draft-ietf-idr-bgp-open-policy-19.txt   draft-ietf-idr-bgp-open-policy-20.txt 
Network Working Group A. Azimov Network Working Group A. Azimov
Internet-Draft Qrator Labs & Yandex Internet-Draft Qrator Labs & Yandex
Intended status: Standards Track E. Bogomazov Intended status: Standards Track E. Bogomazov
Expires: July 11, 2022 Qrator Labs Expires: July 22, 2022 Qrator Labs
R. Bush R. Bush
Internet Initiative Japan & Arrcus, Inc. Internet Initiative Japan & Arrcus, Inc.
K. Patel K. Patel
Arrcus Arrcus
K. Sriram K. Sriram
USA NIST USA NIST
January 7, 2022 January 18, 2022
Route Leak Prevention and Detection using Roles in UPDATE and OPEN Route Leak Prevention and Detection using Roles in UPDATE and OPEN
Messages Messages
draft-ietf-idr-bgp-open-policy-19 draft-ietf-idr-bgp-open-policy-20
Abstract Abstract
Route leaks are the propagation of BGP prefixes that violate Route leaks are the propagation of BGP prefixes that violate
assumptions of BGP topology relationships, e.g., announcing a route assumptions of BGP topology relationships, e.g., announcing a route
learned from one transit provider to another transit provider or a learned from one transit provider to another transit provider or a
lateral (i.e., non-transit) peer or announcing a route learned from lateral (i.e., non-transit) peer or announcing a route learned from
one lateral peer to another lateral peer or a transit provider. one lateral peer to another lateral peer or a transit provider.
These are usually the result of misconfigured or absent BGP route These are usually the result of misconfigured or absent BGP route
filtering or lack of coordination between autonomous systems (ASes). filtering or lack of coordination between autonomous systems (ASes).
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
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This Internet-Draft will expire on July 11, 2022. This Internet-Draft will expire on July 22, 2022.
Copyright Notice Copyright Notice
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document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Peering Relationships . . . . . . . . . . . . . . . . . . . . 4 2.1. Peering Relationships . . . . . . . . . . . . . . . . . . 4
3. BGP Role . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3. BGP Role . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1. BGP Role Capability . . . . . . . . . . . . . . . . . . . 5 3.1. BGP Role Capability . . . . . . . . . . . . . . . . . . . 5
3.2. Role Correctness . . . . . . . . . . . . . . . . . . . . 6 3.2. Role Correctness . . . . . . . . . . . . . . . . . . . . 6
4. BGP Only to Customer (OTC) Attribute . . . . . . . . . . . . 7 4. BGP Only to Customer (OTC) Attribute . . . . . . . . . . . . 7
5. Additional Considerations . . . . . . . . . . . . . . . . . . 9 5. Additional Considerations . . . . . . . . . . . . . . . . . . 8
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
7. Security Considerations . . . . . . . . . . . . . . . . . . . 10 7. Security Considerations . . . . . . . . . . . . . . . . . . . 10
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 11 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
8.1. Normative References . . . . . . . . . . . . . . . . . . 11 8.1. Normative References . . . . . . . . . . . . . . . . . . 11
8.2. Informative References . . . . . . . . . . . . . . . . . 12 8.2. Informative References . . . . . . . . . . . . . . . . . 12
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 12 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 12
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13
1. Introduction 1. Introduction
Route leaks are the propagation of BGP prefixes that violate Route leaks are the propagation of BGP prefixes that violate
assumptions of BGP topology relationships, e.g., announcing a route assumptions of BGP topology relationships, e.g., announcing a route
learned from one transit provider to another transit provider or a learned from one transit provider to another transit provider or a
lateral (i.e., non-transit) peer or announcing a route learned from lateral (i.e., non-transit) peer or announcing a route learned from
one lateral peer to another lateral peer or a transit provider one lateral peer to another lateral peer or a transit provider
[RFC7908]. These are usually the result of misconfigured or absent [RFC7908]. These are usually the result of misconfigured or absent
BGP route filtering or lack of coordination between autonomous BGP route filtering or lack of coordination between autonomous
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Existing approaches to leak prevention rely on marking routes by Existing approaches to leak prevention rely on marking routes by
operator configuration, with no check that the configuration operator configuration, with no check that the configuration
corresponds to that of the eBGP neighbor, or enforcement that the two corresponds to that of the eBGP neighbor, or enforcement that the two
eBGP speakers agree on the relationship. This document enhances the eBGP speakers agree on the relationship. This document enhances the
BGP OPEN message to establish an agreement of the relationship on BGP OPEN message to establish an agreement of the relationship on
each eBGP session between autonomous systems in order to enforce each eBGP session between autonomous systems in order to enforce
appropriate configuration on both sides. Propagated routes are then appropriate configuration on both sides. Propagated routes are then
marked according to the agreed relationship, allowing both prevention marked according to the agreed relationship, allowing both prevention
and detection of route leaks. and detection of route leaks.
