| Internet-Draft | DetNet Queuing Option for IPv6 | April 2022 |
| Xiong & Liu | Expires 21 October 2022 | [Page] |
This document introduces new IPv6 options to signal the DetNet queuing related information for DetNet flows in IPv6 and SRv6 networks.¶
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According to [RFC8655], Deterministic Networking (DetNet) operates at the IP layer and delivers service which provides extremely low data loss rates and bounded latency within a network domain. DetNet data planes has been specified in [RFC8938]. The existing deterministic technologies are facing large-scale number of nodes and long-distance transmission, traffic scheduling, dynamic flows, and other controversial issues in large-scale networks. [draft-liu-detnet-large-scale-requirements] has described the enhancement requirements for DetNet data plane.¶
It is required to support a data plane method of packet treatment including forwarding, service protection, and queuing over Layer 3. As defined in [RFC8939], the DetNet IP data plane primarily uses 6-tuple-based flow identification. It is required to carry Redundancy information for service protection enhancement and explicit path indicator for forwarding enhancement in a native IP packet such as IPv6 and SRv6. The [draft-pthubert-detnet-ipv6-hbh] has proposed Redundancy Information Option and Path Options for IPv6 and SRv6 data plane.¶
As described in [draft-ietf-detnet-bounded-latency], the end-to-end bounded latency depends on the value of queuing delay bound along with the queuing mechanisms. Mutiple queueing mechanisms can be used to ganrantee the bounded latency in DetNet. And many types of queueing mechanisms have been proposed to provide diversified deterministic service for various applications. For example, time-scheduling queuing mechanisms includes the Time Aware Shaping [IIEEE802.1Qbv] and priority-scheduling includes the Credit-Based Shaper[IEEE802.1Q-2014] with Asynchronous Traffic Shaping[IEEE802.1Qcr]. The cyclic-scheduling queueing mechanism has been proposed in [IEEE802.1Qch] and improved in [draft-dang-queuing-with-multiple-cyclic-buffers]. The deadline-scheduling queueing mechanism has been proposed in [draft-stein-srtsn] and improved in [draft-peng-detnet-deadline-based-forwarding]. The per-flow queueing mechanism includes Guaranteed-Service Integrated service (IntServ) [RFC2212]. It is required to carry queuing related information in data plane so as to make appropriate packet forwarding and scheduling decisions to meet the time bounds. The DetNet forwarding nodes along the path can follow the queue scheduling carried in the packet to achieve the end-to-end bounded latency.¶
This document introduces new IPv6 options to signal the DetNet queuing related information for DetNet flows in IPv6 and SRv6 networks.¶
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.¶
This document defines new IPv6 options for DetNet to signal queuing information to the DetNet layers. The format of the options follow the generic definition in section 4.2 of [RFC8200]. The option may be placed either in an HbH or a DoH EH.¶
The DetNet Queuing Information Option helps to discriminate the types of queuing mechanisms and specify the queuing parameters.¶
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 | Queuing Type | TU| QDL | QPL | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Maximum Queuing Delay (variable) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Maximum Queuing Delay variation (variable) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Queuing Parameters (variable) (optional) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option Type: 8-bit identifier of the type of option. Value TBD by IANA; the highest-order 3 bits of thie field is 001 to skip over this option and continue processing the header if the processing IPv6 node does not recognize the Option Type and to permit the Option Data to be changed en route to the packet's final destination.¶
Opt Data Len: 8-bit unsigned integer. Length of the Option Data field of this option, in octets. It is set to 12.¶
Queuing Type(8 bits): indicates the type of queuing mechanisms. The types of queuing mechanisms should cover time-scheduling, priority-scheduling, cyclic-scheduling, deadline-scheduling and per-flow scheduling queuing mechanisms. Other type of queuing mechanisms can be taken into considerations in the future.¶
TU(2 bits): indicates the time units for Queuing Delay.¶
ODL(3 bits): Length of the Queuing Delay field as an unsigned 3-bit integer.¶
OPL(3 bits): Length of the Queuing Parameters field as an unsigned 3-bit integer.¶
Maximum Queuing Delay (variable): indicates the Maximum queuing delay. The value is various when the Queuing type is different.¶
Maximum Queuing Delay variation (variable): indicates the Maximum queuing delay variation. The value is various when the Queuing type is different.¶
Queuing Parameters(variable): it is optional and based on the Queuing type. For example, Cycle Profile ID and Cycle ID may be carried for cyclic-scheduling queuing mechanisms. Deadline-scheduling queuing mechanisms should carry information such as planned Deadline and deadline Deviation and so on.¶
The DetNet Queuing information Option is intended to be placed in an IPv6 HbH EH since it must be processed by every DetNet forwarding node along the path. All DetNet forwarding nodes can use the queuing information to achieve the packet forwarding and queue scheduling.¶
+-----------------------------------+
| DetNet App-Flow |
| (original IP) Packet |
+-----------------------------------+
| other EHs |
+-----------------------------------+--\
| IPv6 Hop-by-Hop Ex Hdr | |
|(DetNet Queuing information Option)| DetNet Options
| | |
+-----------------------------------+--/
| IPv6 Header |
+-----------------------------------+
| Data-Link |
+-----------------------------------+
| Physical |
+-----------------------------------+
The DetNet Queuing information Option is intended to be placed in an DOH EH before an SRH since it must be processed by the DetNet forwarding nodes of the SRv6 segment list. The DetNet forwarding nodes among SRv6 segment list can use the queuing information to achieve the packet forwarding and queue scheduling.¶
+-----------------------------------+
| DetNet App-Flow |
| (original IP) Packet |
+-----------------------------------+
| Segment Routing Header |
+-----------------------------------+ ---\
| IPv6 Destination Ex Hdr | |
|(DetNet Queuing information Option)| DetNet Options
| | |
+-----------------------------------+ ---/
| IPv6 Header |
+-----------------------------------+
| Data-Link |
+-----------------------------------+
| Physical |
+-----------------------------------+
TBA¶
The authors would like to thank Peng Liu, Bin Tan, Aihua Liu Shaofu Peng for their review, suggestions and comments to this document.¶