Multi-homing Deployment Considerations for Distributed-Denial-of-Service Open Threat Signaling (DOTS)
draft-ietf-dots-multihoming-01
The information below is for an old version of the document.
| Document | Type |
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|---|---|---|---|
| Authors | Mohamed Boucadair , Tirumaleswar Reddy.K | ||
| Last updated | 2019-01-21 | ||
| Replaces | draft-boucadair-dots-multihoming | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
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draft-ietf-dots-multihoming-01
Network Working Group M. Boucadair
Internet-Draft Orange
Intended status: Standards Track T. Reddy
Expires: July 25, 2019 McAfee
January 21, 2019
Multi-homing Deployment Considerations for Distributed-Denial-of-Service
Open Threat Signaling (DOTS)
draft-ietf-dots-multihoming-01
Abstract
This document discusses multi-homing considerations for Distributed-
Denial-of-Service Open Threat Signaling (DOTS). The goal is to
provide some guidance for DOTS clients/gateways when multihomed.
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 July 25, 2019.
Copyright Notice
Copyright (c) 2019 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
(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
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include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 4
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Multi-Homing Scenarios . . . . . . . . . . . . . . . . . . . 4
4.1. Residential Single CPE . . . . . . . . . . . . . . . . . 5
4.2. Multi-Homed Enterprise: Single CPE, Multiple Upstream
ISPs . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4.3. Multi-homed Enterprise: Multiple CPEs, Multiple Upstream
ISPs . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4.4. Multi-homed Enterprise with the Same ISP . . . . . . . . 7
5. DOTS Deployment Considerations . . . . . . . . . . . . . . . 7
5.1. Residential CPE . . . . . . . . . . . . . . . . . . . . . 7
5.2. Multi-Homed Enterprise: Single CPE, Multiple Upstream
ISPs . . . . . . . . . . . . . . . . . . . . . . . . . . 9
5.3. Multi-Homed Enterprise: Multiple CPEs, Multiple Upstream
ISPs . . . . . . . . . . . . . . . . . . . . . . . . . . 11
5.4. Multi-Homed Enterprise: Single ISP . . . . . . . . . . . 12
6. Security Considerations . . . . . . . . . . . . . . . . . . . 12
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 12
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
9.1. Normative References . . . . . . . . . . . . . . . . . . 13
9.2. Informative References . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14
1. Introduction
In many deployments, it may not be possible for a network to
determine the cause of a distributed Denial-of-Service (DoS) attack
[RFC4732]. Rather, the network may just realize that some resources
seem to be under attack. To improve such situation, the IETF is
specifying the DDoS Open Threat Signaling (DOTS)
[I-D.ietf-dots-architecture]architecture, where a DOTS client can
inform a DOTS server that the network is under a potential attack and
that appropriate mitigation actions are required. Indeed, because
the lack of a common method to coordinate a real-time response among
involved actors and network domains jeopardizes the efficiency of
DDoS attack mitigation actions, the DOTS protocol is meant to carry
requests for DDoS attack mitigation, thereby reducing the impact of
an attack and leading to more efficient responsive actions.
[I-D.ietf-dots-use-cases] identifies a set of scenarios for DOTS;
most of these scenarios involve a Customer Premises Equipment (CPE).
The high-level DOTS architecture is illustrated in Figure 1
([I-D.ietf-dots-architecture]):
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+-----------+ +-------------+
| Mitigator | ~~~~~~~~~~ | DOTS Server |
+-----------+ +-------------+
|
|
|
+---------------+ +-------------+
| Attack Target | ~~~~~~ | DOTS Client |
+---------------+ +-------------+
Figure 1: Basic DOTS Architecture
[I-D.ietf-dots-architecture] specifies that the DOTS client may be
provided with a list of DOTS servers; each of these servers is
associated with one or more IP addresses. These addresses may or may
not be of the same address family. The DOTS client establishes one
or more DOTS sessions by connecting to the provided DOTS server(s)
addresses.
DOTS may be deployed within networks that are connected to one single
upstream provider. It can also be enabled within networks that are
multi-homed. The reader may refer to [RFC3582] for an overview of
multi-homing goals and motivations. This document discusses DOTS
multi-homing considerations. Specifically, the document aims to:
1. Complete the base DOTS architecture with multi-homing specifics.
Those specifics need to be taken into account because:
* Send a DOTS mitigation request to an arbitrary DOTS server
won't help mitigating a DDoS attack.
