Internet DRAFT - draft-ietf-bier-use-cases
draft-ietf-bier-use-cases
Network Working Group N. Kumar
Internet-Draft R. Asati
Intended status: Informational Cisco
Expires: March 14, 2021 M. Chen
X. Xu
Huawei
A. Dolganow
Nokia
T. Przygienda
Juniper Networks
A. Gulko
Thomson Reuters
D. Robinson
id3as-company Ltd
V. Arya
DirecTV Inc
C. Bestler
Nexenta
September 10, 2020
BIER Use Cases
draft-ietf-bier-use-cases-12.txt
Abstract
Bit Index Explicit Replication (BIER) is an architecture that
provides optimal multicast forwarding through a "BIER domain" without
requiring intermediate routers to maintain any multicast related per-
flow state. BIER also does not require any explicit tree-building
protocol for its operation. A multicast data packet enters a BIER
domain at a "Bit-Forwarding Ingress Router" (BFIR), and leaves the
BIER domain at one or more "Bit-Forwarding Egress Routers" (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 BFER
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
correspond to those routers in the BIER header.
This document describes some of the use cases for BIER.
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
Kumar, et al. Expires March 14, 2021 [Page 1]
Internet-Draft BIER Use Cases September 2020
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 March 14, 2021.
Copyright Notice
Copyright (c) 2020 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 extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Specification of Requirements . . . . . . . . . . . . . . . . 3
3. BIER Use Cases . . . . . . . . . . . . . . . . . . . . . . . 3
3.1. Multicast in L3VPN Networks . . . . . . . . . . . . . . . 3
3.2. Broadcast, Unknown unicast and Multicast (BUM) in EVPN . 4
3.3. IPTV and OTT Services . . . . . . . . . . . . . . . . . . 5
3.4. Multi-Service, Converged L3VPN Network . . . . . . . . . 6
3.5. Control-Plane Simplification and SDN-Controlled Networks 7
3.6. Data Center Virtualization/Overlay . . . . . . . . . . . 8
3.7. Financial Services . . . . . . . . . . . . . . . . . . . 8
3.8. 4K Broadcast Video Services . . . . . . . . . . . . . . . 9
3.9. Distributed Storage Cluster . . . . . . . . . . . . . . . 10
3.10. Hyper Text Transfer Protocol (HTTP) Level Multicast . . . 11
4. Security Considerations . . . . . . . . . . . . . . . . . . . 13
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13
7. Contributing Authors . . . . . . . . . . . . . . . . . . . . 14
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 14
8.1. Normative References . . . . . . . . . . . . . . . . . . 14
8.2. Informative References . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16
Kumar, et al. Expires March 14, 2021 [Page 2]
Internet-Draft BIER Use Cases September 2020
1. Introduction
Bit Index Explicit Replication (BIER) [RFC8279] is an architecture
that provides optimal multicast forwarding through a "BIER domain"
without requiring intermediate routers to maintain any multicast
related per-flow state. BIER also does not require any explicit
tree-building protocol for its operation. A multicast data packet
enters a BIER domain at a "Bit-Forwarding Ingress Router" (BFIR), and
leaves the BIER domain at one or more "Bit-Forwarding Egress Routers"
(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
BFER 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 correspond to those routers in the BIER header.
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
protocol that sets up tree on demand based on users joining a
multicast flow. In that sense, BIER is potentially applicable to
many services where multicast is used and not limited to the examples
described in this draft. In this document we are describing a few
use cases where BIER could provide benefit over using existing
mechanisms.
2. Specification of Requirements
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in RFC
2119 [RFC2119] RFC 8174 [RFC8174] when and only when, they appear in
all capitals, as shown here.
3. BIER Use Cases
3.1. Multicast in L3VPN Networks
The Multicast L3VPN architecture [RFC6513] describes many different
profiles in order to transport L3 multicast across a provider's
network. Each profile has its own different tradeoffs (see section
2.1 [RFC6513]). When using "Multidirectional Inclusive" "Provider
Multicast Service Interface" (MI-PMSI) an efficient tree is built per
VPN, but causes flooding of egress PEs that are part of the VPN, but
have not joined a particular C-multicast flow. This problem can be
solved with the "Selective" PMSI (S-PMSI) by building a special tree
for only those PEs that have joined the C-multicast flow for that
specific VPN. The more S-PMSI's, the less bandwidth is wasted due to
flooding, but causes more state to be created in the provider's
network. This is a typical problem network operators are faced with
Kumar, et al. Expires March 14, 2021 [Page 3]
Internet-Draft BIER Use Cases September 2020
by finding the right balance between the amount of state carried in
the network and how much flooding (waste of bandwidth) is acceptable.
