< draft-ietf-bier-use-cases-08.txt   draft-ietf-bier-use-cases-09.txt >
Network Working Group N. Kumar Network Working Group N. Kumar
Internet-Draft R. Asati Internet-Draft R. Asati
Intended status: Informational Cisco Intended status: Informational Cisco
Expires: August 2, 2019 M. Chen Expires: August 4, 2019 M. Chen
X. Xu X. Xu
Huawei Huawei
A. Dolganow A. Dolganow
Nokia Nokia
T. Przygienda T. Przygienda
Juniper Networks Juniper Networks
A. Gulko A. Gulko
Thomson Reuters Thomson Reuters
D. Robinson D. Robinson
id3as-company Ltd id3as-company Ltd
V. Arya V. Arya
DirecTV Inc DirecTV Inc
C. Bestler C. Bestler
Nexenta Nexenta
January 29, 2019 January 31, 2019
BIER Use Cases BIER Use Cases
draft-ietf-bier-use-cases-08.txt draft-ietf-bier-use-cases-09.txt
Abstract Abstract
Bit Index Explicit Replication (BIER) is an architecture that Bit Index Explicit Replication (BIER) is an architecture that
provides optimal multicast forwarding through a "BIER domain" without provides optimal multicast forwarding through a "BIER domain" without
requiring intermediate routers to maintain any multicast related per- requiring intermediate routers to maintain any multicast related per-
flow state. BIER also does not require any explicit tree-building flow state. BIER also does not require any explicit tree-building
protocol for its operation. A multicast data packet enters a BIER protocol for its operation. A multicast data packet enters a BIER
domain at a "Bit-Forwarding Ingress Router" (BFIR), and leaves the domain at a "Bit-Forwarding Ingress Router" (BFIR), and leaves the
BIER domain at one or more "Bit-Forwarding Egress Routers" (BFERs). BIER domain at one or more "Bit-Forwarding Egress Routers" (BFERs).
The BFIR router adds a BIER header to the packet. The BIER header The BFIR router adds a BIER header to the packet. The BIER header
contains a bit-string in which each bit represents exactly one BFER contains a bit-string in which each bit represents exactly one BFER
to forward the packet to. The set of BFERs to which the multicast to forward the packet to. The set of BFERs to which the multicast
packet needs to be forwarded is expressed by setting the bits that packet needs to be forwarded is expressed by setting the bits that
correspond to those routers in the BIER header. correspond to those routers in the BIER header.
This document describes some of the use-cases for BIER. This document describes some of the use cases for BIER.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 2, 2019. This Internet-Draft will expire on August 4, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
skipping to change at page 2, line 37 skipping to change at page 2, line 37
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Specification of Requirements . . . . . . . . . . . . . . . . 3 2. Specification of Requirements . . . . . . . . . . . . . . . . 3
3. BIER Use Cases . . . . . . . . . . . . . . . . . . . . . . . 3 3. BIER Use Cases . . . . . . . . . . . . . . . . . . . . . . . 3
3.1. Multicast in L3VPN Networks . . . . . . . . . . . . . . . 3 3.1. Multicast in L3VPN Networks . . . . . . . . . . . . . . . 3
3.2. BUM in EVPN . . . . . . . . . . . . . . . . . . . . . . . 4 3.2. BUM in EVPN . . . . . . . . . . . . . . . . . . . . . . . 4
3.3. IPTV and OTT Services . . . . . . . . . . . . . . . . . . 5 3.3. IPTV and OTT Services . . . . . . . . . . . . . . . . . . 5
3.4. Multi-service, converged L3VPN network . . . . . . . . . 6 3.4. Multi-Service, Converged L3VPN Network . . . . . . . . . 6
3.5. Control-plane simplification and SDN-controlled networks 7 3.5. Control-Plane Simplification and SDN-Controlled Networks 7
3.6. Data center Virtualization/Overlay . . . . . . . . . . . 7 3.6. Data Center Virtualization/Overlay . . . . . . . . . . . 7
3.7. Financial Services . . . . . . . . . . . . . . . . . . . 8 3.7. Financial Services . . . . . . . . . . . . . . . . . . . 8
3.8. 4k broadcast video services . . . . . . . . . . . . . . . 9 3.8. 4K Broadcast Video Services . . . . . . . . . . . . . . . 9
3.9. Distributed Storage Cluster . . . . . . . . . . . . . . . 10 3.9. Distributed Storage Cluster . . . . . . . . . . . . . . . 10
3.10. HTTP-Level Multicast . . . . . . . . . . . . . . . . . . 11 3.10. HTTP-Level Multicast . . . . . . . . . . . . . . . . . . 11
4. Security Considerations . . . . . . . . . . . . . . . . . . . 13 4. Security Considerations . . . . . . . . . . . . . . . . . . . 13
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13
7. Contributing Authors . . . . . . . . . . . . . . . . . . . . 13 7. Contributing Authors . . . . . . . . . . . . . . . . . . . . 13
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 13 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
8.1. Normative References . . . . . . . . . . . . . . . . . . 14 8.1. Normative References . . . . . . . . . . . . . . . . . . 13
8.2. Informative References . . . . . . . . . . . . . . . . . 14 8.2. Informative References . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15
1. Introduction 1. Introduction
Bit Index Explicit Replication (BIER) [RFC8279] is an architecture Bit Index Explicit Replication (BIER) [RFC8279] is an architecture
that provides optimal multicast forwarding through a "BIER domain" that provides optimal multicast forwarding through a "BIER domain"
without requiring intermediate routers to maintain any multicast without requiring intermediate routers to maintain any multicast
related per-flow state. BIER also does not require any explicit related per-flow state. BIER also does not require any explicit
tree-building protocol for its operation. A multicast data packet tree-building protocol for its operation. A multicast data packet
skipping to change at page 3, line 24 skipping to change at page 3, line 24
(BFERs). The BFIR router adds a BIER header to the packet. The BIER (BFERs). The BFIR router adds a BIER header to the packet. The BIER
header contains a bit-string in which each bit represents exactly one header contains a bit-string in which each bit represents exactly one
BFER to forward the packet to. The set of BFERs to which the BFER to forward the packet to. The set of BFERs to which the
multicast packet needs to be forwarded is expressed by setting the multicast packet needs to be forwarded is expressed by setting the
bits that correspond to those routers in the BIER header. bits that correspond to those routers in the BIER header.
