Internet DRAFT - draft-liu-msr6-use-cases
draft-liu-msr6-use-cases
Network Working Group Y. Liu
Internet-Draft F. Yang
Intended status: Informational China Mobile
Expires: 12 January 2023 A. Wang
China Telecom
X. Zhang
China Unicom
X. Geng
Z. Li
Huawei
11 July 2022
MSR6(Multicast Source Routing over IPv6) Use Cases
draft-liu-msr6-use-cases-01
Abstract
MSR6 (Multicast Source Routing over IPv6) defines multicast
replication as a Layer 3 function. It reuses existing IPv6 headers,
functions, and capabilities to forward packets through non-multicast
nodes, and adds no flow state at intermediate network nodes.
This document introduces the use cases for MSR6.
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
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 12 January 2023.
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Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the
document authors. All rights reserved.
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
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provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. MSR6 in DCN . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Use of MSR6 TE . . . . . . . . . . . . . . . . . . . . . 3
2.2. Use of MSR6 BE . . . . . . . . . . . . . . . . . . . . . 5
3. MSR6 in SD-WAN . . . . . . . . . . . . . . . . . . . . . . . 5
3.1. SD-WAN over Public Internet . . . . . . . . . . . . . . . 5
3.2. SD-WAN over Service-Provider Network . . . . . . . . . . 7
4. Host-initiated Multicast . . . . . . . . . . . . . . . . . . 8
4.1. Multicast for Surveillance Camera Data Transmission . . . 8
4.2. Multicast for Audio and Video Conferencing . . . . . . . 9
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
6. Security Considerations . . . . . . . . . . . . . . . . . . . 10
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10
8. Normative References . . . . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction
MSR6 (Multicast Source Routing over IPv6) defines multicast
replication as a Layer 3 function. It reuses existing IPv6 headers,
functions, and capabilities to forward packets through non-multicast
nodes, and adds no flow state at intermediate network nodes
([[I-D.cheng-spring-ipv6-msr-design-consideration]]).
MSR6 encodes a set of destination nodes or a multicast tree in an
IPv6 header, which supports both BE(Best Effort) forwarding based on
SPF(Shortest Path First) and TE(Traffic Engineering) forwarding based
on explicit path.
MSR6 focuses on use cases with 1 or several following
characteristics:
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* Large network scale with Numerous multicast service;
* IPsec to guarantee security when multicast transmitting through
Internet;
* Host Initiated or overlay Multicast Transport.
These characteristics also corresponds to MSR6 deployment modes
introduced in [I-D.cheng-spring-ipv6-msr-design-consideration],
including P2MP Multicast Tunnel, Multicast Overlay Network and Host-
Initiated Multicast.
This document describes diverse use cases the MSR6 technology may be
Used in different deployment modes.
2. MSR6 in DCN
There are applications in data center with point-to-multipoint
communication patterns that would benefit from network multicast
service, without which, these applications, when migrating to public
clouds, will use server based packet replication techniques. This
leads to CPU load inflation and prevents tenants from sustaining high
throughputs and low latencies for multicast workloads.
At the same time, An increasing number of organizations are adopting
IPv6 in their clouds, driven by the public IPv4 space exhaustion,
private IPv4 scarcity, especially within large-scale networks, and
the need to provide connectivity to IPv6-only clients.
Similar as the case in DCN, MSR6 could also be used in other large
scale network, like nationwide inter-AS network or large metro
network. For example OTT live streaming could be conveyed in a
nationwide network with multiple multicast source distributed in
different areas.
2.1. Use of MSR6 TE
The following figure shows an example of a data center network with
dual-homes hosts for reliability. There are about 10k swtiches, 9k
of which are leaves, and 100k adjacencies.