Some of the complexity with L3VPN's comes due to providing different
profiles to accommodate these trade-offs.
With BIER there is no trade-off between State and Flooding. Since
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
of the VPN egress PEs. Due to that behaviour, there is no need for
S-PMSI's.
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
some MVPN profiles it is also required to know which Ingress PE
forwarded the packet. Based on the PMSI the packet is received from,
the target VPN is determined. This also means there is a requirement
to have at least a PMSI per VPN or per VPN/ingress PE. This means
the amount of state created in the network is proportional to the VPN
and ingress PEs. Creating PMSI state per VPN can be prevented by
applying the procedures as documented in [RFC5331]. This however has
not been very much adopted/implemented due to the excessive flooding
it would cause to egress PEs since *all* VPN multicast packets are
forwarded to *all* PEs that have one or more VPNs attached to it.
With BIER, the destination PEs are identified in the multicast
packet, so there is no flooding concern when implementing [RFC5331].
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
procedures as defined in [RFC5331]. Also see [RFC8556] for more
information.
With BIER only a few MVPN profiles will remain relevant, simplifying
the operational cost and making it easier to be interoperable among
different vendors.
3.2. Broadcast, Unknown unicast and Multicast (BUM) in EVPN
The current widespread adoption of L2VPN services [RFC4664],
especially the upcoming EVPN solution [RFC7432] which transgresses
many limitations of Virtual Private LAN Service (VPLS), introduces
the need for an efficient mechanism to replicate broadcast, unknown
unicast and multicast (BUM) traffic towards the PEs that participate
in the same EVPN instances (EVIs). As simplest deployable mechanism,
ingress replication is used but poses accordingly a high burden on
the ingress node as well as saturating the underlying links with many
copies of the same frame headed to different PEs. Fortunately
enough, EVPN signals internally PMSI attribute [RFC6513] to establish
transport for BUM frames and with that allows to deploy a plethora of
Kumar, et al. Expires March 14, 2021 [Page 4]
Internet-Draft BIER Use Cases September 2020
multicast replication services that the underlying network layer can
provide. It is therefore relatively simple to deploy BIER P-Tunnels
for EVPN and with that distribute BUM traffic without creating
P-router states in the core that are required by Protocol Independent
Multicast (PIM), Multipoint LDP (mLDP) or comparable solutions.
Specifically, the same I-PMSI attribute suggested for mVPN can be
used easily in EVPN, and given that EVPN can multiplex and
disassociate BUM frames on p2mp and mp2mp trees using upstream
assigned labels, BIER P-Tunnel will support BUM flooding for any
number of EVIs over a single sub-domain for maximum scalability but
allow at the other extreme of the spectrum to use a single BIER sub-
domain per EVI if such a deployment is necessary.
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
participating in the EVIs multiplexed on the PMSI. Given the
properties of BIER it is however possible to encode in the receiver
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 and can allow delivering the frame to only the set of receivers
interested in a frame even though many others participate in the same
PMSI.
As another significant advantage, it is imaginable that the same BIER
tunnel needed for BUM frames can optimize the delivery of the
multicast frames though the signaling of group memberships for the
PEs involved, but has not been specified as of date.
3.3. IPTV and OTT Services
IPTV is a service, well known for its characteristics of allowing
both live and on-demand delivery of media traffic over an end-to-end
managed IP network.
Over The Top (OTT) is a similar service, well known for its
characteristics of allowing live and on-demand delivery of media
traffic between IP domains, where the source is often on an external
network relative to the receivers.
Content Delivery Networks (CDN) operators provide layer 4
applications, and often some degree of managed layer 3 IP networks,
that enable media to be securely and reliably delivered to many
receivers. In some models they may place applications within third
party networks, or they may place those applications at the edges of
their own managed network peerings and similar inter-domain
connections. CDNs provide capabilities to help publishers scale to
meet large audience demand. Their applications are not limited to
Kumar, et al. Expires March 14, 2021 [Page 5]
Internet-Draft BIER Use Cases September 2020
audio and video delivery, but may include static and dynamic web
content, or optimized delivery for Massive Multiplayer Gaming and
similar. Most publishers will use a CDN for public Internet
delivery, and some publishers will use a CDN internally within their
IPTV networks to resolve layer 4 complexity.
