TRILL: RBridge Channel Tunnel Protocol
draft-ietf-trill-channel-tunnel-04
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft that was ultimately published as RFC 7978.
|
|
|---|---|---|---|
| Authors | Donald E. Eastlake 3rd , Mohammed Umair , Yizhou Li | ||
| Last updated | 2015-03-08 | ||
| Replaces | draft-eastlake-trill-channel-tunnel | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
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| Additional resources | Mailing list discussion | ||
| Stream | WG state | WG Document | |
| Document shepherd | Susan Hares | ||
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draft-ietf-trill-channel-tunnel-04
INTERNET-DRAFT Donald Eastlake
Updates: 7178 Huawei
Intended status: Proposed Standard Mohammed Umair
IPinfusion
Yizhou Li
Huawei
Expires: September 7, 2015 March 8, 2015
TRILL: RBridge Channel Tunnel Protocol
<draft-ietf-trill-channel-tunnel-04.txt>
Abstract
The IETF TRILL (Transparent Interconnection of Lots of Links)
protocol includes an optional mechanism, called RBridge Channel and
specified in RFC 7178, for the transmission of typed messages between
TRILL switches in the same campus and between TRILL switches and end
stations on the same link. This document specifies two optional
extensions to the RBridge Channel protocol: (1) A standard method to
tunnel a variety of payload types by encapsulating them in an RBridge
Channel message; and (2) A method to support security facilities for
RBridge Channel messages. This document updates RFC 7178.
Status of This Memo
This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79.
Distribution of this document is unlimited. Comments should be sent
to the authors or the TRILL working group mailing list:
trill@ietf.org
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts.
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."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/1id-abstracts.html. The list of Internet-Draft
Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
D. Eastlake & Y. Li [Page 1]
INTERNET-DRAFT TRILL: RBridge Channel Tunnel
Table of Contents
1. Introduction............................................3
1.1 Terminology and Acronyms..............................3
2. Channel Tunnel Packet Format............................5
3. Tunnel Payload Types....................................8
3.1 Null Payload...........................................8
3.2 RBridge Channel Message Payload........................8
3.3 TRILL Data Packet......................................9
3.4 TRILL IS-IS Packet....................................10
3.5 Ethernet Frame........................................11
4. Security, Keying, and Algorithms.......................14
4.1 Basic Security Format.................................14
4.2 Authentication and Encryption Coverage................15
4.3 Derived Keying Material...............................15
4.4 SType None............................................16
4.5 RFC 5310 Based Authentication.........................16
4.6 DTLS Based Security...................................17
4.7 RFC 5310 Based Encryption and Authentication..........18
5. Channel Tunnel Errors..................................20
5.1 SubERRs under ERR 6...................................20
5.2 Nested RBridge Channel Errors.........................20
6. IANA Considerations....................................21
7. Security Considerations................................22
Normative References......................................23
Informative References....................................24
Appendix Z: Change History................................25
Acknowledgements..........................................26
Authors' Addresses........................................27
D. Eastlake & Y. Li [Page 2]
INTERNET-DRAFT TRILL: RBridge Channel Tunnel
1. Introduction
The IETF TRILL base protocol [RFC6325] has been extended with an
optional RBridge Channel [RFC7178] facility to support transmission
of typed messages (for example BFD [RFC7175]) between two TRILL
switches (RBridges) in the same campus and between RBridges and end
stations on the same link. When sent between RBridges in the same
campus, a TRILL Data packet with a TRILL header is used and the
destination RBridge is indicated by nickname. When sent between a
RBridge and an end station on the same link in either direction a
native RBridge Channel messages [RFC7178] is used with no TRILL
header and the destination port or ports are indicated by a MAC
address. (There is no mechanism to stop end stations on the same
link, from sending native RBridge Channel messages to each other;
however, such use is outside the scope of this document.)
This document updates [RFC7178] and specifies extensions to RBridge
Channel that provides two additional facilities as listed below.
Implementation and use of each of these facilities is optional,
except that there are two payload types that MUST be implemented.
Both of these facilities can be used in the same packet.
