Network Working Group J. Arango
Internet-Draft S. Venaas
Intended status: Experimental Cisco Systems
Expires: December 16, 2016 I. Kouvelas
Arista Networks Inc.
D. Farinacci
lispers.net
June 14, 2016
PIM Join Attributes for LISP Environments
draft-ietf-pim-join-attributes-for-lisp-04.txt
Abstract
This document defines two PIM Join/Prune attributes that support the
construction of multicast distribution trees where the root and
receivers are located in different LISP sites. These attributes
allow the receiver site to select between unicast and multicast
underlay transport and to convey the receiver ETR's RLOC address to
the control plane of the root ITR.
Status of This Memo
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This Internet-Draft will expire on December 16, 2016.
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carefully, as they describe your rights and restrictions with respect
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Notation . . . . . . . . . . . . . . . . . . . . 3
3. PIM Join/Prune Attributes . . . . . . . . . . . . . . . . . . 3
4. The Transport Attribute . . . . . . . . . . . . . . . . . . . 3
4.1. Transport Attribute Format . . . . . . . . . . . . . . . 4
4.2. Using the Transport Attribute . . . . . . . . . . . . . . 4
5. Receiver ETR RLOC Attribute . . . . . . . . . . . . . . . . . 5
5.1. Receiver RLOC Attribute Format . . . . . . . . . . . . . 5
5.2. Using the Receiver RLOC Attribute . . . . . . . . . . . . 6
6. Security Considerations . . . . . . . . . . . . . . . . . . . 6
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
8. Normative References . . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
The construction of multicast distribution trees where the root and
receivers are located in different LISP sites [RFC6830] is defined in
[RFC6831]. Creation of (root-EID,G) state in the root site requires
that unicast LISP-encapsulated Join/Prune messages be sent from an
ETR on the receiver site to an ITR on the root site.
[RFC6831] specifies that (root-EID,G) data packets are to be LISP-
encapsulated into (root-RLOC,G) multicast packets. However, a wide
deployment of multicast connectivity between LISP sites is unlikely
to happen any time soon. In fact, some implementations are initially
focusing on unicast transport with head-end replication between root
and receiver sites.
The unicast LISP-encapsulated Join/Prune message specifies the (root-
EID,G) state that needs to be established in the root site, but
conveys nothing about the receivers capability or desire to use
multicast as the underlying transport. This document specifies a
Join/Prune attribute that allows the receiver ETR to select the
desired transport.
Knowledge of the receiver ETR's RLOC address is also essential to the
control plane of the root ITR. It determines the downstream
destination for unicast head-end replication and identifies the
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receiver ETR that needs to be notified should the root of the
distribution tree move to another site.
Service providers may implement URPF policies requiring that the
outer source address of the LISP-encapsulated Join/Prune message be
the address of the receiver ETR's core-facing interface used to
physically transmit the message. However, due to policy and load
balancing considerations, the outer source address may not be the
RLOC on which the receiver site wishes to receive a particular flow.
This document specifies a Join/Prune attribute that conveys the
appropriate receiver ETR's RLOC address to the control plane of the
root ITR.
2. Requirements Notation
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].
3. PIM Join/Prune Attributes
PIM Join/Prune attributes are defined in [RFC5384] by introducing a
new Encoded-Source type that, in addition to the Join/Prune source,
can carry multiple type-length-value (TLV) attributes. These
attributes apply to the individual Join/Prune sources on which they
are stored.
The attributes defined in this document conform to the format of the
encoding type defined in [RFC5384]. The attributes would typically
be the same for all the sources in the Join/Prune message. Hence we
RECOMMEND using the hierarchical Join/Prune attribute scheme defined
in [I-D.ietf-pim-hierarchicaljoinattr]. This hirarchichal system
allows attributes to be conveyed on the Upstream Neighbor Address
field, thus enabling the efficient application of a single attribute
instance to all the sources in the Join/Prune message.
LISP xTRs do not exchange PIM Hello Messages and hence no Hello
option is defined to negotiate support for these attributes. Systems
that support unicast head-end replication are assumed to support
these attributes.
