Internet DRAFT - draft-ietf-bier-mldp-signaling-over-bier
draft-ietf-bier-mldp-signaling-over-bier
Network Working Group H. Bidgoli, Ed.
Internet-Draft J. Kotalwar
Intended status: Standards Track Nokia
Expires: 23 April 2024 I. Wijnands
M. Mishra
Cisco System
Z. Zhang
Juniper Networks
E. Leyton
Verizon
21 October 2023
M-LDP Signaling Through BIER Core
draft-ietf-bier-mldp-signaling-over-bier-03
Abstract
Consider an end-to-end Multipoint LDP (mLDP) network, where it is
desirable to deploy BIER in a segment of this network. It might be
desirable to deploy BIER with minimal disruption to the mLDP network
or a redesign of the network.
This document describes a procedure needed for mLDP tunnels to be
signaled over and stitched through a BIER core, allowing LDP routers
to run traditional mLDP services through a BIER core.
Status of This Memo
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This Internet-Draft will expire on 23 April 2024.
Copyright Notice
Copyright (c) 2023 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Provisions Relating to IETF Documents (https://trustee.ietf.org/
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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 . . . . . . . . . . . . . . . . . . . . . . . 3
3. mLDP Signaling Through BIER domain . . . . . . . . . . . . . 4
3.1. Ingress BBR procedure . . . . . . . . . . . . . . . . . . 5
3.1.1. Automatic tLDP session Creation . . . . . . . . . . . 5
3.1.2. ECMP Method on IBBR . . . . . . . . . . . . . . . . . 5
3.2. Egress BBR procedure . . . . . . . . . . . . . . . . . . 5
3.2.1. IBBR procedure for arriving upstream assigned
label . . . . . . . . . . . . . . . . . . . . . . . . 6
3.2.2. BIER Interface ID SUB-TLVs . . . . . . . . . . . . . 6
4. Datapath Forwarding . . . . . . . . . . . . . . . . . . . . . 7
4.1. Datapath traffic flow . . . . . . . . . . . . . . . . . . 7
5. Recursive FEC . . . . . . . . . . . . . . . . . . . . . . . . 7
6. IANA Consideration . . . . . . . . . . . . . . . . . . . . . 7
7. Security Considerations . . . . . . . . . . . . . . . . . . . 8
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
9.1. Normative References . . . . . . . . . . . . . . . . . . 8
9.2. Informative References . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
Some operators that are using mLDP P2MP LSPs for their multicast
transport would like to deploy BIER technology in some segments of
their network. This draft explains a method to signal mLDP services
through a BIER domain, with minimal disruption and operational impact
to the mLDP domain.
2. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
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2.1. Definitions
Some of the terminology specified in [RFC8279]is replicated here and
extended by necessary definitions:
BIER:
Bit Index Explicit Replication, The overall architecture of
forwarding multicast using a Bit Position.
BFR:
Bit Forwarding Router, A router that participates in Bit Index
Multipoint Forwarding. A BFR is identified by a unique BFR prefix in
a BIER domain.
BFIR:
Bit-Forwarding Ingress Router, The ingress border router that inserts
the Bit Map into the packet. Each BFIR must have a valid BFR-id
assigned. BFIR is a term used for data plane packet forwarding.
BFER:
Bit-Forwarding Egress Router, A router that participates in Bit Index
Forwarding as leaf. Each BFER must have a valid BFR-id assigned.
BFER is a term used for data plane packet forwarding.
BBR:
BIER Boundary router. The router between the LDP domain and BIER
domain.
IBBR:
Ingress BIER Boundary Router. The ingress router from a signaling
point of view. It maintains mLDP adjacency toward the LDP domain and
determines if the Multipoint LDP FEC needs to be signaled across the
BIER domain via Targeted LDP.
EBBR:
Egress BIER Boundary Router. The egress router in a BIER domain from
signaling point of view. It terminates the targeted LDP signaling
through the BIER domain. It also keeps track of all IBBRs that are
part of this P2MP tree
BIFT:
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Bit Index Forwarding Table.
BIER sub-domain:
A further distinction within a BIER domain identified by its unique
sub-domain identifier. A BIER sub-domain can support multiple
BitString Lengths.
BFR-id:
An optional, unique identifier for a BFR within a BIER sub-domain,
all BFERs and BFIRs need to be assigned a BFR-id.