This document provides configuration automation using BGP Roles, This document specifies a means of replacing the operator driven
which are negotiated using a BGP Role Capability in the OPEN message configuration-based method of route leak prevention, described above,
[RFC5492]. An eBGP speaker may require the use of this capability with a built-in method for route leak prevention and detection.
and confirmation of BGP Role with a neighbor for the BGP OPEN to
succeed. This method uses a new configuration parameter, BGP Role, which is
negotiated using a BGP Role Capability in the OPEN message [RFC5492].
An eBGP speaker may require the use of this capability and
confirmation of BGP Role with a neighbor for the BGP OPEN to succeed.
An optional, transitive BGP Path Attribute, called Only to Customer An optional, transitive BGP Path Attribute, called Only to Customer
(OTC), is specified in Section 4. It prevents ASes from creating (OTC), is specified in Section 4. It prevents ASes from creating
leaks and detects leaks created by the ASes in the middle of an AS leaks and detects leaks created by the ASes in the middle of an AS
path. The main focus/applicability is the Internet (IPv4 and IPv6 path. The main focus/applicability is the Internet (IPv4 and IPv6
unicast route advertisements). unicast route advertisements).
1.1. Terminology 2. Terminology
In the rest of this document, the term "Peer" is used to refer to a
"lateral (i.e., non-transit) peer" for simplicity. Also, the terms
Provider and Customer are used to refer to a transit provider and a
transit customer, respectively. Further, the terms RS and RS-Client
are used to refer to a Route Server and its client, respectively.
The terms "local AS" and "remote AS" are used to refer to the two The terms "local AS" and "remote AS" are used to refer to the two
ends of an eBGP session. The "local AS" is the AS where the protocol ends of an eBGP session. The "local AS" is the AS where the protocol
action being described is to be performed, and "remote AS" is the AS action being described is to be performed, and "remote AS" is the AS
at the other end of the eBGP session in consideration. at the other end of the eBGP session in consideration.
The use of the term "route is ineligible" in this document has the The use of the term "route is ineligible" in this document has the
same meaning as in [RFC4271], i.e., "route is ineligible to be same meaning as in [RFC4271], i.e., "route is ineligible to be
installed in Loc-RIB and will be excluded from the next phase of installed in Loc-RIB and will be excluded from the next phase of
route selection." route selection."
2. Peering Relationships 2.1. Peering Relationships
The terms defined and used in this document (see below) do not The terms defined and used in this document (see below) do not
necessarily represent business relationships based on payment necessarily represent business relationships based on payment
agreements. These terms are used to represent restrictions on BGP agreements. These terms are used to represent restrictions on BGP
route propagation, sometimes known as the Gao-Rexford model [Gao]. route propagation, sometimes known as the Gao-Rexford model [Gao].
The following is a list of BGP Roles for eBGP peering and the The following is a list of BGP Roles for eBGP peering and the
corresponding rules for route propagation: corresponding rules for route propagation:
Provider: MAY propagate any available route to a Customer. Provider: MAY propagate any available route to a Customer.
Customer: MAY propagate any route learned from a Customer, or Customer: MAY propagate any route learned from a Customer, or
locally originated, to a Provider. All other routes MUST NOT be locally originated, to a Provider. All other routes MUST NOT be
propagated. propagated.
Route Server (RS): MAY propagate any available route to a Route Route Server (RS): MAY propagate any available route to a Route
Server Client (RS-Client). Server Client (RS-Client).
RS-Client: MAY propagate any route learned from a Customer, or Route Server Client (RS-Client): MAY propagate any route learned
locally originated, to an RS. All other routes MUST NOT be from a Customer, or locally originated, to an RS. All other
propagated. routes MUST NOT be propagated.