4. The Transport Attribute
It is essential that a mechanism be provided by which the desired
transport can be conveyed by receiver sites. Root sites with
multicast connectivity will want to leverage multicast replication.
However, not all receiver sites can be expected to have multicast
connectivity. It is thus desirable that root sites be prepared to
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support (root-EID,G) state with a mixture of multicast and unicast
output state. This document specifies a Join/Prune attribute that
allows the receiver to select the desired underlying transport.
4.1. Transport Attribute Format
0 1 2
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|F|E| Type = TBD| Length = 1 | Transport |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
F-bit: The Transitive bit. Specifies whether the attribute is
transitive or non-transitive. MUST be set to zero. This
attribute is ALWAYS non-transitive.
E-bit: End-of-Attributes bit. Specifies whether this attribute is
the last. Set to zero if there are more attributes. Set to 1 if
this is the last attribute.
Type: The Transport Attribute type is TBD.
Length: The length of the Transport Attribute value. MUST be set
to 1.
Transport: The type of transport being requested. Set to 0 for
multicast. Set to 1 for unicast.
4.2. Using the Transport Attribute
Hierarchical Join/Prune attribute instances
[I-D.ietf-pim-hierarchicaljoinattr] SHOULD be used when the same
Transport Attribute is to be applied to all the sources within the
Join/Prune message or all the sources within a group set. The root
ITR MUST accept Transport Attributes in the Upstream Neighbor
Encoded-Unicast address, Encoded-Group addresses, and Encoded-Source
addresses.
There MUST NOT be more than one Transport Attribute within the same
encoded address. If an encoded address has more than one instance of
the attribute, the root ITR MUST discard all affected Join/Prune
sources.
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5. Receiver ETR RLOC Attribute
When a receiver ETR requests unicast head-end replication for a given
(root-EID,G) entry, the PIM control plane of the root ITR must
maintain an output interface list ("oif-list") entry for the receiver
ETR and its corresponding RLOC address. This allows the root ITR to
perform unicast LISP-encapsulation of multicast data packets to each
and every receiver ETR that has requested unicast head-end
replication.
The PIM control plane of the root ITR could potentially determine the
RLOC address of the receiver ETR from the outer source address field
of LISP-encapsulated Join/Prune message. However, receiver ETRs are
subject to URPF checks by the network providers on each core-facing
interface. The outer source address must therefore be the RLOC of
the core-facing interface used to physically transmit the LISP-
encapsulated Join/Prune message. Due to policy and load balancing
considerations, that may not be the RLOC on which the receiver site
wishes to receive a particular flow. This document specifies a Join/
Prune attribute that conveys the appropriate receiver RLOC address to
the PIM control plane of the root ITR.
To support root-EID mobility, receiver ETRs must also be tracked by
the LISP control plane of the root ITR, regardless of the underlying
transport. When the root-EID moves to a new root ITR in a different
LISP site, the receiver ETRs do not know the root-EID has moved and
therefore do not know the RLOC of the new root ITR. This is true for
both unicast and multicast transport modes. The new root ITR does
not have any receiver ETR state. Therefore, it is the responsability
of the old root ITR to inform the receiver ETRs that the root-EID has
moved. When the old root ITR detects that the root-EID has moved, it
sends a LISP SMR message to each receiver ETR. The receiver ETRs do
a mapping database lookup to retrieve the RLOC of the new root ITR.
The old root ITR detects that the root-EID has moved when it receives
a Map-Notify from the Map-Server. The transmission of the Map-Notify
is triggered when the new root ITR registers the root-EID
[I-D.portoles-lisp-eid-mobility]. When a receiver ETR determines
that the root ITR has changed it will send a LISP-encapsulated PIM
prune message to the old root XTR and a LISP-encapsulated PIM join
message to the new root XTR.
5.1. Receiver RLOC Attribute Format
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|F|E|Type=TBD+1 | Length | Addr Family | Receiver RLOC
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...
F-bit: The Transitive bit. Specifies whether this attribute is
transitive or non-transitive. MUST be set to zero. This
attribute is ALWAYS non-transitive.