The obvious advantage of BIER is that there is no per flow multicast The obvious advantage of BIER is that there is no per flow multicast
state in the core of the network and there is no tree building state in the core of the network and there is no tree building
protocol that sets up tree on demand based on users joining a protocol that sets up tree on demand based on users joining a
multicast flow. In that sense, BIER is potentially applicable to multicast flow. In that sense, BIER is potentially applicable to
many services where Multicast is used and not limited to the examples many services where multicast is used and not limited to the examples
described in this draft. In this document we are describing a few described in this draft. In this document we are describing a few
use-cases where BIER could provide benefit over using existing use cases where BIER could provide benefit over using existing
mechanisms. mechanisms.
2. Specification of Requirements 2. Specification of Requirements
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 this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
3. BIER Use Cases 3. BIER Use Cases
3.1. Multicast in L3VPN Networks 3.1. Multicast in L3VPN Networks
The Multicast L3VPN architecture [RFC6513] describes many different The Multicast L3VPN architecture [RFC6513] describes many different
profiles in order to transport L3 Multicast across a providers profiles in order to transport L3 multicast across a provider's
network. Each profile has its own different tradeoffs (see section network. Each profile has its own different tradeoffs (see section
2.1 [RFC6513]). When using "Multidirectional Inclusive" "Provider 2.1 [RFC6513]). When using "Multidirectional Inclusive" "Provider
Multicast Service Interface" (MI-PMSI) an efficient tree is build per Multicast Service Interface" (MI-PMSI) an efficient tree is built per
VPN, but causes flooding of egress PE's that are part of the VPN, but VPN, but causes flooding of egress PE's that are part of the VPN, but
have not joined a particular C-multicast flow. This problem can be have not joined a particular C-multicast flow. This problem can be
solved with the "Selective" PMSI to build a special tree for only solved with the "Selective" PMSI (S-PMSI) by building a special tree
those PE's that have joined the C-multicast flow for that specific for only those PEs that have joined the C-multicast flow for that
VPN. The more S-PMSI's, the less bandwidth is wasted due to specific VPN. The more S-PMSI's, the less bandwidth is wasted due to
flooding, but causes more state to be created in the providers flooding, but causes more state to be created in the provider's
network. This is a typical problem network operators are faced with network. This is a typical problem network operators are faced with
by finding the right balance between the amount of state carried in by finding the right balance between the amount of state carried in
the network and how much flooding (waste of bandwidth) is acceptable. the network and how much flooding (waste of bandwidth) is acceptable.
Some of the complexity with L3VPN's comes due to providing different Some of the complexity with L3VPN's comes due to providing different
profiles to accommodate these trade-offs. profiles to accommodate these trade-offs.
With BIER there is no trade-off between State and Flooding. Since With BIER there is no trade-off between State and Flooding. Since
the receiver information is explicitly carried within the packet, the receiver information is explicitly carried within the packet,
there is no need to build S-PMSI's to deliver multicast to a sub-set there is no need to build S-PMSI's to deliver multicast to a sub-set
of the VPN egress PE's. Due to that behaviour, there is no need for of the VPN egress PE's. Due to that behaviour, there is no need for
S-PMSI's. S-PMSI's.
Mi-PMSI's and S-PMSI's are also used to provide the VPN context to MI-PMSI's and S-PMSI's are also used to provide the VPN context to
the Egress PE router that receives the multicast packet. Also, in the egress PE router that receives the multicast packet. Also, in
some MVPN profiles it is also required to know which Ingress PE some MVPN profiles it is also required to know which Ingress PE
forwarded the packet. Based on the PMSI the packet is received from, forwarded the packet. Based on the PMSI the packet is received from,
the target VPN is determined. This also means there is a requirement the target VPN is determined. This also means there is a requirement
to have a least a PMSI per VPN or per VPN/Ingress PE. This means the to have at least a PMSI per VPN or per VPN/ingress PE. This means
amount of state created in the network is proportional to the VPN and the amount of state created in the network is proportional to the VPN
ingress PE's. Creating PMSI state per VPN can be prevented by and ingress PEs. Creating PMSI state per VPN can be prevented by
applying the procedures as documented in [RFC5331]. This however has applying the procedures as documented in [RFC5331]. This however has
not been very much adopted/implemented due to the excessive flooding not been very much adopted/implemented due to the excessive flooding
it would cause to Egress PE's since *all* VPN multicast packets are it would cause to egress PEs since *all* VPN multicast packets are
forwarded to *all* PE's that have one or more VPN's attached to it. forwarded to *all* PEs that have one or more VPNs attached to it.
