Internet DRAFT - draft-bishnoi-mpls-ldp-node-group
draft-bishnoi-mpls-ldp-node-group
MPLS Working Group Sandeep Bishnoi
Internet Draft Pranjal Kumar Dutta
Intended status: Standards Track Alcatel-Lucent
Expires: April 2010
October 19, 2009
LDP Node and FEC group
draft-bishnoi-mpls-ldp-node-group-00.txt
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Internet-Draft LDP Node and FEC Group October 2009
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Abstract
[RFC5036] and [MLDP] describes the Label Distribution Protocol (LDP)
for setup of point-to-point (P2P), point to multi-point (P2MP) and
multipoint-to-multipoint (MP2MP) Label Switched Paths (LSPs).
Upstream node selection for P2MP/MP2MP LSP and label map propagation
for P2P is based on route availability and local policy. If multiple
paths are available then there is no method for selection of certain
preferred nodes. A new method is defined in this document that can
optionally be used as a tiebreaker among multiple available paths in
upstream node selection. This method provides a mechanism to guide
traffic via specific set of nodes in a network.
Table of Contents
1. Introduction...................................................2
2. Terminology....................................................3
3. Conventions used in this document..............................3
4. Structure for LDP Node group mapping and FEC group advertisement3
4.1. Node group advertisement..................................3
4.2. FEC group mapping.........................................4
5. Limitations....................................................5
6. Security Considerations........................................5
7. IANA Considerations............................................5
8. References.....................................................5
8.1. Normative References......................................5
9. Acknowledgments................................................6
1. Introduction
LDP downstream node selection for P2P LSP and upstream node selection
for P2MP/MP2MP LSP is based on route availability at each node. If
multiple such paths are available then node resolving LDP FEC based
on route is based on local policy.
In case of availability of multiple paths, there is no mechanism to
direct traffic towards preferred nodes or restrict traffic to flow
via nodes that are not preferred. Few applications that use LDP LSP
also require redundant paths for minimum downtime of service. One of
the requirements for such applications is to establish LSP via
disjoint nodes.
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This proposal defines a method to identify and select a preferred
node group to setup LSP. Scheme defined in this document also allows
restricting traffic flow within a certain set of nodes and also
avoiding nodes that belong to a group that is not preferred. This
proposal is only for preferred node selection and does not address
selection or avoiding preferred links.
This document defines a node level attribute to identify selection
group and a mechanism to advertise and propagate an LDP FEC with
group attribute. This scheme may be applied to P2P and P2MP/MP2MP
LSP. This method can be applied to P2P LSP during decision process to
send label map to a peer. For P2MP/MP2MP LSP, this method is applied
during upstream node selection.
This document defines two new LDP parameters:
. Node group
. FEC group mapping
2. Terminology
This document uses the terminology defined in [RFC5036] and [MLDP].
3. 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].
4. LDP node and FEC group
Group mapping of a node may be advertised to a peer using "Node Group
Capability" message. Group mapping per FEC may be advertised to a
peer using "FEC Group TLV" in Label Map message.
4.1. Node Group Capability
An LSR may advertise node group map capability to an LDP peer using
method defined in [RFC5561]. Node group message must be silently
discarded if the receiving node does not support it.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1|0| Node Group Capability | Length |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
| Node Group Map |
|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type: Node Group Capability (TBD)
Node Group Map: A 32-bit node group map.
4.2. FEC Group TLV
FEC group mapping TLV may be included in Label Map message to
advertise node group to be used for upstream node selection. FEC
group mapping must be silently discarded if the receiving node does
not support it.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1|0| FEC Group Mapping | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
| Include Group |
|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Exclude Group |
|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|I|E| Reserved |
|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type: FEC Group Mapping (TBD)
Include Group: 32-bit map of node groups to include while propagating
label map
Exclude Group: 32-bit map of node groups to exclude while propagating
label map
Include Type (I): Strict (1) or Loose (0)
Exclude Type (E): Strict (1) or Loose (0)
A node processing P2P LSP label map message propagates it further to
upstream node based on criteria defined in [RFC5036]. A node
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processing P2MP/MP2MP LSP label map message selects a single upstream
node based on criteria defined in [MLDP].
If a FEC group mapping is included in label map message then the
receiving node may choose sending the label map message further to
its peers based on group mapping received in label map. FEC group
mapping must then match peer node group advertisement to qualify to
receive a label map.
For P2P LSP, if include type is "Strict" then the label map message
MUST only be propagated to peers that have all the groups. If exclude
type is "Strict" then the label map message MUST not be propagated to
peers that have any of the groups.
For P2MP/MP2MP LSP, if include type is "Strict" then the label map
message MUST only be propagated to a peer that has all the groups. If
exclude type is "Strict" then the label map message MUST not be
propagated to a peer that has any of the groups.
If multiple peers qualify then include and exclude type must be used
as a tiebreaker. "Strict" is preferred over "Loose" group map.
5. Limitations
This scheme does not guarantee setup of LSP if "Strict" group option
for an LDP FEC is enabled. This scheme requires proper network
provisioning for it to work.
6. Security Considerations
The same security considerations apply as for the base LDP
specification, as described in [RFC5036] and MP LDP specification, as
described in [MLDP].
7. IANA Considerations
This document requires allocation of Node Group Capability and FEC
Group TLV.
8. References
8.1. Normative References
[MLDP] I. Minei, K., Kompella, I. Wijnands, B. Thomas, "Label
Distribution Protocol Extensions for Point-to-Multipoint
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and Multipoint-to-Multipoint Label Switched Paths",
draft-ietf-mpls-ldp-p2mp-06.txt, May 2008
[RFC5036] Andersson, L., Minei, I., and B. Thomas, "LDP
Specification", RFC 5036, October 2007.
[RFC5561] B. Thomas, K. Raza, S. Aggarwal, R. Aggarwal,
JL. Le Roux, "LDP Capabilities", RFC 5561, July 2009.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
9. Acknowledgments
The authors would like to acknowledge the comments and suggestions
from Wim Henderickx.
This document was prepared using 2-Word-v2.0.template.dot.
Authors' Addresses
Sandeep Bishnoi
Alcatel-Lucent
701 E Middlefield Road,
Mountain View, CA 94043
USA
Email: sandeep.bishnoi@alcatel-lucent.com
Pranjal Kumar Dutta
Alcatel-Lucent
701 E Middlefield Road,
Mountain View, CA 94043
USA
Email: pdutta@alcatel-lucent.com
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