Internet DRAFT - draft-ymbk-idr-l3nd-ulpc
draft-ymbk-idr-l3nd-ulpc
Network Working Group R. Bush
Internet-Draft Arrcus & IIJ
Intended status: Standards Track K. Patel
Expires: 29 November 2023 Arrcus
28 May 2023
L3ND Upper-Layer Protocol Configuration
draft-ymbk-idr-l3nd-ulpc-07
Abstract
This document adds PDUs to the Layer-3 Neighbor Discovery protocol to
communicate the parameters needed to exchange inter-device Upper
Layer Protocol Configuration for upper-layer protocols such as the
BGP family.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
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 29 November 2023.
Copyright Notice
Copyright (c) 2023 IETF Trust and the persons identified as the
document authors. All rights reserved.
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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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Reading and Terminology . . . . . . . . . . . . . . . . . . . 2
3. Upper-Layer Protocol Configuration PDU . . . . . . . . . . . 3
3.1. ULPC BGP Attribute sub-TLVs . . . . . . . . . . . . . . . 4
3.1.1. BGP ASN . . . . . . . . . . . . . . . . . . . . . . . 5
3.1.2. BGP IPv4 Address . . . . . . . . . . . . . . . . . . 5
3.1.3. BGP IPv6 Address . . . . . . . . . . . . . . . . . . 6
3.1.4. BGP Authentication sub-TLV . . . . . . . . . . . . . 6
3.1.5. BGP Miscellaneous Flags . . . . . . . . . . . . . . . 6
4. Security Considerations . . . . . . . . . . . . . . . . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
7.1. Normative References . . . . . . . . . . . . . . . . . . 8
7.2. Informative References . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
Massive Data Centers (MDCs) which use upper-layer protocols such as
BGP4 and other routing protocols may use the Layer-3 Neighbor
Discovery Protocol, L3ND, [I-D.ymbk-idr-l3nd] to reveal the inter-
device links of the topology. It is desirable for devices to
facilitate the configuration parameters of those upper layer
protocols to enable more hands-free configuration. This document
defines a new L3ND PDU to communicate these Upper-Layer Protocol
Configuration parameters.
2. Reading and Terminology
The reader is assumed to have read Layer-3 Neighbor Discovery
[I-D.ymbk-idr-l3nd]. The terminology and PDUs there are assumed
here.
Familiarity with the BGP4 Protocol [RFC4271] is assumed.
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3. Upper-Layer Protocol Configuration PDU
To communicate parameters required to configure peering and operation
of Upper-Layer Protocols at IP layer-3 and above, e.g., BGP sessions
on a link, a neutral sub-TLV based Upper-Layer Protocol PDU is
defined as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Version = 0 | Type = 8 | Payload Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | ULPC Type | AttrCount |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Serial Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute List ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Version, Type, and Payload Length as defined in
[I-D.ymbk-idr-l3nd] apply to this PDU.
The BGP Authentication sub-TLV provides for provisioning MD5, which
is a quite weak hash, horribly out of fashion, and kills puppies.
But, like it or not, it has been sufficient against the kinds of
attacks BGP TCP sessions have endured. So it is what BGP deployments
use.
As the ULPC PDU may contain keying material, e.g. [RFC2385], it
SHOULD BE over TLS.
ULPC Type: A one byte integer denoting the type of the upper-layer
protocol
0 : Reserved
1 : BGP
2-255 : Reserved
The one octet AttrCount is the number of attribute sub-TLVs in the
Attribute List.
The Attribute List is a, possibly null, set of sub-TLVs describing
the configuration attributes of the specific upper-layer protocol.
An Attribute consists of a one octet Attribute Type, a one octet
Attribute Length of the number of octets in the Attribute, and a
Payload of arbitrary length up to 253 octets.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attr Type = 1 | Attr Len | Payload |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.1. ULPC BGP Attribute sub-TLVs
The parameters needed for BGP peering on a link are exchanged in sub-
TLVs within an Upper-Layer Protocol PDU. The following describe the
various sub-TLVs for BGP.