(1) A standard method to tunnel a variety of payload types by
encapsulating them in an RBridge Channel message.
(2) A method to provide security facilities for RBridge Channel
messages.
In case of conflict between this document and [RFC7178], this
document takes precedence.
1.1 Terminology and Acronyms
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].
This document uses terminology and acronyms defined in [RFC6325] and
[RFC7178]. Some of these are repeated below for convenience along
with additional terms and acronyms.
AES - Advanced Encryption Standard.
CCM - Counter with CBC-MAC
Data Label - VLAN or FGL.
DTLS - Datagram TLS [RFC6347].
D. Eastlake & Y. Li [Page 3]
INTERNET-DRAFT TRILL: RBridge Channel Tunnel
FGL - Fine Grained Label [RFC7172].
HKDF - Hash based Key Derivation Function [RFC5869].
RBridge - An alternative term for a TRILL switch.
SHA - Secure Hash Algorithm [RFC6234].
TRILL - Transparent Interconnection of Lots of Links or Tunneled
Routing in the Link Layer.
TRILL switch - A device that implements the TRILL protocol
[RFC6325], sometimes referred to as an RBridge.
D. Eastlake & Y. Li [Page 4]
INTERNET-DRAFT TRILL: RBridge Channel Tunnel
2. Channel Tunnel Packet Format
The general structure of an RBridge Channel message between two TRILL
switches (RBridges) in the same campus is shown in Figure 1 below.
The structure of a native RBridge Channel message sent between an
RBridge and an end station on the same link, in either direction, is
shown in Figure 2 and, compared with the first case, omits the TRILL
Header, inner Ethernet addresses, and Data Label. A Protocol field in
the RBridge Channel Header gives the type of RBridge Channel message
and indicates how to interpret the Channel Protocol Specific Payload
[RFC7178].
+-----------------------------------+
| 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
+-----------------------------------+
| Ethernet Link Header |
+-----------------------------------+
| RBridge Channel Header |
+-----------------------------------+
| Channel Protocol Specific Payload |
+-----------------------------------+
| FCS |
+-----------------------------------+
Figure 2. Native RBridge Channel Frame
The RBridge Channel Header looks like this:
D. Eastlake & Y. Li [Page 5]
INTERNET-DRAFT TRILL: RBridge Channel Tunnel
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x8946 | CHV | Channel Protocol |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | ERR | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ /
/ Channel Protocol Specific Data /
/-+-+-+-+-+- /
Figure 3. RBridge Channel Header
where 0x8946 is the RBridge Channel Ethertype and CHV is the Channel
Header Version, currently zero.
The extensions specified herein are in the form of an RBridge Channel
protocol, the Channel Tunnel Protocol. Figure 4 below expands the
RBridge Channel Header and Protocol Specific Payload above for the
case of the Channel Tunnel Protocol.
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
RBridge Channel Header:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x8946 | 0x0 | Tunnel Protocol =tbd1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | ERR |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Channel Tunnel Protocol Specific: | SubERR| RESV4 | SType | PType |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Security Information, variable length (0 length if SType = 0)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...
| Tunneled Data, variable length
| ...
Figure 4. Channel Tunnel Header Structure
The RBridge Channel Header field specific to the RBridge Channel
Tunnel Protocol is the Protocol field. Its contents MUST be the value
allocated for this purpose (see Section 6).
The RBridge Tunnel Channel Protocol Specific Data fields are as
follows:
SubERR: This field provides further details when a Tunnel Channel
error is indicated in the RBridge Channel ERR field. If ERR is
zero, then SubERR MUST be sent as zero and ignored on receipt.
See Section 5.
D. Eastlake & Y. Li [Page 6]
INTERNET-DRAFT TRILL: RBridge Channel Tunnel
RESV4: This field MUST be sent as zero. If non-zero when received,
this is an error condition (see Section 4).
SType: This field describes the type of security information and
features, including keying material, being provided. See
Section 4.
PType: Payload type. This describes the tunneled data. See Section
3 below.
Security Information: Variable length information. Length is zero
if SType is zero. See Section 4.
