Network Working Group H. Bidgoli, Ed.
Internet-Draft Nokia
Intended status: Standards Track S. Venaas
Expires: 16 May 2022 Cisco System, Inc.
M. Mishra
Cisco System
Z. Zhang
Juniper Networks
M. McBride
Futurewei Technologies Inc.
12 November 2021
PIM Light
draft-hb-pim-light-01
Abstract
This document specifies a new Protocol Independent Multicast
interface which does not need PIM Hello to accept PIM Join/Prunes or
PIM Asserts.
Status of This Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on 16 May 2022.
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Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions used in this document . . . . . . . . . . . . . . 2
2.1. Definitions . . . . . . . . . . . . . . . . . . . . . . . 2
3. PIM Light Interface . . . . . . . . . . . . . . . . . . . . . 3
3.1. PLI Configuration . . . . . . . . . . . . . . . . . . . . 4
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . 4
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 4
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 4
7.1. Normative References . . . . . . . . . . . . . . . . . . 4
7.2. Informative References . . . . . . . . . . . . . . . . . 4
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 4
1. Introduction
It might be desirable to create a PIM interface between routers where
only PIM Join/Prunes and Asserts packets are triggered over it
without having a full PIM neighbor discovery. As an example, this
type of PIM interface can be useful in some scenarios where the
multicast state needs to be signaled over a network or medium which
is not capable of or has no need for creating full PIM neighborship
between its Peer Routers. These type of PIM interfaces are called
PIM Light Interfaces (PLI).
2. Conventions used in this document
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 BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2.1. Definitions
This draft uses definitions used in [RFC7761]
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3. PIM Light Interface
RFC [RFC7761] section 4.3.1 describes the PIM neighbor discovery via
Hello messages. It also describes that PIM Join/Prune or Assert
messages are not accepted from a router unless a Hello message has
been heard from that router.
In some scenarios it is desired to build a multicast state between
two directly attach or remote routers without establishing a PIM
neighborship. There could be many reasons for this desired, but one
example is the desired to signal multicast states upstream between
two or more PIM Domains via a network or medium that is not optimized
for or does not require PIM Neighbor establishment. An example is a
BIER network connecting multiple PIM domains and PIM Join/prune
messages are tunneled via bier as per
[draft-ietf-bier-pim-signaling].
A PIM Light Interface (PLI) does accept Join/Prune and Assert
messages from a unknown PIM router, without receiving a PIM Hello
message form the router. Lack of Hello Messages on a PLI means there
is no mechanism to learn about the neighboring PIM routers on each
interface and there is no DR Priority options communicated between
Routers either. As such the router doesn't create any General-
Purpose state for neighboring PIM routers and it accepts and installs
each Join message from upstream routers in its multicast routing
table.
Because of this a PLI needs to be created in very especial cases and
the application that is using these PLIs should ensure there is no
multicast duplication of packets. As an example, multiple upstream
routers sending the same multicast stream to a single downstream
router.
As an example, in a BIER domain which is connecting 2 PIM networks.
A PLI can be used to connect edge BIER routers and only multicast
states communicated via PIM Join/prunes over the BIER domain. In
this case to ensure there is no multicast stream duplication the PIM
routers attached on each side of the BIER domain might want to
establish PIM Adjacency via [RFC7761] to ensure DR selection on the
edge of the BIER router while PLI is used in core of the BIER Domain.
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3.1. PLI Configuration
Since a PLI doesn't require PIM Hello Messages and PIM neighbor
adjacency is not checked for join/prune/assert messages, there needs
to be a mechanism to enable PLI on interfaces for security purpose,
while on some other interfaces this may be enabled automatically. An
example of the latter is the logical interface for a BIER sub-domain
[draft-ietf-bier-pim-signaling].
4. IANA Considerations
5. Security Considerations
6. Acknowledgments
7. References
7.1. Normative References
[draft-ietf-bier-pim-signaling]
"H.Bidgoli, F.XU, J. Kotalwar, I. Wijnands, M.Mishra, Z.
Zhang, "PIM Signaling Through BIER Core"", July 2021.
[RFC2119] "S. Brandner, "Key words for use in RFCs to Indicate
Requirement Levels"", March 1997.
[RFC7761] "B.Fenner, M.Handley, H. Holbrook, I. Kouvelas, R. Parekh,
Z.Zhang "PIM Sparse Mode"", March 2016.
[RFC8174] "B. Leiba, "ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words"", May 2017.
7.2. Informative References
[RFC8279] "Wijnands, IJ., Rosen, E., Dolganow, A., Przygienda, T.
and S. Aldrin, "Multicast using Bit Index Explicit
Replication"", October 2016.
Authors' Addresses
Hooman Bidgoli (editor)
Nokia
Ottawa
Canada
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Email: hooman.bidgoli@nokia.com
Stig
Cisco System, Inc.
San Jose,
United States of America
Email: stig@cisco.com
Mankamana Mishra
Cisco System
Milpitas,
United States of America
Email: mankamis@cisco.com
Zhaohui Zhang
Juniper Networks
Boston,
United States of America
Email: zzhang@juniper.com
Mike
Futurewei Technologies Inc.
Santa Clara,
United States of America
Email: michael.mcbride@futurewei.com
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