* Blindly forking all DOTS mitigation requests among all
available DOTS servers is suboptimal.
* Sequentially contacting DOTS servers may increase the delay
before a mitigation plan is enforced.
2. Identify DOTS deployment schemes in a multi-homing context, where
DOTS services can be offered by all or a subset of upstream
providers.
3. Sketch guidelines and recommendations for placing DOTS requests
in multi-homed networks, e.g.,:
* Select the appropriate DOTS server(s).
* Identify cases where anycast is not recommended.
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This document adopts the following methodology:
o Identify and extract viable deployment candidates from
[I-D.ietf-dots-use-cases].
o Augment the description with multi-homing technicalities, e.g.,
* One vs. multiple upstream network providers
* One vs. multiple interconnect routers
* Provider-Independent (PI) vs. Provider-Aggregatable (PA) IP
addresses
o Describe the recommended behavior of DOTS clients and gateways for
each case.
Multi-homed DOTS agents are assumed to make use of the protocols
defined in [I-D.ietf-dots-signal-channel] and
[I-D.ietf-dots-data-channel]; no specific extension is required to
the base DOTS protocols for deploying DOTS in a multi-homed context.
2. 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.
3. Terminology
This document makes use of the terms defined in
[I-D.ietf-dots-architecture] and [RFC4116].
IP indifferently refers to IPv4 or IPv6.
4. Multi-Homing Scenarios
This section describes some multi-homing scenarios that are relevant
to DOTS. In the following sub-sections, only the connections of
border routers are shown; internal network topologies are not
elaborated.
This section distinguishes between residential CPEs vs. enterprise
CPEs because PI addresses may be used for enterprises while this is
not the current practice for residential CPEs.
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4.1. Residential Single CPE
The scenario shown in Figure 2 is characterized as follows:
o The home network is connected to the Internet using one single CPE
(Customer Premises Equipment).
o The CPE is connected to multiple provisioning domains (i.e., both
fixed and mobile networks). Provisioning domain (PvD) is
explained in [RFC7556].
o Each of these provisioning domains assigns IP addresses/prefixes
to the CPE and provides additional configuration information such
as a list of DNS servers, DNS suffixes associated with the
network, default gateway address, and DOTS server's name
[I-D.boucadair-dots-server-discovery]. These addresses/prefixes
are assumed to be Provider-Aggregatable (PA).
o Because of ingress filtering, packets forwarded by the CPE towards
a given provisioning domain must be sent with a source IP address
that was assigned by that domain [RFC8043].
+-------+ +-------+
|Fixed | |Mobile |
|Network| |Network|
+---+---+ +---+---+
| | Service Providers
............|....................|.......................
+---------++---------+ Home Network
||
+--++-+
| CPE |
+-----+
... (Internal Network)
Figure 2: Typical Multi-homed Residential CPE
4.2. Multi-Homed Enterprise: Single CPE, Multiple Upstream ISPs
The scenario shown in Figure 3 is characterized as follows:
o The enterprise network is connected to the Internet using one
single router.
o That router is connected to multiple provisioning domains (i.e.,
managed by distinct administrative entities).
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Unlike the previous scenario, two sub-cases can be considered for an
enterprise network with regards to assigned addresses:
1. PI addresses/prefixes: The enterprise is the owner of the IP
addresses/prefixes; the same address/prefix is then used when
establishing communications over any of the provisioning domains.
2. PA addresses/prefixes: each of the provisioning domains assigns
IP addresses/prefixes to the enterprise network.
+------+ +------+
| ISP1 | | ISP2 |
+---+--+ +--+---+
| | Service Providers
............|....................|.......................
+---------++---------+ Enterprise Network
||
+--++-+
| rtr |
+-----+
... (Internal Network)
Figure 3: Multi-homed Enterprise Network (Single CPE connected to
Multiple Networks)
4.3. Multi-homed Enterprise: Multiple CPEs, Multiple Upstream ISPs
This scenario is similar to the one described in Section 4.2; the
main difference is that dedicated routers are used to connect to each
provisioning domain.
+------+ +------+
| ISP1 | | ISP2 |
+---+--+ +--+---+
| | Service Providers
......................|..........|.......................
| | Enterprise Network
+---+--+ +--+---+
| rtr1 | | rtr2 |
+------+ +------+
... (Internal Network)
Figure 4: Multi-homed Enterprise Network (Multiple CPEs, Multiple
ISPs)
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4.4. Multi-homed Enterprise with the Same ISP
This scenario is a variant of Section 4.2 and Section 4.3 in which
multi-homing is supported by the same ISP (i.e., same provisioning
domain).
