< draft-jiang-detnet-ring-03.txt   draft-jiang-detnet-ring-04.txt >
Network Working Group Y. Jiang
Internet-Draft N. Finn
Intended status: Standards Track Huawei
J. Ryoo
ETRI
B. Varga
Ericsson
L. Geng
China Mobile
Expires: October 2019 April 24, 2019
Deterministic Networking Application in Ring Topologies DetNet Working Group Y. Jiang
draft-jiang-detnet-ring-03 Internet-Draft N. Finn
Intended status: Standards Track Huawei Technologies
Expires: December 19, 2019 J. Ryoo
ETRI
B. Varga
Ericsson
L. Geng
China Mobile
June 17, 2019
Deterministic Networking Application in Ring Topologies
draft-jiang-detnet-ring-04
Abstract Abstract
Deterministic Networking (DetNet) provides a capability to carry Deterministic Networking (DetNet) provides a capability to carry data
data flows for real-time applications with extremely low data loss flows for real-time applications with extremely low data loss rates
rates and bounded latency. This document describes how DetNet can and bounded latency. This document describes how DetNet can be used
be used in ring topologies to support Point-to-Point (P2P) and in ring topologies to support Point-to-Point (P2P) and Point-to-
Point-to-Multipoint (P2MP) real-time services. Multipoint (P2MP) real-time services.
Status of this Memo Status of This Memo
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Table of Contents Table of Contents
1. Introduction ............................................... 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Conventions used in this document ....................... 3 2. Conventions Used in This Document . . . . . . . . . . . . . . 3
1.2. Terminology ............................................. 4 3. Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . 3
2. P2P DetNet Ring ............................................ 4 4. P2P DetNet Ring . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. DetNet applications on a single ring for P2P traffic .... 4 4.1. DetNet applications on a single ring for P2P traffic . . 4
2.2. Implementation implications of a DetNet ring for P2P 4.2. Implementation implications of a DetNet ring for P2P
traffic ...................................................... 5 traffic . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. P2MP DetNet Ring ........................................... 5 5. P2MP DetNet Ring . . . . . . . . . . . . . . . . . . . . . . 5
3.1. DetNet applications on a single ring for P2MP traffic ... 5 5.1. DetNet applications on a single ring for P2MP traffic . . 5
3.2. Section LSPs as underlay (Service layer replication) .... 6 5.2. Section LSPs as underlay (service sub-layer replication) 6
3.3. P2MP LSP tunnels as underlay (LSP layer replication) .... 7 5.3. P2MP LSP tunnels as underlay (forwarding sub-layer
4. DetNet Ring Interconnections ............................... 8 replication) . . . . . . . . . . . . . . . . . . . . . . 7
4.1. Single node interconnection ............................. 8 6. DetNet Ring Interconnections . . . . . . . . . . . . . . . . 8
4.2. Dual node interconnection ............................... 9 6.1. Single node interconnection . . . . . . . . . . . . . . . 8
4.2.1. Dual node interconnection for P2P traffic ............ 9 6.2. Dual node interconnection . . . . . . . . . . . . . . . . 9
4.2.2. Dual node interconnection for P2MP traffic using 6.2.1. Dual node interconnection for P2P traffic . . . . . . 9
section LSP ................................................. 10 6.2.2. Dual node interconnection for P2MP traffic using
4.2.3. Dual node interconnection for P2MP traffic using P2MP section LSP . . . . . . . . . . . . . . . . . . . . . 10
LSP 11 6.2.3. Dual node interconnection for P2MP traffic using P2MP
5. Resource reservation ...................................... 11 LSP . . . . . . . . . . . . . . . . . . . . . . . . . 11
6. Security Considerations ................................... 11 7. Resource Reservation . . . . . . . . . . . . . . . . . . . . 11
7. IANA Considerations ....................................... 12 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
8. References ................................................ 12 9. Security Considerations . . . . . . . . . . . . . . . . . . . 11
8.1. Normative References ................................... 12 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
8.2. Informative References ................................. 12 10.1. Normative References . . . . . . . . . . . . . . . . . . 12
9. Acknowledgments ........................................... 13 10.2. Informative References . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13
1. Introduction 1. Introduction
An overview of Deterministic Networking (DetNet) architecture is The overall architecture for Deterministic Networking (DetNet), which
given in [I-D.ietf-detnet-architecture], and DetNet data plane provides a capability to carry specified unicast or multicast data
encapsulations are specified in [I-D.ietf-detnet-dp-sol]. But there flows for real-time applications with extremely low data loss rates
is not any discussion on a ring topology in [I-D.ietf-detnet- and bounded latency, is specified in [I-D.ietf-detnet-architecture],
architecture] yet. Furthermore, [I-D.ietf-detnet-use-cases] and the generic data plane framework, which is common to any DetNet
outlines several Detnet use cases where multicast capability is data plane implementations, is provided at
needed. If a multicast service replicates all of its packets from [I-D.ietf-detnet-data-plane-framework]. In addition to the DetNet
the source (as a traditional Virtual Private LAN Service (VPLS) architecture documents, RFC 8578 [RFC8578] outlines several DetNet
does), the requirements of deterministic delay and high use cases where multicast capability is needed. If a multicast
availability for all these replicated packets will pose a great service replicates all of its packets from the source (as a
challenge to the Detnet network. traditional Virtual Private LAN Service (VPLS) does), the
requirements of deterministic delay and high availability for all
these replicated packets will pose a great challenge to the DetNet
network.