In a typical IPTV environment the egress routers connecting to the
receivers will build the tree towards the ingress router connecting
to the IPTV servers. The egress routers would rely on IGMP/MLD
(static or dynamic) to learn about the receivers interest in one or
more multicast groups/channels. Interestingly, BIER could allow
provisioning any new multicast group/channel by only modifying the
channel mapping on ingress routers. This is deemed beneficial for
the linear IPTV video broadcasting in which all receivers behind all
egress PE routers would receive the IPTV video traffic.
With BIER in an IPTV environment, there is no need for tree building
from egress to ingress. Further, any addition of new channels or new
egress routers can be directly controlled from the ingress router.
When a new channel is included, the multicast group is mapped to a
bit string that includes all egress routers. Ingress router would
start sending the new channel and deliver it to all egress routers.
As it can be observed, there is no need for static IGMP provisioning
in each egress router whenever a new group/channel is added.
Instead, it can be controlled from ingress router itself by
configuring the new group to bit mask mapping on ingress router.
With BIER in OTT environment, the edge routers in CDN domain
terminating the OTT user session connect to the ingress BIER routers
connecting content provider domains or a local cache server and
leverage the scalability benefit that BIER could provide. This may
rely on Multi-Protocol BGP (MP-BGP) interoperation (or similar)
between the egress of one 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 a single CDN operator this could be
well managed in the layer 4 applications that they provide and it may
be that the initial 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 that remote domain, and by doing so keeps
the BIER domains discrete.
3.4. Multi-Service, Converged L3VPN Network
Increasingly operators deploy single networks for multiple services.
For example a single metro core network could be deployed to provide
residential IPTV retail service, residential IPTV wholesale service,
and business L3VPN service with multicast. It may often be desired
by an operator to use a single architecture to deliver multicast for
Kumar, et al. Expires March 14, 2021 [Page 6]
Internet-Draft BIER Use Cases September 2020
all of those services. In some cases, governing regulations may
additionally require same service capabilities for both wholesale and
retail multicast services. To meet those requirements, some
operators use the multicast architecture as defined in [RFC5331].
However, the need to support many L3VPNs, with some of those L3VPNs
scaling to hundreds of egress PEs and thousands of C-multicast flows,
make scaling/efficiency issues defined in earlier sections of this
document even more prevalent. Additionally support for tens of
millions of BGP multicast A-D and join routes alone could be required
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
ingress for each L3VPN or individual or group of c-multicast flows.
As described earlier, any addition of a new IPTV channel or new
egress router can be directly controlled from ingress router and
there is no flooding concern when implementing [RFC5331].
3.5. Control-Plane Simplification and SDN-Controlled Networks
With the advent of Software Defined Networking, some operators are
looking at various ways to reduce the overall cost of providing
networking services including multicast delivery. Some of the
alternatives being considered include minimizing capex cost through
deployment of network elements with a simplified control plane
function, minimizing operational cost by reducing control protocols
required to achieve a particular service, etc. Segment routing as
described in [RFC8402] provides a solution that could be used to
provide simplified control plane architecture for unicast traffic.
With Segment routing deployed for unicast, a solution that simplifies
control plane for multicast would thus also be required, or
operational and capex cost reductions will not be achieved to their
full potential.
With BIER, there is no longer a need to run control protocols
required to build a distribution tree. If L3VPN with multicast, for
example, is deployed using [RFC5331] with MPLS in P-instance, the
MPLS control plane would no longer be required. BIER also allows
migration of C-multicast flows from non-BIER to BIER-based
architecture, which simplifies the operation of transitioning the
control plane. Finally, for operators, who desire a centralized,
offloaded control plane, multicast overlay as well as BIER forwarding
could be used with controller-based programming.
