Internet DRAFT - draft-chen-mpls-cqf-lsp-dp
draft-chen-mpls-cqf-lsp-dp
Network Working Group Z. Chen
Internet-Draft L. Qiang
Intended status: Informational Huawei
Expires: September 10, 2019 March 9, 2019
MPLS-LSP Data Plane for Cyclic Queuing and Forwarding
draft-chen-mpls-cqf-lsp-dp-00
Abstract
Large-scale Deterministic Network (LDN) [ldn] aims to achieve bounded
latency forwarding on layer-3 networks that contain long-distance
links, large number of nodes and flows. LDN requires a data plane
mechanism to indicate different forwarding cycles in the upstream
node. This document proposes to use multiple MPLS labels to indicate
this kind of information, for MPLS-LSP data plane.
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].
Status of This Memo
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Table of Contents
1. Introduction (LDN Background) . . . . . . . . . . . . . . . . 2
2. MPLS-LSP Data Plane for CQF . . . . . . . . . . . . . . . . . 3
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
4. Security Considerations . . . . . . . . . . . . . . . . . . . 4
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
6. Normative References . . . . . . . . . . . . . . . . . . . . 4
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction (LDN Background)
Large-scale Deterministic Network (LDN) [ldn] aims to achieve bounded
latency forwarding on layer-3 networks that contain long-distance
links, large number of nodes and flows. Figure 1 illustrates the
basic mechanism of LDN, where an upstream Node A and a downstream
Node B are considered. Each interface of a LDN router has three
cyclic scheduled queues, i.e., at any given time (or cycle), one of
the queues is sending packets and the others are receiving.
| cycle x | cycle x+1 |
Node A +-----------+-----------+
\
\packet
\receiving
\
| V | cycle y+1|
Node B +-----------+-----------+
cycle y \packets
\sending
\
\
V
Figure 1
In order to achieve end-to-end bounded latency, LDN requires that all
packets sent from the upstream router in a specific cycle MUST be
sent by the downstream router within another (one) specific cycle.
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For example, as shown in Figure 1, the packets sent by Node A within
cycle x MUST be put into single receiving queue in Node B, and then
be sent out within cycle y+1. The mapping relationship between x and
y+1 could be configured by a centralized controller, or be self-
learned by each peer of neighbors at the data plane.
Therefore, LDN requires a data plane mechanism to indicate which
upstream node's cycle a packet belongs to, so that the downstream
node could use this indication to put the packet into the right
receiving queue. This document proposes to use multiple MPLS labels
to indicate this kind of information, for MPLS-LSP data plane.
2. MPLS-LSP Data Plane for CQF
Allocate labels 1001,1002,1003 for LSP1
<-----------------------------------------
+----------------+ +----------------+
| Label:1003 | | Label:3007 |
| ----------+ | | ----------+ |
| Queue 1 | | | Queue 1 | |
| ----------+ | | ----------+ |
| | | |
| Label:1001 | | Label:3008 |
| ----------+ | | ----------+ |
| Queue 2 | +------------------+ Queue 2 | |
| ----------+ | | ----------+ |
| | | |
| Label:1002 | | Label:3009 |
| ----------+ | | ----------+ |
| Queue 3 | | | Queue 3 | |
| ----------+ | | ----------+ |
+----------------+ +----------------+
Upstream Node Downstream Node
Figure 2
Figure 2 shows the overall mechanism of MPLS-LSP data plane for CQF,
where the downstream node allocates three different MPLS labels
(i.e., 1000, 1002, and 1003) for LSP1, and advertises this
information to the upstream node by using signaling protocols such as
RSVP-TE. Each of these labels is associated with a specific queue in
the upstream node.
Assume that packets sent from the upstream node's queue 1, queue 2,
and queue 3 SHOULD be put into the downstream node's queue 3, queue1,
and queue 2, respectively. Note that how to establish such mapping
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relationships is out of the scope of this document. Based on these
mapping relationships, the downstream node SHOULD install its FIB
like the one shown in Figure 3.
Downstream Node's FIB
+------------+----------+---------+--------------+
| In-label | OutIF | OutQ | Out-label |
+------------+----------+---------+--------------+
| 1003 | 3 | 3 | 3009 |
+------------+----------+---------+--------------+
| 1001 | 3 | 1 | 3007 |
+------------+----------+---------+--------------+
| 1002 | 3 | 2 | 3008 |
+------------+----------+---------+--------------+
Figure 3
Therefore, the packets sent from the upstream node's queue 1 will be
put into the downstream node's queue 3, the packets sent from the
upstream node's queue 2 will be put into the downstream node's queue
1, and the packets sent from the upstream node's queue 3 will be put
into the downstream node's queue 2. In this way, end-to-end latency
could be bounded, as per [ldn].
3. IANA Considerations
TBD.
4. Security Considerations
TBD.
5. Acknowledgements
TBD.
6. Normative References
[ldn] Qiang, L., Liu, B., Eckert, T., and L. Geng, "Large-Scale
Deterministic Network", March 2019.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
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Authors' Addresses
Zhe Chen
Huawei
Email: chenzhe17@huawei.com
Li Qiang
Huawei
Email: qiangli3@huawei.com
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