Internet DRAFT - draft-hb-bier-mldp-signaling-over-bier
draft-hb-bier-mldp-signaling-over-bier
BIER Workgroup H. Bidgoli
Internet Draft J. Kotalwar
Intended status: Standard Track Nokia
Z.Zhang
Juniper Networks
Eddie Leyton
Vrizon
Mankamana Mishra
I. Wijanands
Cisco System, Inc.
Expires: May 6, 2020 November 3, 2019
M-LDP Signaling Through BIER Core
draft-hb-bier-mldp-signaling-over-bier-01
Abstract
Bit Index Explicit Replication (BIER) is an architecture that
provides multicast forwarding through a "BIER domain" without
requiring intermediate routers to maintain multicast related per-flow
state. Neither does BIER require an 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. Such 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 the according set of bits switched on in
BIER packet header.
This document describes the procedure needed for mLDP tunnels to be
signaled over and stitched through a BIER core, allowing LDP routers
to run traditional Multipoint LDP services through a BIER core.
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), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts.
Bidgoli, et al. Expires May 6, 2020 [Page 1]
Internet-Draft MLDP Signaling Through BIER Core November 3, 2019
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." The list
of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html
This Internet-Draft will expire on October 8, 2017.
Copyright Notice
Copyright (c) 2019 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
(http://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. Conventions used in this document . . . . . . . . . . . . . . . 3
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
3.1.1. ECMP Method on IBBR . . . . . . . . . . . . . . . . . . 6
3.2. Egress BBR procedure method . . . . . . . . . . . . . . . . 6
3.2.1. IBBR procedure upon arriving upstream assigned label . 6
4. Datapath Forwarding . . . . . . . . . . . . . . . . . . . . . . 7
4.1. Datapath traffic flow . . . . . . . . . . . . . . . . . . . 7
5. Recursive FEC . . . . . . . . . . . . . . . . . . . . . . . . . 7
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
7. Security Considerations . . . . . . . . . . . . . . . . . . . . 7
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7
8.1. Normative References . . . . . . . . . . . . . . . . . . . 7
8.2. Informative References . . . . . . . . . . . . . . . . . . 8
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 8
Bidgoli, et al. Expires May 6, 2020 [Page 2]
Internet-Draft MLDP Signaling Through BIER Core November 3, 2019
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
Some operators that are using mLDP P2MP LSPs for their multicast
transport would like to deploy BIER technology in some segment of
their network. This draft explains a method to signal mLDP services
and stitch the mLDP datapath labels 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 RFC 2119 [RFC2119].
2.1. Definitions
Some of the terminology specified in [I-D.draft-ietf-bier-
architecture-05] 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 term used for dataplain packet
forwarding.
BFER:
Bit Forwarding Egress Router. A router that participates in
Bit Index Forwarding as leaf. Each BFER must be a BFR. Each
BFER must have a valid BFR-id assigned. BFIR is term used for
dataplain packet forwarding.
Bidgoli, et al. Expires May 6, 2020 [Page 3]
Internet-Draft MLDP Signaling Through BIER Core November 3, 2019
BBR:
BIER Boundary router. The router between the LDP domain and
BIER domain.
IBBR:
Ingress BIER Boundary Router. The ingress router from
signaling point of view. It maintains mLDP adjacency toward
the LDP domain and determines if the mLDP FEC needs to be
signaled across the BIER domain via targeted ldp.
EBBR:
Egress BIER Boundary Router. The egress router in BIER domain
from signaling point of view. It terminates the targeted ldp
signaling through BIER domain. It also keeps track of all
IBBRs that are part of this p2mp tree
BFT:
Bit Forwarding Tree used to reach all BFERs in a domain.
BIFT:
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.
3. mLDP Signaling Through BIER domain
Bidgoli, et al. Expires May 6, 2020 [Page 4]
Internet-Draft MLDP Signaling Through BIER Core November 3, 2019
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 documents provides some details and defines some needed
procedures.
3.1. Ingress BBR procedure
The Ingress BBR (IBBR) is connected to the mLDP on one side and a
bier domain on the other side. 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 the 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
A tLDP session can be generated automatically from every IBBR to
EBBR. As an example when a mLDP FEC arrives on the IBBR, it can
automatically start a tLDP Session with the EBBR. In this case both
IBBR and EBBR should be in auto-discovery mode and react to the
arriving FEC or tLDP Signaling packets (i.e. targeted hellos, keep-
alives etc...).
The Root node address in the mLDP FEC can be used to find the EBBR.
To identify the EBBR same procedures as [RFC7060} section 2.1 can be
Bidgoli, et al. Expires May 6, 2020 [Page 5]
Internet-Draft MLDP Signaling Through BIER Core November 3, 2019
used or the procedures as explained in the [draft-ietf-bier-pim-
signaling] appendix A. After fining the IBBR the tLDP session can be
initiated from the IBBR to EBBR.
3.1.1. ECMP Method on IBBR
If 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 smallest EBBR IP address to establish its mLDP
signaling to.
