Internet Engineering Task Force (IETF) D. Eastlake 3rd

Internet Engineering Task Force (IETF) D. Eastlake 3rd
Request for Comments: 8381 Y. Li
Category: Standards Track W. Hao
ISSN: 2070-1721 Huawei
A. Banerjee
Cisco
May 2018

Transparent Interconnection of Lots of Links (TRILL):
Vendor-Specific RBridge Channel Protocol

Abstract

The IETF TRILL (Transparent Interconnection of Lots of Links)
protocol is implemented by devices called TRILL switches or RBridges
(Routing Bridges). TRILL includes a general mechanism, called an
RBridge Channel, for the transmission of typed messages between
RBridges in the same campus and between RBridges and end stations on
the same link. This document specifies a method to send vendor-
specific messages over the RBridge Channel facility.

Status of This Memo

This is an Internet Standards Track document.

This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.

Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc8381.

Eastlake, et al. Standards Track [Page 1]

RFC 8381 TRILL: Vendor Channel May 2018

Copyright Notice

Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved.

This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.

Table of Contents

1. Introduction ....................................................2
1.1. Terminology and Acronyms ...................................3
2. Vendor Channel Packet Format ....................................3
3. Vendor Channel Errors ...........................................6
3.1. Sending an Error Response ..................................7
4. IANA Considerations .............................................9
5. Security Considerations .........................................9
6. References .....................................................10
6.1. Normative References ......................................10
6.2. Informative References ....................................10
Authors' Addresses ................................................11

1. Introduction

The IETF TRILL (Transparent Interconnection of Lots of Links)
protocol [RFC6325] [RFC7780] is implemented by devices called TRILL
switches or RBridges (Routing Bridges). It provides efficient least-
cost transparent routing in multi-hop networks with arbitrary
topologies and link technologies, using link-state routing and a hop
count.

The TRILL protocol includes an RBridge Channel facility [RFC7178] to
support typed message transmission between RBridges in the same
campus and between RBridges and end stations on the same link. This
document specifies a method of sending messages specified by a
particular organization, indicated by OUI (Organizationally Unique
Identifier) [RFC7042] or CID (Company Identifier) [802], over the
RBridge Channel facility. Such organization-specific messages could,
for example, be used for vendor-specific diagnostic or control
messages.

Eastlake, et al. Standards Track [Page 2]

RFC 8381 TRILL: Vendor Channel May 2018

However, note that a range of RBridge Channel protocol numbers are
available based on RFC publication. Those intending to use the
RBridge Channel facility are encouraged to document their use in an
RFC and to use RBridge Channel protocol numbers based on such RFC
publication.

1.1. Terminology and Acronyms

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.

This document uses the acronyms defined in [RFC6325] supplemented by
the following additional acronyms:

CID - Company Identifier [802]

FGL - Fine-Grained Labeling

OUI - Organizationally Unique Identifier [RFC7042]

TRILL switch - An alternative term for an RBridge

2. Vendor Channel Packet Format

The general structure of an RBridge Channel packet on a link between
TRILL switches (RBridges) is shown in Figure 1 below. When an
RBridge Channel message is sent between an RBridge and an end station
on the same link, in either direction, it is called a Native RBridge
Channel message and the TRILL Header (including the Inner Ethernet
Addresses and Data Label area) is omitted as shown in Figure 2. The
type of RBridge Channel packet is given by a Protocol field in the
RBridge Channel Header that indicates how to interpret the Channel-
Protocol-Specific Payload. See [RFC7178].

