Network Working Group Z. Li
Internet-Draft Huawei
Intended status: Standards Track L. Ou
Expires: December 19, 2016 Y. Luo
China Telcom Co., Ltd.
S. Lu
Tencent
S. Zhuang
N. Wu
Huawei
June 17, 2016
BGP FlowSpec Extensions for Routing Policy Distribution (RPD)
draft-li-idr-flowspec-rpd-02
Abstract
This document describes a mechanism to use BGP Flowspec address
family as routing-policy distribution protocol. This mechanism is
called BGP FlowSpec Extensions for Routing Policy Distribution (BGP-
FS RPD).
Requirements Language
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 RFC 2119 [RFC2119].
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 http://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 December 19, 2016.
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Copyright Notice
Copyright (c) 2016 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
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
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.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Definitions and Acronyms . . . . . . . . . . . . . . . . . . 3
3. Problem Statements . . . . . . . . . . . . . . . . . . . . . 4
3.1. Inbound Traffic Control . . . . . . . . . . . . . . . . . 4
3.2. Outbound Traffic Control . . . . . . . . . . . . . . . . 5
4. Proposed Solution . . . . . . . . . . . . . . . . . . . . . . 5
5. Protocol Extensions . . . . . . . . . . . . . . . . . . . . . 6
5.1. FlowSpec Traffic Actions for Routing Policy Distribution 6
5.2. Option 1: BGP Policy Attribute . . . . . . . . . . . . . 6
5.2.1. Match Fields Format . . . . . . . . . . . . . . . . . 7
5.2.2. Action Fields Format . . . . . . . . . . . . . . . . 8
5.2.3. Operation Examples . . . . . . . . . . . . . . . . . 9
5.3. Option 2: BGP Wide Community . . . . . . . . . . . . . . 12
5.3.1. New Wide Community Atoms . . . . . . . . . . . . . . 12
5.3.2. Operation examples . . . . . . . . . . . . . . . . . 13
5.4. Capability Negotiation . . . . . . . . . . . . . . . . . 19
6. Consideration . . . . . . . . . . . . . . . . . . . . . . . . 19
6.1. Route-Policy . . . . . . . . . . . . . . . . . . . . . . 19
7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 20
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21
9. Security Considerations . . . . . . . . . . . . . . . . . . . 21
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 21
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 21
11.1. Normative References . . . . . . . . . . . . . . . . . . 21
11.2. Informative References . . . . . . . . . . . . . . . . . 22
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 22
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1. Introduction
Some difficulties exist when optimize traffic paths on a traditional
IP network:
o Traffic can only be adjusted device by device. All routers that
the traffic traverses need to be configured. The configuration
workload is heavy. The operation is not only time consuming but
also prone to misconfiguration for Service Providers.
o The routing policies used to control network routes are complex,
posing difficulties to subsequent maintenance, high maintenance
skills are required.
Hence, an automatic mechanism for setting up routing policies is
desirable which can simplify the complexity of routing policies
configuration. This document describes a mechanism to use BGP
Flowspec address family [RFC5575] as route-policy distribution
protocol. This mechanism is called BGP FlowSpec Extensions for
Routing Policy Distribution (BGP-FS RPD).
2. Definitions and Acronyms
BGP Flow Specification route: BGP Flow Specification routes are
defined in RFC 5575. Each BGP Flow Specification route contains BGP
Network Layer Reachability Information (NLRI) and Extended Community
Attributes, which carry traffic filtering rules and actions to be
taken on filtered traffic.
BGP Flow Specification peer relationship: A BGP Flow Specification
peer relationship is established between the device that generates
BGP Flow Specification routes and each network ingress that will
transmit the BGP Flow Specification routes. After receiving the BGP
Flow Specification routes, the peer delivers preferred BGP Flow
Specification routes to the forwarding plane. The routes are then
converted into traffic policies that control attack traffic.
o ACL:Access Control List
o BGP: Border Gateway Protocol
o FS: Flow Specification
o PBR:Policy-Based Routing
o RPD: Routing Policy Distribution
o VPN: Virtual Private Network
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3. Problem Statements
It is obvious that providers have the requirements to adjust their
business traffic from time to time because:
o Business development or network failure introduces link congestion
and overload.
o Network transmission quality decreased as the result of delay,
loss and need to adjust traffic to other paths.
o To control OPEX and CPEX, prefer the transit provider with lower
price.