In fact, ring topologies have been very popular and widely deployed Ring topologies have been very popular and widely deployed in network
in network arrangements for various transport networks, such as arrangements for various transport networks, such as Synchronous
Synchronous Digital Hierarchy, Synchronous Optical Network, Optical Digital Hierarchy, Synchronous Optical Network, Optical Transport
Transport Network, and Ethernet. The IETF has done some work on Network, and Ethernet. For Multi-Protocol Label Switching -
ring protection in Multi-Protocol Label Switching - Transport Transport Profile (MPLS-TP), the applicability of the MPLS-TP linear
Profile (MPLS-TP), such as [RFC6974] and [RFC8227]. All these works, protection [RFC6378][RFC7271] for ring topologies and the ring-
except Ethernet ring protection, typically use swapping or steering specific protection mechanism are specified in RFC 6974 [RFC6974] and
as the protection mechanism. As ring topologies are widely deployed RFC 8227 [RFC8227], respectively. All these works, except Ethernet
for transport networks, it is also necessary for DetNet to support ring protection, typically use swapping or steering as the protection
ring topologies (currently, there is not any discussion on a ring mechanism. As ring topologies are widely deployed for transport
topology in [I-D.ietf-detnet-architecture] yet). networks, it is also necessary for the DetNet to support ring
topologies.
This draft demonstrates how DetNet can be used in a ring topology. This document demonstrates how the DetNet can be used in a ring
Specifically, DetNet ring supports for Point-to-Point (P2P) and topology. Specifically, DetNet ring supports for Point-to-Point
Point-to-Multipoint (P2MP, for multicast services) are discussed in (P2P) and Point-to-Multipoint (P2MP, for multicast services) are
details. This document assumes that MPLS encapsulation for DetNet discussed in details. This document assumes that the Multi-Protocol
is supported as specified in [I-D.ietf-detnet-dp-sol-mpls] and all Label Switching (MPLS) encapsulation for DetNet is supported as
nodes in a ring network can support the Multi-Protocol Label specified in [I-D.ietf-detnet-mpls] and all nodes in a ring network
Switching (MPLS) functionalities. It should be noted that it is can support the MPLS functionalities. It should be noted that it is
more convenient for DetNet to support a ring topology with the more convenient for the DetNet to support a ring topology with the
intrinsic duplication and elimination mechanism, as there is no intrinsic duplication and elimination mechanism, as there is no need
need of swapping or steering operations (consequently, its of swapping or steering operations (consequently, its Operations,
Operations, Administration and Maintenance (OAM) can also be Administration and Maintenance (OAM) can also be simplified) for
simplified) for any service protection. service protection.
1.1. Conventions used in this document 2. Conventions Used in This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
this document are to be interpreted as described in [RFC2119]. "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.
1.2. Terminology 3. Abbreviations
This document uses the following abbreviations:
DetNet Deterministic Networking DetNet Deterministic Networking
LSP Label Switched Path
LSP Label Switched Path
MPLS Multi-Protocol Label Switching MPLS Multi-Protocol Label Switching
MPLS-TP Multi-Protocol Label Switching - Transport Profile MPLS-TP Multi-Protocol Label Switching - Transport Profile
P2MP Point-to-Multipoint
P2MP Point-to-Point P2P Point-to-Point
PEF Packet Elimination Function
P2P Point-to-Multipoint POF Packet Ordering Function
PRF Packet Replication Function
PEF Packet Elimination Function, see [I-D.ietf-detnet-
architecture]
POF Packet Ordering Function, see [I-D.ietf-detnet-
architecture]
PRF Packet Replication Function, see [I-D.ietf-detnet-
architecture]
PW Pseudowire PW Pseudowire
2. P2P DetNet Ring 4. P2P DetNet Ring
2.1. DetNet applications on a single ring for P2P traffic This section describes how the DetNet can deliver P2P traffic over a
single ring.
Figure 1 depicts an example of the DetNet ring for P2P real time 4.1. DetNet applications on a single ring for P2P traffic
traffic. Nodes A and C are DetNet aware devices, and P2P DetNet
traffic is transported from node A to node C.
A clockwise and a counter clockwise Pseudowire (PW, or S-Label as Figure 1 shows an example of the DetNet ring for P2P real time
described in [I-D.ietf-detnet-dp-sol-mpls]) and Label Switched Path traffic. Nodes A and C are DetNet aware devices, and P2P DetNet
(LSP, or T-Label as described in [I-D.ietf-detnet-dp-sol-mpls]) traffic is transported from node A to node C.
tunnel are configured from node A to node C respectively. The
DetNet traffic is replicated by a Packet Replication Function (PRF)
in node A, encapsulated with the specific PW and LSP labels, and
transported on both LSP paths towards node C. Upon reception of the
traffic, node C terminates the LSP and is aware of the DetNet
traffic by inspection of the PW label carried in each packet. A
Packet Elimination Function (PEF) in node C guarantees that only
one copy of the DetNet service exits on egress with the help of the
DetNet sequence number. A Packet Ordering Function (POF) can
further re-order packets in node C before transport of these
packets to the destination.