E-bit: End-of-Attributes bit. Specifies whether this attribute is
the last. Set to zero if there are more attributes. Set to 1 if
this is the last attribute.
Type: The Receiver RLOC Attribute type is TBD+1.
Length: The length in octets of the attribute value. MUST be set
to the length in octets of the receiver RLOC address plus one
octet to account for the Address Family field.
Addr Family: The PIM Address Family of the receiver RLOC as defined
in [RFC4601].
Receiver RLOC: The RLOC address on which the receiver ETR wishes to
receiver the unicast-encapsulated flow.">
5.2. Using the Receiver RLOC Attribute
Hierarchical Join/Prune attribute instances
[I-D.ietf-pim-hierarchicaljoinattr] SHOULD be used when the same
Receiver RLOC attribute is to be applied to all the sources within
the message or all the sources within a group set. The root ITR MUST
accept Transport Attributes in the Upstream Neighbor Encoded-Unicast
address, Encoded-Group addresses, and Encoded-Source addresses.
There MUST NOT be more than one Receiver RLOC Attribute within the
same encoded address. If an encoded address has more than one
instance of the attribute, the root ITR MUST discard all affected
Join/Prune sources.
6. Security Considerations
Security of the Join Attribute is only guaranteed by the security of
the PIM packet. The attributes specified herein do not enhance or
diminish the privacy or authenticity of a Join/Prune message. A site
that legitimately or maliciously sends and delivers a Join/Prune
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message to another site will equally be able to append these and any
other attributes it wishes.
7. IANA Considerations
Two new PIM Join/Prune attribute types need to be assigned. Type 5
is being requested for the Transport Attribute. Type 6 is being
requested for the Receiver RLOC Attribute.
8. Normative References
[AFI] IANA, , "Address Family Numbers",
http://www.iana.org/assignments/address-family-numbers.
[I-D.ietf-pim-hierarchicaljoinattr]
Venaas, S., Arango, J., and I. Kouvelas, "Hierarchical
Join/Prune Attributes", draft-ietf-pim-
hierarchicaljoinattr-08 (work in progress), April 2016.
[I-D.portoles-lisp-eid-mobility]
Portoles-Comeras, M., Ashtaputre, V., Moreno, V., Maino,
F., and D. Farinacci, "LISP L2/L3 EID Mobility Using a
Unified Control Plane", draft-portoles-lisp-eid-
mobility-00 (work in progress), April 2016.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC4601] Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas,
"Protocol Independent Multicast - Sparse Mode (PIM-SM):
Protocol Specification (Revised)", RFC 4601,
DOI 10.17487/RFC4601, August 2006,
<http://www.rfc-editor.org/info/rfc4601>.
[RFC5384] Boers, A., Wijnands, I., and E. Rosen, "The Protocol
Independent Multicast (PIM) Join Attribute Format",
RFC 5384, DOI 10.17487/RFC5384, November 2008,
<http://www.rfc-editor.org/info/rfc5384>.
[RFC6830] Farinacci, D., Fuller, V., Meyer, D., and D. Lewis, "The
Locator/ID Separation Protocol (LISP)", RFC 6830,
DOI 10.17487/RFC6830, January 2013,
<http://www.rfc-editor.org/info/rfc6830>.
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[RFC6831] Farinacci, D., Meyer, D., Zwiebel, J., and S. Venaas, "The
Locator/ID Separation Protocol (LISP) for Multicast
Environments", RFC 6831, DOI 10.17487/RFC6831, January
2013, <http://www.rfc-editor.org/info/rfc6831>.
Authors' Addresses
Jesus Arango
Cisco Systems
170 Tasman Drive
San Jose, CA 95134
USA
Email: jearango@cisco.com
Stig Venaas
Cisco Systems
170 Tasman Drive
San Jose, CA 95134
USA
Email: stig@cisco.com
Isidor Kouvelas
Arista Networks Inc.
5453 Great America Parkway
Santa Clara, CA 95054
USA
Email: kouvelas@arista.com
Dino Farinacci
lispers.net
San Jose, CA
USA
Email: farinacci@gmail.com
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