< draft-ietf-manet-dlep-multi-hop-extension-06.txt   draft-ietf-manet-dlep-multi-hop-extension-07.txt >
Network Working Group B. Cheng Network Working Group B. Cheng
Internet-Draft MIT Lincoln Laboratory Internet-Draft MIT Lincoln Laboratory
Intended status: Standards Track L. Berger, Ed. Intended status: Standards Track L. Berger, Ed.
Expires: September 12, 2019 LabN Consulting, L.L.C. Expires: November 6, 2019 LabN Consulting, L.L.C.
March 11, 2019 May 5, 2019
DLEP Multi-Hop Forwarding Extension Dynamic Link Exchange Protocol (DLEP) Multi-Hop Forwarding Extension
draft-ietf-manet-dlep-multi-hop-extension-06 draft-ietf-manet-dlep-multi-hop-extension-07
Abstract Abstract
This document defines an extension to the DLEP protocol that enables This document defines an extension to the Dynamic Link Exchange
the reporting and control of Multi-Hop Forwarding by DLEP capable Protocol (DLEP) that enables the reporting and control of Multi-Hop
modems. Forwarding by DLEP capable modems.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on September 12, 2019. This Internet-Draft will expire on November 6, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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3. Extension Data Items . . . . . . . . . . . . . . . . . . . . 3 3. Extension Data Items . . . . . . . . . . . . . . . . . . . . 3
3.1. Hop Count . . . . . . . . . . . . . . . . . . . . . . . . 3 3.1. Hop Count . . . . . . . . . . . . . . . . . . . . . . . . 3
3.2. Hop Control . . . . . . . . . . . . . . . . . . . . . . . 5 3.2. Hop Control . . . . . . . . . . . . . . . . . . . . . . . 5
3.2.1. Reset . . . . . . . . . . . . . . . . . . . . . . . . 6 3.2.1. Reset . . . . . . . . . . . . . . . . . . . . . . . . 6
3.2.2. Terminate . . . . . . . . . . . . . . . . . . . . . . 7 3.2.2. Terminate . . . . . . . . . . . . . . . . . . . . . . 7
3.2.3. Direct Connection . . . . . . . . . . . . . . . . . . 7 3.2.3. Direct Connection . . . . . . . . . . . . . . . . . . 7
3.2.4. Suppress Forwarding . . . . . . . . . . . . . . . . . 7 3.2.4. Suppress Forwarding . . . . . . . . . . . . . . . . . 7
4. Security Considerations . . . . . . . . . . . . . . . . . . . 8 4. Security Considerations . . . . . . . . . . . . . . . . . . . 8
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
5.1. Extension Type Value . . . . . . . . . . . . . . . . . . 8 5.1. Extension Type Value . . . . . . . . . . . . . . . . . . 8
5.2. Data Item Values . . . . . . . . . . . . . . . . . . . . 8 5.2. Data Item Values . . . . . . . . . . . . . . . . . . . . 9
5.3. Hop Control Actions Registry . . . . . . . . . . . . . . 9 5.3. Hop Control Actions Registry . . . . . . . . . . . . . . 9
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
6.1. Normative References . . . . . . . . . . . . . . . . . . 9 6.1. Normative References . . . . . . . . . . . . . . . . . . 10
6.2. Informative References . . . . . . . . . . . . . . . . . 10 6.2. Informative References . . . . . . . . . . . . . . . . . 10
Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . 10 Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction 1. Introduction
The Dynamic Link Exchange Protocol (DLEP) is defined in [RFC8175]. The Dynamic Link Exchange Protocol (DLEP) is defined in [RFC8175].
It provides the exchange of link related control information between It provides the exchange of link related control information between
DLEP peers. DLEP peers are comprised of a modem and a router. DLEP a modem and a router. DLEP defines a base set of mechanisms as well
defines a base set of mechanisms as well as support for possible as support for possible extensions. This document defines one such
extensions. This document defines one such extension. extension.