The Channel Tunnel protocol is integrated with the RBridge Channel
facility. Channel Tunnel errors are reported as if they were RBridge
Channel errors, using newly allocated code points in the ERR field of
the RBridge Channel Header supplemented by the SubERR field.
D. Eastlake & Y. Li [Page 7]
INTERNET-DRAFT TRILL: RBridge Channel Tunnel
3. Tunnel Payload Types
The RBridge Channel Tunnel Protocol can carry a variety of payloads
as indicated by the PType field. Values are shown in the table below
with further explanation after the table.
PType Section Description
----- ------- -----------
0 Reserved
1 3.1 Null
2 3.2 RBridge Channel message
3 3.3 TRILL Data packet
4 3.4 TRILL IS-IS packet
5 3.5 Ethernet Frame
6-14 (Available for assignment by IETF Review)
15 Reserved
Table 1. Payload Type Values
While implementation of the Channel Tunnel protocol is optional, if
it is implemented PTypes 1 (Null) and 2 (RBridge Channel message)
MUST be implemented. PTypes 3, 4, and 5 MAY be implemented. The
processing of any particular Channel Protocol message and its payload
depends on meeting local security and other policy at the destination
TRILL switch or end station.
3.1 Null Payload
The Null payload type (PType=1) is intended to be used for testing or
messages such as key negotiation or the like. It indicates that there
is no payload. Any data after the Security Information fields is
ignored. Any particular use of the Null Payload should specify what
VLAN or priority should be used when relevant.
3.2 RBridge Channel Message Payload
A PType of 2 indicates that the payload of the Channel Tunnel message
is an encapsulated RBridge Channel message without the initial
RBridge Channel Ethertype. Typical reasons for sending an RBridge
Channel message inside a Channel Tunnel message are to provide
security services, such as authentication or encryption.
This payload type looks like the following:
D. Eastlake & Y. Li [Page 8]
INTERNET-DRAFT TRILL: RBridge Channel Tunnel
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RBridge-Channel (0x8946) | 0x0 | Tunnel Protocol = tbd1|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | ERR | SubERR| RESV4 | SType | 0x2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Possible Security information
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0 | Channel Protocol | Flags | ERR |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Channel Protocol Specific Data ... |
|
Figure 5. Tunneled Channel Message Channel Tunnel Structure
3.3 TRILL Data Packet
A PType of 3 indicates that the payload of the Tunnel protocol
message is an encapsulated TRILL Data packet as shown in the figure
below. (There is no TRILL Ethertype before the inner TRILL Data
packet because that is just part of the Ethernet link header for a
TRILL Data packet, not part of the TRILL header itself. The Optional
Flags Word is only present if the F bit in the TRILL Header is 1.)
If this PType is implemented and the message meets local policy for
acceptance, the tunneled TRILL Data packet is handled as if it had
been received by the destination TRILL switch on the port where the
Channel Tunnel message was received.
D. Eastlake & Y. Li [Page 9]
INTERNET-DRAFT TRILL: RBridge Channel Tunnel
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RBridge-Channel (0x8946) | 0x0 | Tunnel Protocol = tbd1|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | ERR | SubERR| RESV4 | SType | 0x3 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Possible Security information
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| V |A|C|M| RESV |F| Hop Count | Egress Nickname |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ingress Nickname | Optional Flags Word |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Optional Flags Word (cont.) | Inner.MacDA |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Inner.MacDA continued |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Inner.MacSA |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Inner.MacSA (cont.) | Inner Data Label ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...
| TRILL Data Packet payload
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...
Figure 6. Nested TRILL Data Packet Channel Tunnel Structure
3.4 TRILL IS-IS Packet
A PType of 4 indicates that the payload of the Tunnel protocol
message is an encapsulated TRILL IS-IS PDU packet without the initial
L2-IS-IS Ethertype as shown in the figure below. If this PType is
implemented, the tunneled TRILL IS-IS packet is processed by the
destination RBridge if it meets local policy. One possible use is to
expedite the receipt of a link state PDU by some TRILL switch or
switches with an immediate requirement for the enclosed link state
PDU. Any link local IS-IS PDU (Hello, CSNP, or PSNP [IS-IS]; MTU-
probe, MTU-ack [RFC7176]; or circuit scoped FS-LSP, FS-CSNP or FS-
PSNP [RFC7356]) received via this channel tunnel payload type MUST be
discarded.