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+-------+ +---------------+ +----------------+ +--------+
| DC-GW +---+ CORE1 | | CORE2 | ...| COREn |
+---+---+ ++------+--+--+-+ ++-+--+----+-----+ +--------+
| | | | | | | | |
+----+----+ | | | +-------------------------+
| Server | | +-------------------+ | | | |
|(source1)| | | | | | | | |
+---------+ | | | | +--------+ | | |
| | | | | | | |
| | +----------------+ | | |
| | | | | | | |
++---+-+ +------+ +-+----+ ++----++ +------+
|SPINE1| |SPINE2| |SPINE3| |SPINE4| ...|SPINEn|
++----++ ++---+-+ +-+--+-+ ++----++ +------+
| | | | | | | |
| +-------+ | | +--------+ |
| | | | | | | |
| +-------+ | | | +------+ | |
| | | | | | | |
++--+-+ ++-+--+ ++--+-+ ++--+-+ +-----+
|LEAF1| |LEAF2| |LEAF3| |LEAF4| ...|LEAFn|
+-----+ +-----+ +-----+ +-----+ +-----+
| | | | |
+- - - -+ +- - - -+ +- - - -+ +- - - -+ +- - - -+
| Server| | Server| |Server3| |Server4|...| Server|
+- - - -+ +- - - -+ +- - - -+ +- - - -+ +- - - -+
For multicast application in DCN, multicast source could be inside
DCN or outside DCN.
For example, a multicast stream could be from source1 to service 3
and server 4. The multicast tree is from DC-Gateway to LEAF3 and
LEAF4, which could be presented as:
DC-GW(ingress
node)-->CORE1---->SPINE3--[replicate]--->LEAF3(leaf)+LEAF4(leaf)
MSR6 could be used in Data Center Network(DCN) to provide scalable
multicast solution. Only the nodes/adjacencies in the multicast tree
are encoded in the packet with segment/bitstring, which decouples
from network size and number of services.
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2.2. Use of MSR6 BE
As illustrated in the following figure, a data-center may contain: a
network fabric configured in unicast-only mode, hosts running as
virtual machines (VMs) managed by tenants, central replicators (C-R)
for providing MSR6 packet delivery service among the hosts of a
tenant.
+----+ +----+ +----+
|C-R1| |C-R2| |C-Rn| ====>Central-Replicator
+-+--+ +-+--+ +-+--+
| | |
+-----+--------+--------+-----+
| Spine +Leaf +vSwitch Fabric |
| (Unicast Only) |
+--+--+--+--+--+--+--+--+--+--+
| | | | | | | |
h1 | h3 h4 | h6 | h8 ====>Tenant-1
| | |
h2 h5 h7 ====>Tenant-2
Take tenant-1 for example. The host h1 can send multicast flow using
MSR6 packets to C-R1, the MSR6 packets include one or more of the
destination hosts h3/h4/h6/h8 encoding in the MSR6 header. An MSR6
packet may be sent to C-R1 where it is replicated and sends to the
desired destination hosts. An MSR6 packet may be sent to C-R1 where
it is replicated and sends to the part of the destination hosts, and
another copy to C-R2 for replication and delivery to the left
destination hosts.
A Tenant may have a dedicated set of C-Rs for its own use, or a
Tenant may use a shared C-Rs for its replication requirement among
VMs.
3. MSR6 in SD-WAN
3.1. SD-WAN over Public Internet
SD-WAN can be deployed based on public Internet, where the underlay
network is providing nothing else but a simple service normally
called "Best Effort" unicast. In this case, security is one of the
fundamental requiremnt in SD-WAN network. Multicast services for SD-
WAN also request encryption. The following figure shows an example
of SD-WAN multicast.
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IPv6 Network +-----+ +-----+
| CPE1| | CPE2|
+-----+ +-----+
**********
**** ****
** Internet **
**** ****
**********
+-----+ +-----+ +-----+ +-----+
| CPE3| | CPE4| ... |CPE98| |CPE99|
+-----+ +-----+ +-----+ +-----+
********** | |
**** **** +---------+
** Internet ** | Server |
**** **** | (source)|
********** +---------+
+-----+ +-----+
| CPE5| | CPE6|
+-----+ +-----+
| |
+- - - - - - - - - -+
| Server (Receiver) |
+- - - - - - - - - -+
A multicast case in SD-WAN is from CE99 to CE3, CE5 and CE6. The
multicast tree could presented as:
CE99(ingress node)-->CPE2--[replicate]-->CE3(leaf)+CE4--[replicate]--
->CE5(leaf)+CE6(leaf)
For MSR6, which is designed based on native IPv6, it is allowed to
reuse IPv6 Authentication header and Encapsulating Security Payload
header.