Peer: MAY propagate any route learned from a Customer, or locally Peer: MAY propagate any route learned from a Customer, or locally
originated, to a Peer. All other routes MUST NOT be propagated. originated, to a Peer. All other routes MUST NOT be propagated.
If the local AS has one of the above Roles (in the order shown), then If the local AS has one of the above Roles (in the order shown), then
the corresponding peering relationship with the remote AS is the corresponding peering relationship with the remote AS is
Provider-to-Customer, Customer-to-Provider, RS-to-RS-Client, RS- Provider-to-Customer, Customer-to-Provider, RS-to-RS-Client, RS-
Client-to-RS, or Peer-to-Peer (i.e., lateral peers), respectively. Client-to-RS, or Peer-to-Peer (i.e., lateral peers), respectively.
These are called normal peering relationships. These are called normal peering relationships.
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As specified in Section 4, the Only to Customer (OTC) Attribute is As specified in Section 4, the Only to Customer (OTC) Attribute is
used to identify all the routes in the AS that have been received used to identify all the routes in the AS that have been received
from a Peer, Provider, or RS. from a Peer, Provider, or RS.
3. BGP Role 3. BGP Role
The BGP Role characterizes the relationship between the eBGP speakers The BGP Role characterizes the relationship between the eBGP speakers
forming a session. One of the Roles described below SHOULD be forming a session. One of the Roles described below SHOULD be
configured at the local AS for each eBGP session (see definitions in configured at the local AS for each eBGP session (see definitions in
Section 1.1) based on the local AS's knowledge of its Role. The only Section 2) based on the local AS's knowledge of its Role. The only
exception is when the eBGP connection is Complex (see Section 5). exception is when the eBGP connection is Complex (see Section 5).
BGP Roles are mutually confirmed using the BGP Role Capability BGP Roles are mutually confirmed using the BGP Role Capability
(described in Section 3.1) on each eBGP session. (described in Section 3.1) on each eBGP session.
Allowed Roles for eBGP sessions are: Allowed Roles for eBGP sessions are:
o Provider - the local AS is a transit Provider of the remote AS; o Provider - the local AS is a transit Provider of the remote AS;
o Customer - the local AS is a transit Customer of the remote AS; o Customer - the local AS is a transit Customer of the remote AS;
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NOT advertise multiple versions of the BGP Role Capability. NOT advertise multiple versions of the BGP Role Capability.
3.2. Role Correctness 3.2. Role Correctness
Section 3.1 described how BGP Role encodes the relationship on each Section 3.1 described how BGP Role encodes the relationship on each
eBGP session between autonomous systems (ASes). eBGP session between autonomous systems (ASes).
The mere receipt of BGP Role Capability does not automatically The mere receipt of BGP Role Capability does not automatically
guarantee the Role agreement between two eBGP neighbors. If the BGP guarantee the Role agreement between two eBGP neighbors. If the BGP
Role Capability is advertised, and one is also received from the Role Capability is advertised, and one is also received from the
peer, the roles MUST correspond to the relationships in Table 2. If peer, the Roles MUST correspond to the relationships in Table 2. If
the roles do not correspond, the BGP speaker MUST reject the the Roles do not correspond, the BGP speaker MUST reject the
connection using the Role Mismatch Notification (code 2, subcode connection using the Role Mismatch Notification (code 2, subcode
TBD). TBD).
+---------------+----------------+ +---------------+----------------+
| Local AS Role | Remote AS Role | | Local AS Role | Remote AS Role |
+---------------+----------------+ +---------------+----------------+
| Provider | Customer | | Provider | Customer |
| Customer | Provider | | Customer | Provider |
| RS | RS-Client | | RS | RS-Client |
| RS-Client | RS | | RS-Client | RS |
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Attribute in the received UPDATE message) is used in the route leak Attribute in the received UPDATE message) is used in the route leak
prevention and detection procedures described in Section 4. prevention and detection procedures described in Section 4.