+---+#############+---+ +---+#############+---+
| B |-------------| C | +-- DetNet | B |-------------| C | +-- DetNet
+---+ +---+ egress +---+ +---+ egress
#/ *\ #/ *\
#/ *\ #/ *\
#/ *\ #/ *\
+---+ +---+ +---+ +---+
DetNet--+ | A | | D | DetNet--+ | A | | D |
ingress +---+ +---+ ingress +---+ +---+
\* */ \* */
\* */ \* */
\* */ \* */
+---+*************+---+ +---+*************+---+
| F |-------------| E | | F |-------------| E |
+---+ +---+ +---+ +---+
----- Physical Links ----- Physical Links
##### Clockwise_ ##### Clockwise_
***** Counter Clockwise ***** Counter Clockwise
Figure 1: DetNet Ring for P2P traffic Figure 1: DetNet Ring for P2P traffic
2.2. Implementation implications of a DetNet ring for P2P traffic A clockwise and a counter clockwise Label Switched Paths (LSPs) are
configured from node A to node C using the DetNet forwarding labels
(F-Labels) are configured from node A to node C. The DetNet service
sub-layer functions are provided at nodes A and C utilizing the
DetNet service label(s) (S-Label) and DetNet control word (d-CW) as
described in [I-D.ietf-detnet-mpls]. The P2P traffic is replicated
by a Packet Replication Function (PRF) in node A, encapsulated with
the d-CW and specific S-Label and F-Label(s), and transported on both
LSP paths towards node C. Upon reception of the traffic, node C
terminates the LSP and is aware of the DetNet traffic by inspection
of the S-Label carried in each packet. A Packet Elimination Function
(PEF) in node C guarantees that only one copy of the DetNet service
exits on egress with the help of the DetNet sequence number. A
Packet Ordering Function (POF) can further reorder packets in node C
before transport of these packets to the destination.
In a DetNet ring for P2P traffic, one path may be far longer than 4.2. Implementation implications of a DetNet ring for P2P traffic
the other path for the DetNet (this is a DetNet issue more general
than a ring).
The buffer needs to be large enough to accommodate for the sequence In a DetNet ring for P2P traffic, one path may be far longer than the
number difference between these two paths. Otherwise, some packets other path. The buffer for reordering at the egress needs to be
may get lost when a link fault causes traffic switching from a path large enough to accommodate for the sequence number difference
to another path. between these two paths.
3. P2MP DetNet Ring 5. P2MP DetNet Ring
3.1. DetNet applications on a single ring for P2MP traffic 5.1. DetNet applications on a single ring for P2MP traffic
Figure 2 further depicts an example of the DetNet ring for P2MP Figure 2 shows an example of the DetNet ring for P2MP real time
real time traffic. Nodes A, B, C, E and F are DetNet aware devices, traffic. Nodes A, B, C, E and F are DetNet aware devices, and P2MP
and P2MP DetNet traffic is transported from head-end node A to DetNet traffic is transported from head-end node A to multiple tail-
multiple tail-end nodes C, E and F. end nodes C, E and F.
Two approaches are described in Section 3.2 and 3.3 for P2MP Two approaches are described in Section 5.2 and Section 5.3 for P2MP
traffic. traffic.
+---+#############+---+ +---+#############+---+
| B |-------------| C | +-- DetNet | B |-------------| C | +-- DetNet
+---+*************+---+ egress +---+*************+---+ egress
#/ *\# #/ *\#
#/ *\# #/ *\#
#/ *\# #/ *\#
+---+ +---+ +---+ +---+
DetNet--+ | A | | D | DetNet--+ | A | | D |
ingress +---+ +---+ ingress +---+ +---+
\* */# \* */#
\* */# \* */#
\* */# \* */#
+---+*************+---+ +---+*************+---+
DetNet--+ | F |-------------| E |+-- DetNet DetNet--+ | F |-------------| E |+-- DetNet
egress +---+#############+---+ egress egress +---+#############+---+ egress
----- Physical Links ----- Physical Links
##### Clockwise traffic ##### Clockwise traffic
***** Counter Clockwise traffic ***** Counter Clockwise traffic
Figure 2: DetNet Ring for P2MP traffic Figure 2: DetNet Ring for P2MP traffic
3.2. Section LSPs as underlay (Service layer replication) 5.2. Section LSPs as underlay (service sub-layer replication)
If section LSPs are used as an underlay for DetNet services, a If section LSPs are used as an underlay for DetNet services, a
bidirectional section LSP tunnel is set up between each pair of bidirectional section LSP tunnel is set up between each pair of
neighboring nodes in the ring (e.g., node A and node B, ..., node F neighboring nodes in the ring (e.g., node A and node B, ..., node F
and node A). In this case, DetNet PW layer replicates the DetNet and node A). In this case, the DetNet sub-layer replicates the
packets from one tail-end to another neighboring tail-end. DetNet packets from one tail-end to another neighboring tail-end.