With BIER, the destination PE's are identified in the multicast With BIER, the destination PEs are identified in the multicast
packet, so there is no flooding concern when implementing [RFC5331]. packet, so there is no flooding concern when implementing [RFC5331].
For that reason there is no need to create multiple BIER domain's per For that reason there is no need to create multiple BIER domains per
VPN, the VPN context can be carry in the multicast packet using the VPN, the VPN context can be carry in the multicast packet using the
procedures as defined in [RFC5331]. Also see [I-D.ietf-bier-mvpn] procedures as defined in [RFC5331]. Also see [I-D.ietf-bier-mvpn]
for more information. for more information.
With BIER only a few MVPN profiles will remain relevant, simplifying With BIER only a few MVPN profiles will remain relevant, simplifying
the operational cost and making it easier to be interoperable among the operational cost and making it easier to be interoperable among
different vendors. different vendors.
3.2. BUM in EVPN 3.2. BUM in EVPN
The current widespread adoption of L2VPN services [RFC4664], The current widespread adoption of L2VPN services [RFC4664],
especially the upcoming EVPN solution [RFC7432] which transgresses especially the upcoming EVPN solution [RFC7432] which transgresses
many limitations of VPLS, introduces the need for an efficient many limitations of VPLS, introduces the need for an efficient
mechanism to replicate broadcast, unknown and multicast (BUM) traffic mechanism to replicate broadcast, unknown and multicast (BUM) traffic
towards the PEs that participate in the same EVPN instances (EVIs). towards the PEs that participate in the same EVPN instances (EVIs).
As simplest deployable mechanism, ingress replication is used but As simplest deployable mechanism, ingress replication is used but
poses accordingly a high burden on the ingress node as well as poses accordingly a high burden on the ingress node as well as
saturating the underlying links with many copies of the same frame saturating the underlying links with many copies of the same frame
headed to different PEs. Fortunately enough, EVPN signals internally headed to different PEs. Fortunately enough, EVPN signals internally
P-Multicast Service Interface (PMSI) [RFC6513] attribute to establish PMSI attribute [RFC6513] to establish transport for BUM frames and
transport for BUM frames and with that allows to deploy a plethora of with that allows to deploy a plethora of multicast replication
multicast replication services that the underlying network layer can services that the underlying network layer can provide. It is
provide. It is therefore relatively simple to deploy BIER P-Tunnels therefore relatively simple to deploy BIER P-Tunnels for EVPN and
for EVPN and with that distribute BUM traffic without building of with that distribute BUM traffic without creating P-router states in
P-router state in the core required by PIM, mLDP or comparable the core that are required by PIM, mLDP or comparable solutions.
solutions.
Specifically, the same I-PMSI attribute suggested for mVPN can be Specifically, the same I-PMSI attribute suggested for mVPN can be
used easily in EVPN and given EVPN can multiplex and disassociate BUM used easily in EVPN, and given that EVPN can multiplex and
frames on p2mp and mp2mp trees using upstream assigned labels, BIER disassociate BUM frames on p2mp and mp2mp trees using upstream
P-Tunnel will support BUM flooding for any number of EVIs over a assigned labels, BIER P-Tunnel will support BUM flooding for any
single sub-domain for maximum scalability but allow at the other number of EVIs over a single sub-domain for maximum scalability but
extreme of the spectrum to use a single BIER sub-domain per EVI if allow at the other extreme of the spectrum to use a single BIER sub-
such a deployment is necessary. domain per EVI if such a deployment is necessary.
Multiplexing EVIs onto the same PMSI forces the PMSI to span more Multiplexing EVIs onto the same PMSI forces the PMSI to span more
than the necessary number of PEs normally, i.e. the union of all PEs than the necessary number of PEs normally, i.e. the union of all PEs
participating in the EVIs multiplexed on the PMSI. Given the participating in the EVIs multiplexed on the PMSI. Given the
properties of BIER it is however possible to encode in the receiver properties of BIER it is however possible to encode in the receiver
bitmask only the PEs that participate in the EVI the BUM frame bitmask only the PEs that participate in the EVI that the BUM frame
targets. In a sense BIER is an inclusive as well as a selective tree targets. In a sense, BIER is an inclusive as well as a selective
and can allow to deliver the frame to only the set of receivers tree and can allow delivering the frame to only the set of receivers
interested in a frame even though many others participate in the same interested in a frame even though many others participate in the same
PMSI. PMSI.
As another significant advantage, it is imaginable that the same BIER As another significant advantage, it is imaginable that the same BIER
tunnel needed for BUM frames can optimize the delivery of the tunnel needed for BUM frames can optimize the delivery of the
multicast frames though the signaling of group memberships for the multicast frames though the signaling of group memberships for the
PEs involved has not been specified as of date. PEs involved, but has not been specified as of date.
3.3. IPTV and OTT Services 3.3. IPTV and OTT Services
IPTV is a service, well known for its characteristics of allowing IPTV is a service, well known for its characteristics of allowing
both live and on-demand delivery of media traffic over end-to-end both live and on-demand delivery of media traffic over an end-to-end
Managed IP network. managed IP network.
Over The Top (OTT) is a similar service, well known for its Over The Top (OTT) is a similar service, well known for its
characteristics of allowing live and on-demand delivery of media characteristics of allowing live and on-demand delivery of media
traffic between IP domains, where the source is often on an external traffic between IP domains, where the source is often on an external
network relative to the receivers. network relative to the receivers.