3.1. Inbound Traffic Control
In the scenario below, for reasons above, the provider of AS100
saying P may wish the inbound traffic from AS200 enters AS100 through
link L3 instead of others. Since P doesn't have administration over
AS200, so there is no way for P to modify the route selection
criteria directly.
Traffic from PE1 to Prefix1
----------------------------------->
+-----------------+ +-------------------------+
| +---------+ | L1 | +----+ +----------+|
| |Speaker1 | +------------+ |IGW1| |policy ||
| +---------+ |** L2**| +----+ |controller||
| | ** ** | +----------+|
| +---+ | **** | |
| |PE1| | **** | |
| +---+ | ** ** | |
| +---------+ |** L3**| +----+ |
| |Speaker2 | +------------+ |IGW2| AS100 |
| +---------+ | L4 | +----+ |
| | | |
| AS200 | | |
| | | ... |
| | | |
| +---------+ | | +----+ +-------+ |
| |Speakern | | | |IGWn| |Prefix1| |
| +---------+ | | +----+ +-------+ |
+-----------------+ +-------------------------+
Prefix1 advertise from AS100 to AS200
<----------------------------------------
Figure 1: Inbound Traffic Control case
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3.2. Outbound Traffic Control
In this scenario, the provider of AS100 saying P wishes to prefer
link L3 for the traffic to the destination Prefix2 among multiple
exits and links. This preference can be dynamic and change
frequently because of the reasons above. So the provider P expects
an efficient and convenient solution.
Traffic from PE2 to Prefix2
----------------------------------->
+-------------------------+ +-----------------+
|+----------+ +----+ |L1 | +---------+ |
||policy | |IGW1| +------------+ |Speaker1 | |
||controller| +----+ |** **| +---------+ |
|+----------+ |L2** ** | +-------+|
| | **** | |Prefix2||
| | **** | +-------+|
| |L3** ** | |
| AS100 +----+ |** **| +---------+ |
| |IGW2| +------------+ |Speaker2 | |
| +----+ |L4 | +---------+ |
| | | |
|+---+ | | AS200 |
||PE2| ... | | |
|+---+ | | |
| +----+ | | +---------+ |
| |IGWn| | | |Speakern | |
| +----+ | | +---------+ |
+-------------------------+ +-----------------+
Prefix2 advertise from AS200 to AS100
<----------------------------------------
Figure 2: Outbound Traffic Control case
4. Proposed Solution
BGP FlowSpec [RFC5575] leverages the BGP control plane to simplify
the distribution of filter rules. New filter rules can be injected
to all BGP peers simultaneously without changing router
configuration. Though the typical application of it is for DDOS
mitigation, it doesn't mean BGP Flowspec only takes effect on the
forwarding plane.
This document introduces a mechanism that uses BGP Flowspec as a
route-policy distribution protocol. It can be the same powerful as
the device-based route-policy while still has the efficiency and
convenience of BGP Flowspec.
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This draft will use the term BGP-FS RPD as the abbreviation of
FlowSpec Extensions for Routing Policy Distribution.
5. Protocol Extensions
5.1. FlowSpec Traffic Actions for Routing Policy Distribution
The traffic-action extended community consists of 6 bytes of which
only the 2 least significant bits of the 6th byte (from left to
right) are currently defined in [RFC5575]. Terminal Action (bit 47)
and Sample (bit 46) defines in [RFC5575], this document defines Route
Policy Distribution Flag(Bit 45).