Some modem technologies support mobile ad hoc network (MANET) Some modem technologies support mobile ad hoc network (MANET)
forwarding where connectivity to destinations is provided via forwarding where connectivity to destinations is provided via
forwarding in intermediate modems. This document refers to forwarding in intermediate modems. This document refers to
forwarding by intermediate modems as 'multi-hop forwarding'. example forwarding by intermediate modems as 'multi-hop forwarding'. DLEP
using . DLEP Destination messages can be used to report such Destination messages can be used to report such reachable
reachable destinations, see [RFC8175], but do not provide any destinations, see [RFC8175], but do not provide any information
information related to the number or capacity of the hops. The related to the number or capacity of the hops. The extension defined
extension defined in this document enables modems to inform routers in this document enables modems to inform routers when multi-hop
when multi-hop forwarding is being used, and routers to request that forwarding is being used, and routers to request that modems change
modems change multi-hop forwarding behavior. The extension defined multi-hop forwarding behavior. The extension defined in this
in this document is referred to as "Multi-Hop Forwarding", where each document is referred to as "Multi-Hop Forwarding", where each modem
modem that transmits/sends data to reach a particular destination is that transmits/sends data to reach a particular destination is
counted as a hop. counted as a hop.
It is important to note that the use of the hop control mechanism It is important to note that the use of the hop control mechanism
defined in this can result in connectivity changes and even loss of defined in this document can result in connectivity changes and even
the ability to reach one or more destinations. The defined mechanism loss of the ability to reach one or more destinations. The defined
will report such connectivity changes, but the details of what a mechanism will report such connectivity changes, but the details of
router does or how it reacts to such are out scope of this document. what a router does or how it reacts to such are out scope of this
document.
This document defines a new DLEP Extension Type Value in Section 2 This document defines a new DLEP Extension Type Value in Section 2
which is used to indicate the use of the extension, and three new which is used to indicate the use of the extension, and three new
DLEP Data Items in Section 3. DLEP Data Items in Section 3.
1.1. Key Words 1.1. Key Words
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
2. Extension Usage and Identification 2. Extension Usage and Identification
The use of the Multi-Hop Forwarding Extension SHOULD be configurable. The use of the Multi-Hop Forwarding Extension SHOULD be configurable.
To indicate that the extension is to be used, an implementation MUST Per [RFC8175], to indicate that the extension is to be used, an
include the Multi-Hop Forwarding Extension Type Value in the implementation includes the Multi-Hop Forwarding Extension Type Value
Extensions Supported Data Item. The Extensions Supported Data Item in the Extensions Supported Data Item. The Extensions Supported Data
is sent and processed according to [RFC8175]. Item is sent and processed according to [RFC8175].
The Multi-Hop Forwarding Extension Type Value is TBA1, see Section 5. The Multi-Hop Forwarding Extension Type Value is TBA1, see Section 5.
3. Extension Data Items 3. Extension Data Items
Three data items are defined by this extension. The Hop Count Data Three data items are defined by this extension. The Hop Count Data
Item is used by a modem to provide the number of modem hops traversed Item is used by a modem to provide the number of modem hops traversed
to reach a particular destination. The Hop Control Data Item is used to reach a particular destination. The Hop Control Data Item is used
by a router to request that a modem alter connectivity to a by a router to request that a modem alter connectivity to a
particular destination. The Suppress Forwarding Data Item is used by particular destination. The Suppress Forwarding Data Item is used by
a router to request that a modem disable multi-hop forwarding on a router to request that a modem disable multi-hop forwarding on
either a device or destination basis. either a device or destination basis.
3.1. Hop Count 3.1. Hop Count
The Hop Count Data Item is used by a modem to indicate the number of The Hop Count Data Item is used by a modem to indicate the number of
modem that transmits/sends data to reach a particular destination, modems that transmit/send data to reach a particular destination,
i.e., hops, between the modem and a specific destination. In other i.e., hops, between the modem and a specific destination. In other
words, each hop represents a transmission and the number of hops is words, each hop represents a transmission and the number of hops is
equal to the number of transmissions required to go from a router equal to the number of transmissions required to go from a router
connected modem to the destination's connected modem. The minimum connected modem to the destination's connected modem. The minimum
number of hops is 1, which represents transmission to destinations number of hops is 1, which represents transmission to destinations
that are directly reachable via the router's locally connected modem. that are directly reachable via the router's locally connected modem.