Eastlake, et al. Standards Track [Page 3]

RFC 8381 TRILL: Vendor Channel May 2018

Packet Structure

+-----------------------------------+
| Link Header |
+-----------------------------------+
| TRILL Header |
+-----------------------------------+
| Inner Ethernet Addresses |
+-----------------------------------+
| Data Label (VLAN or FGL) |
+-----------------------------------+
| RBridge Channel Header |
+-----------------------------------+
| Channel-Protocol-Specific Payload |
+-----------------------------------+
| Link Trailer (FCS if Ethernet) |
+-----------------------------------+

Figure 1: RBridge Channel Packet Structure

Message Structure

+-----------------------------------+
| Link Header |
+-----------------------------------+
| RBridge Channel Header |
+-----------------------------------+
| Channel Protocol Specific Payload |
+-----------------------------------+
| Link Trailer (FCS if Ethernet) |
+-----------------------------------+

Figure 2: Native RBridge Channel Message Structure

Figure 3 below expands the RBridge Channel Header and Channel
Protocol Specific Payload above for the case of the Vendor-Specific
RBridge Channel Tunnel Protocol. 0x8946 is the Ethertype [RFC7042]
assigned by the IEEE for the RBridge Channel protocol.

Eastlake, et al. Standards Track [Page 4]

RFC 8381 TRILL: Vendor Channel May 2018

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
RBridge Channel Header:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RBridge-Channel (0x8946) | 0x0 | Channel Protocol=0x008|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | ERR |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
RBridge Channel Protocol Specific:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Vendor ID = OUI/CID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|OUI/CID (cont.)| VERR | Sub-Protocol | Sub-Version |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Vendor-Protocol-Specific Data
|
| ...

Figure 3: Channel Tunnel Message Structure

The fields in Figure 3 related to the Vendor RBridge Channel Protocol
are as follows:

Channel Protocol: The RBridge Channel Protocol value allocated
for the Vendor Channel (see Section 4).

Vendor ID: This field indicates the vendor specifying the
particular use or uses of the Vendor Channel. The vendor to
whom the OUI or CID in this field has been allocated is in
charge of specifying Vendor Channel messages using their
identifier. Depending on the first byte of this field as
follows:

OUI: When the bottom two bits of the first byte of the Vendor
ID are zero (that is, the first byte is 0bXXXXXX00), the
Vendor ID is an OUI.

CID: When the bottom two bits of the first byte are a one
followed by a zero (that is, the first byte is 0bXXXXXX10),
the Vendor ID is a CID.

Other: Other values of the bottom two bits of the first byte of
the Vendor ID are invalid, and a VERR of 2 MUST be returned,
subject to possible rate limiting (see Section 3).

VERR: Vendor Channel Error. See Section 3.

Eastlake, et al. Standards Track [Page 5]

RFC 8381 TRILL: Vendor Channel May 2018

Sub-Protocol: Actually, the vendor specifying their use of the
Vendor Channel can do whatever they want with the bits after
the VERR field. But it is strongly RECOMMENDED that they use
the sub-protocol / sub-version fields indicated so that
multiple and evolving uses can be specified based on a single
OUI.

Sub-Version: See explanation above of the Sub-Protocol field.
This field is provided to indicate the version of the
particular vendor's Sub-Protocol.

3. Vendor Channel Errors

The VERR field values from 0x0 through 0x0F (inclusive) and the value
0xFF are reserved for specification by the IETF. See Section 4. All
other values of VERR are available for whatever use the vendor
specifies, except that a Vendor Channel implementation MUST NOT send
a Vendor Channel Error in response to a Vendor Channel message with a
nonzero VERR.

The VERR values thus far specified by the IETF are as follows:

0. The VERR field is zero in Vendor Channel messages unless the
Vendor Channel packet is reporting an error.

1. The value one indicates that the length of the RBridge-Channel-
Specific Data is less than 4 bytes. This means that at least the
VERR byte and possibly part or all of the OUI is truncated. If
an RBridge that implements the Vendor Channel facility receives
such a Vendor Channel message, it MUST expand it to extend
through the VERR field, set that field to one, and return the
packet as described in Section 3.1.

2. The OUI/CID field value is unknown. If an RBridge implements the
Vendor Channel facility and receives a Vendor Channel packet with
a zero VERR field and an OUI/CID field it does not recognize and
the SL flag is zero in the RBridge Channel Header, it MUST set
the VERR field to the value two and return the packet as
described in Section 3.1.