D. Eastlake & Y. Li [Page 10]
INTERNET-DRAFT TRILL: RBridge Channel Tunnel
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RBridge-Channel (0x8946) | 0x0 | Tunnel Protocol = tbd1|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | ERR | SubERR| RESV4 | SType | 0x4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Possible Security information
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...
| 0x83 | rest of IS-IS PDU
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...
Figure 7. Tunneled TRILL IS-IS Packet Structure
3.5 Ethernet Frame
If PType is 5, the Tunnel Protocol payload is an Ethernet frame as
might be received from or sent to an end station except that the
tunneled Ethernet frame's FCS is omitted, as shown in Figure 8.
(There is still an overall FCS if the RBridge Channel message is
being sent on an Ethernet link.) If this PType is implemented and the
message meets local policy, the tunneled frame is handled as if it
had been received on the port on which the Tunnel Protocol message
was received.
The priority of the RBridge Channel message can be copied from the
Ethernet frame VLAN tag, if one is present, except that priorities 6
or 7 SHOULD only be used for important control messages.
D. Eastlake & Y. Li [Page 11]
INTERNET-DRAFT TRILL: RBridge Channel Tunnel
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RBridge-Channel (0x8946) | 0x0 | Tunnel Protocol = tbd1|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | ERR | SubERR| RESV4 | SType | 0x5 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Possible Security information
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MacDA |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MacDA (cont.) | MacSA |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MacSA (cont.) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Any Ethernet frame tagging...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...
| Ethernet frame payload...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...
Figure 8. Ethernet Frame Channel Tunnel Structure
In the case of a non-Ethernet link, such as a PPP link [RFC6361], the
ports on the link are considered to have link local synthetic 48-bit
MAC addresses constructed by concatenating three 16-bit quantities.
This constructed address MAY be used as the MacSA and, if the RBridge
Channel message is link local, the source TRILL switch will have the
information to construct such a MAC address for the destination TRILL
switch port and that MAC address MAY be used as the MacDA.
These MAC addresses are constructed as follows: 0xFEFF, the nickname
of the TRILL switch used in TRILL Hellos sent on that port, and the
Port ID that the TRILL switch has assigned to that port, as shown in
Figure 9. (Both the nickname and Port ID of the port on which a
TRILL Hello is sent appear in the Special VLANs and Flags sub-TLV
[RFC7176] in that Hello.) The resulting MAC address has the Local
bit on and the Group bit off [RFC7042]. Since end stations are
connected to TRILL switches over Ethernet, there will be no end
stations on a non-Ethernet link in a TRILL campus. Thus such
synthetic MAC addresses cannot conflict on the link with a real
Ethernet port address.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0xFEFF | Nickname |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Port ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
D. Eastlake & Y. Li [Page 12]
INTERNET-DRAFT TRILL: RBridge Channel Tunnel
Figure 9. Synthetic MAC Address
D. Eastlake & Y. Li [Page 13]
INTERNET-DRAFT TRILL: RBridge Channel Tunnel
4. Security, Keying, and Algorithms
The following table gives the assigned values of the SType field and
their meaning.
SType Section Meaning
----- ------- -------
0 4.4 None
1 4.5 [RFC5310] Based Authentication
2 4.6 DTLS Based Security
3 4.7 [RFC5310] Based Encryption and Authentication
4-14 Available for assignment on IETF Review
15 Reserved
Table 3. SType Values
4.1 Basic Security Format
For all SType values except zero, the Security Information starts
with a byte of flag bits and a byte of remaining length as follows:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...
|A|E| RESV | Size | More Info
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...
Figure 12. Security Information Format
The fields are as follows:
A: Zero if authentication is not being provided. One if it is.
E: Zero if encryption is not being provided. One if it is.