The goal is to provide the minimal set of configuration parameters
needed by BGP OPEN to successfully start a BGP peering. The goal is
specifically not to replace or conflict with data exchanged during
BGP OPEN. Multiple sources of truth are a recipe for complexity and
hence pain.
If there are multiple BGP sessions on a link, e.g., IPv4 and IPv6,
then separate BGP ULPC PDUs should be sent, one for each address
family.
A peer receiving BGP ULPC PDUs has only one active BGP ULPC PDU for
an particular address family on a specific link at any point in time;
receipt of a new BGP ULPC PDU for a particular address family
replaces the data any previous one; but does not actually affect the
session.
If there are one or more open BGP sessions, receipt of a new BGP ULPC
PDU SHOULD not affect these sessions. The received data are stored
for a future session restart.
As a link may have multiple encapsulations and multiple addresses for
an IP encapsulation, which address of which encapsulation is to be
used for the BGP session MUST be specified.
For each BGP peering on a link here MUST be one agreed encapsulation,
and the addresses used MUST be in the corresponding L3ND IPv4/IPv6
Encapsulation PDUs. If the choice is ambiguous, an Attribute may be
used to signal preferences.
If a peering address has been announced as a loopback, i.e. MUST BE
flagged as such in the L3ND Encapsulation PDU (see
[I-D.ymbk-idr-l3nd] Sec. 10.2), a two or three hop BGP session MUST
be established as needed. Otherwise a direct one hop session is
used. The BGP session to a loopback will forward to the peer's
address which was marked as Primary in the L3ND Encapsulation Flags,
iff it is in a subnet which is shared with both BGP speakers. If the
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primary is not in a common subnet, then the BGP speaker MAY pick a
forwarding next hop that is in a subnet they share. If there are
multiple choices, the BGP speaker SHOULD have signaled which subnet
to choose in an Upper-Layer Protocol Configuration PDU Attribute.
Attributes MUST be unique in the Attribute List. I.e. a particular
Attr Type MUST NOT occur more than once in the Attribute List. If a
ULPC PDU is received with more than one occurrence of a particular
Attr Type, an Error ACK MUST be returned.
As there are separate PDU Attr Types for IPv4 and IPv6 peering
addresses, separate sessions for the two AFIs MAY be created for the
same ASN in one ULPC PDU.
3.1.1. BGP ASN
The four octet Autonomous System number MUST be specified. If the AS
Number is less than 32 bits, it is padded with high order zeros.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attr Type = 1 | Attr Len = 4 | My ASN ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.1.2. BGP IPv4 Address
The BGP IPv4 Address sub-TLV announces the sender's four octet IPv4
BGP peering source address and one octet Prefix Lenth to be used by
the receiver. At least one of IPv4 or IPv6 BGP source addresses MUST
be announced.
As usual, the BGP OPEN capability negotiation will determine the AFI/
SAFIs to be transported over the peering, see [RFC4760].
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attr Type = 2 | Attr Len = 5 | My IPv4 Peering Address ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ | Prefix Len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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3.1.3. BGP IPv6 Address
The BGP IPv6 Address sub-TLV announces the sender's 16 octet IPv6 BGP
peering source address and one octet Prefix Length to be used by the
receiver. At least one of IPv4 or IPv6 BGP source addresses MUST be
announced.
As usual, the BGP OPEN capability negotiation will determine the AFI/
SAFIs to be transported over the peering, see [RFC4760].
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attr Type = 3 | Attr Len = 17 | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| |
+ +
| My IPv6 Peering Address |
+ +
| |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | Prefix Len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.1.4. BGP Authentication sub-TLV
The BGP Authentication sub-TLV provides any authentication data
needed to OPEN the BGP session. Depending on operator configuration
of the environment, it might be a simple MD5 key (see [RFC2385]), the
name of a key chain in a KARP database (see [RFC7210]), or one of
multiple Authentication sub-TLVs to support hop[RFC4808].