Kumar, et al. Expires March 14, 2021 [Page 7]
Internet-Draft BIER Use Cases September 2020
3.6. Data Center Virtualization/Overlay
Virtual eXtensible Local Area Network (VXLAN) [RFC7348] is a kind of
network virtualization overlay technology which is intended for
multi-tenancy data center networks. To emulate a layer 2 flooding
domain across the layer 3 underlay, it requires a 1:1 or n:1 mapping
between the VXLAN Virtual Network Instance (VNI) and the
corresponding IP multicast group. In other words, it requires
enabling the multicast capability in the underlay. For instance, it
requires enabling PIM-SM [RFC7761] or PIM-BIDIR [RFC5015] multicast
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
multicast groups in the underlay which would become a significant
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
inefficiency bandwidth utilization which is not optimal in data
center networks. More importantly, it is recognized by many data
center operators as an undesireable burden to run multicast in data
center networks from the perspective of network operation and
maintenance. As a result, many VXLAN implementations claim to
support the ingress replication capability since ingress replication
eliminates the burden of running multicast in the underlay. Ingress
replication is an acceptable choice in small-sized networks where the
average number of receivers per multicast flow is not too large.
However, in multi-tenant data center networks, especially those in
which the Network Virtualization Edge (NVE)functionality is enabled
on a large number of physical servers, the average number of NVEs per
VN instance would be very large. As a result, the ingress
replication scheme would result in a serious bandwidth waste in the
underlay and a significant replication burden on ingress NVEs.
With BIER, there is no need for maintaining that huge amount of
multicast state in the underlay anymore while the delivery efficiency
of overlay BUM traffic is the same as if any kind of stateful
multicast protocols such as PIM-SM or PIM-BIDIR is enabled in the
underlay.
3.7. Financial Services
Financial services extensively rely on IP multicast to deliver stock
market data and its derivatives, and critically require optimal
latency path (from publisher to subscribers), deterministic
convergence (so as to deliver market data derivatives fairly to each
client) and secured delivery.
Current multicast solutions, e.g. PIM, mLDP, etc., however, don't
sufficiently address the above requirements. The reason is that the
current solutions are primarily subscriber driven, i.e. multicast
Kumar, et al. Expires March 14, 2021 [Page 8]
Internet-Draft BIER Use Cases September 2020
tree is setup using reverse path forwarding techniques, and as a
result, the chosen path for market data may not be latency optimal
from publisher to the (market data) subscribers.
As the number of multicast flows grows, the convergence time might
increase and make it somewhat nondeterministic from the first to the
last flow depending on platforms/implementations. Also, by having
more protocols in the network, the variability to ensure secured
delivery of multicast data increases, thereby undermining the overall
security aspect.
BIER enables setting up the most optimal path from publisher to
subscribers by leveraging unicast routing relevant for the
subscribers. With BIER, the multicast convergence is as fast as
unicast, uniform and deterministic regardless of number of multicast
flows. This makes BIER a perfect multicast technology to achieve
fairness for market derivatives per each subscriber.
3.8. 4K Broadcast Video Services
In a broadcast network environment, the media content is sourced from
various content providers across different locations. The 4k
broadcast video is an evolving service placing enormous demand on
network infrastructure in terms of low latency, faster convergence,
high throughput, and high bandwidth.
In a typical broadcast satellite network environment, the receivers
are the satellite terminal nodes which will receive the content from
various sources and feed the data to the satellite. Typically a
multicast group address is assigned for each source. Currently the
receivers can join the sources using either PIM-SM [RFC7761] or PIM-
SSM [RFC4607].
In such network scenarios, normally PIM will be the multicast routing
protocol used to establish the tree between ingress connecting the
content media sources to egress routers connecting the receivers. In
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
by receiver to signal the source address to the egress router. In
either case, as the number of sources increases, the number of
multicast trees in the core also increases resulting in more
multicast state entries in the core and increasing the convergence
time.
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
state. The obvious advantage with BIER is the low multicast state
maintained in the core and the faster convergence (which is typically
Kumar, et al. Expires March 14, 2021 [Page 9]
Internet-Draft BIER Use Cases September 2020
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
receiver facility can act as BFER routers. Any addition of a new
content source or new satellite Terminal nodes can be added
seamlessly in to the BEIR domain. The group membership from the
receivers to the sources can be provisioned either by Border Gateway
Protocol (BGP) or an SDN controller.