RESV: Six reserved bits that MUST be sent as zero and ignored on
receipt. In the future, meanings may be assigned to these bits and
those meanings may differ for different STypes.
Size: The number of bytes, as an unsigned integer, of More Info in
the Security Information after the Size byte itself.
More Info: Additional Security Information of length Size. Contents
depends on the SType.
The A and E bits are intended as hints and to assist is debugging.
They are not guaranteed to be correct. They can be interpreted as
follows:
D. Eastlake & Y. Li [Page 14]
INTERNET-DRAFT TRILL: RBridge Channel Tunnel
A E Comments
----- ----------
0 0 Neither authentication nor encryption is being provided.
1 0 Authentication only. The payload should be parsable by a
security ignorant receiver. The Size field permits
skipping the More Info field.
0 1 Encryption only. Some form of opportunistic security
[RFC7435].
1 1 Authentication and Encryption.
4.2 Authentication and Encryption Coverage
Authentication in the RBridge Channel case (see Figure 1) is computed
across the inner Ethernet Addresses, Data Label, relevant Channel
Tunnel header information, and the payload. To be more precise, the
covered area starts with the byte immediately after the TRILL Header
ingress nickname or optional flag word, if present, and extends to
just before the TRILL Data packet link trailer, for example just
before the FCS for Ethernet. If an authentication value is included
in the Info field specified in Section 4.1, it is treated as zero
when authentication is calculated. If an authentication value is
included in a payload after the security information, it is
calculated as provided by the SType and algorithms in use.
Authentication in the native RBridge Channel case (see Figure 2), is
as specified in the above paragraph except that it starts with the
RBridge Channel Ethertype, since there are no TRILL Header, inner
Ethernet address, or Data Label.
If encryption is provided, it covers the payload from right after the
Channel Tunnel header security information through to just before the
TRILL Data packet link trailer.
4.3 Derived Keying Material
In some cases, it is possible to use keying material derived from
[RFC5310] IS-IS keying material. In such cases, the More Info field
shown in Section 4.1 includes a two byte Key ID to identify the IS-IS
keying material. The keying material actually used in Channel Tunnel
security is derived from the IS-IS keying material as follows:
HKDF-Expand-SHA256 ( IS-IS-key, "Channel Tunnel" | 0x0S, L )
D. Eastlake & Y. Li [Page 15]
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where "|" indicates concatenation, HKDF is as in [RFC5869], SHA256 is
as in [RFC6234],IS-IS-key is the input keying material, "Channel
Tunnel" is the 14-character [RFC20] string indicated, 0x0S is a
single byte where S is the SType for which this key derivation is
being used, and L is the length of output keying material needed.
4.4 SType None
No security services are being invoked. The length of the Security
Information field (see Figure 6) is zero.
4.5 RFC 5310 Based Authentication
The Security Information (see Figure 6) is the flags and Size bytes
specified in Section 4.1 with the value of the [RFC5310] Key ID and
Authentication Data as shown in Figure 13.
1 1 1 1 1 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1|0| RESV | Size |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Key ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+
| Authentication Data (Variable)
+
|
+-+-+-+-+-+-+-+-+-+-+-+-+-...
Figure 13. SType 1 Security Information
o RESV: Six bits that MUST be sent as zero and ignored or receipt.
o Size: Set to 2 + the size of Authentication Data in bytes.
o Key ID: specifies the same keying value and authentication
algorithm that that Key ID specifies for TRILL IS-IS LSP [RFC5310]
Authentication TLVs. The keying material actually used is derived
as shown in Section 4.3.
o Authentication Data: The authentication data produced by the key
and algorithm associated with the Key ID acting on the packet as
specified in Section 4.2. Length of authentication data depends on
the algorithm.
D. Eastlake & Y. Li [Page 16]
INTERNET-DRAFT TRILL: RBridge Channel Tunnel
4.6 DTLS Based Security
DTLS supports key negotiation and provides both encryption and
authentication. This optional SType in Channel Tunnel uses DTLS 1.2
[RFC6347]. It is intended for pairwise use. The presumption is that
in the RBridge Channel case (Figure 1) the M bit in the TRILL Header
would be zero and in the native RBridge Channel case (Figure 2), the
Outer.MacDA would be individually addressed.