The DetNet head-end (i.e., node A) in the ring needs to support The DetNet head-end (i.e., node A) in the ring needs to support
DetNet replication function. Upon reception on node A, the DetNet DetNet replication function. Upon reception on node A, the DetNet
traffic is replicated in node A, encapsulated with the specific PW traffic is replicated with a d-CW, encapsulated with a S-Label and a
and section LSP labels, and then transported on both section LSPs section LSP label per DetNet member flow, and transported on both
(i.e., A-B and A-F) originated from the head-end. section LSPs (i.e., A-B and A-F).
All intermediate nodes (non tail-ends) on the ring SHOULD All intermediate nodes (non tail-ends) on the ring MUST transparently
transparently forward the DetNet traffic with a specific PW to the forward the DetNet packet, which contains a d-CW and S-Label, to the
next hop on the ring in the same direction. next hop on the ring.
All DetNet tail-ends except the penultimate node (egress nodes such All DetNet tail-ends except the penultimate node (egress nodes such
as nodes C and E in the clockwise, and node F, E and C in the as nodes C and E in the clockwise, and nodes F, E and C in the
counter clockwise) on the ring MUST support both DetNet PRF and PEF counter clockwise) on the ring MUST support both DetNet PRF and PEF
functions, and MAY further support a DetNet POF function. For the functions, and MAY further support a DetNet POF function. For the
example of Figure 2, upon reception of the clockwise traffic, node example of Figure 2, upon reception of the clockwise traffic, node C
C terminates the section LSP and is aware of the DetNet traffic by terminates the section LSP and recognizes the DetNet flow by
inspection of the PW label in the packet. Firstly, node C needs to inspection of the S-label in the packet. Firstly, node C needs to
transparently forward the DetNet traffic with a specific PW to the forward the DetNet packet to the next hop on the ring in the
next hop on the ring in the same direction. Secondly, DetNet clockwise direction. Secondly, the DetNet packet is also directed to
traffic is directed to a DetNet PEF associated with a specific PW, a DetNet PEF associated with the DetNet flow, only one copy is
only one copy of the DetNet service is selected by inspection of egressed from the ring by inspection of the sequence number in the
the DetNet sequence number. Furthermore, if DetNet POF function is d-CW. Furthermore, if the DetNet POF function is enabled, the
enabled, the packets in the DetNet flow are reordered before exit packets in the DetNet flow are reordered before exit to DetNet
to DetNet egress. egress.
If multiple endpoints are attached to a tail-end node, a multicast If multiple endpoints are attached to a tail-end node, a multicast
module can be used to forward the filtered DetNet traffic to all module can be used to forward the traffic to all these endpoints.
these endpoints.
To avoid a loop of DetNet service, the penultimate node in the ring To avoid a loop of DetNet service, the penultimate node in the ring
(such as node B on the counter clock-wise LSP) needs to terminate (such as node B on the counter clock-wise LSP) MUST terminate the
the DetNet flow. For example, upon reception of the clockwise DetNet flow. For example, upon reception of the clockwise DetNet
DetNet traffic, node F terminates the DetNet traffic by inspection traffic, node F terminates the DetNet traffic by inspection of the
of the PW label in the packet. As an alternative, the last DetNet S-Label in the packet. As an alternative, the last DetNet tail-end
tail-end (such as node C on the counter clock-wise LSP) may (such as node C on the counter clock-wise LSP) MAY terminate the
terminate the DetNet flow, so that the bandwidth from this node to DetNet flow, so that the bandwidth from this node to the penultimate
the penultimate node can be saved. node can be saved.
3.3. P2MP LSP tunnels as underlay (LSP layer replication) 5.3. P2MP LSP tunnels as underlay (forwarding sub-layer replication)
If P2MP LSPs are used as an underlay for the DetNet service, a P2MP If P2MP LSPs are used as an underlay for the DetNet service, a P2MP
unidirectional LSP tunnel in clockwise is set up from head-end unidirectional LSP tunnel in clockwise is set up from head-end
(ingress node A) to all the tail-ends (egress nodes C, E and F) for (ingress node A) to all the tail-ends (egress nodes C, E and F) for
the ring, and another P2MP unidirectional LSP tunnel in counter the ring, and another P2MP unidirectional LSP tunnel in counter
clockwise is set up from head-end (ingress node A) to all the tail- clockwise is set up from head-end (ingress node A) to all the tail-
ends (egress nodes F, E and C) for the ring. Thus, a PRF in LSP ends (egress nodes F, E and C) for the ring. Thus, a PRF in LSP
layer replicates the DetNet packets from one tail-end to another layer replicates the DetNet packets from one tail-end to another
neighboring tail-end. neighboring tail-end.
The DetNet head-end (i.e., node A) in the ring needs to support The DetNet head-end (i.e., node A) in the ring needs to support the
DetNet PRF function. Upon reception on node A, the DetNet traffic DetNet PRF function. Upon reception on node A, the DetNet traffic is
is replicated, encapsulated with the specific PW and P2MP LSP replicated with a d-CW, encapsulated with a S-Label per DetNet member
labels, and transported on both P2MP LSP tunnels in the ring. flow, and transported on both P2MP LSP tunnels in the ring.