The data item also contains an indication of when a destination which The data item also contains an indication of when a destination which
currently has a hop count of greater than one (1) could be made currently has a hop count of greater than one (1) could be made
directly reachable by a modem, e.g., by re-aiming an antenna. directly reachable by a modem, e.g., by re-aiming an antenna.
The Hop Count Data Item SHOULD be carried in the Destination Up, The Hop Count Data Item SHOULD be carried in the Destination Up,
Destination Update, Destination Announce Response, and Link Destination Update, Destination Announce Response, and Link
Characteristics Response Messages when the Hop Count to a destination Characteristics Response Messages when the Hop Count to a destination
is greater than one (1). is greater than one (1).
A router receiving a Hop Count Data Item can use this information in A router receiving a Hop Count Data Item can use this information in
its forwarding and routing decisions, and specific use is out of its forwarding and routing decisions, and specific use is out of
scope of this document. The absence of the Hop Count Data Item MUST scope of this document. When using this extension, the absence of
be interpreted by the router as a Hop Count value of one (1). the Hop Count Data Item MUST be interpreted by the router as a Hop
Count value of one (1).
The format of the Hop Count Data Item is: The format of the Hop Count Data Item is:
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Item Type | Length | | Data Item Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|P| Reserved | Hop Count | |P| Reserved | Hop Count |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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required (i.e., number of times a packet will be transmitted) to required (i.e., number of times a packet will be transmitted) to
reach the destination indicated in the message. The special value reach the destination indicated in the message. The special value
of 255 (0xFF) is used to indicate that the number of hops is an of 255 (0xFF) is used to indicate that the number of hops is an
unknown number greater than one (1). This field MUST contain a unknown number greater than one (1). This field MUST contain a
value of at least one (1) if the associated destination is value of at least one (1) if the associated destination is
reachable. reachable.
A value of zero (0) is used to indicate that processing of a Hop A value of zero (0) is used to indicate that processing of a Hop
Control action, see Section 3.2, has resulted in the destination Control action, see Section 3.2, has resulted in the destination
no longer being reachable. A zero value MUST NOT be used in any no longer being reachable. A zero value MUST NOT be used in any
message other then a Link Characteristics Response Message. message other than a Link Characteristics Response Message.
3.2. Hop Control 3.2. Hop Control
The Hop Control Data Item is used by a router to request a change in The Hop Control Data Item is used by a router to request a change in
connectivity to a particular destination, or in multi-hop processing connectivity to a particular destination, or in multi-hop processing
on a device wide basis. A router can request multi-hop reachable on a device wide basis. A router can request that a multi-hop
destination be changed to a single hop. A router can also indicate reachable destination be changed to a single hop. A router can also
that the modem terminates a previous direct connectivity request to a indicate that the modem terminates a previous direct connectivity
particular destination. request to a particular destination.
The Hop Control Data Item MAY be carried in a Session Update Message The Hop Control Data Item MAY be carried in a Session Update Message
sent by a router when the control applies to the whole device, or a sent by a router when the control applies to the whole device, or a
Link Characteristics Request Message when the control applies to a Link Characteristics Request Message when the control applies to a
particular destination. particular destination.
A modem that receives the Hop Control Data Item in a Link A modem that receives the Hop Control Data Item in a Link
Characteristics Request Message SHOULD take whatever actions are Characteristics Request Message SHOULD take whatever actions are
needed to make the change indicated by the data item for the needed to make the change indicated by the data item for the
associated destination MAC address. Once the change is made, fails associated destination MAC address. Once the change is made, fails
or is rejected, the modem MUST respond with a Link Characteristics or is rejected, the modem MUST respond with a Link Characteristics
Response Message containing an updated Hop Count Data Item. Note Response Message containing an updated Hop Count Data Item. Note
that other destinations can be impacted as a result of the change and that other destinations can be impacted as a result of the change and
such changes are reported in Destination Down and Destination Update such changes are reported in Destination Down and Destination Update
Messages. The modem MUST notify the router of each destination that Messages. The modem MUST notify the router of each destination that
is not identified in the Link Characteristics Response Message and is is not identified in the Link Characteristics Response Message and is
no longer reachable via a Destination Down Message. The modem MUST no longer reachable via a Destination Down Message. The modem MUST
also notify the router of each destination that is not identified in also notify the router of each impacted destination that is not
the Link Characteristics Response Message and has a changed Hop Count identified in the Link Characteristics Response Message via a
impacted via a Destination Update Message. Destination Update Message.