Content Delivery Networks (CDN) operators provide layer 4 Content Delivery Networks (CDN) operators provide layer 4
applications, and often some degree of managed layer 3 IP network, applications, and often some degree of managed layer 3 IP networks,
that enable media to be securely and reliably delivered to many that enable media to be securely and reliably delivered to many
receivers. In some models they may place applications within third receivers. In some models they may place applications within third
party networks, or they may place those applications at the edges of party networks, or they may place those applications at the edges of
their own managed network peerings and similar inter-domain their own managed network peerings and similar inter-domain
connections. CDNs provide capabilities to help publishers scale to connections. CDNs provide capabilities to help publishers scale to
meet large audience demand. Their applications are not limited to meet large audience demand. Their applications are not limited to
audio and video delivery, but may include static and dynamic web audio and video delivery, but may include static and dynamic web
content, or optimized delivery for Massive Multiplayer Gaming and content, or optimized delivery for Massive Multiplayer Gaming and
similar. Most publishers will use a CDN for public Internet similar. Most publishers will use a CDN for public Internet
delivery, and some publishers will use a CDN internally within their delivery, and some publishers will use a CDN internally within their
IPTV networks to resolve layer 4 complexity. IPTV networks to resolve layer 4 complexity.
In a typical IPTV environment the egress routers connecting to the In a typical IPTV environment the egress routers connecting to the
receivers will build the tree towards the ingress router connecting receivers will build the tree towards the ingress router connecting
to the IPTV servers. The egress routers would rely on IGMP/MLD to the IPTV servers. The egress routers would rely on IGMP/MLD
(static or dynamic) to learn about the receiver's interest in one or (static or dynamic) to learn about the receiver's interest in one or
more multicast group/channels. Interestingly, BIER could allows more multicast groups/channels. Interestingly, BIER could allow
provisioning any new multicast group/channel by only modifying the provisioning any new multicast group/channel by only modifying the
channel mapping on ingress routers. This is deemed beneficial for channel mapping on ingress routers. This is deemed beneficial for
the linear IPTV video broadcasting in which every receivers behind the linear IPTV video broadcasting in which all receivers behind all
every egress PE routers would receive the IPTV video traffic. egress PE routers would receive the IPTV video traffic.
With BIER in IPTV environment, there is no need of tree building from With BIER in an IPTV environment, there is no need for tree building
egress to ingress. Further, any addition of new channel or new from egress to ingress. Further, any addition of new channels or new
egress routers can be directly controlled from ingress router. When egress routers can be directly controlled from the ingress router.
a new channel is included, the multicast group is mapped to Bit When a new channel is included, the multicast group is mapped to a
string that includes all egress routers. Ingress router would start bit string that includes all egress routers. Ingress router would
sending the new channel and deliver it to all egress routers. As it start sending the new channel and deliver it to all egress routers.
can be observed, there is no need for static IGMP provisioning in As it can be observed, there is no need for static IGMP provisioning
each egress routers whenever a new channel/stream is added. Instead, in each egress router whenever a new group/channel is added.
it can be controlled from ingress router itself by configuring the Instead, it can be controlled from ingress router itself by
new group to Bit Mask mapping on ingress router. configuring the new group to bit mask mapping on ingress router.
With BIER in OTT environment, these edge routers in CDN domain With BIER in OTT environment, the edge routers in CDN domain
terminating the OTT user session connect to the Ingress BIER routers terminating the OTT user session connect to the ingress BIER routers
connecting content provider domains or a local cache server and connecting content provider domains or a local cache server and
leverage the scalability benefit that BIER could provide. This may leverage the scalability benefit that BIER could provide. This may
rely on MBGP interoperation (or similar) between the egress of one rely on MBGP interoperation (or similar) between the egress of one
domain and the ingress of the next domain, or some other SDN control domain and the ingress of the next domain, or some other SDN control
plane may prove a more effective and simpler way to deploy BIER. For plane may prove a more effective and simpler way to deploy BIER. For
a single CDN operator this could be well managed in the Layer 4 a single CDN operator this could be well managed in the layer 4
applications that they provide and it may be that the initial applications that they provide and it may be that the initial
receiver in a remote domain is actually an application operated by receiver in a remote domain is actually an application operated by
the CDN which in turn acts as a source for the Ingress BIER router in the CDN which in turn acts as a source for the ingress BIER router in
that remote domain, and by doing so keeps the BIER more descrete on a that remote domain, and by doing so keeps the BIER domains discrete.
domain by domain basis.
3.4. Multi-service, converged L3VPN network 3.4. Multi-Service, Converged L3VPN Network
Increasingly operators deploy single networks for multiple-services. Increasingly operators deploy single networks for multiple services.
For example a single Metro Core network could be deployed to provide For example a single metro core network could be deployed to provide
Residential IPTV retail service, residential IPTV wholesale service, residential IPTV retail service, residential IPTV wholesale service,
and business L3VPN service with multicast. It may often be desired and business L3VPN service with multicast. It may often be desired
by an operator to use a single architecture to deliver multicast for by an operator to use a single architecture to deliver multicast for
all of those services. In some cases, governing regulations may all of those services. In some cases, governing regulations may
additionally require same service capabilities for both wholesale and additionally require same service capabilities for both wholesale and
retail multicast services. To meet those requirements, some retail multicast services. To meet those requirements, some
operators use multicast architecture as defined in [RFC5331]. operators use the multicast architecture as defined in [RFC5331].