All DetNet tail-ends (egress nodes such as node C, E and F in All DetNet tail-ends (egress nodes such as nodes C, E and F in
Figure 2) on the ring need to support the DetNet PEF function. For Figure 2) on the ring need to support the DetNet PEF function. For
example, upon reception of the traffic, node C pops the P2MP LSP example, upon reception of the traffic, node C pops the P2MP LSP
label and is aware of the DetNet traffic by inspection of the PW label and is aware of the DetNet traffic by inspection of the S-Label
label in the label stack. Traffic from both directions with the label in the label stack. Two DetNet member flows are identified
same PW is directed to the same PEF so that only one copy of the with their S-Labels and directed to the same PEF so that only one
DetNet service is selected by inspection of the DetNet sequence copy of the DetNet service is selected by inspection of the DetNet
number. Furthermore, if DetNet POF function is enabled, the packets sequence number in the d-CW. Furthermore, if DetNet POF function is
in the DetNet flow are reordered before exit to DetNet egress. enabled, the packets in the DetNet flow are reordered before exit to
DetNet egress.
If multiple endpoints are attached to a tail-end node, a multicast If multiple endpoints are attached to a tail-end node, a multicast
module can be used to forward the filtered DetNet traffic to all module can be used to forward the filtered DetNet traffic to all
these endpoints. these endpoints
4. DetNet Ring Interconnections 6. DetNet Ring Interconnections
Two DetNet rings can be connected via one or more interconnection Two DetNet rings can be connected via one or more interconnection
nodes. Figures 3(a) and 3(b) show the ring interconnection nodes. Figure 3 shows the ring interconnection scenarios with a
scenarios with a single node and dual nodes respectively. In the single node and dual nodes. In the interconnected rings, each ring
interconnected rings, each ring operates in the same way as operates in the same way as described in Section 4 and Section 5
described in Sections 2 and 3 except the node or nodes that are except the node or nodes that are used to interconnect two rings.
used to interconnect two rings.
S T
B C S T O----O
O----O O----O / \
/ \ / \ B I1/ \
/ \ / \ O----O Ring R O U
A O Ring L O Ring R O U / \ /
\ /I\ / / \ /
\ / \ / A O Ring L O----O
O----O O----O \ /I2 V
F E W V \ /
O----O
F E
(a) (b)
Figure 3: DetNet ring interconnection with: (a) single node (node I),
and (b) dual nodes (nodes I1 and I2)
In this section, we describe the behavior of interconnection nodes In this section, we describe the behavior of interconnection nodes
with the traffic going from Ring L to Ring R. Symmetrical with the traffic going from Ring L to Ring R. Symmetrical
description is assumed for the traffic in the other direction (i.e., description is assumed for the traffic in the other direction (i.e.,
from Ring R to Ring L). from Ring R to Ring L).
S T 6.1. Single node interconnection
B C S T O---O
O---O O---O / \
/ \ / \ B I1/ \
/ \ / \ O---O Ring R O U
A O Ring L O Ring R O U / \ /
\ /I\ / / \ /
\ / \ / A O Ring L O---O
O---O O---O \ /I2 V
F E W V \ /
O---O
F E
(a) (b)
Figure 3: DetNet ring interconnection with: (a) single node (node
I), and (b) dual nodes (nodes I1 and I2).
4.1. Single node interconnection
In the case of the single node interconnection, as shown in Figure In the case of the single node interconnection, as shown in
3(a), both P2P and P2MP DetNet traffic that needs to be transported Figure 3(a), both P2P and P2MP DetNet traffic that needs to be
between Ring L and Ring R uses a single interconnection node transported between Ring L and Ring R use a single interconnection
between two rings. Thus, the interconnection node acts as a DetNet node between two rings. Thus, the interconnection node acts as a
relay node, which provides both PRF and PEF functions. DetNet relay node, which provides both PRF and PEF functions.
For P2P DetNet traffic going from Ring L to Ring R, interconnection For P2P DetNet traffic going from Ring L to Ring R, interconnection
node I receives the same Detnet flow traffic from both node C and node I receives the same DetNet flow traffic from both node C and
node E (i.e., clockwise and counter-clockwise), a PEF in node I node E (i.e., clockwise and counter-clockwise), a PEF in node I
performs packet elimination, and a PRF in node I replicates the performs packet elimination, and a PRF in node I replicates the
packet, node I then sends one copy to node S and another copy to packet, node I then sends one copy to node S and another copy to node
node W. W.
For P2MP DetNet traffic going from Ring L to Ring R, For P2MP DetNet traffic going from Ring L to Ring R, interconnection
interconnection node I performs the same packet elimination and node I performs the same packet elimination and replication functions
replication functions as described above. In addition, node I as described above. In addition, node I further transparently
further transparently forwards the P2MP DetNet traffic on Ring L in forwards the P2MP DetNet traffic on Ring L in the same direction if
the same direction if it is not the last tail-end node. it is not the last tail-end node.
4.2. Dual node interconnection 6.2. Dual node interconnection
In order to prevent a single point of failure, two interconnection In order to prevent a single point of failure, two interconnection
nodes can be used as shown in Figure 3(b). To provide high nodes can be used as shown in Figure 3(b). To provide high
availability for DetNet services, dual node interconnection is availability for DetNet services, dual node interconnection is
recommended. Two interconnection nodes act as DetNet relay nodes, recommended. Two interconnection nodes act as DetNet relay nodes,
each provides both packet replication and elimination functions. each provides both packet replication and elimination functions.