Failures may occur for multiple reasons, for example, the Failures may occur for multiple reasons, for example, the
transmission characteristics of the link don't support the one-hop transmission characteristics of the link don't support the one-hop
connection at the time of the request. Requests may be rejected by connection at the time of the request. Requests can be rejected by
local policy. local policy.
A modem that receives the Hop Control Data Item in a Session Update A modem that receives the Hop Control Data Item in a Session Update
Message SHOULD take whatever actions are needed to make the change Message SHOULD take whatever actions are needed to make the change
indicated by the data item for all known destinations. Once the indicated by the data item for all known destinations. Once the
change is made, or fails or is rejected, the modem MUST respond with change is made, or fails or is rejected, the modem MUST respond with
a Session Update Response Message with an appropriate Status Code. a Session Update Response Message with an appropriate Status Code.
Destination specific impact resulting from the processing of a Hop Destination specific impact resulting from the processing of a Hop
Control Data Item in a Session Update Message is provided via Control Data Item in a Session Update Message is provided via
Destination Down and Destination Update Messages. The modem MUST Destination Down and Destination Update Messages. The modem MUST
notify the router of each destination that is no longer reachable via notify the router of each destination that is no longer reachable via
a Destination Down Message. The modem MUST notify the router of any a Destination Down Message. The modem MUST notify the router of any
changes in Hop Counts via Destination Update Messages. changes in Hop Counts via Destination Update Messages.
The format of the Hop Control Data Item is: The format of the Hop Control Data Item is:
0 1 2 3 0 1 2 3
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The Terminate Action is only valid on a per destination basis and The Terminate Action is only valid on a per destination basis and
MUST NOT be sent in a Session Update Message message. It indicates MUST NOT be sent in a Session Update Message message. It indicates
that a direct connection is no longer needed with the destination that a direct connection is no longer needed with the destination
identified in the message. This request has no impact for multi-hop identified in the message. This request has no impact for multi-hop
destinations and may fail even in a single hop case, i.e. can result destinations and may fail even in a single hop case, i.e. can result
in the Hop Count to the destination not being impacted by the in the Hop Count to the destination not being impacted by the
processing of the request. processing of the request.
3.2.3. Direct Connection 3.2.3. Direct Connection
The Direct Connection is only valid on a per destination basis and The Direct Connection Action is only valid on a per destination basis
MUST NOT be sent in a Session Update Message message. It indicates and MUST NOT be sent in a Session Update Message message. It
that the modem SHOULD attempt to establish a direct connection with indicates that the modem SHOULD attempt to establish a direct
the destination identified in the message. This action SHOULD only connection with the destination identified in the message. This
be sent for destinations for which the Hop Count is greater than 1 action SHOULD only be sent for destinations for which the Hop Count
and has the P-Bit set in the previously received Hop Count Data Item. is greater than 1 and has the P-Bit set in the previously received
Results of the request for the destination identified in the message Hop Count Data Item. Results of the request for the destination
are provided as described above. identified in the message are provided as described above.
3.2.4. Suppress Forwarding 3.2.4. Suppress Forwarding
The Suppress Forwarding Action is used by a router to indicate to its The Suppress Forwarding Action is used by a router to indicate to its
peer that multi-hop forwarding performed by the modem is to be peer that multi-hop forwarding performed by the modem is to be
suppressed. A router may request that multi-hop forwarding may be suppressed. A router can request that multi-hop forwarding may be
suppressed on a device wide or destination specific basis. suppressed on a device wide or destination specific basis.