Editor's Note: The use of anycast addresses is to be consistently
discussed.
5. DOTS Deployment Considerations
Table 1 provides some sample, non-exhaustive, deployment schemes to
illustrate how DOTS agents may be deployed for each of the scenarios
introduced in Section 4.
+---------------------------+-------------------------+-------------+
| Scenario | DOTS client | DOTS |
| | | gateway |
+---------------------------+-------------------------+-------------+
| Residential CPE | CPE | N/A |
+---------------------------+-------------------------+-------------+
| Single CPE, Multiple | internal hosts or CPE | CPE |
| provisioning domains | | |
+---------------------------+-------------------------+-------------+
| Multiple CPEs, Multiple | internal hosts or all | CPEs (rtr1 |
| provisioning domains | CPEs (rtr1 and rtr2) | and rtr2) |
+---------------------------+-------------------------+-------------+
| Multi-homed enterprise, | internal hosts or all | CPEs (rtr1 |
| Single provisioning | CPEs (rtr1 and rtr2) | and rtr2) |
| domain | | |
+---------------------------+-------------------------+-------------+
Table 1: Sample Deployment Cases
These deployment schemes are further discussed in the following sub-
sections.
5.1. Residential CPE
Figure 5 depicts DOTS sessions that need to be established between a
DOTS client (C) and two DOTS servers (S1, S2) within the context of
the scenario described in Section 4.1.
For each provisioning domain, the DOTS client MUST resolve the DOTS
server's name provided by a provisioning domain
([I-D.boucadair-dots-server-discovery]) using the DNS servers learned
from the respective provisioning domain. The DOTS client MUST use
the source address selection algorithm defined in [RFC6724] to select
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the candidate source addresses to contact each of these DOTS servers.
DOTS sessions must be established and maintained with each of the
DOTS servers because the mitigation scope of these servers is
restricted. The DOTS client SHOULD use the certificate provisioned
by a provisioning domain to authenticate itself to the DOTS server
provided by the same provisioning domain.
When conveying a mitigation request to protect the attack target(s),
the DOTS client among the DOTS servers available MUST select a DOTS
server whose network has assigned the prefixes from which target
prefixes and target IP addresses are derived. This implies that if
no appropriate DOTS server is found, the DOTS client must not send
the mitigation request to any DOTS server.
For example, a mitigation request to protect target resources bound
to a PA IP address/prefix cannot be satisfied by a provisioning
domain another domain than the one that owns those addresses/
prefixes. Consequently, if a CPE detects a DDoS attack that spreads
over all its network attachments, it must contact both DOTS servers
for mitigation purposes. Nevertheless, if the DDoS attack is
received from one single network, then only the DOTS server of that
network must be contacted.
The DOTS client MUST be able to associate a DOTS server with each
provisioning domain. For example, if the DOTS client is provisioned
with S1 using DHCP when attaching to a first network and with S2
using Protocol Configuration Option (PCO) when attaching to a second
network, the DOTS client must record the interface from which a DOTS
server was provisioned. DOTS signaling session to a given DOTS
server must be established using the interface from which the DOTS
server was provisioned.
+--+
-----------|S1|
/ +--+
/
/
+---+/
| C |
+---+\
\
\
\ +--+
-----------|S2|
+--+
Figure 5: DOTS associations for a multihomed residential CPE
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5.2. Multi-Homed Enterprise: Single CPE, Multiple Upstream ISPs
Figure 6 illustrates a first set of DOTS associations that can be
established with a DOTS gateway, which is enabled within the context
of the scenario described in Section 4.2. This deployment is
characterized as follows:
o One of more DOTS clients are enabled in hosts located in the
internal network.
o A DOTS gateway is enabled to aggregate and then relay the requests
towards upstream DOTS servers.
When PA addresses/prefixes are in use, the same considerations
discussed in Section 5.1 need to be followed by the DOTS gateway to
contact its DOTS server(s). The DOTS gateways can be reachable from
DOTS clients by using an unicast address or an anycast address.
Nevertheless, when PI addresses/prefixes are assigned, the DOTS
gateway MUST send the same request to all its DOTS servers.