3.9. Distributed Storage Cluster
Distributed Storage Clusters can benefit from dynamically targeted
multicast messaging both for dynamic load-balancing negotiations and
efficient concurrent replication of content to multiple targets.
For example, in the NexentaEdge storage cluster (by Nexenta Systems)
a Chunk Put transaction is accomplished with the following steps:
o The Client multicasts a 'Chunk Put Request' to a multicast group
known as a Negotiating Group. This group holds a small number of
storage targets that are collectively responsible for providing
storage for a stable subset of the chunks to be stored. In
NexentaEdge this is based upon a cryptographic hash of the Object
Name or the Chunk payload.
o Each recipient of the 'Chunk Put Request' unicasts a 'Chunk Put
Response' to the Client indicating when it could accept a transfer
of the Chunk.
o The Client selects a different multicast group (a Rendezvous
Group) which will target the set storage targets selected to hold
the Chunk. This is a subset of the Negotiation Group, presumably
selected so as to complete the transfer as early as possible.
o The Client multicasts a 'Chunk Put Accept' message to inform the
Negotiation Group of what storage targets have been selected, when
the transfer will occur and over what multicast group.
o The client performs the multicast transfer over the Rendezvous
Group at the agreed upon time.
o Each recipient sends a 'Chunk Put Ack' to positively or negatively
acknowledge the chunk transfer.
o The client will retry the entire transaction as needed if there
are not yet sufficient replicas of the Chunk.
Chunks are retrieved by multicasting a 'Chunk Get Request' to the
same Negotiating Group, collecting 'Chunk Get Responses', picking one
Kumar, et al. Expires March 14, 2021 [Page 10]
Internet-Draft BIER Use Cases September 2020
source from those responses, sending a 'Chunk Get Accept' message to
identify the selected source and having the selected storage server
unicast the chunk to the source.
Chunks are found by the Object Name or by having the payload
cryptographic hash of payload chunks be recorded in a "chunk
reference" in a metadata chunk. The metadata chunks are found using
the Object Name.
The general pattern in use here, which should apply to other cluster
applications, is that multicast messages are sent amongst a
dynamically selected subset of the entire cluster, which may result
in exchanging further messages over a smaller subset even more
dynamically selected.
Currently the distributed storage application discussed use of
Multicast Listener Discovery (MLD) [RFC3810] managed IPV6 multicast
groups. This in turn requires either a push-based mechanism for
dynamically configuring Rendezvous Groups or pre-provisioning a very
large number of potential Rendezvous Groups and dynamically selecting
the multicast group that will deliver to the selected set of storage
targets.
BIER would eliminate the need for a vast number of multicast groups.
The entire cluster can be represented as a single BIER domain using
only the default sub-domain. Each Negotiating Group is simply a
subset of the whole that is deterministically selected by the
Cryptographic Hash of the Object Name or Chunk Payload. Each
Rendezvous Group is a further subset of the Negotiating Group.
In a simple mapping of the MLD managed multicast groups, each
Negotiating Group could be represented by a short bit string selected
by a Set Identifier. The Set Identier effectively becomes the
Negotiating Group. To address the entire Negotiating Group the bit
string is set to all ones. To later address a subset of the group a
subset bit string is used.
This allows a short fixed size BIER header to multicast to a very
large storage cluster.
3.10. Hyper Text Transfer Protocol (HTTP) Level Multicast
Scenarios where a number of HTTP [RFC7231] clients are quasi-
synchronously accessing the same HTTP-level resource can benefit from
the dynamic multicast group formation enabled by BIER.
For example, in the FLIPS (Flexible IP Services) solution by
InterDigital, network attachment points (NAPs) provide a protocol
Kumar, et al. Expires March 14, 2021 [Page 11]
Internet-Draft BIER Use Cases September 2020
mapping from HTTP to an efficient BIER-compliant transfer along a
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
server connects). This is accomplished with the following steps:
o at the client NAP, the HTTP request is terminated at the HTTP
level at a local HTTP proxy.
o the HTTP request is published by the client NAP towards the Fully
Qualified Domain Names (FQDN) of the server defined in the HTTP
request
* if no local BIER forwarding information exists to the server
(NAP), a path computation entity (PCE) is consulted, which
calculates a unicast path to the egress NAP (here the server
NAP). The PCE provides the forwarding information to the
client NAP, which in turn caches the result.