TRILL switches that implement the Channel Tunnel DTLS SType SHOULD
support the use of certificates for DTLS. In this case the Size field
shown in Section 4.1 MUST be zero and the Security Information is as
shown in Figure 14.
Also, if they support certificates, they MUST support the following
algorithm:
o TLS_RSA_WITH_AES_128_CBC_SHA256 [RFC5246]
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1|1| RESV | 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 14. DTLS Cert or Special Pre-shared Key Security Information
TRILL switches that support the Channel Tunnel DTLS SType MUST
support the use of pre-shared keys for DTLS. The Size field as shown
in Section 4.1 MUST be either zero or 2. If Size is zero as shown in
Figure 14, a pre-shared key specifically associated with Channel
Tunnel DTLS is used. If Size is 2 as shown in Figure 15, a two byte
[RFC5310] Key ID is present and the pre-shared key is derived from
the secret key associated with that Key ID as shown in Section 4.3.
The following cryptographic algorithms MUST be supported for use with
pre-shared keys:
o TLS_PSK_WITH_AES_128_CBC_SHA256 [RFC5487]
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1|1| RESV | 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Key ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 15. DTLS Derived Pre-shared Key Security Information
D. Eastlake & Y. Li [Page 17]
INTERNET-DRAFT TRILL: RBridge Channel Tunnel
When DTLS security is used, the entire payload of the Channel Tunnel
packet, starting just after the Security Information and ending just
before the link trailer, is a DTLS record [RFC6347].
4.7 RFC 5310 Based Encryption and Authentication
This SType is based on pre-existing [RFC5310] keying material but
does not use any algorithm that may be associated with a Key ID under
[RFC5310]. Instead it uses the derived key as specified in Section
4.3 with the algorithm specified by a Crypto Suite ID. Key
negotiation is not provided and this SType is intended for multi-
destination message use. The presumption is that in the RBridge
Channel case (Figure 1) the M bit in the TRILL Header would be one
and in the native RBridge Channel case (Figure 2), the Outer.MacDA
would be group addressed.
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1|1| RESV | 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Key ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Crypto Suite ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 16. DTLS Derived Pre-shared Key Security Information
4.7.1 Channel-Tunnel-CCM
The initially specified Crypto Suite has ID 0x0001, is called
Channel-Tunnel-CCM (Channel Tunnel Counter with CBC-MAC), and is
mandatory to implement if this SType is supported.
Channel-Tunnel-CCM is based on [RFC3610] using AES-128 as the
encryption function. The minimum authentication field size permitted
is 8 octets. There is additional authenticated data which is the
authenticated data indicated in Section 4.2 up to but not including
any of the Tunneled Data (Figure 4). The message size is limited to
2**16 - 2**8 bytes so the length of the length of message field is
always 2 bytes. There are thus 13 bytes available for nonce
[RFC3610]. Since it is possible that the same Key ID could be used by
different TRILL switches, the nonce MUST include an identifier for
the originating TRILL switch. It is RECOMMENDED that this be the
first 6 bytes of its IS-IS System ID as these will be unique across
the campus. The remaining 7 bytes (56 bits) need to be such that the
nonce is always unique for a particular key, for example a counter
for which care is taken that it is always incremented after each use
and its value is preserved over TRILL switch crashes, re-starts, and
D. Eastlake & Y. Li [Page 18]
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the like. Should there be a danger of exhausting such a counter, the
TRILL switch MUST take steps such as causing re-keying of the
[RFC5310] key ID it is using and/or changing to use a different Key
ID.
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5. Channel Tunnel Errors
RBridge Channel Tunnel Protocol errors are reported like RBridge
Channel level errors. The ERR field is set to one of the following
error codes:
ERR Meaning
--- ---------
6 Unknown or unsupported field value
7 Authentication failure
8 Error in nested RBridge Channel message
(more TBD?)
Table 4. Additional ERR Values
5.1 SubERRs under ERR 6
If the ERR field is 6, the SubERR field indicates the problematic
field or value as show in the table below.
