz-detnet-
enhanced-data-plane-02>.
[I-D.eckert-detnet-tcqf]
Eckert, T. T., Bryant, S., Malis, A. G., and G. Li,
"Deterministic Networking (DetNet) Data Plane - Tagged
Cyclic Queuing and Forwarding (TCQF) for bounded latency
with low jitter in large scale DetNets", Work in Progress,
Internet-Draft, draft-eckert-detnet-tcqf-02, 13 March
2023, <https://datatracker.ietf.org/doc/html/draft-eckert-
detnet-tcqf-02>.
Li, et al. Expires 28 October 2023 [Page 16]
Internet-Draft ipv6 for CQF variants April 2023
[IEEE8021Q]
"IEEE Standard for Local and Metropolitan Area Network —
Bridges and Bridged Networks", IEEE Std 802.1Q-2018,
DOI 10.1109/ieeestd.2018.8403927, 2018,
<https://doi.org/10.1109/ieeestd.2018.8403927>.
[multipleCQF]
Finn, N., "Multiple Cyclic Queuing and Forwarding",
October 2021,
<https://www.ieee802.org/1/files/public/docs2021/new-finn-
multiple-CQF-0921-v02.pdf>.
[IPV6-PARMS]
IANA, ., "Internet Protocol Version 6 (IPv6) Parameters",
n.d., <https://www.iana.org/assignments/ipv6-parameters/
ipv6-parameters.xhtml>.
Authors' Addresses
Yizhou Li
Huawei Technologies
Email: liyizhou@huawei.com
Shoushou Ren
Huawei Technologies
Email: renshoushou@huawei.com
Guangpeng Li
Huawei Technologies
Email: liguangpeng@huawei.com
Fan Yang
Huawei Technologies
Email: shirley.yangfan@huawei.com
Jeong-dong Ryoo
ETRI
Email: ryoo@etri.re.kr
Peng Liu
China Mobile
Email: liupengyjy@chinamobile.com
Li, et al. Expires 28 October 2023 [Page 17]