+ if the local BIER forwarding information exists in the NAP-
local cache, it is used instead.
o Upon arrival of a client NAP request at the server NAP, the server
NAP proxy forwards the HTTP request as a well-formed HTTP request
locally to the server.
* If no client NAP forwarding information exists for the reverse
direction, this information is requested from the PCE. Upon
arrival of such reverse direction forwarding information, it is
stored in a local table for future use.
o Upon arrival of any further client NAP request at the server NAP
to an HTTP request whose response is still outstanding, the client
NAP is added to an internal request table and the request is
suppressed from being sent to the server.
* If no client NAP forwarding information exists for the reverse
direction, this information is requested from the PCE. Upon
arrival of such reverse direction forwarding information, it is
stored in a local table for future use.
o Upon arrival of an HTTP response at the server NAP, the server NAP
consults its internal request table for any outstanding HTTP
requests to the same request
the server NAP retrieves the stored BIER forwarding information
for the reverse direction for all outstanding HTTP requests
found above and determines the path information to all client
NAPs through a binary OR over all BIER forwarding identifiers
Kumar, et al. Expires March 14, 2021 [Page 12]
Internet-Draft BIER Use Cases September 2020
with the same SI field. This newly formed joint BIER multicast
response identifier is used to send the HTTP response across
the network, while the procedure is executed until all requests
have been served.
o Upon arrival of the HTTP response at a client NAP, it will be sent
by the client NAP proxy to the locally connected client.
A number of solutions exist to manage necessary updates in locally
stored BIER forwarding information for cases of client/server
mobility as well as for resilience purposes.
Applications for HTTP-level multicast are manifold. Examples are
HTTP-level streaming (HLS) services, provided as an OTT offering,
either at the level of end user clients (connected to BIER-enabled
NAPs) or site-level clients. Others are corporate intranet storage
cluster solutions that utilize HTTP- level synchronization. In
multi-tenant data centre scenarios such as outlined in Section 3.6.,
the aforementioned solution can satisfy HTTP-level requests to
popular services and content in a multicast delivery manner.
BIER enables such solution through the bitfield representation of
forwarding information, which is in turn used for ad-hoc multicast
group formation at the HTTP request level. While such solution works
well in SDN-enabled intra- domain scenarios, BIER would enable the
realization of such scenarios in multi-domain scenarios over legacy
transport networks without relying on SDN-controlled infrastructure.
Also see [I-D.ietf-bier-multicast-http-response] for more
information.
4. Security Considerations
There are no security issues introduced by this draft.
5. IANA Considerations
There are no IANA consideration introduced by this draft.
6. Acknowledgments
The authors would like to thank IJsbrand Wijnands, Greg Shepherd and
Christian Martin for their contribution.
The authors would also like to thank Anoop Ghanwani and Suneesh Babu
for the thorough review and comments.
Kumar, et al. Expires March 14, 2021 [Page 13]
Internet-Draft BIER Use Cases September 2020
7. Contributing Authors
Dirk Trossen
InterDigital Inc
Email: dirk.trossen@interdigital.com
8. References
8.1. Normative 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>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8279] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A.,
Przygienda, T., and S. Aldrin, "Multicast Using Bit Index
Explicit Replication (BIER)", RFC 8279,
DOI 10.17487/RFC8279, November 2017,
<https://www.rfc-editor.org/info/rfc8279>.
[RFC8556] Rosen, E., Ed., Sivakumar, M., Przygienda, T., Aldrin, S.,
and A. Dolganow, "Multicast VPN Using Bit Index Explicit
Replication (BIER)", RFC 8556, DOI 10.17487/RFC8556, April
2019, <https://www.rfc-editor.org/info/rfc8556>.
8.2. Informative References
[I-D.ietf-bier-multicast-http-response]
Trossen, D., Rahman, A., Wang, C., and T. Eckert,
"Applicability of BIER Multicast Overlay for Adaptive
Streaming Services", draft-ietf-bier-multicast-http-
response-04 (work in progress), July 2020.
[RFC3810] Vida, R., Ed. and L. Costa, Ed., "Multicast Listener
Discovery Version 2 (MLDv2) for IPv6", RFC 3810,
DOI 10.17487/RFC3810, June 2004,
<https://www.rfc-editor.org/info/rfc3810>.