4.2.1. Dual node interconnection for P2P traffic 6.2.1. Dual node interconnection for P2P traffic
For the P2P DetNet traffic that flows from Ring L to Ring R, the For the P2P DetNet traffic that flows from Ring L to Ring R in
operation of interconnection nodes I1 and I2 follows the Figure 3(b), the operations of interconnection nodes I1 and I2 are
description on relay nodes shown in Figure 1 of Section 3.2.4 in described below.
[I-D.ietf-detnet-architecture]. In the following, the operation is
explained with Figure 3(a).
When interconnection node I1 receives clockwise traffic from node B, When interconnection node I1 receives clockwise traffic from node B,
it replicates the traffic and sends one copy to interconnection it replicates the traffic and sends one copy to interconnection node
node I2 and another copy to a PEF in node I1. I2 and the other copy to a PEF in interconnection node I1.
When interconnection node I1 receives counter-clockwise traffic When interconnection node I1 receives counter-clockwise traffic from
from interconnection node I2, it also forwards the traffic to the interconnection node I2, it forwards the traffic to the PEF of
PEF of I1. interconnection node I1.
At the PEF of I1, duplicate elimination is performed for the At the PEF of interconnection node I1, duplicate elimination is
clockwise traffic from node B and the counter-clockwise traffic performed for the clockwise traffic from node B and the counter-
from interconnection node I2, and only one copy is sent to the clockwise traffic from interconnection node I2, and only one copy is
clockwise direction of Ring R (i.e., sent towards node S). sent to the clockwise direction of Ring R (i.e., sent towards node
Furthermore, if DetNet POF function is enabled on I1, the packets S). Furthermore, if DetNet POF function is enabled on
in the DetNet flow are reordered before exit to Ring R. interconnection node I1, the packets in the DetNet flow are reordered
before being forwarded to Ring R.
When interconnection node I2 receives counter-clockwise traffic When interconnection node I2 receives counter-clockwise traffic from
from node E, it replicates the traffic and sends one copy to node E, it replicates the traffic and sends one copy to
interconnection node I1 and another copy to a PEF in node I2. interconnection node I1 and the other copy to a PEF in
interconnection node I2.
When interconnection node I2 receives clockwise traffic from When interconnection node I2 receives clockwise traffic from
interconnection node I1, it also forwards the traffic to the PEF of interconnection node I1, it forwards the traffic to the PEF of
I2. interconnection node I2.
At the PEF of I2, duplicate elimination is performed for the At the PEF of interconnection node I2, duplicate elimination is
counter-clockwise traffic from node E and the clockwise traffic performed for the counter-clockwise traffic from node E and the
from interconnection node I1, and only one copy is sent to the clockwise traffic from interconnection node I1, and only one copy is
counter-clockwise direction of Ring R (i.e., sent towards node V). sent to the counter-clockwise direction of Ring R (i.e., sent towards
Furthermore, if DetNet POF function is enabled on node I2, the node V). Furthermore, if DetNet POF function is enabled on
packets in the DetNet flow are reordered before exit to Ring R. interconnection node I2, the packets in the DetNet flow are reordered
before being forwarded to Ring R.
4.2.2.Dual node interconnection for P2MP traffic using section LSP 6.2.2. Dual node interconnection for P2MP traffic using section LSP
For the P2MP traffic that flows from Ring L to Ring R, each ring is For the P2MP traffic that flows from Ring L to Ring R in Figure 3(b),
configured and operated as described in Section 3.2 except the each ring is configured and operated as described in Section 5.2
interconnection nodes, whose operations are described below. except the interconnection nodes, whose operations are described
below.
When interconnection node I1 receives clockwise traffic from node B, When interconnection node I1 receives clockwise traffic from node B,
its PRF replicates the traffic and sends one copy to its PRF replicates the traffic and sends one copy to interconnection
interconnection node I2 and another copy to node I1's PEF. node I2 and the other copy to interconnection node I1's PEF.
When interconnection node I1 receives the counter-clockwise traffic When interconnection node I1 receives the counter-clockwise traffic
from interconnection node I2, its PRF replicates the traffic and from interconnection node I2, its PRF replicates the traffic and
sends one copy to node B and another copy to node I1's PEF unless sends one copy to node B and the other copy to interconnection node
I1's PEF unless interconnection node I1 is the penultimate node for
the counter-clockwise traffic on Ring L. In the case that
interconnection node I1 is the penultimate node for the counter- interconnection node I1 is the penultimate node for the counter-
clockwise traffic on Ring L. In the case that interconnection node clockwise traffic on Ring L, the counter-clockwise traffic from
I1 is the penultimate node for the counter-clockwise traffic on interconnection node I2 is only forwarded to interconnection node
Ring L, the counter-clockwise traffic from interconnection node I2 I1's PEF.
is only forwarded to node I1's PEF.
At node I1's PEF, duplicate elimination is performed for the At interconnection node I1's PEF, duplicate elimination is performed
clockwise traffic from node B and the counter-clockwise traffic for the clockwise traffic from node B and the counter-clockwise
from interconnection node I2, and only one copy is sent to the traffic from interconnection node I2, and only one copy is sent to
clockwise direction of Ring R (i.e., sent towards node S). the clockwise direction of Ring R (i.e., sent towards node S).