4. BGP Only to Customer (OTC) Attribute 4. BGP Only to Customer (OTC) Attribute
The Only to Customer (OTC) Attribute is an optional transitive path The Only to Customer (OTC) Attribute is an optional transitive path
attribute of the UPDATE message with Attribute Type Code 35 and a attribute of the UPDATE message with Attribute Type Code 35 and a
length of 4 octets. The purpose of this attribute is to guarantee length of 4 octets. The purpose of this attribute is to guarantee
that once a route is sent to a Customer, Peer, or RS-Client, it will that once a route is sent to a Customer, Peer, or RS-Client, it will
subsequently go only to Customers. The attribute value is an AS subsequently go only to Customers. The attribute value is an AS
number (ASN) determined by the policy described below. number (ASN) determined by the procedures described below.
The following ingress policy applies to the processing of the OTC The following ingress procedure applies to the processing of the OTC
Attribute: Attribute on route receipt:
1. If a route with the OTC Attribute is received from a Customer or 1. If a route with the OTC Attribute is received from a Customer or
RS-Client, then it is a route leak and MUST be considered RS-Client, then it is a route leak and MUST be considered
ineligible (see Section 1.1). ineligible (see Section 2).
2. If a route with the OTC Attribute is received from a Peer and the 2. If a route with the OTC Attribute is received from a Peer and the
Attribute has a value that is not equal to the remote (i.e., Attribute has a value that is not equal to the remote (i.e.,
Peer's) AS number, then it is a route leak and MUST be considered Peer's) AS number, then it is a route leak and MUST be considered
ineligible. ineligible.
3. If a route is received from a Provider, Peer, or RS, and the OTC 3. If a route is received from a Provider, Peer, or RS, and the OTC
Attribute is not present, then it MUST be added with a value Attribute is not present, then it MUST be added with a value
equal to the AS number of the remote AS. equal to the AS number of the remote AS.
The following egress policy applies to the processing of the OTC The following egress procedure applies to the processing of the OTC
Attribute: Attribute on route advertisement:
1. If a route is to be advertised to a Customer, Peer, or RS-Client 1. If a route is to be advertised to a Customer, Peer, or RS-Client
(when the sender is an RS), and the OTC Attribute is not present, (when the sender is an RS), and the OTC Attribute is not present,
then an OTC Attribute MUST be added with a value equal to the AS then an OTC Attribute MUST be added with a value equal to the AS
number of the local AS. number of the local AS.
2. If a route already contains the OTC Attribute, it MUST NOT be 2. If a route already contains the OTC Attribute, it MUST NOT be
propagated to Providers, Peers, or RS(s). propagated to Providers, Peers, or RS(s).
The described policies provide both leak prevention for the local AS The above-described procedures provide both leak prevention for the
and leak detection and mitigation multiple hops away. In the case of local AS and leak detection and mitigation multiple hops away. In
prevention at the local AS, the presence of an OTC Attribute the case of prevention at the local AS, the presence of an OTC
indicates to the egress router that the route was learned from a Attribute indicates to the egress router that the route was learned
Peer, Provider, or RS, and it can be advertised only to the from a Peer, Provider, or RS, and it can be advertised only to the
customers. The same OTC Attribute which is set locally also provides customers. The same OTC Attribute which is set locally also provides
a way to detect route leaks by an AS multiple hops away if a route is a way to detect route leaks by an AS multiple hops away if a route is
received from a Customer, Peer, or RS-Client. received from a Customer, Peer, or RS-Client. For example, if an AS
sets the OTC Attribute on a route sent to a Peer and the route is
subsequently received by a compliant AS from a Customer, then the
receiving AS detects (based on the presence of the OTC Attribute)
that the route is a leak.
The OTC Attribute may be set by the egress policy of the remote AS or The OTC Attribute might be set at the egress of the remote AS or at
by the ingress policy of the local AS. In both scenarios, the OTC the ingress of the local AS, i.e., if the remote AS is noncompliant
value will be the same. This makes the scheme more robust and with this specification, then the local AS will have to set the OTC
benefits early adopters. Attribute if it is absent. In both scenarios, the OTC value will be
the same. This makes the scheme more robust and benefits early
adopters.
If an eBGP speaker receives an UPDATE with an OTC Attribute with a If an eBGP speaker receives an UPDATE with an OTC Attribute with a
length different from 4 octets, then the UPDATE SHALL be considered length different from 4 octets, then the UPDATE SHALL be considered
malformed. If malformed, the UPDATE message SHALL be handled using malformed. If malformed, the UPDATE message SHALL be handled using
the approach of "treat-as-withdraw" [RFC7606]. the approach of "treat-as-withdraw" [RFC7606].