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attr Type = 4 | Attr Len | ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~
~ BGP Authentication Data ... ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.1.5. BGP Miscellaneous Flags
The BGP session OPEN has extensive, and a bit complex, capability
negotiation facilities. In case one or more extra attributes might
be needed, the two octet BGP Miscellaneous Flags sub-TLV may be used.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attr Type = 5 | Attr Len = 2 | Misc Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Misc Flags:
Bit 0: GTSM
Bit 1: BFD
Bit 2-15: Must be zero
The GTSM flag, when 1, indicates that the sender wishes to enable the
[RFC5082] Generalized TTL Security Mechanism for the session.
The BFD flag, when 1, indicates that the sender wishes to enable the
[RFC5880] Bidirectional Forwarding Detection for the session.
4. Security Considerations
All the Security considerations of [I-D.ymbk-idr-l3nd] apply to this
PDU.
As the ULPC PDU may contain keying material, see Section 3.1.4, it
SHOULD BE over TLS, not clear TCP.
Any keying material in the PDU SHOULD BE salted and hashed.
The BGP Authentication sub-TLV provides for provisioning MD5, which
is a quite weak hash, horribly out of fashion, and kills puppies.
But, like it or not, it has been sufficient against the kinds of
attacks BGP TCP sessions have endured. So it is what BGP deployments
use.
5. IANA Considerations
This document requests the IANA create a new entry in the L3ND PDU
Type registry as follows:
PDU
Code PDU Name
---- -------------------
9 ULPC
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This document requests the IANA create a registry for L3ND ULPC Type,
which may range from 0 to 255. The name of the registry should be
L3ND-ULPC-Type. The policy for adding to the registry is RFC
Required per [RFC5226], either standards track or experimental. The
initial entries should be the following:
Value Name
----- -------------------
0 Reserved
1 BGP
2-255 Reserved
6. Acknowledgments
The authors thank Rob Austein, Sue Hares, and Russ Housley.
7. References
7.1. Normative References
[I-D.ymbk-idr-l3nd]
Bush, R., Housley, R., Austein, R., Hares, S., and K.
Patel, "Layer-3 Neighbor Discovery", Work in Progress,
Internet-Draft, draft-ymbk-idr-l3nd-05, 1 October 2022,
<https://datatracker.ietf.org/doc/html/draft-ymbk-idr-
l3nd-05>.
[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>.
[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Border Gateway Protocol 4 (BGP-4)", RFC 4271,
DOI 10.17487/RFC4271, January 2006,
<https://www.rfc-editor.org/info/rfc4271>.
[RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
"Multiprotocol Extensions for BGP-4", RFC 4760,
DOI 10.17487/RFC4760, January 2007,
<https://www.rfc-editor.org/info/rfc4760>.
[RFC5082] Gill, V., Heasley, J., Meyer, D., Savola, P., Ed., and C.
Pignataro, "The Generalized TTL Security Mechanism
(GTSM)", RFC 5082, DOI 10.17487/RFC5082, October 2007,
<https://www.rfc-editor.org/info/rfc5082>.
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[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", RFC 5226,
DOI 10.17487/RFC5226, May 2008,
<https://www.rfc-editor.org/info/rfc5226>.
[RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection
(BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010,
<https://www.rfc-editor.org/info/rfc5880>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
7.2. Informative References
[RFC2385] Heffernan, A., "Protection of BGP Sessions via the TCP MD5
Signature Option", RFC 2385, DOI 10.17487/RFC2385, August
1998, <https://www.rfc-editor.org/info/rfc2385>.
[RFC4808] Bellovin, S., "Key Change Strategies for TCP-MD5",
RFC 4808, DOI 10.17487/RFC4808, March 2007,
<https://www.rfc-editor.org/info/rfc4808>.
[RFC7210] Housley, R., Polk, T., Hartman, S., and D. Zhang,
"Database of Long-Lived Symmetric Cryptographic Keys",
RFC 7210, DOI 10.17487/RFC7210, April 2014,
<https://www.rfc-editor.org/info/rfc7210>.
Authors' Addresses
Randy Bush
Arrcus & IIJ
5147 Crystal Springs
Bainbridge Island, WA 98110
United States of America
Email: randy@psg.com
Keyur Patel
Arrcus
2077 Gateway Place, Suite #400
San Jose, CA 95119
United States of America
Email: keyur@arrcus.com
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