Furthermore, if DetNet POF function is enabled on node I1, the Furthermore, if DetNet POF function is enabled on node I1, the
packets in the DetNet flow are reordered before exit to Ring R. packets in the DetNet flow are reordered before being forwarded to
Ring R.
When interconnection node I2 receives the counter-clockwise traffic When interconnection node I2 receives the counter-clockwise traffic
from node E, its PRF replicates the traffic and sends one copy to from node E, its PRF replicates the traffic and sends one copy to
interconnection node I1 and another copy to node I2's PEF. interconnection node I1 and the other copy to node I2's PEF.
When interconnection node I2 receives the clockwise traffic from When interconnection node I2 receives the clockwise traffic from
interconnection node I1, its PRF replicates the traffic and sends interconnection node I1, its PRF replicates the traffic and sends one
one copy to node E and another copy to node I2's PEF unless copy to node E and the other copy to interconnection node I2's PEF
interconnection node I2 is the penultimate node for the clockwise unless interconnection node I2 is the penultimate node for the
traffic in Ring L. In the case that interconnection node I2 is the clockwise traffic on Ring L. In the case that interconnection node
penultimate node for the clockwise traffic in Ring L, the clockwise I2 is the penultimate node for the clockwise traffic on Ring L, the
traffic from interconnection node I1 is only forwarded to node I2's clockwise traffic from interconnection node I1 is only forwarded to
PEF. node I2's PEF.
At node I2's PEF, duplicate elimination is performed for the At node I2's PEF, duplicate elimination is performed for the counter-
counter-clockwise traffic from node E and the clockwise traffic clockwise traffic from node E and the clockwise traffic from
from interconnection node I1, and only one copy is sent to the interconnection node I1, and only one copy is sent to the counter-
counter-clockwise direction of Ring R (i.e., sent towards node V). clockwise direction of Ring R (i.e., sent towards node V).
Furthermore, if DetNet POF function is enabled on node I2, the Furthermore, if DetNet POF function is enabled on interconnection
packets in the DetNet flow are reordered before exit to Ring R. node I2, the packets in the DetNet flow are reordered before being
forwarded to Ring R.
4.2.3.Dual node interconnection for P2MP traffic using P2MP LSP 6.2.3. Dual node interconnection for P2MP traffic using P2MP LSP
If P2MP LSPs are used in the interconnected rings, two P2MP If P2MP LSPs are used in the interconnected rings, two P2MP
unidirectional LSP tunnels are used on each ring for the clockwise unidirectional LSP tunnels are used on each ring for the clockwise
and counter-clockwise directions. and counter-clockwise directions.
When the P2MP traffic is forwarded from one ring to another ring, When the P2MP traffic is forwarded from one ring to another ring, for
for example from Ring L to Ring R in Figure 3(b), each P2MP LSP in example from Ring L to Ring R in Figure 3(b), each P2MP LSP in Ring L
Ring L MUST include interconnection nodes I1 and I2 as its tail- MUST include interconnection nodes I1 and I2 as its tail-ends. For
ends. For Ring R, one P2MP LSP is set up from interconnection node Ring R, one P2MP LSP is set up from interconnection node I1 to all
I1 to all the tail-ends in the clockwise direction on Ring R, and the tail-ends in the clockwise direction on Ring R, and the other
the other P2MP LSP is set up from interconnection node I2 to all P2MP LSP is set up from interconnection node I2 to all the tail-ends
the tail-ends in the counter-clockwise direction on Ring R. in the counter-clockwise direction on Ring R. Therefore, an
Therefore, an interconnection node acts as a tail-end for one ring interconnection node acts as a tail-end for one ring and a head-end
and a head-end for another ring in one direction, and performs the for another ring in one direction, and performs the same operation of
same operation of tail-end and head-end as specified in Section 3.3. tail-end and head-end as specified in Section 5.3.
5. Resource reservation 7. Resource Reservation
In order to guarantee that DetNet flows don't suffer from network In order to guarantee that DetNet flows do not suffer from network
congestion, resource reservation considerations as outlined in congestion, the DetNet data plane considerations on resource
Section 4.3.2 of [I-D.ietf-detnet-architecture] apply here. reservation and allocation as described in
[I-D.ietf-detnet-data-plane-framework] apply here.
6. Security Considerations 8. IANA Considerations
This document describes the application of DetNet on general ring There are no IANA actions required by this document
topologies. Thus the security considerations as described in [I-
D.ietf-detnet-dp-sol] also apply to this document.
7. IANA Considerations 9. Security Considerations
There are no IANA actions required by this document. This document describes the application of DetNet MPLS on ring
topologies. Thus, the security considerations described in
[I-D.ietf-detnet-mpls] are also applied to this document. If any new
security considerations specific to ring topologies are identified,
they will be added in a future version of this draft.
8. References 10. References
8.1. Normative References 10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [I-D.ietf-detnet-architecture]
Requirement Levels", BCP 14, RFC 2119, March 1997 Finn, N., Thubert, P., Varga, B., and J. Farkas,
"Deterministic Networking Architecture", draft-ietf-
detnet-architecture-13 (work in progress), May 2019.