ILM:
MPLS Incoming Label Map.
3. mLDP Signaling Through BIER domain
BBR BBR
|---LDP Domain--|-----BIER domain-----|---LDP domain--|
S--( A )-----------( B ) ---- ( C ) ---- ( D )-----------( E )--h
EBBR IBBR
Sig <----MLDP------|<----targeted LDP----|<---MLDP------
(new)
BFIR BFER
------------->|--------BIER-------->|-------------> Datapatah
(new)
Figure 1: BIER boundary router
As per figure 1, point-to-multipoint and multipoint-to-multipoint
LSPs established via mLDP [RFC6388] can be signaled through a bier
domain via Targeted LDP sessions. This procedure is explained in
[RFC7060] (Using LDP Multipoint Extension on Targeted LDP Sessions).
This document provides details and defines some needed procedures.
.
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3.1. Ingress BBR procedure
In Figure 1, the Ingress BBR (IBBR) is connected to the mLDP domain
on downstream and a BIER domain on the upstream. To connect the LDP
domains via BIER domain, IBBR needs to establish a targeted LDP
session with EBBR closest to the root of the P2MP or MP2MP LSP. To
do so IBBR will follow procedures in [RFC7060] in particular section
6 "Targeted mLDP with Multicast Tunneling".
The Target LDP session can be established manually via configuration
or via automated mechanism.
3.1.1. Automatic tLDP session Creation
tLDP sessions can be signaled automatically from every IBBR to the
appropriate EBBR. When mLDP FEC arrives at the IBBR from LDP domain,
IBBR can automatically start a tLDP session to the EBBR closest to
the root node. Both IBBR and EBBR should be in auto-discovery mode
and react to the arriving tLDP signaling packets (i.e. targeted
hellos, keep-alives etc...) to establish the session automatically.
The root node address in the mLDP FEC can be used to find the EBBR.
To identify the EBBR, the same procedures as [RFC7060] section 2.1
can be used or the procedures as explained in the
[draft-ietf-bier-pim-signaling] appendix A.
3.1.2. ECMP Method on IBBR
If the IBBR finds multiple equal cost EBBRs on the path to the root,
it can use a vendor specific algorithm to choose between the EBBRs.
These algorithms are beyond the scope of this draft. As an example
the IBBR can use the lowest EBBR IP address to establish its mLDP
signaling to.
3.2. Egress BBR procedure
The Egress BBR (EBBR) is connected to the upstream mLDP domain. The
EBBR should accept the tLDP session generated form the IBBR. It
should assign a unique "upstream assigned label" for each arriving
FEC generated by the IBBRs.
The EBBR should follow the [RFC7060] procedures with the following
modifications:
* The label assigned by the EBBR cannot be Implicit Null. This is
to ensure that the identity of each p2mp and/or mp2mp tunnel in
the BIER domain is uniquely distinguished.
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* The label can be assigned from a domain-wide Common Block (DCB)
[draft-ietf-bess-mvpn-evpn-aggregation-label]
* The Interface ID TLV, as per [RFC6389] should includes a new BIER
sub-tlv as tunnel identifier.
The EBBR will also generate a new label and FEC toward the root in
the LDP domain. The EBBR Should stitch this generated label with the
"upstream assigned label" to complete the P2MP or MP2MP LSP.
With the same token the EBBR should track all the arriving FECs and
the IBBRs that are generating these FECs. The EBBR will use this
information to build the bier header for each set of common FEC
arriving from the IBBRs.
3.2.1. IBBR procedure for arriving upstream assigned label
Upon receiving the "upstream assigned label", the IBBR should create
its own stitching instruction between the "upstream assigned label"
and the downstream signaled label.
3.2.2. BIER Interface ID SUB-TLVs
As per [RFC6389] when LDP is used for upstream label assignment,the
Interface ID TLV is used for signaling the Tunnel Identifier and it
carries sub-TLVs. This document defines two new Interface ID sub-
TLVs for BIER.