SubERR Meaning (for ERR = 6)
------ ---------------------
0 Non-zero RESV4 nibble
1 Unsupported SType
2 Unsupported PType
4 Unsupported crypto algorithm
5 Unknown Key ID
(more TBD)
Table 5. SubERR values under ERR 6
5.2 Nested RBridge Channel Errors
If
a Channel Tunnel message is sent with security and with a payload
type (PType) indicating a nested RBridge Channel message
and
there is an error in the processing of that nested message that
results in a return RBridge Channel message with a non-zero ERR
field,
then that returned message SHOULD also be nested in an Channel Tunnel
message using the same type of security. In this case, the ERR field
in the Channel Tunnel envelope is set to 8 indicating that there is a
nested error being tunneled back.
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6. IANA Considerations
IANA has assigned tbd1 as the RBridge Channel protocol number the
"Channel Tunnel" protocol from the range assigned by Standards
Action.
The added RBridge Channel protocols registry entry on the TRILL
Parameters web page is as follows:
Protocol Description Reference
-------- -------------- ---------
tbd1 Tunnel Channel [this document]
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7. Security Considerations
The RBridge Channel tunnel facility has potentially positive and
negative effects on security.
On the positive side, it provides optional security that can be used
to authenticate and/or encrypt RBridge Channel messages. Some RBridge
Channel message payloads, such as BFD [RFC7175], provide their own
security but where this is not true, consideration should be give to
requiring use of the security features of the Tunnel Protocol.
On the negative side, the optional ability to tunnel various payload
types and to tunnel them not just between TRILL switches but to and
from end stations can increase risk unless precautions are taking.
The processing of decapsulated Tunnel Protocol payloads is not a good
place to be liberal in what you accept as the tunneling facility
makes it easier for unexpected messages to pop up in unexpected
places in a TRILL campus due to accidents or the actions of an
adversary. Local policies should generally be strict and only process
payload types required and then only with adequate authentication for
the particular circumstances.
In connection with the use of DTLS for security as specified in
Section 4.5, see [RFC7457].
See [RFC7178] for general RBridge Channel Security Considerations.
See [RFC6325] for general TRILL Security Considerations.
D. Eastlake & Y. Li [Page 22]
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Normative References
[IS-IS] - ISO/IEC 10589:2002, Second Edition, "Information technology
-- Telecommunications and information exchange between systems
-- Intermediate System to Intermediate System intra-domain
routeing information exchange protocol for use in conjunction
with the protocol for providing the connectionless-mode network
service (ISO 8473)", 2002.
[RFC20] - Cerf, V., "ASCII format for network interchange", STD 80,
RFC 20, October 1969, <http://www.rfc-editor.org/info/rfc20>.
[RFC2119] - Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3610] - Whiting, D., Housley, R., and N. Ferguson, "Counter with
CBC-MAC (CCM)", RFC 3610, September 2003, <http://www.rfc-
editor.org/info/rfc3610>.
[RFC5246] - Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246, August 2008,
<http://www.rfc-editor.org/info/rfc5246>.
[RFC5310] - Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R.,
and M. Fanto, "IS-IS Generic Cryptographic Authentication", RFC
5310, February 2009.
[RFC5487] - Badra, M., "Pre-Shared Key Cipher Suites for TLS with
SHA-256/384 and AES Galois Counter Mode", RFC 5487, March 2009,
<http://www.rfc-editor.org/info/rfc5487>.
[RFC5869] - Krawczyk, H. and P. Eronen, "HMAC-based Extract-and-
Expand Key Derivation Function (HKDF)", RFC 5869, May 2010,
<http://www.rfc-editor.org/info/rfc5869>.
[RFC6325] - Perlman, R., D. Eastlake, D. Dutt, S. Gai, and A.
Ghanwani, "RBridges: Base Protocol Specification", RFC 6325,
July 2011.
[RFC6347] - Rescorla, E. and N. Modadugu, "Datagram Transport Layer
Security Version 1.2", RFC 6347, January 2012, <http://www.rfc-
editor.org/info/rfc6347>.