However, the need to support many L3VPNs, with some of those L3VPNs However, the need to support many L3VPNs, with some of those L3VPNs
scaling to hundreds of egress PE's and thousands of C-multicast scaling to hundreds of egress PE's and thousands of C-multicast
flows, make scaling/efficiency issues defined in earlier sections of flows, make scaling/efficiency issues defined in earlier sections of
this document even more prevalent. Additionally support for ten's of this document even more prevalent. Additionally support for tens of
millions of BGP multicast A-D and join routes alone could be required millions of BGP multicast A-D and join routes alone could be required
in such networks with all consequences such a scale brings. in such networks with all of the consequences that such a scale
brings.
With BIER, again there is no need of tree building from egress to With BIER, again there is no need of tree building from egress to
ingress for each L3VPN or individual or group of c-multicast flows. ingress for each L3VPN or individual or group of c-multicast flows.
As described earlier on, any addition of a new IPTV channel or new As described earlier, any addition of a new IPTV channel or new
egress router can be directly controlled from ingress router and egress router can be directly controlled from ingress router and
there is no flooding concern when implementing [RFC5331]. there is no flooding concern when implementing [RFC5331].
3.5. Control-plane simplification and SDN-controlled networks 3.5. Control-Plane Simplification and SDN-Controlled Networks
With the advent of Software Defined Networking, some operators are With the advent of Software Defined Networking, some operators are
looking at various ways to reduce the overall cost of providing looking at various ways to reduce the overall cost of providing
networking services including multicast delivery. Some of the networking services including multicast delivery. Some of the
alternatives being consider include minimizing capex cost through alternatives being considered include minimizing capex cost through
deployment of network-elements with simplified control plane deployment of network elements with a simplified control plane
function, minimizing operational cost by reducing control protocols function, minimizing operational cost by reducing control protocols
required to achieve a particular service, etc. Segment routing as required to achieve a particular service, etc. Segment routing as
described in [I-D.ietf-spring-segment-routing] provides a solution described in [RFC8402] provides a solution that could be used to
that could be used to provide simplified control-plane architecture provide simplified control plane architecture for unicast traffic.
for unicast traffic. With Segment routing deployed for unicast, a With Segment routing deployed for unicast, a solution that simplifies
solution that simplifies control-plane for multicast would thus also control plane for multicast would thus also be required, or
be required, or operational and capex cost reductions will not be operational and capex cost reductions will not be achieved to their
achieved to their full potential. full potential.
With BIER, there is no longer a need to run control protocols With BIER, there is no longer a need to run control protocols
required to build a distribution tree. If L3VPN with multicast, for required to build a distribution tree. If L3VPN with multicast, for
example, is deployed using [RFC5331] with MPLS in P-instance, the example, is deployed using [RFC5331] with MPLS in P-instance, the
MPLS control plane would no longer be required. BIER also allows MPLS control plane would no longer be required. BIER also allows
migration of C-multicast flows from non-BIER to BIER-based migration of C-multicast flows from non-BIER to BIER-based
architecture, which makes transition to control-plane simplified architecture, which simplifies the operation of transitioning the
network simpler to operationalize. Finally, for operators, who would control plane. Finally, for operators, who desire a centralized,
desire centralized, offloaded control plane, multicast overlay as offloaded control plane, multicast overlay as well as BIER forwarding
well as BIER forwarding could migrate to controller-based could be used with controller-based programming.
programming.
3.6. Data center Virtualization/Overlay 3.6. Data Center Virtualization/Overlay
Virtual eXtensible Local Area Network (VXLAN) [RFC7348] is a kind of Virtual eXtensible Local Area Network (VXLAN) [RFC7348] is a kind of
network virtualization overlay technology which is intended for network virtualization overlay technology which is intended for
multi-tenancy data center networks. To emulate a layer2 flooding multi-tenancy data center networks. To emulate a layer 2 flooding
domain across the layer3 underlay, it requires to have a mapping domain across the layer 3 underlay, it requires a 1:1 or n:1 mapping
between the VXLAN Virtual Network Instance (VNI) and the IP multicast between the VXLAN Virtual Network Instance (VNI) and the
group in a ratio of 1:1 or n:1. In other words, it requires to corresponding IP multicast group. In other words, it requires
enable the multicast capability in the underlay. For instance, it enabling the multicast capability in the underlay. For instance, it
requires to enable PIM-SM [RFC4601] or PIM-BIDIR [RFC5015] multicast requires enabling PIM-SM [RFC4601] or PIM-BIDIR [RFC5015] multicast
routing protocol in the underlay. VXLAN is designed to support 16M routing protocol in the underlay. VXLAN is designed to support 16M
VNIs at maximum. In the mapping ratio of 1:1, it would require 16M VNIs at maximum. In the mapping ratio of 1:1, it would require 16M
multicast groups in the underlay which would become a significant multicast groups in the underlay which would become a significant
challenge to both the control plane and the data plane of the data challenge to both the control plane and the data plane of the data
center switches. In the mapping ratio of n:1, it would result in center switches. In the mapping ratio of n:1, it would result in
inefficiency bandwidth utilization which is not optimal in data inefficiency bandwidth utilization which is not optimal in data
center networks. More importantly, it is recognized by many data center networks. More importantly, it is recognized by many data
center operators as a unaffordable burden to run multicast in data center operators as an undesireable burden to run multicast in data
center networks from network operation and maintenance perspectives. center networks from the perspective of network operation and
As a result, many VXLAN implementations are claimed to support the maintenance. As a result, many VXLAN implementations claim to
ingress replication capability since ingress replication eliminates support the ingress replication capability since ingress replication
the burden of running multicast in the underlay. Ingress replication eliminates the burden of running multicast in the underlay. Ingress
is an acceptable choice in small-sized networks where the average replication is an acceptable choice in small-sized networks where the
number of receivers per multicast flow is not too large. However, in average number of receivers per multicast flow is not too large.
multi-tenant data center networks, especially those in which the NVE However, in multi-tenant data center networks, especially those in
functionality is enabled on a high amount of physical servers, the which the NVE functionality is enabled on a large number of physical
average number of NVEs per VN instance would be very large. As a servers, the average number of NVEs per VN instance would be very
result, the ingress replication scheme would result in a serious large. As a result, the ingress replication scheme would result in a
bandwidth waste in the underlay and a significant replication burden serious bandwidth waste in the underlay and a significant replication
on ingress NVEs. burden on ingress NVEs.