+--+
-----------|S1|
+---+ / +--+
| C1|----+ /
+---+ | /
+---+ +-+-+/
| C3|------| G |
+---+ +-+-+\
+---+ | \
| C2|----+ \
+---+ \ +--+
-----------|S2|
+--+
Figure 6: Multiple DOTS Clients, Single DOTS Gateway, Multiple DOTS
Servers
An alternate deployment model is depicted in Figure 7. This
deployment assumes that:
o One or more DOTS clients are enabled in hosts located in the
internal network. These DOTS clients may use
[I-D.boucadair-dots-server-discovery] to discover their DOTS
server(s).
o These DOTS clients communicate directly with upstream DOTS
servers.
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If PI addresses/prefixes are in use, the DOTS client MUST send the
mitigation request for all its PI addresses/prefixes to all the DOTS
servers. The use of anycast addresses is NOT RECOMMENDED.
If PA addresses/prefixes are used, the same considerations discussed
in Section 5.1 need to be followed by the DOTS clients. Because DOTS
clients are not embedded in the CPE and multiple addreses/prefixes
may not be assigned to the DOTS client (typically in an IPv4
context), some issues arise to steer traffic towards the appropriate
DOTS server by using the appropriate source IP address. These
complications discussed in [RFC4116] are not specific to DOTS.
+--+
+--------|C1|--------+
| +--+ |
+--+ +--+ +--+
|S2|------|C3|------|S1|
+--+ +--+ +--+
| +--+ |
+--------|C2|--------+
+--+
Figure 7: Multiple DOTS Clients, Multiple DOTS Servers
Another deployment approach is to enable many DOTS clients; each of
them is responsible for handling communications with a specific DOTS
server (see Figure 8).
+--+
+--------|C1|
| +--+
+--+ +--+ +--+
|S2| |C2|------|S1|
+--+ +--+ +--+
Figure 8: Single Homed DOTS Clients
Each DOTS client is provided with policies (e.g., prefix filter) that
will trigger DOTS communications with the DOTS servers. Such
policies will help the DOTS client to select the appropriate
destination IP address.
The CPE MUST select the appropriate source IP address when forwarding
DOTS messages received from an internal DOTS client. If anycast
addresses are used to reach DOTS servers, the CPE may not be able to
select the appropriate provisioning domain to which the mitigation
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request should be forwarded. As a consequence, the request may not
be forwarded to the appropriate DOTS server.
5.3. Multi-Homed Enterprise: Multiple CPEs, Multiple Upstream ISPs
The deployments depicted in Figures 7 and 8 also apply to the
scenario described in Section 4.3. One specific problem for this
scenario is to select the appropriate exit router when contacting a
given DOTS server.
An alternative deployment scheme is shown in Figure 9:
o DOTS clients are enabled in hosts located in the internal network.
o A DOTS gateway is enabled in each CPE (rtr1, rtr2).
o Each of these DOTS gateways communicates with the DOTS server of
the provisioning domain.
When PI addresses/prefixes are used, DOTS clients MUST contact all
the DOTS gateways to send a DOTS message. DOTS gateways will then
relay the request to the DOTS server. Note that the use of anycast
addresses is NOT RECOMMENDED to establish DOTS sessions between DOTS
clients and DOTS gateways.
When PA addresses/prefixes are used, but no filter rules are provided
to DOTS clients, the latter MUST contact all DOTS gateways
simultaneously to send a DOTS message. Upon receipt of a request by
a DOTS gateway, it MUST check whether the request is to be forwarded
upstream (if the target IP prefix is managed by the upstream server)
or rejected.
When PA addresses/prefixes are used, but specific filter rules are
provided to DOTS clients using some means that are out of scope of
this document, the clients MUST select the appropriate DOTS gateway
to reach. The use of anycast addresses is NOT RECOMMENDED to reach
DOTS gateways.
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+---+
+------------| C1|----+
| +---+ |
+--+ +-+-+ +---+ +-+-+ +--+
|S2|------|G2 |------| C3|------|G1 |------|S1|
+--+ +-+-+ +---+ +-+-+ +--+
| +---+ |
+------------| C2|----+
+---+
Figure 9: Multiple DOTS Clients, Multiple DOTS Gateways, Multiple
DOTS Servers
5.4. Multi-Homed Enterprise: Single ISP
The key difference of the scenario described in Section 4.4 compared
to the other scenarios is that multi-homing is provided by the same
ISP. Concretely, that ISP can decide to provision the enterprise
network with:
1. The same DOTS server for all network attachments.
2. Distinct DOTS servers for each network attachment. These DOTS
servers need to coordinate when a mitigation action is received
from the enterprise network.