A modem which receives the Suppress Forwarding Data Item in a Session A modem that receives the Suppress Forwarding Data Item in a Session
Update Message MUST suppress multi-hop forwarding on a device wide Update Message MUST suppress multi-hop forwarding on a device wide
basis. This means that data traffic originating from the modem's basis. This means that data traffic originating from the modem's
peer router SHALL only be sent by the modem to destinations that are peer router SHALL only be sent by the modem to destinations that are
one modem hop away, and that any data traffic received by the modem one modem hop away, and that any data traffic received by the modem
from another modem that is not destined to the peer router SHALL be from another modem that is not destined to the peer router SHALL be
dropped. Impact to destination hop counts are provided to the router dropped. Impact to destination hop counts are provided to the router
by the modem as described above. by the modem as described above.
A modem which receives the Suppress Forwarding Data Item in a Link A modem that receives the Suppress Forwarding Data Item in a Link
Characteristics Request Message MUST suppress multi-hop forwarding Characteristics Request Message MUST suppress multi-hop forwarding
for only the destination indicated in the message. This means that for only the destination indicated in the message. This means that
data traffic originating from the modem's peer router SHALL be sent data traffic originating from the modem's peer router SHALL be sent
by the modem to the destination indicated in the Link Characteristics by the modem to the destination indicated in the Link Characteristics
Request Message only when it is one modem hop away. Notably, data Request Message only when it is one modem hop away. Notably, data
traffic received by the modem from another modem can be forwarded by traffic received by the modem from another modem can be forwarded by
the modem per its normal processing. Results are provided as the modem per its normal processing. Results are provided as
described above. described above.
4. Security Considerations 4. Security Considerations
The extension enables the reporting and control of forwarding The extension enables the reporting and control of forwarding
information by DLEP capable modems. The extension does not information by DLEP capable modems. The extension does not
inherently introduce any additional threats above those documented in inherently introduce any additional vulnerabilities above those
[RFC8175]. The approach taken to Security in that document applies documented in [RFC8175]. The approach taken to Security in that
equally when running the extension defined in this document. document applies equally when running the extension defined in this
document.
This extension does define one mechanism that is worth particular This extension does define one mechanism that is worth particular
note. This extension includes a Hop Control mechanism, see note. This extension includes a Hop Control mechanism, see
Section 3.2, that is similar to the Link Characteristics Request Section 3.2, that is similar to the Link Characteristics Request
Message defined in [RFC8175] in that it can impact the set of Message defined in [RFC8175] in that it can impact the set of
destinations reported as reachable. With the Link Characteristics destinations reported as reachable. With the Link Characteristics
Request Message, this risk is implicit. With the Hop Control Request Message, this risk is implicit. With the Hop Control
mechanism defined in this document it is more likely. From a mechanism defined in this document it is more likely. From a
security perspective, implementations should be aware of this security perspective, implementations should be aware of this
increased risk and may choose to implement additional configuration increased risk and may choose to implement additional configuration
control mechanisms to ensure that the Hop Control mechanism is only control mechanisms to ensure that the Hop Control mechanism is only
used under conditions intended by the network operator. used under conditions intended by the network operator.
Implementations of the extension defined in this document MUST
support configuration of TLS usage, as describe in [RFC8175], in
order to protect configurations where injection attacks are possible,
i.e., when the link between a modem and router is not otherwise
protected.
Note that this extension does allow a compromised or impersonating
modem to suppress transmission by the router or a switch that
interconnects the modem and router. Similar attacks are generally
possible base DLEP, for example an impersonating modem may cause a
session reset or a compromised modem simply can drop all traffic
destined to, or sent by a router. [RFC8175] defines the use of TLS
to protect against the impersonating attacker.
5. IANA Considerations 5. IANA Considerations
This document requests the assignment of 3 values by IANA. All This document requests the assignment of 3 values by IANA. All
assignments are to registries defined by [RFC8175]. It also requests assignments are to registries defined by [RFC8175]. It also requests
creation of one new registry. creation of one new registry.
5.1. Extension Type Value 5.1. Extension Type Value
This document requests 1 new assignment to the DLEP Extensions This document requests 1 new assignment to the DLEP Extensions
Registry named "Extension Type Values" in the range with the Registry named "Extension Type Values" in the range with the
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