With BIER, there is no need for maintaining that huge amount of With BIER, there is no need for maintaining that huge amount of
multicast states in the underlay anymore while the delivery multicast state in the underlay anymore while the delivery efficiency
efficiency of overlay BUM traffic is the same as if any kind of of overlay BUM traffic is the same as if any kind of stateful
stateful multicast protocols such as PIM-SM or PIM-BIDIR is enabled multicast protocols such as PIM-SM or PIM-BIDIR is enabled in the
in the underlay. underlay.
3.7. Financial Services 3.7. Financial Services
Financial services extensively rely on IP Multicast to deliver stock Financial services extensively rely on IP multicast to deliver stock
market data and its derivatives, and critically require optimal market data and its derivatives, and critically require optimal
latency path (from publisher to subscribers), deterministic latency path (from publisher to subscribers), deterministic
convergence (so as to deliver market data derivatives fairly to each convergence (so as to deliver market data derivatives fairly to each
client) and secured delivery. client) and secured delivery.
Current multicast solutions e.g. PIM, mLDP etc., however, don't Current multicast solutions, e.g. PIM, mLDP, etc., however, don't
sufficiently address the above requirements. The reason is that the sufficiently address the above requirements. The reason is that the
current solutions are primarily subscriber driven i.e. multicast tree current solutions are primarily subscriber driven, i.e. multicast
is setup using reverse path forwarding techniques, and as a result, tree is setup using reverse path forwarding techniques, and as a
the chosen path for market data may not be latency optimal from result, the chosen path for market data may not be latency optimal
publisher to the (market data) subscribers. from publisher to the (market data) subscribers.
As the number of multicast flows grows, the convergence time might As the number of multicast flows grows, the convergence time might
increase and make it somewhat nondeterministic from the first to the increase and make it somewhat nondeterministic from the first to the
last flow depending on platforms/implementations. Also, by having last flow depending on platforms/implementations. Also, by having
more protocols in the network, the variability to ensure secured more protocols in the network, the variability to ensure secured
delivery of multicast data increases, thereby undermining the overall delivery of multicast data increases, thereby undermining the overall
security aspect. security aspect.
BIER enables setting up the most optimal path from publisher to BIER enables setting up the most optimal path from publisher to
subscribers by leveraging unicast routing relevant for the subscribers by leveraging unicast routing relevant for the
subscribers. With BIER, the multicast convergence is as fast as subscribers. With BIER, the multicast convergence is as fast as
unicast, uniform and deterministic regardless of number of multicast unicast, uniform and deterministic regardless of number of multicast
flows. This makes BIER a perfect multicast technology to achieve flows. This makes BIER a perfect multicast technology to achieve
fairness for market derivatives per each subscriber. fairness for market derivatives per each subscriber.
3.8. 4k broadcast video services 3.8. 4K Broadcast Video Services
In a broadcast network environment, the media content is sourced from In a broadcast network environment, the media content is sourced from
various content providers across different locations. The 4k various content providers across different locations. The 4k
broadcast video is an evolving service with enormous demand on broadcast video is an evolving service placing enormous demand on
network infrastructure in terms of Low latency, faster convergence, network infrastructure in terms of low latency, faster convergence,
high throughput, and high bandwidth. high throughput, and high bandwidth.
In a typical broadcast satellite network environment, the receivers In a typical broadcast satellite network environment, the receivers
are the satellite Terminal nodes which will receive the content from are the satellite terminal nodes which will receive the content from
various sources and feed the data to the satellite. Typically a various sources and feed the data to the satellite. Typically a
multicast group address is assigned for each source. Currently the multicast group address is assigned for each source. Currently the
receivers can join the sources using either PIM-SM [RFC4601] or PIM- receivers can join the sources using either PIM-SM [RFC4601] or PIM-
SSM [RFC4607]. SSM [RFC4607].
In such network scenarios, normally PIM will be the multicast routing In such network scenarios, normally PIM will be the multicast routing
protocol used to establish the tree between Ingress connecting the protocol used to establish the tree between ingress connecting the
content media sources to egress routers connecting the receivers. In content media sources to egress routers connecting the receivers. In
PIM-SM mode, the receivers relies on shared tree to learn the source PIM-SM mode, the receivers relies on shared tree to learn the source
address and build source tree while in PIM-SSM mode, IGMPv3 is used address and build source tree while in PIM-SSM mode, IGMPv3 is used
by receiver to signal the source address to the egress router. In by receiver to signal the source address to the egress router. In
either case, as the number of sources increases, the number of either case, as the number of sources increases, the number of
multicast trees in the core also increases resulting with more multicast trees in the core also increases resulting in more
multicast state entries in the core and increasing the convergence multicast state entries in the core and increasing the convergence
time. time.