Eastlake, et al. Standards Track [Page 6]

RFC 8381 TRILL: Vendor Channel May 2018

3. The value 3 indicates that the Sub-Protocol field value is
unknown. An RBridge SHOULD set the VERR field to 3 and return
the packet as described in Section 3.1 if it implements the
Vendor Channel facility and it receives a Vendor Channel packet
meeting the following conditions:
(a) a zero VERR field in the RBridge Channel Header,
(b) a zero SL flag in the RBridge Channel Header,
(c) an OUI/CID that it implements, and
(d) a Sub-Protocol field value it does not recognize even though
it implements and uses the Sub-Protocol field.

4. The value 4 indicates that the Sub-Version field value is
unknown. An RBridge SHOULD set the VERR field to 4 and return
the packet as described in Section 3.1 if it implements the
Vendor RBridge Channel facility and it receives a Vendor Channel
packet meeting the following conditions:
(a) a zero VERR field in the RBridge Channel Header,
(b) a zero SL flag in the RBridge Channel Header,
(c) an OUI/CID and Sub-Protocol that it implements, and
(d) a Sub-Version field value it does not recognize even though
it implements and uses the Sub-Version field.

Uniform error handling is generally advisable for the sake of
maintenance and understandability; however, "SHOULD" is chosen for
errors 3 and 4 above because, as long as each message is
distinguished by a vendor's OUI/CID, it is up to that vendor to
decide between standard and nonstandard error handling.

3.1. Sending an Error Response

The IETF-specified Vendor Channel errors are sent in response to a
received RBridge Channel packet by setting the VERR field as
specified above and modifying the packet as specified below. (The
ERR field will be zero because, if it were nonzero, the packet would
have been handled at the general RBridge Channel level rather than
being passed down to the Vendor Channel level.)

The RBridge Channel Header is modified by setting the SL flag. (The
flags in the Channel Header and the semantics of the SL flag are
specified in [RFC7178].)

o If an error 1 is being generated because of truncation, the
RBridge-Channel-Specific Data area is extended to include the VERR
byte.

Eastlake, et al. Standards Track [Page 7]

RFC 8381 TRILL: Vendor Channel May 2018

o If a Vendor Channel message was sent between RBridges, the TRILL
Header is modified by (1) clearing the M bit, (2) setting the
egress nickname to the ingress nickname as received, (3) setting
the ingress nickname to a nickname held by the TRILL switch
sending the error packet, and (4) setting the hop count to the
usual value on TRILL Data packets used by the TRILL switch sending
the error packet.

o If a Vendor Channel message was sent between an RBridge and an end
station in either direction, the outer MAC addresses are modified
by (1) setting the Outer.MacDA to the Outer.MacSA as received and
(2) setting the Outer.MacSA to the MAC address of the port of the
TRILL switch or end station sending the error packet.

o The priority of the error response message MAY be reduced from the
priority of the Vendor Chanel message causing the error, unless it
was already minimum priority, and the Drop Eligibility Indicator
bit MAY be set in an error response. (See Section 4.1.1 of
[RFC6325].)

o Vendor Channel error responses MAY be rate-limited.

It is generally anticipated that the entire packet in which an error
was detected would be sent back, modified as above, as the protocol
specific payload, so that, for example, error responses could more
easily be matched with messages sent; however, except for errors 1
and 2, this is up to the vendor specifying how their Vendor RBridge
Channel messages are to be used.

Note that if you receive a Vendor Channel error message with error 1,
indicating a truncation error, you cannot trust the apparent
"OUI/CID" in that Vendor Channel error message.

Eastlake, et al. Standards Track [Page 8]

RFC 8381 TRILL: Vendor Channel May 2018

4. IANA Considerations

IANA has allocated 0x008 for the Vendor-Specific RBridge Channel
Protocol from the range of RBridge Channel protocols allocated by
Standards Action.

IANA has established a subregistry as follows in the TRILL Parameters
registry (indented under "RBridge Channel Error Codes" after "RBridge
Channel SubError Codes"):

Registry: Vendor RBridge Channel Error Codes
Registration Procedures: Standards Action
Reference: RFC 8381

Code Description Reference
---- ----------- ---------
0x00 No error RFC 8381
0x01 Message too short RFC 8381
0x02 Unknown OUI/CID RFC 8381
0x03 Unknown Sub-Protocol RFC 8381
0x04 Unknown Sub-Version RFC 8381
0x05-0x0F Unassigned -
0x10-0xFE Reserved for vendor use RFC 8381
0xFF Reserved RFC 8381

5. Security Considerations

See [RFC6325] for general TRILL Security Considerations.