[I-D.ietf-detnet-architecture] Finn, N., Thubert, P., Varga, B., [I-D.ietf-detnet-data-plane-framework]
and J. Farkas, "Deterministic Networking Architecture", Varga, B., Farkas, J., Berger, L., Fedyk, D., Malis, A.,
draft-ietf-detnet-architecture (work in progress), June Bryant, S., and J. Korhonen, "DetNet Data Plane
2018 Framework", draft-ietf-detnet-data-plane-framework-00
(work in progress), May 2019.
[I-D.ietf-detnet-dp-sol-mpls] Korhonen, J., Varga, B., "DetNet MPLS [I-D.ietf-detnet-mpls]
Data Plane Encapsulation", draft-ietf-detnet-dp-sol-mpls Varga, B., Farkas, J., Berger, L., Fedyk, D., Malis, A.,
(work in progress), October 2018 Bryant, S., and J. Korhonen, "DetNet Data Plane: MPLS",
draft-ietf-detnet-mpls-00 (work in progress), May 2019.
8.2. Informative References [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>.
[I-D.ietf-detnet-dp-sol] Korhonen, J., Andersson, L., Jiang, Y., [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
and etc., "DetNet Data Plane Encapsulation", draft-ietf- 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
detnet-dp-sol (work in progress), March 2018 May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[I-D.ietf-detnet-use-cases] Grossman, E., "Deterministic Networking 10.2. Informative References
Use Cases", draft-ietf-detnet-use-cases (work in
progress), October 2018
[RFC6974] Weingarten, Y., Bryant, S., and etc., "Applicability of [RFC6378] Weingarten, Y., Ed., Bryant, S., Osborne, E., Sprecher,
MPLS Transport Profile for Ring Topologies", RFC 6974, N., and A. Fulignoli, Ed., "MPLS Transport Profile (MPLS-
July 2013 TP) Linear Protection", RFC 6378, DOI 10.17487/RFC6378,
October 2011, <https://www.rfc-editor.org/info/rfc6378>.
[RFC8227] Cheng, W., Wang, L., and etc., "MPLS-TP Shared-Ring [RFC6974] Weingarten, Y., Bryant, S., Ceccarelli, D., Caviglia, D.,
Protection (MSRP) Mechanism for Ring Topology", RFC 8227, Fondelli, F., Corsi, M., Wu, B., and X. Dai,
August 2017 "Applicability of MPLS Transport Profile for Ring
Topologies", RFC 6974, DOI 10.17487/RFC6974, July 2013,
<https://www.rfc-editor.org/info/rfc6974>.
9. Acknowledgments [RFC7271] Ryoo, J., Ed., Gray, E., Ed., van Helvoort, H.,
D'Alessandro, A., Cheung, T., and E. Osborne, "MPLS
Transport Profile (MPLS-TP) Linear Protection to Match the
Operational Expectations of Synchronous Digital Hierarchy,
Optical Transport Network, and Ethernet Transport Network
Operators", RFC 7271, DOI 10.17487/RFC7271, June 2014,
<https://www.rfc-editor.org/info/rfc7271>.
The authors would like to thank Loa Anderson for his discussion. [RFC8227] Cheng, W., Wang, L., Li, H., van Helvoort, H., and J.
Dong, "MPLS-TP Shared-Ring Protection (MSRP) Mechanism for
Ring Topology", RFC 8227, DOI 10.17487/RFC8227, August
2017, <https://www.rfc-editor.org/info/rfc8227>.
[RFC8578] Grossman, E., Ed., "Deterministic Networking Use Cases",
RFC 8578, DOI 10.17487/RFC8578, May 2019,
<https://www.rfc-editor.org/info/rfc8578>.
Authors' Addresses Authors' Addresses
Yuanlong Jiang Yuanlong Jiang
Huawei Technologies Co., Ltd. Huawei Technologies
Bantian, Longgang district Bantian, Longgang district
Shenzhen 518129, China Shenzhen 518129
China
Phone: +86-18926415311 Phone: +86-18926415311
Email: jiangyuanlong@huawei.com Email: jiangyuanlong@huawei.com
Norman Finn Norman Finn
Huawei Technologies Co. Ltd Huawei Technologies
3755 Avocado Blvd, 3755 Avocado Blvd
California 91941, USA California 91941
USA
Phone: +1 925 980 6430 Phone: +1 925 980 6430
Email: norman.finn@mail01.huawei.com Email: norman.finn@mail01.huawei.com
Jeong-dong Ryoo Jeong-dong Ryoo
ETRI ETRI
218 Gajeongno 218 Gajeongno
Yuseong-gu, Daejeon 305-700, South Korea Yuseong-gu, Daejeon 34129
South Korea
Phone: +82-42-860-5384 Phone: +82-42-860-5384
Email: ryoo@etri.re.kr Email: ryoo@etri.re.kr
Balazs Varga Balazs Varga
Ericsson Ericsson
Konyves Kalman krt. 11/B Konyves Kalman krt. 11/B
Budapest 1097 Budapest 1097
Hungary Hungary
Email: balazs.a.varga@ericsson.com Email: balazs.a.varga@ericsson.com
Liang Geng Liang Geng
China Mobile China Mobile
Beijing, China Beijing
China
Email: gengliang@chinamobile.com Email: gengliang@chinamobile.com
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