With BIER in 4k broadcast satellite network environment, there is no With BIER in 4k broadcast satellite network environment, there is no
need to run PIM in the core and no need to maintain any multicast need to run PIM in the core and no need to maintain any multicast
state. The obvious advantage with BIER is the low multicast state state. The obvious advantage with BIER is the low multicast state
maintained in the core and the faster convergence (which is typically maintained in the core and the faster convergence (which is typically
at par with the unicast convergence). The edge router at the content at par with the unicast convergence). The edge router at the content
source facility can act as BIFR router and the edge router at the source facility can act as BIFR router and the edge router at the
receiver facility can act as BFER routers. Any addition of a new receiver facility can act as BFER routers. Any addition of a new
content source or new satellite Terminal nodes can be added content source or new satellite Terminal nodes can be added
seamlessly in to the BEIR domain. The group membership from the seamlessly in to the BEIR domain. The group membership from the
receivers to the sources can be provisioned either by BGP or SDN receivers to the sources can be provisioned either by BGP or an SDN
controller. controller.
3.9. Distributed Storage Cluster 3.9. Distributed Storage Cluster
Distributed Storage Clusters can benefit from dynamically targeted Distributed Storage Clusters can benefit from dynamically targeted
multicast messaging both for dynamic load-balancing negotiations and multicast messaging both for dynamic load-balancing negotiations and
efficient concurrent replication of content to multiple targets. efficient concurrent replication of content to multiple targets.
For example, in the NexentaEdge storage cluster (by Nexenta Systems) For example, in the NexentaEdge storage cluster (by Nexenta Systems)
a Chunk Put transaction is accomplished with the following steps: a Chunk Put transaction is accomplished with the following steps:
o The Client multicast a Chunk Put Request to a multicast group o The Client multicasts a Chunk Put Request to a multicast group
known as a Negotiating Group. This group holds a small number of known as a Negotiating Group. This group holds a small number of
storage targets that are collectively responsible for providing storage targets that are collectively responsible for providing
storage for a stable subset of the chunks to be stored. In storage for a stable subset of the chunks to be stored. In
NexentaEdge this is based upon a cryptographic hash of the Object NexentaEdge this is based upon a cryptographic hash of the Object
Name or the Chunk payload. Name or the Chunk payload.
o Each recipient of the Chunk Put Request unicast a Chunk Put o Each recipient of the Chunk Put Request unicasts a Chunk Put
Response to the Client indicating when it could accept a transfer Response to the Client indicating when it could accept a transfer
of the Chunk. of the Chunk.
o The Client selects a different multicast group (a Rendezvous o The Client selects a different multicast group (a Rendezvous
Group) which will target the set storage targets selected to hold Group) which will target the set storage targets selected to hold
the Chunk. This is a subset of the Negotiation Group, presumably the Chunk. This is a subset of the Negotiation Group, presumably
selected so as to complete the transfer as early as possible. selected so as to complete the transfer as early as possible.
o >The Client multicast a Chunk Put Accept message to inform the o >The Client multicasts a Chunk Put Accept message to inform the
Negotiation Group of what storage targets have been selected, when Negotiation Group of what storage targets have been selected, when
the transfer will occur and over what multicast group. the transfer will occur and over what multicast group.
o The client performs the multicast transfer over the Rendezvous o The client performs the multicast transfer over the Rendezvous
Group at the agreed upon time. Group at the agreed upon time.
o Each recipient sends a Chunk Put Ack to positively or negatively o Each recipient sends a Chunk Put Ack to positively or negatively
acknowledge the chunk transfer. acknowledge the chunk transfer.
o The client will retry the entire transaction as needed if there o The client will retry the entire transaction as needed if there
skipping to change at page 11, line 31 skipping to change at page 11, line 26
selected set of storage targets. selected set of storage targets.
BIER would eliminate the need for a vast number of multicast groups. BIER would eliminate the need for a vast number of multicast groups.
The entire cluster can be represented as a single BIER domain using The entire cluster can be represented as a single BIER domain using
only the default sub-domain. Each Negotiating Group is simply a only the default sub-domain. Each Negotiating Group is simply a
subset of the whole that is deterministically selected by the subset of the whole that is deterministically selected by the
Cryptographic Hash of the Object Name or Chunk Payload. Each Cryptographic Hash of the Object Name or Chunk Payload. Each
Rendezvous Group is a further subset of the Negotiating Group. Rendezvous Group is a further subset of the Negotiating Group.
In a simple mapping of the MLD managed multicast groups, each In a simple mapping of the MLD managed multicast groups, each
Negotiating Group could be represented by a short Bitstring selected Negotiating Group could be represented by a short bit string selected
by a Set Identifier. The Set Indentier effectively becomes the by a Set Identifier. The Set Identier effectively becomes the
Negotiating Group. To address the entire Negotiating Group you set Negotiating Group. To address the entire Negotiating Group the bit
the Bitstring to all ones. To later address a subset of the group a string is set to all ones. To later address a subset of the group a
subset Bitstring is used. subset bit string is used.
This allows a short fixed size BIER header to multicast to a very This allows a short fixed size BIER header to multicast to a very
large storage cluster. large storage cluster.
3.10. HTTP-Level Multicast 3.10. HTTP-Level Multicast
Scenarios where a number of HTTP-level clients are quasi- Scenarios where a number of HTTP-level clients are quasi-
synchronously accessing the same HTTP-level resource can benefit from synchronously accessing the same HTTP-level resource can benefit from
the the dynamic multicast group formation enabled by BIER. the dynamic multicast group formation enabled by BIER.