Below is the Interface ID BIER sub-TLV for IPv4 BIER prefix:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type (TBD1) | 15 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IBBR Prefix IPv4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| sub-domain-id| BFR-id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Below is the Interface ID BIER sub-TLV for IPv6 BIER prefix:
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type (TBD2) | 23 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IBBR Prefix IPv6 |
~ ........ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| sub-domain-id| BFR-id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
4. Datapath Forwarding
4.1. Datapath traffic flow
On the BFIR when the MPLS label for P2MP/MP2MP LSP arrives from
upstream, a lookup in the ILM table is done and the label is swapped
with the tLDP upstream assigned label. The BFIR will note all the
BFERs that are interested in specific P2MP/MP2MP LSP (as per section
3.2). The BFIR will put the corresponding BIER header with the bit
index set for all the IBBRs interested in this stream. The BFIR will
set the BIERHeader.Proto = MPLS and will forward the BIER packet into
the BIER domain.
In the BIER domain, normal BIER forwarding procedure will be done, as
per [RFC8279]
The BFERs will receive the BIER packet and will look at the protocol
field of BIER header, indicating MPLS protocol. The BFER will remove
the BIER header and will do a lookup in the ILM table for the
upstream assigned label and perform its corresponding action.
It should be noted that these procedures are also valid if BFIR is
the ILER and/or BFER is the ELER as per [RFC7060]
5. Recursive FEC
The procedures above are also valid for mLDP recursive FEC. The root
used to determine the EBBR is the outer root of the FEC. The entire
recursive FEC needs to be preserved when it is forwarded via tLDP and
the label request.
6. IANA Consideration
IANA maintains a registry of Interface ID Types for use in GMPLS in
the registry "Generalized Multi-Protocol Label Switching (GMPLS)
Signaling Parameters" and sub-registry "Interface_ID Types"
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This document defines and requests two new Interface_ID Type for BIER
from the Interface_ID Types space,
* BIER IPv4 prefix TLV (Value TBD)
* BIER IPv6 prefix TLV (Value TBD)
7. Security Considerations
While in the BIER domain the security considerations of [RFC8279] are
relevant to this document.
The implementation should also take into account the security
recommendations of [RFC6389].
8. Acknowledgments
Authors would like to acknowledge Jingrong Xie and Nabeel Cocker for
his comments and help on this draft.
9. References
9.1. Normative References
[draft-ietf-bess-mvpn-evpn-aggregation-label]
"Z. Zhang, E. Rosen, W. Lin, Z. Li, I. Wijnands, "MVPN/
EVPN Tunnel Aggregation with Common Labels"", 27 April
2018.
[draft-ietf-bier-pim-signaling]
"H, Bidgoli, F. Xu, J. Kotalwar, I. Wijnands, M. Mishra,
Z. Zhang", 29 July 2020.
[RFC2119] "S. Bradner, "Key words for use in RFCs to Indicate
Requirement Levels"", March 1997.
[RFC6388] "IJ. Wijnands, I. Minei, K. Kompella, B.Thomas "Label
Distribution Protocol Extensions for Point-to-Multipoint
and Multipoint-to-Multipoint LSP"".
[RFC6389] "R Aggarwal, JL. Le Roux, "MPLS Upstream Label Assignment
for LDP"", November 2011.
[RFC7060] "M. Napierala, E. Rosen, I. Wijnands", November 2013.
[RFC8279] "I. Wijnands, E. Rosen, A. ADolganow, T. Prygienda, S.
Aldrin", November 2017.
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9.2. Informative References
[RFC8401] "Ginsberg, L., Przygienda, T., Aldrin, S., and Z. Zhang,
"BIER Support via ISIS"", June 2018.
[RFC8444] "Psenak, P., Kumar, N., Wijnands, IJ., Dolganow, A.,
Przygienda, T., Zhang, Z., and S. Aldrin, "OSPF Extensions
for Bit Index Explicit Replication"", June 2018.
[RFC8556] "Rosen, E., Ed., Sivakumar, M., Wijnands, IJ., Aldrin,
S.,Dolganow, A., and T. Przygienda, "Multicast VPN Using
Index Explicit Replication (BIER)", April 2018.
Authors' Addresses
Hooman Bidgoli (editor)
Nokia
Ottawa
Canada
Email: hooman.bidgoli@nokia.com
Jayant Kotalwar
Nokia
Montain View,
United States of America
Email: jayant.kotalwar@nokia.com
IJsbrand Wijnands
Cisco System
Diegem
Belgium
Email: ice@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
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Eddie Leyton
Verizon
Email: Edward.leyton@verizonwireless.com
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