As shown in the following figure, MSR6 header, as an IPv6 extension
header, will not be encrypted during the P2MP transmission. So there
is no encryption and decryption between each replication nodes and
its downstream nodes. Encryption and decryption only happens
respectively on the MSR6 Ingress Node and MSR6 Egress node, which
could increase packet processing efficiency in the intermediate
nodes.
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+--------------------------------+
| IPv6 Header |
+--------------------------------+
| IPv6 EH (MSR6 EH or Options) |
+--------------------------------+
| IPSec Header (ESP) |
+--------------------------------+
| Payload |
+--------------------------------+
3.2. SD-WAN over Service-Provider Network
Another typical deployment mode of SD-WAN is based on a Service
provider(SP) network, where the underlay network is a managed
network.
As illustrated in the following figure, the MSR6 packet delivery
service can enable the underlay network to provide a new service to
SD-WAN.
+-----------------------------------------------------+
/ (S,G)pkt /
/ [E2]------->[h2] /
/ : /
/ (S,G)pkt : (S,G)pkt /
/ [h1]------->[E1] : [E3]------->[h3] /
/ : : : /
/ : : : (S,G)pkt /
/ : : : [E4]------->[h4] / WAN
/ : : : : / Overlay
+-------------------:-----:--------:-----:------------+
: : : :
| : : : : |
| : : : : /|\
(MSR6 packet)| : : : : / | \
\ | / : : : : |(MSR6 packet)
\|/ : : : ....: |
| : : : : |
: : : :
+------:-----:--------:-:----------+
/ : [B2] : : /
/ : | : : /
/ [B1] \ [B4] /
/ \ | / /
/ \ | / /
/ +--[B3]--+ / SP
/ / Underlay
+----------------------------------+
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SD-WAN Edge E1 encapsulate the received (S,G) packet into an MSR6
header, transforming the packet an MSR6 packet, and send to Service
provider backbone router B1. According to the MSR6 routing and
forwarding table that has pre-built for the SD-WAN, the underlay
network delivery the received MSR6 packet to E2/E3/E4. E2/E3/E4 then
decapsulates the outer MSR6 header, obtains the original (S,G)
packet, and forward to h2/h3/h4.
4. Host-initiated Multicast
There are some enterprise cases where the hosts and network device
are managed and maintained in the same domain. MSR6 could be used to
simplify multicast deployment without control plane protocol for
multicast joining and leaving. The host could send/receive MSR6
packet and the network could replicate the packet based on MSR6
header.
4.1. Multicast for Surveillance Camera Data Transmission
In automated factory, surveillance cameras are usually deployed to
ensure security. Data from these surveillance cameras is transmitted
to different sites for analysis, processing and storage.
As illustrated in the following figure, the MSR6 packet delivery
service can be used in an Industry Environment.
+----+ +----+ +----+
[C1]----+ | | +--------+ R4 +----{H1: Storage&Archive}
| R1 +--------+ | +----+
[C2]----+ | | | +----+
+----+ | R3 +--------+ R5 +----{H2: AI}
| | +----+
+----+ | | +----+
[Cn]----+ R2 +--------+ +--------+ R6 +----[H3: Live Monitor]
+----+ +----+ +----+
C1/C2/Cn: Camera
R1/R2/R3/R4/R5/R6: Router
H1/H2/H3: Host of Applications to process the camera video.
With the MSR6 packet delivery service supported by the network, the
cameras can send the packet to a few applications directly by using
MSR6 packets to encode the desired destination hosts of applications.
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4.2. Multicast for Audio and Video Conferencing
Multicast can save bandwidth for audio and video conferencing in
large enterprises. Selective Forwarding Units (SFU)
[I-D.ietf-avtcore-rtp-topologies-update], is associated centralized
unit for scalable video coding and simulcasting, which could be used
in audio and video conferences.