See [RFC7178] for general RBridge Channel Security Considerations.

Neither the Vendor-Specific RBridge Channel Protocol nor the basic
RBridge Channel Protocol [RFC7178] provide any security assurances or
features. (The basic RBridge Channel Protocol's first use was as an
envelope for Bidirectional Forwarding Detection (BFD) messages
[RFC7175], which provide their own security.) Any needed security
can be provided by fields or processing within the Vendor-Protocol-
Specific Data, which is outside the scope of this document.
Alternatively or in addition, use of a Vendor Channel MAY be nested
inside the RBridge Channel Header Extension Protocol [RFC7978]; this
can provide some security services.

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RFC 8381 TRILL: Vendor Channel May 2018

6. References

6.1. Normative References

[802] IEEE 802, "IEEE Standard for Local and Metropolitan Area
Networks: Overview and Architecture",
DOI 10.1109/IEEESTD.2014.6847097, IEEE Std 802-2014.

[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>.

[RFC6325] Perlman, R., Eastlake 3rd, D., Dutt, D., Gai, S., and A.
Ghanwani, "Routing Bridges (RBridges): Base Protocol
Specification", RFC 6325, DOI 10.17487/RFC6325, July 2011,
<https://www.rfc-editor.org/info/rfc6325>.

[RFC7042] Eastlake 3rd, D. and J. Abley, "IANA Considerations and
IETF Protocol and Documentation Usage for IEEE 802
Parameters", BCP 141, RFC 7042, DOI 10.17487/RFC7042,
October 2013, <https://www.rfc-editor.org/info/rfc7042>.

[RFC7178] Eastlake 3rd, D., Manral, V., Li, Y., Aldrin, S., and D.
Ward, "Transparent Interconnection of Lots of Links
(TRILL): RBridge Channel Support", RFC 7178,
DOI 10.17487/RFC7178, May 2014,
<https://www.rfc-editor.org/info/rfc7178>.

[RFC7780] Eastlake 3rd, D., Zhang, M., Perlman, R., Banerjee, A.,
Ghanwani, A., and S. Gupta, "Transparent Interconnection
of Lots of Links (TRILL): Clarifications, Corrections, and
Updates", RFC 7780, DOI 10.17487/RFC7780, February 2016,
<https://www.rfc-editor.org/info/rfc7780>.

[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>.

6.2. Informative References

[RFC7175] Manral, V., Eastlake 3rd, D., Ward, D., and A. Banerjee,
"Transparent Interconnection of Lots of Links (TRILL):
Bidirectional Forwarding Detection (BFD) Support", RFC
7175, DOI 10.17487/RFC7175, May 2014,
<https://www.rfc-editor.org/info/rfc7175>.

Eastlake, et al. Standards Track [Page 10]

RFC 8381 TRILL: Vendor Channel May 2018

[RFC7978] Eastlake 3rd, D., Umair, M., and Y. Li, "Transparent
Interconnection of Lots of Links (TRILL): RBridge Channel
Header Extension", RFC 7978, DOI 10.17487/RFC7978,
September 2016, <https://www.rfc-editor.org/info/rfc7978>.

Authors' Addresses

Donald Eastlake 3rd
Huawei Technologies
155 Beaver Street
Milford, MA 01757
United States of America

Phone: +1-508-333-2270
EMail: [email protected]

Yizhou Li
Huawei Technologies
101 Software Avenue,
Nanjing 210012
China

Phone: +86-25-56622310
Email: [email protected]

Weiguo Hao
Huawei Technologies
101 Software Avenue,
Nanjing 210012
China

Phone: +86-25-56623144
Email: [email protected]

Ayan Banerjee
Cisco

Email: [email protected]

Eastlake, et al. Standards Track [Page 11]