For example, in the FLIPS (Flexible IP Services) solution by For example, in the FLIPS (Flexible IP Services) solution by
InterDigital, network attachment points (NAPs) provide a protocol InterDigital, network attachment points (NAPs) provide a protocol
mapping from HTTP to an efficient BIER-compliant transfer along a mapping from HTTP to an efficient BIER-compliant transfer along a
bit-indexed path between an ingress (here the NAP to which the bit-indexed path between an ingress (here the NAP to which the
clients connect) and an egress (here the NAP to which the HTTP-level clients connect) and an egress (here the NAP to which the HTTP-level
server connects). This is accomplished with the following steps: server connects). This is accomplished with the following steps:
o at the client NAP, the HTTP request is terminated at the HTTP o at the client NAP, the HTTP request is terminated at the HTTP
level at a local HTTP proxy. level at a local HTTP proxy.
skipping to change at page 13, line 41 skipping to change at page 13, line 34
5. IANA Considerations 5. IANA Considerations
There are no IANA consideration introduced by this draft. There are no IANA consideration introduced by this draft.
6. Acknowledgments 6. Acknowledgments
The authors would like to thank IJsbrand Wijnands, Greg Shepherd and The authors would like to thank IJsbrand Wijnands, Greg Shepherd and
Christian Martin for their contribution. Christian Martin for their contribution.
The authors would also like to thank Anoop Ghanwani for his thorough
review and comments.
7. Contributing Authors 7. Contributing Authors
Dirk Trossen Dirk Trossen
InterDigital Inc InterDigital Inc
Email: dirk.trossen@interdigital.com Email: dirk.trossen@interdigital.com
8. References 8. References
8.1. Normative References 8.1. Normative References
[I-D.ietf-bier-mvpn] [I-D.ietf-bier-mvpn]
Rosen, E., Sivakumar, M., Wijnands, I., Aldrin, S., Rosen, E., Sivakumar, M., Wijnands, I., Aldrin, S.,
Dolganow, A., and T. Przygienda, "Multicast VPN Using Dolganow, A., and T. Przygienda, "Multicast VPN Using
BIER", draft-ietf-bier-mvpn-01 (work in progress), July BIER", draft-ietf-bier-mvpn-01 (work in progress), July
2015. 2015.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
skipping to change at page 14, line 25 skipping to change at page 14, line 18
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC8279] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A., [RFC8279] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A.,
Przygienda, T., and S. Aldrin, "Multicast Using Bit Index Przygienda, T., and S. Aldrin, "Multicast Using Bit Index
Explicit Replication (BIER)", RFC 8279, Explicit Replication (BIER)", RFC 8279,
DOI 10.17487/RFC8279, November 2017, DOI 10.17487/RFC8279, November 2017,
<https://www.rfc-editor.org/info/rfc8279>. <https://www.rfc-editor.org/info/rfc8279>.
8.2. Informative References 8.2. Informative References
[I-D.ietf-spring-segment-routing]
Filsfils, C., Previdi, S., Decraene, B., Litkowski, S.,
and r. rjs@rob.sh, "Segment Routing Architecture", draft-
ietf-spring-segment-routing-04 (work in progress), July
2015.
[RFC4601] Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas, [RFC4601] Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas,
"Protocol Independent Multicast - Sparse Mode (PIM-SM): "Protocol Independent Multicast - Sparse Mode (PIM-SM):
Protocol Specification (Revised)", RFC 4601, Protocol Specification (Revised)", RFC 4601,
DOI 10.17487/RFC4601, August 2006, DOI 10.17487/RFC4601, August 2006,
<https://www.rfc-editor.org/info/rfc4601>. <https://www.rfc-editor.org/info/rfc4601>.
[RFC4607] Holbrook, H. and B. Cain, "Source-Specific Multicast for [RFC4607] Holbrook, H. and B. Cain, "Source-Specific Multicast for
IP", RFC 4607, DOI 10.17487/RFC4607, August 2006, IP", RFC 4607, DOI 10.17487/RFC4607, August 2006,
<https://www.rfc-editor.org/info/rfc4607>. <https://www.rfc-editor.org/info/rfc4607>.
skipping to change at page 15, line 26 skipping to change at page 15, line 10
eXtensible Local Area Network (VXLAN): A Framework for eXtensible Local Area Network (VXLAN): A Framework for
Overlaying Virtualized Layer 2 Networks over Layer 3 Overlaying Virtualized Layer 2 Networks over Layer 3
Networks", RFC 7348, DOI 10.17487/RFC7348, August 2014, Networks", RFC 7348, DOI 10.17487/RFC7348, August 2014,
<https://www.rfc-editor.org/info/rfc7348>. <https://www.rfc-editor.org/info/rfc7348>.
[RFC7432] Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A., [RFC7432] Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A.,
Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based
Ethernet VPN", RFC 7432, DOI 10.17487/RFC7432, February Ethernet VPN", RFC 7432, DOI 10.17487/RFC7432, February
2015, <https://www.rfc-editor.org/info/rfc7432>. 2015, <https://www.rfc-editor.org/info/rfc7432>.
[RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
July 2018, <https://www.rfc-editor.org/info/rfc8402>.
Authors' Addresses Authors' Addresses
Nagendra Kumar Nagendra Kumar
Cisco Cisco
7200 Kit Creek Road 7200 Kit Creek Road
Research Triangle Park, NC 27709 Research Triangle Park, NC 27709
US US
Email: naikumar@cisco.com Email: naikumar@cisco.com
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