MSR6 could provide multicast among SFUs as illustrated in the
following figure. In practice, these SFUs may be open Real-Time-
Communication(RTC) gateways, either private RTC implementation or
open RTC like WebRTC, to support WAN scope meeting.
{SFU1} {SFU2}
| |
C1a----[R1]-----[BR1]-------[BR2]------[R2]------C2a
/ \ / \
C1b---+ \ / \ {SFU3}
\ / \ |
\ / +--[R3]------C3a
[BR3]
\ {SFU4}
\ |
+-------[R4]------C4a
C1x/C2a/C3a/C4a: WebRTC Client;
R1/R2/R3/R4: Router;
BR1/BR2/BR3: Backbone Router;
SFU1/SFU2/SFU3/SFU4: Selective Forwarding Unit (WebRTC Gateway);
When SFU1 receives a RTC flow packet from C1a, the next step is to
forward it to one or more of SFU2, SFU3 and SFU4, depending on the
RTC session established by them. The SFU1 can send the packet using
MSR6 packets with the destination hosts SFU2/SFU3/SFU4 encoding in
the MSR6 header. The enterprise WAN, including the edge routers
R1/R2/R3 and backbone routers BR1/BR2/BR3 get the MSR6 packet
multicast to its final destinations.
Using the socket API as defined in [RFC3493] and [RFC3542], it has
been testd that this could work on a host operation system.
Following is an illustration of code that can enable a socket to send
and receive an IPv6 packet with a Destination Options Header.
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//Code for the Sending Procedure (SFU1).
sock_fd = socket(AF_INET6, SOCK_DGRAM, IPPROTO_UDP);
setsockopt(sock_fd, IPPROTO_IPV6, IPV6_DSTOPTS, (void *)extbuf, len);
//Code for the Receiving Procedure (SFU2)
sock_fd = socket(AF_INET6, SOCK_DGRAM, IPPROTO_UDP);
setsockopt(sock_fd, IPPROTO_IPV6, IPV6_RECVDSTOPTS, &on, sizeof(on));
5. IANA Considerations
This document makes no request of IANA.
6. Security Considerations
TBD
7. Acknowledgements
TBD
8. Normative References
[I-D.cheng-spring-ipv6-msr-design-consideration]
Cheng, W., Mishra, G., Li, Z., Wang, A., Qin, Z., and C.
Fan, "Design Consideration of IPv6 Multicast Source
Routing (MSR6)", Work in Progress, Internet-Draft, draft-
cheng-spring-ipv6-msr-design-consideration-01, 25 October
2021, <https://www.ietf.org/archive/id/draft-cheng-spring-
ipv6-msr-design-consideration-01.txt>.
[I-D.ietf-avtcore-rtp-topologies-update]
Westerlund, M. and S. Wenger, "RTP Topologies", Work in
Progress, Internet-Draft, draft-ietf-avtcore-rtp-
topologies-update-10, 2 July 2015,
<https://www.ietf.org/archive/id/draft-ietf-avtcore-rtp-
topologies-update-10.txt>.
[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>.
[RFC3493] Gilligan, R., Thomson, S., Bound, J., McCann, J., and W.
Stevens, "Basic Socket Interface Extensions for IPv6",
RFC 3493, DOI 10.17487/RFC3493, February 2003,
<https://www.rfc-editor.org/info/rfc3493>.
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[RFC3542] Stevens, W., Thomas, M., Nordmark, E., and T. Jinmei,
"Advanced Sockets Application Program Interface (API) for
IPv6", RFC 3542, DOI 10.17487/RFC3542, May 2003,
<https://www.rfc-editor.org/info/rfc3542>.
[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>.
Authors' Addresses
Yisong Liu
China Mobile
Email: liuyisong@chinamobile.com
Feng Yang
China Mobile
Email: yangfeng@chinamobile.com
Aijun Wang
China Telecom
Email: wangaj3@chinatelecom.cn
Xueru Zhang
China Unicom
Email: zhangxr49@chinaunicom.cn
Xuesong Geng
Huawei
Email: gengxuesong@huawei.com
Zhenbin Li
Huawei
Email: lizhenbin@huawei.com
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