The Flow Specification Traffic Actions for Routing Policy
Distribution:
40 41 42 43 44 45 46 47
+---+---+---+---+---+---+---+---+
| reserved | R | S | T |
+---+---+---+---+---+---+---+---+
Figure 3: FlowSpec Traffic-action
Route Policy Distribution Flag(Bit 45): When this bit is set, the
corresponding filtering rules will be used as Route Policy.
5.2. Option 1: BGP Policy Attribute
This document defines and uses a new BGP attribute called the "BGP
Policy attribute". This is an optional BGP attribute. The format of
this attribute is defined as follows:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Match fields (Variable) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Action fields (Variable) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: BGP Policy Attribute
Match fields: Match Fields define the matching criteria for the BGP
Policy Attribute.
Action fields: Action fields define the action being applied to the
target route.
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5.2.1. Match Fields Format
Match Fields define the matching criteria for the BGP Policy
Attribute.
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Match Type (2 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Number of Sub-TLVs (2 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Sub-TLVs (Variable) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: Match Fields Format
Match Type:
0: Permit, specifies the permit mode of a match rule. If a route
matches the matching criteria of the BGP Policy Attribute, the
actions defined by the Action fields of the BGP Policy Attribute are
performed. If a route does not match the matching criteria for the
BGP Policy Attribute, then nothing needs to do with this route.
1: Deny, specifies the deny mode of a match rule. In the deny mode,
If a route does not match the matching criteria of the BGP Policy
Attribute, the actions defined by the Action fields of the BGP Policy
Attribute are performed. If a route matches the matching criteria of
the BGP Policy Attribute, then nothing needs to do with this route.
Number of Sub-TLVs: The number of Sub-TLVs contain in Match fields.
The contents of Match fields are encoded as Sub-TLVs, where each TLV
has the following format:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type (2 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length (2 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Values (Variable) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: Sub-TLVs Format
Type: The Type field contains a value of 1-65534. The values 0 and
65535 are reserved for future use.
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Length: The Length field represents the total length of a given TLV's
value field in octets.
Values: The Value field contains the TLV value.
Supported format of the TLVs can be:
Type 1: IPv4 Neighbor
Type 2: IPv6 Neighbor
Type 3: ASN List
...
To be added in later versions.
5.2.2. Action Fields Format
Action fields define the action being applied to the targeted route.
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Action Type (2 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Action Length (2 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Action Values (Variable) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7: Action Fields Format
Action Type: The Action Type field contains a value of 1-65534. The
values 0 and 65535 are reserved for future use.
Action Length: The Action Length field represents the total length of
the Action Values in octets.
Action Values: The Action Values field contain parameters of the
action.
Supported format of the TLVs can be:
Type 1: Route-Preference
Type 2: Route-Prepend-AS
...
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To be added in later versions.
5.2.3. Operation Examples
5.2.3.1. Inbound Traffic Control
The traffic destined for Prefix1 needs to be scheduled to link
Speaker1 -> IGW2 for transmission.
The Policy Controller constructs a BGP-FS RPD route and pushes it to
all the IGW routers, the route carries:
1. Prefix1 in the Destination Prefix component of the BGP-FS NLRI;
2. Flow Specification Traffic Action Extended Community with the
Route Policy Distribution Flag(Bit 45) set. When this bit is
set, the corresponding filtering rules will be used as Routing
Policies.
3. NO_ADVERTISE Community [RFC1997]
4. BGP Policy Attribute:
* Match Type: 2, Deny
* IPv4 Neighbor Sub-TLV: Local BGP Speaker IGW2, Remote BGP Peer
Speaker1
* Action Type: Route-Prepend-AS
* Action Value: Prepend-AS times is 5
IGW1 processes the received BGP-FS RPD route as follows:
1. IGW1 gets the target prefix Prefix1 from the Destination Prefix
component in the BGP FS NLRI of the BGP FS RPD route;
2. IGW1 identifies the Route Policy Distribution Flag carrying in
the Flow Specification Traffic Action Extended Community, then
IGW1 knows that the corresponding filtering rules will be used as
Routing Policies.