The procedures specified in this document are NOT RECOMMENDED to be The procedures specified in this document are NOT RECOMMENDED to be
used between autonomous systems in an AS Confederation [RFC5065]. If used between autonomous systems in an AS Confederation [RFC5065]. If
an OTC Attribute is added on egress from the AS Confederation, its an OTC Attribute is added on egress from the AS Confederation, its
value MUST equal the AS Confederation Identifier. Also, on egress value MUST equal the AS Confederation Identifier. Also, on egress
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The procedures specified in this document in scenarios that use The procedures specified in this document in scenarios that use
private AS numbers behind an Internet-facing ASN (e.g., a data center private AS numbers behind an Internet-facing ASN (e.g., a data center
network [RFC7938] or stub customer) may be used, but any details are network [RFC7938] or stub customer) may be used, but any details are
outside the scope of this document. On egress from the Internet- outside the scope of this document. On egress from the Internet-
facing AS, the OTC Attribute MUST NOT contain a value other than the facing AS, the OTC Attribute MUST NOT contain a value other than the
Internet-facing ASN. Internet-facing ASN.
Once the OTC Attribute has been set, it MUST be preserved unchanged Once the OTC Attribute has been set, it MUST be preserved unchanged
(this also applies to an AS Confederation). (this also applies to an AS Confederation).
The described ingress and egress policies are applicable only for The described ingress and egress procedures are applicable only for
unicast IPv4 and IPv6 address families and MUST NOT be applied to unicast IPv4 and IPv6 address families and MUST NOT be applied to
other address families by default. The operator MUST NOT have the other address families by default. The operator MUST NOT have the
ability to modify the policies defined in this section. ability to modify the procedures defined in this section.
5. Additional Considerations 5. Additional Considerations
Roles MUST NOT be configured on an eBGP session with a Complex Roles MUST NOT be configured on an eBGP session with a Complex
peering relationship. If multiple eBGP sessions can segregate the peering relationship. If multiple eBGP sessions can segregate the
Complex peering relationship into eBGP sessions with normal peering Complex peering relationship into eBGP sessions with normal peering
relationships, BGP Roles SHOULD be used on each of the resulting eBGP relationships, BGP Roles SHOULD be used on each of the resulting eBGP
sessions. sessions.
An operator may want to achieve an equivalent outcome by configuring An operator may want to achieve an equivalent outcome by configuring
policies on a per-prefix basis to follow the definitions of peering policies on a per-prefix basis to follow the definitions of peering
relations as described in Section 2. However, in this case, there relations as described in Section 2.1. However, in this case, there
are no built-in measures to check the correctness of the per-prefix are no built-in measures to check the correctness of the per-prefix
peering configuration. peering configuration.
The incorrect setting of BGP Roles and/or OTC Attributes may affect The incorrect setting of BGP Roles and/or OTC Attributes may affect
prefix propagation. Further, this document does not specify any prefix propagation. Further, this document does not specify any
special handling of incorrect AS numbers in the OTC Attribute. special handling of incorrect AS numbers in the OTC Attribute.
In AS migration scenarios [RFC7705], a given router may represent
itself as any one of several different ASes. This should not be a
problem since the egress procedures in Section 4 specify that the OTC
Attribute is to be attached as part of route transmission.
Therefore, a router is expected to set the OTC value equal to the ASN
it is currently representing itself as.
6. IANA Considerations 6. IANA Considerations
IANA has registered a new BGP Capability (Section 3.1) in the IANA has registered a new BGP Capability (Section 3.1) in the
"Capability Codes" registry's "IETF Review" range [RFC5492]. The "Capability Codes" registry's "IETF Review" range [RFC5492]. The
description for the new capability is "BGP Role". IANA has assigned description for the new capability is "BGP Role". IANA has assigned
the value 9 [to be removed upon publication: the value 9 [to be removed upon publication:
https://www.iana.org/assignments/capability-codes/capability- https://www.iana.org/assignments/capability-codes/capability-
codes.xhtml]. This document is the reference for the new capability. codes.xhtml]. This document is the reference for the new capability.
