Internet DRAFT - draft-vgovindan-pim-jp-extensions-lisp
draft-vgovindan-pim-jp-extensions-lisp
Internet Engineering Task Force V. Govindan
Internet-Draft S. Venaas
Intended status: Experimental Cisco
Expires: 6 December 2021 4 June 2021
PIM Join/ Prune Attributes for LISP Environments using Underlay
Multicast
draft-vgovindan-pim-jp-extensions-lisp-01
Abstract
This document specifies an extension to PIM Receiver RLOC Join/ Prune
attribute that supports the construction of multicast distribution
trees where the root and receivers are located in different Locator/
ID Separation Protocol (LISP) sites and are connected using underlay
IP Multicast. This attribute allows the receiver site to signal the
underlay multicast group to the control plane of the root ITR
(Ingress Tunnel Router).
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). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
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."
This Internet-Draft will expire on 6 December 2021.
Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved.
Govindan & Venaas Expires 6 December 2021 [Page 1]
Internet-Draft PIM Join Attributes for LISP Mcast June 2021
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://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 . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. The case for extending the Received ETR RLOC Attribute of RFC
8059 . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
4. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 4
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
6. Security Considerations . . . . . . . . . . . . . . . . . . . 4
7. Normative References . . . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
The construction of multicast distribution trees where the root and
receivers are located in different LISP sites [RFC6830] is defined in
[RFC6831].
[RFC6831] specifies that (root-EID, G) data packets are to be LISP-
encapsulated into (root-RLOC, G) multicast packets. [RFC8059]
defines PIM J/P attribute extensions to construct multicast
distribution trees. This document extends the Receiver ETR RLOC PIM
J/P attribute [RFC8059] to facilitate the construction of underlay
multicast trees for (root-RLOC, G).
Specifically, the assignment of the underlay multicast group needs to
be done in consonance with the downstream xTR nodes and avoid
unnecessary replication or traffic hairpinning.
Since the Receiver RLOC Attribute defined in [RFC8059] only addresses
the Ingress Replication case, an extension of the scope of that PIM
J/P attribute is defined by this draft to include scenarios where the
underlay uses Multicast transport. The scope extension proposed here
complies with the base specification [RFC5384].
This document uses terminology defined in [RFC6830], such as EID,
RLOC, ITR, and ETR.
Govindan & Venaas Expires 6 December 2021 [Page 2]
Internet-Draft PIM Join Attributes for LISP Mcast June 2021
1.1. Requirements Language
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. The case for extending the Received ETR RLOC Attribute of RFC 8059
When LISP based Multicast trees can be built using IP Multicast in
the underlay, the mapping between the overlay group address and the
underlay group address becomes a very crucial engineering decision:
Flexible mapping of overlay to underlay group ranges:
Three different types of overlay to underlay group mappings are
possible: Many to one mapping: Many (root-EID, G) flows originating
from a RLOC can be mapped to the same underlay (root-RLOC, G-u)
flow. One to many mapping: Conversely the same overlay flow can be
mapped to two or more flows e.g. (root-RLOC, G-u1) and (root-RLOC,
G-u2) to cater to the requirements of downstream xTR nodes. One to
one mapping: Every (root-EID, G) flow is mapped to a different
(root-RLOC, G-u) flow. The overlay can use ASM while the underlay
can use SSM ranges.
Multicast Address Range constraints:
It is possible that under certain circumstances, differnt subsets of
xTRs subscribing to the same overlay multicast stream would be
constrained to use different underlay multicast mapping ranges.
This definitely involves a trade-off between replication and the
flexibility in assigning address ranges and could be required in
certain situations further below.
Inter-site PxTR:
When multiple LISP sites are connected through a LISP based transit,
the site border node interconnects the site-facing interfaces and
the external LISP based core. Under such circumstances, there could
be different ranges of multicast group addresses used for building
the (S-RLOC, G) trees inside the LISP site and the external LISP
based core. This is desired for various reasons:
Hardware resource restrictions:
Platform limitations could force engineering decisions to be made on
restricting multicast address ranges in the underlay.
Other Use-cases:
TBD
Govindan & Venaas Expires 6 December 2021 [Page 3]
Internet-Draft PIM Join Attributes for LISP Mcast June 2021
Editorial Note: Comments from Stig: There should be some text
indicating that the group address used should ideally only be used
for LISP encapsulation (if ASM), and perhaps that it is preferrable
to use an SSM group. Also, that the group obviously must be a group
that the underlay supports/allows. I think it is also worth noting
that ideally, different ETRs should request the same group.
3. Acknowledgements
The authors would like to thank Dino Farinacci and Victor Moreno for
their valuable comments.
4. Contributors
Sankaralingam
Cisco
Email: sankt@cisco.com
Amit Kumar
Cisco
Email: kumaram3@cisco.com
5. IANA Considerations
No new requests to IANA
6. Security Considerations
There is perhaps a new attack vector where an attacker can send a
bunch of joins with different group addresses. It may interfere with
other multicast traffic if those group addresses overlap. Also, it
may take up a lot of resources if replication for thousands of groups
are requested. However PIM authentication (?) should come to the
rescue here. TBD Since explicit tracking would be done, perhaps it
is worth enforcing that for each ETR RLOC (the RLOC used as the
source of the overlay join), there could be a configurable number of
maximum permissible group(s). TBD
Ed Note: To be addressed - Comments from Stig: Regarding security
considerations and PIM authentication. The only solution we have
here is to use IP-Sec to sign the J/P messages. I don't know if
anyone has tried to us IPSec between LISP RLOCs. Are there any LISP
security mechanisms that would help here for authenticating LISP
encapsulated messages between xTRs?
Govindan & Venaas Expires 6 December 2021 [Page 4]
Internet-Draft PIM Join Attributes for LISP Mcast June 2021
7. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC5384] Boers, A., Wijnands, I., and E. Rosen, "The Protocol
Independent Multicast (PIM) Join Attribute Format",
RFC 5384, DOI 10.17487/RFC5384, November 2008,
<https://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,
<https://www.rfc-editor.org/info/rfc6830>.
[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, <https://www.rfc-editor.org/info/rfc6831>.
[RFC7761] Fenner, B., Handley, M., Holbrook, H., Kouvelas, I.,
Parekh, R., Zhang, Z., and L. Zheng, "Protocol Independent
Multicast - Sparse Mode (PIM-SM): Protocol Specification
(Revised)", STD 83, RFC 7761, DOI 10.17487/RFC7761, March
2016, <https://www.rfc-editor.org/info/rfc7761>.
[RFC8059] Arango, J., Venaas, S., Kouvelas, I., and D. Farinacci,
"PIM Join Attributes for Locator/ID Separation Protocol
(LISP) Environments", RFC 8059, DOI 10.17487/RFC8059,
January 2017, <https://www.rfc-editor.org/info/rfc8059>.
Authors' Addresses
Vengada Prasad Govindan
Cisco
Email: venggovi@cisco.com
Stig Venaas
Cisco
Email: svenaas@cisco.com
Govindan & Venaas Expires 6 December 2021 [Page 5]