In both cases, DOTS agents enabled within the enterprise network MAY
decide to select one or all network attachments to send DOTS
mitigation requests.
6. Security Considerations
DOTS-related security considerations are discussed in Section 4 of
[I-D.ietf-dots-architecture].
TBD: In Home networks, if EST is used then how will the DOTS gateway
(EST client) be provisioned with credentials for initial enrolment
(see Section 2.2 in RFC 7030).
7. IANA Considerations
This document does not require any action from IANA.
8. Acknowledgements
Thanks to Roland Dobbins, Nik Teague, Jon Shallow, Dan Wing, Wei Pan,
and Christian Jacquenet for sharing their comments on the mailing
list.
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Thanks to Kirill Kasavchenko for the comments.
9. References
9.1. Normative References
[I-D.ietf-dots-architecture]
Mortensen, A., Andreasen, F., K, R., Teague, N., Compton,
R., and c. christopher_gray3@cable.comcast.com,
"Distributed-Denial-of-Service Open Threat Signaling
(DOTS) Architecture", draft-ietf-dots-architecture-10
(work in progress), December 2018.
[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>.
[RFC6724] Thaler, D., Ed., Draves, R., Matsumoto, A., and T. Chown,
"Default Address Selection for Internet Protocol Version 6
(IPv6)", RFC 6724, DOI 10.17487/RFC6724, September 2012,
<https://www.rfc-editor.org/info/rfc6724>.
[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>.
9.2. Informative References
[I-D.boucadair-dots-server-discovery]
Boucadair, M., K, R., and P. Patil, "Distributed-Denial-
of-Service Open Threat Signaling (DOTS) Server Discovery",
draft-boucadair-dots-server-discovery-05 (work in
progress), October 2018.
[I-D.ietf-dots-data-channel]
Boucadair, M., K, R., Nishizuka, K., Xia, L., Patil, P.,
Mortensen, A., and N. Teague, "Distributed Denial-of-
Service Open Threat Signaling (DOTS) Data Channel
Specification", draft-ietf-dots-data-channel-24 (work in
progress), December 2018.
[I-D.ietf-dots-signal-channel]
K, R., Boucadair, M., Patil, P., Mortensen, A., and N.
Teague, "Distributed Denial-of-Service Open Threat
Signaling (DOTS) Signal Channel Specification", draft-
ietf-dots-signal-channel-26 (work in progress), December
2018.
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[I-D.ietf-dots-use-cases]
Dobbins, R., Migault, D., Fouant, S., Moskowitz, R.,
Teague, N., Xia, L., and K. Nishizuka, "Use cases for DDoS
Open Threat Signaling", draft-ietf-dots-use-cases-17 (work
in progress), January 2019.
[RFC3582] Abley, J., Black, B., and V. Gill, "Goals for IPv6 Site-
Multihoming Architectures", RFC 3582,
DOI 10.17487/RFC3582, August 2003,
<https://www.rfc-editor.org/info/rfc3582>.
[RFC4116] Abley, J., Lindqvist, K., Davies, E., Black, B., and V.
Gill, "IPv4 Multihoming Practices and Limitations",
RFC 4116, DOI 10.17487/RFC4116, July 2005,
<https://www.rfc-editor.org/info/rfc4116>.
[RFC4732] Handley, M., Ed., Rescorla, E., Ed., and IAB, "Internet
Denial-of-Service Considerations", RFC 4732,
DOI 10.17487/RFC4732, December 2006,
<https://www.rfc-editor.org/info/rfc4732>.
[RFC7556] Anipko, D., Ed., "Multiple Provisioning Domain
Architecture", RFC 7556, DOI 10.17487/RFC7556, June 2015,
<https://www.rfc-editor.org/info/rfc7556>.
[RFC8043] Sarikaya, B. and M. Boucadair, "Source-Address-Dependent
Routing and Source Address Selection for IPv6 Hosts:
Overview of the Problem Space", RFC 8043,
DOI 10.17487/RFC8043, January 2017,
<https://www.rfc-editor.org/info/rfc8043>.
Authors' Addresses
Mohamed Boucadair
Orange
Rennes 35000
France
Email: mohamed.boucadair@orange.com
Tirumaleswar Reddy
McAfee, Inc.
Embassy Golf Link Business Park
Bangalore, Karnataka 560071
India
Email: TirumaleswarReddy_Konda@McAfee.com
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