[RFC7172] - Eastlake 3rd, D., Zhang, M., Agarwal, P., Perlman, R.,
and D. Dutt, "Transparent Interconnection of Lots of Links
(TRILL): Fine-Grained Labeling", RFC 7172, May 2014.
[RFC7176] - Eastlake 3rd, D., Senevirathne, T., Ghanwani, A., Dutt,
D., and A. Banerjee, "Transparent Interconnection of Lots of
Links (TRILL) Use of IS-IS", RFC 7176, May 2014,
D. Eastlake & Y. Li [Page 23]
INTERNET-DRAFT TRILL: RBridge Channel Tunnel
<http://www.rfc-editor.org/info/rfc7176>.
[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, May 2014.
[RFC7356] - Ginsberg, L., Previdi, S., and Y. Yang, "IS-IS Flooding
Scope Link State PDUs (LSPs)", RFC 7356, September 2014,
<http://www.rfc-editor.org/info/rfc7356>.
[rfc7180bis] - Eastlake, D., Zhang, M., Perlman, R. Banerjee, A.,
Ghanwani, A., and S. Gupta, "TRILL: Clarifications,
Corrections, and Updates", Draft-ietf-trill-rfc7180bis, work in
progress.
Informative References
[RFC6234] - Eastlake 3rd, D. and T. Hansen, "US Secure Hash
Algorithms (SHA and SHA-based HMAC and HKDF)", RFC 6234, May
2011.
[RFC6361] - Carlson, J. and D. Eastlake 3rd, "PPP Transparent
Interconnection of Lots of Links (TRILL) Protocol Control
Protocol", RFC 6361, August 2011
[RFC7042] - Eastlake 3rd, D. and J. Abley, "IANA Considerations and
IETF Protocol and Documentation Usage for IEEE 802 Parameters",
BCP 141, RFC 7042, October 2013.
[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,
May 2014.
[RFC7435] - Dukhovni, V., "Opportunistic Security: Some Protection
Most of the Time", RFC 7435, December 2014, <http://www.rfc-
editor.org/info/rfc7435>.
[RFC7457] - Sheffer, Y., Holz, R., and P. Saint-Andre, "Summarizing
Known Attacks on Transport Layer Security (TLS) and Datagram
TLS (DTLS)", RFC 7457, February 2015, <http://www.rfc-
editor.org/info/rfc7457>.
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Appendix Z: Change History
From -00 to -01
1. Fix references for RFCs published, etc.
2. Explicitly mention in the Abstract and Introduction that this
document updates [RFC7178].
3. Add this Change History Appendix.
From -01 to -02
1. Remove section on the "Scope" feature as mentioned in
http://www.ietf.org/mail-archive/web/trill/current/msg06531.html
2. Editorial changes to IANA Considerations to correspond to draft-
leiba-cotton-iana-5226bis-11.txt.
3. Improvements to the Ethernet frame payload type.
4. Other Editorial changes.
From -02 to -03
1. Update TRILL Header to correspond to [rfc7180bis].
2. Remove a few remnants of the "Scope" feature that was removed from
-01 to -02.
3. Substantial changes to and expansion of Section 4 including adding
details of DTLS security.
4. Updates and additions to the References.
5. Other minor editorial changes.
From -03 to -04
1. Add SType for [RFC5310] keying based security that provides
encryption as well as authentication.
2. Editorial improvements and fixes.
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Acknowledgements
The contributions of the following are hereby acknowledged:
TBD
The document was prepared in raw nroff. All macros used were defined
within the source file.
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Authors' Addresses
Donald E. Eastlake, 3rd
Huawei Technologies
155 Beaver Street
Milford, MA 01757 USA
Phone: +1-508-333-2270
EMail: d3e3e3@gmail.com
Mohammed Umair
IPinfusion
EMail: mohammed.umair2@gmail.com
Yizhou Li
Huawei Technologies
101 Software Avenue,
Nanjing 210012, China
Phone: +86-25-56622310
EMail: liyizhou@huawei.com
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D. Eastlake & Y. Li [Page 28]