The BGP Role capability includes a Value field, for which IANA is The BGP Role capability includes a Value field, for which IANA is
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7. Security Considerations 7. Security Considerations
The security considerations of BGP (as specified in [RFC4271] and The security considerations of BGP (as specified in [RFC4271] and
[RFC4272]) apply. [RFC4272]) apply.
This document proposes a mechanism using BGP Role for the prevention This document proposes a mechanism using BGP Role for the prevention
and detection of route leaks that are the result of BGP policy and detection of route leaks that are the result of BGP policy
misconfiguration. A misconfiguration of the BGP Role may affect misconfiguration. A misconfiguration of the BGP Role may affect
prefix propagation. For example, if a downstream (i.e., towards a prefix propagation. For example, if a downstream (i.e., towards a
Customer) peering link were misconfigured with a Provider or Peer Customer) peering link were misconfigured with a Provider or Peer
role, this will limit the number of prefixes that can be advertised Role, this will limit the number of prefixes that can be advertised
in this direction. On the other hand, if an upstream provider were in this direction. On the other hand, if an upstream provider were
misconfigured (by a local AS) with the Customer role, this may result misconfigured (by a local AS) with the Customer Role, this may result
in propagating routes that are received from other Providers or in propagating routes that are received from other Providers or
Peers. But the BGP Role negotiation and the resulting confirmation Peers. But the BGP Role negotiation and the resulting confirmation
of Roles make such misconfigurations unlikely. of Roles make such misconfigurations unlikely.
Setting the strict mode of operation for BGP Role negotiation as the Setting the strict mode of operation for BGP Role negotiation as the
default may result in a situation where the eBGP session will not default may result in a situation where the eBGP session will not
come up after a software update. Implementations with such default come up after a software update. Implementations with such default
behavior are strongly discouraged. behavior are strongly discouraged.
Removing the OTC Attribute or changing its value can limit the Removing the OTC Attribute or changing its value can limit the
skipping to change at page 12, line 17 skipping to change at page 12, line 17
[Gao] Gao, L. and J. Rexford, "Stable Internet routing without [Gao] Gao, L. and J. Rexford, "Stable Internet routing without
global coordination", IEEE/ACM Transactions on global coordination", IEEE/ACM Transactions on
Networking, Volume 9, Issue 6, pp 689-692, DOI Networking, Volume 9, Issue 6, pp 689-692, DOI
10.1109/90.974523, December 2001, 10.1109/90.974523, December 2001,
<https://ieeexplore.ieee.org/document/974523>. <https://ieeexplore.ieee.org/document/974523>.
[RFC4272] Murphy, S., "BGP Security Vulnerabilities Analysis", [RFC4272] Murphy, S., "BGP Security Vulnerabilities Analysis",
RFC 4272, DOI 10.17487/RFC4272, January 2006, RFC 4272, DOI 10.17487/RFC4272, January 2006,
<https://www.rfc-editor.org/info/rfc4272>. <https://www.rfc-editor.org/info/rfc4272>.
[RFC7705] George, W. and S. Amante, "Autonomous System Migration
Mechanisms and Their Effects on the BGP AS_PATH
Attribute", RFC 7705, DOI 10.17487/RFC7705, November 2015,
<https://www.rfc-editor.org/info/rfc7705>.
[RFC7938] Lapukhov, P., Premji, A., and J. Mitchell, Ed., "Use of [RFC7938] Lapukhov, P., Premji, A., and J. Mitchell, Ed., "Use of
BGP for Routing in Large-Scale Data Centers", RFC 7938, BGP for Routing in Large-Scale Data Centers", RFC 7938,
DOI 10.17487/RFC7938, August 2016, DOI 10.17487/RFC7938, August 2016,
<https://www.rfc-editor.org/info/rfc7938>. <https://www.rfc-editor.org/info/rfc7938>.
[RFC8205] Lepinski, M., Ed. and K. Sriram, Ed., "BGPsec Protocol [RFC8205] Lepinski, M., Ed. and K. Sriram, Ed., "BGPsec Protocol
Specification", RFC 8205, DOI 10.17487/RFC8205, September Specification", RFC 8205, DOI 10.17487/RFC8205, September
2017, <https://www.rfc-editor.org/info/rfc8205>. 2017, <https://www.rfc-editor.org/info/rfc8205>.
Acknowledgments Acknowledgments
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