BFD for Multipoint Networks over Point-to-Multi-Point MPLS LSP
ZTE Corp.
gregimirsky@gmail.com
Routing
MPLS Working Group
Internet-Draft
BFD
Multipoint LSP
This document describes procedures for using Bidirectional Forwarding Detection (BFD) for multipoint networks
to detect data plane failures in Multiprotocol Label Switching (MPLS) point-to-multipoint (p2mp)
Label Switched Paths (LSPs). It also describes applicability of out-band solutions to bootstrap a BFD session
in this environment.
MPLS: Multiprotocol Label Switching
LSP: Label Switched Path
BFD: Bidirectional Forwarding Detection
p2mp: Point-to-Multipoint
FEC: Forwarding Equivalence Class
G-ACh: Generic Associated Channel
ACH: Associated Channel Header
GAL: G-ACh Label
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.
defines a method of using Bidirectional
Detection (BFD) to monitor and detect unicast failures
between the sender (head) and one or more receivers (tails) in multipoint or multicast
networks. This document describes procedures for using such mode of BFD protocol
to detect data plane failures in Multiprotocol Label Switching (MPLS) point-to-multipoint (p2mp)
Label Switched Paths (LSPs). The document also describes applicability of out-band solutions
to bootstrap a BFD session in this environment.
defines the tail of multipoint BFD session
demultiplexes received BFD control packet based not on Your Discriminator, as defined in ,
but using source IP address, My Discriminator and the identity of the multipoint tree
which the Multipoint BFD Control packet was received from. The identity of the multipoint tree
MAY be provided by the p2mp MPLS LSP label in case of inclusive p-tree or upstream assigned label
in case of aggregate p-tree.
IP/UDP encapsulation for multipoint BFD over p2mp MPLS LSP follows the same rules as
defined in Section 7 for BFD over p2p LSP:
UDP destination port MUST be set to 3784;
destination IP address MUST be from the 127/8 range for IPv4 and
from the 0:0:0:0:0:FFFF:7F00/104 range for IPv6;
if multiple alternative paths for the given p2mp LSP Forwarding
Equivalence Class(FEC) exist, the MultipointHead
SHOULD use Entropy Label used for LSP Ping
to excercise that particular alternative path;
or the MultipointHead MAY use, as destination IP address, the IP address discovered by LSP Ping traceroute
to exercise that particular alternate path.
Non-IP encapsulation for multipoint BFD over p2mp MPLS LSP MUST use Generic
Associated Channel (G-ACh) Label (GAL) at the bottom of the label
stack followed by Associated Channel Header (ACH). Channel Type field in ACH MUST be set to
BFD CV . To provide identity of the MultipointHead for the particular
multipoint BFD session this document defines new Source MEP ID type TBA1
IP Address. If the Legnth value is 4, then the Value field contains IPv4 address. If the Length
value is 16, then the Value field contains IPv6 address. Any other value of the Length field MUST
be considered as error and the BFD control packet MUST be discarded.
MaultipointHead MAY use LSP Ping using in Target FEC TLV, as appropriate,
sub-TLVs defined in Section 3.1 .
BGP-BFD Attribute MAY be used to bootstrap multipoint BFD
session on a tail.
IANA is required to allocate value (TBD) for the
Source Source MEP ID IP Address type from the "CC/CV MEP-ID TLV" registry
which is under the "Pseudowire Associated Channel Types" registry.
Value
Description
Reference
TBA1
IP Address
This document
Thi document does not introduce new security aspects but inherits all security considerations
from , , ,
, , and .