3.2. Egress BBR procedure method
The Egress BBR (EBBR) is connected to the mLDP domain which the root
of the P2MP or MP2MP LSP resides on. The EBBR should accept the tLDP
session generated form IBBR. It should assign a unique "upstream
assigned label" for each arriving FEC generated by IBBRs.
The EBBR should follow the [RFC7060] procedures with following
modifications:
- The label assigned by EBBR cannot be Implicit Null. This is to
ensure that identity of each p2mp and/or mp2mp tunnel in BIER domain
is uniquely distinguished.
- The label can be assigned from a domain-wide Common Block (DCB) [I-
D.zzhang-bess-mvpn-evpn-aggregation-label], as well as upstream
assigned.
- The Interface ID TLV [RFC6389]includes a new BIER sub-domain sub-
tlv (type TBD)
The EBBR will also generate a new label and FEC toward the ROOT on
the mLDP domain. The EBBR Should stitch this generate label with the
"upstream assigned label" to complete the p2MP or MP2MP LSP. This
stitch point should be stored on the datapath (ILM) table for packet
forwarding.
With same token the EBBR should track all the arriving FECs and the
IBBRs that are generating these FECs. 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 upon arriving upstream assigned label
Upon receiving the "upstream assigned label", IBBR should create its
own stitching instruction between the "upstream assigned label" and
Bidgoli, et al. Expires May 6, 2020 [Page 6]
Internet-Draft MLDP Signaling Through BIER Core November 3, 2019
the down stream label that was signaled to it. IBBR should download
these instructions to the datapath.
4. Datapath Forwarding
4.1. Datapath traffic flow
On BFIR when the MPLS label for P2MP/MP2MP LSP arrives a lookup in
ILM table is done and the label is swapped with tLDP upstream
assigned label. The BFIR will note all the BFERs that are interested
in specific p2mp/mp2mp LSP (as per section 3.2). BFIR will put the
corresponding BIER header with bit index set for all IBBRs interested
in this P2MP LSP. BFIR will set the BIERHeader.Proto = MPLS and will
forward the BIER packet into BIER domain.
In the BIER domain normal BIER forwarding procedure will be done, as
per [RFC 8279]
The IBBRs will receive the BIER packet, will look at the protocol of
BIER header (MPLS). 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 valid if BFIR is the
ILER and/or BFER is the ELER as per [RFC 7060]
5. Recursive FEC
The above procedures also will work with a mLDP recursive FEC. The
root used to determine the EBBR is the outer root of the FEC. The
entire recursive FEC needs to be preserve when it is forwarded via
tLDP and the label request.
6. IANA Considerations
This document contains no actions for IANA.
7. Security Considerations
TBD
8. References
8.1. Normative References
[BIER_ARCH] Wijnands, IJ., Rosen, E., Dolganow, A., Przygienda, T.,
and S. Aldrin, "Multicast using Bit Index Explicit Replication",
Bidgoli, et al. Expires May 6, 2020 [Page 7]
Internet-Draft MLDP Signaling Through BIER Core November 3, 2019
internet-draft draft-ietf-bier-architecture-08, October 2016.
8.2. Informative References
[BIER_MVPN] Rosen, E., Ed., Sivakumar, M., Wijnands, IJ., Aldrin, S.,
Dolganow, A., and T. Przygienda, "Multicast VPN Using Bier",
internet-draft draft-ietf-bier-mvpn-08, January 2017.
[ISIS_BIER_EXTENSIONS] Ginsberg, L., Przygienda, T., Aldrin, S., and
Z. Zhang, "BIER Support via ISIS", internet-draft draft-ietf-bier-
isis-extensions-06.txt, March 2017.
[OSPF_BIER_EXTENSIONS] Psenak, P., Kumar, N., Wijnands, IJ.,
Dolganow, A., Przygienda, T., Zhang, Z., and S. Aldrin, "OSPF
Extensions for Bit Index Explicit Replication", internet-draft draft-
ietf-ospf-bier-extensions-09.txt, March 2017.
7. Acknowledgments Authors would like to acknowledge Jingrong Xie for
his comments and help on this draft.
Authors' Addresses
Hooman Bidgoli (editor)
Nokia
600 March Rd.
Ottawa, Ontario K2K 2E6
Canada
Email: hooman.bidgoli@nokia.com
Jayant Kotalwar
Nokia
380 N Bernardo Ave,
Mountain View, CA 94043
US
Email: jayant.kotalwar@nokia.com
Zhaohui Zhang
Juniper Networks
EMail: zzhang@juniper.net
IJsbrand Wijnands
Cisco Systems
EMail: ice@cisco.com
Bidgoli, et al. Expires May 6, 2020 [Page 8]
Internet-Draft MLDP Signaling Through BIER Core November 3, 2019
Eddie Leyton
Vrizon
Email: Edward.leyton@verizonwireless.com
Mankamana Mishra
Cisco System
821 alder drive
Milpitas California
USA
Email: mankamis@cisco.com
Bidgoli, et al. Expires May 6, 2020 [Page 9]