[RFC4607] Holbrook, H. and B. Cain, "Source-Specific Multicast for
IP", RFC 4607, DOI 10.17487/RFC4607, August 2006,
<https://www.rfc-editor.org/info/rfc4607>.
Kumar, et al. Expires March 14, 2021 [Page 14]
Internet-Draft BIER Use Cases September 2020
[RFC4664] Andersson, L., Ed. and E. Rosen, Ed., "Framework for Layer
2 Virtual Private Networks (L2VPNs)", RFC 4664,
DOI 10.17487/RFC4664, September 2006,
<https://www.rfc-editor.org/info/rfc4664>.
[RFC5015] Handley, M., Kouvelas, I., Speakman, T., and L. Vicisano,
"Bidirectional Protocol Independent Multicast (BIDIR-
PIM)", RFC 5015, DOI 10.17487/RFC5015, October 2007,
<https://www.rfc-editor.org/info/rfc5015>.
[RFC5331] Aggarwal, R., Rekhter, Y., and E. Rosen, "MPLS Upstream
Label Assignment and Context-Specific Label Space",
RFC 5331, DOI 10.17487/RFC5331, August 2008,
<https://www.rfc-editor.org/info/rfc5331>.
[RFC6513] Rosen, E., Ed. and R. Aggarwal, Ed., "Multicast in MPLS/
BGP IP VPNs", RFC 6513, DOI 10.17487/RFC6513, February
2012, <https://www.rfc-editor.org/info/rfc6513>.
[RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Semantics and Content", RFC 7231,
DOI 10.17487/RFC7231, June 2014,
<https://www.rfc-editor.org/info/rfc7231>.
[RFC7348] Mahalingam, M., Dutt, D., Duda, K., Agarwal, P., Kreeger,
L., Sridhar, T., Bursell, M., and C. Wright, "Virtual
eXtensible Local Area Network (VXLAN): A Framework for
Overlaying Virtualized Layer 2 Networks over Layer 3
Networks", RFC 7348, DOI 10.17487/RFC7348, August 2014,
<https://www.rfc-editor.org/info/rfc7348>.
[RFC7432] Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A.,
Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based
Ethernet VPN", RFC 7432, DOI 10.17487/RFC7432, February
2015, <https://www.rfc-editor.org/info/rfc7432>.
[RFC7761] Fenner, B., Handley, M., Holbrook, H., Kouvelas, I.,
Parekh, R., Zhang, Z., and L. Zheng, "Protocol Independent
Multicast - Sparse Mode (PIM-SM): Protocol Specification
(Revised)", STD 83, RFC 7761, DOI 10.17487/RFC7761, March
2016, <https://www.rfc-editor.org/info/rfc7761>.
[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>.
Kumar, et al. Expires March 14, 2021 [Page 15]
Internet-Draft BIER Use Cases September 2020
Authors' Addresses
Nagendra Kumar
Cisco
7200 Kit Creek Road
Research Triangle Park, NC 27709
US
Email: naikumar@cisco.com
Rajiv Asati
Cisco
7200 Kit Creek Road
Research Triangle Park, NC 27709
US
Email: rajiva@cisco.com
Mach(Guoyi) Chen
Huawei
Email: mach.chen@huawei.com
Xiaohu Xu
Huawei
Email: xuxiaohu@huawei.com
Andrew Dolganow
Nokia
750D Chai Chee Rd
06-06 Viva Business Park 469004
Singapore
Email: andrew.dolganow@nokia.com
Tony Przygienda
Juniper Networks
1194 N. Mathilda Ave
Sunnyvale, CA 95089
USA
Email: prz@juniper.net
Kumar, et al. Expires March 14, 2021 [Page 16]
Internet-Draft BIER Use Cases September 2020
Arkadiy Gulko
Thomson Reuters
195 Broadway
New York NY 10007
USA
Email: arkadiy.gulko@thomsonreuters.com
Dom Robinson
id3as-company Ltd
UK
Email: Dom@id3as.co.uk
Vishal Arya
DirecTV Inc
2230 E Imperial Hwy
CA 90245
USA
Email: varya@directv.com
Caitlin Bestler
Nexenta Systems
451 El Camino Real
Santa Clara, CA
US
Email: caitlin.bestler@nexenta.com
Kumar, et al. Expires March 14, 2021 [Page 17]