3. IGW1 uses the target prefix Prefix1 to choose the matching
routes, in this case, IGW1 will choose the current best route of
Prefix1;
4. IGW1 gets the matching criteria from the BGP Policy Attribute:
Local BGP Speaker IGW2, Remote BGP Speaker1;
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5. IGW1 gets the action from the BGP Policy Attribute: Route-
Prepend-AS, 5 times;
IGW1 checks the matching criteria and finds that it doesn't hits the
matching criteria: Local BGP Speaker IGW2, Remote BGP Speaker1, at
the same time the Match Type is "Deny" mode, so IGW1 sends the best
route of Prefix1 to Speaker1 and Speaker2 with performing the Action
instructions from the BGP-FS RPD route: Prepend Local AS 5 times.
IGW2 processes the received BGP FS RPD route as follows:
1. IGW2 gets the target prefix Prefix1 from the Destination Prefix
component in the BGP-FS NLRI of the BGP FS RPD route;
2. IGW2 identifies the Route Policy Distribution Flag carrying in
the Flow Specification Traffic Action Extended Community, then
IGW2 knows that the corresponding filtering rules will be used as
Routing Policies.
3. IGW2 uses the target prefix Prefix1 to choose the matching
routes, in this case, IGW2 will choose the current best route of
Prefix1;
4. IGW2 gets the matching criteria from the BGP Policy Attribute:
Local BGP Speaker IGW2, Remote BGP Speaker1;
5. IGW2 gets the action from the BGP Policy Attribute: Route-
Prepend-AS, 5 times;
IGW2 checks the matching criteria and finds that there is a speaker
which hits the matching criteria: Local BGP Speaker IGW2, Remote BGP
Peer Speaker1, but the Match Type is "Deny" mode, so IGW2 sends the
best route of Prefix1 to Speaker1, without performing the Action
instructions from the BGP-FS RPD route. At the same time, IGW2 sends
the best route of Prefix1 to Speaker2 with performing the Action
instructions from the BGP-FS RPD route: Prepend Local AS 5 times.
In the similar manner, other IGWs will perform the same Action
instructions as IGW1. Then the traffic destined for Prefix1 has been
be scheduled to link L3 for transmission.
5.2.3.2. Outbound Traffic Control
In this scenario, if the bandwidth usage of a link exceeds the
specified threshold, the Policy Controller automatically identifies
which traffic needs to be scheduled and the Policy Controller
automatically calculates traffic control paths based on network
topology and traffic information.
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For example, the outbound traffic destined for Prefix2 needs to be
scheduled to link IGW2 -> Speaker1 for transmission.
The Policy Controller sends a BGP-FS RPD route to IGW2, the route
carries:
1. Prefix2 in the Destination Prefix component of the BGP-FS NLRI;
2. Flow Specification Traffic Action Extended Community with the
Route Policy Distribution Flag(Bit 45) set. When this bit is
set, the corresponding filtering rules will be used as Routing
Policies.
3. NO_ADVERTISE Community [RFC1997]
4. BGP Policy Attribute:
* Match Type: 1, Permit
* IPv4 Neighbor Sub-TLV: Local BGP Speaker IGW2, Remote BGP Peer
Speaker1
* Action Type: Route-Preference
* Action Value: none
IGW2 processes the received BGP FS RPD route as follows:
1. IGW2 gets the target prefix Prefix2 from the Destination Prefix
component in the BGP-FS NLRI of the BGP FS RPD route;
2. IGW2 identifies the Route Policy Distribution Flag carrying in
the Flow Specification Traffic Action Extended Community, then
IGW2 knows that the corresponding filtering rules will be used as
Routing Policies.
3. IGW2 uses the target prefix Prefix2 to choose the matching
routes, in this case, the prefix Prefix2 has two more routes:
Prefix Next-Hop Local BGP Speaker Remote BGP Peer
Prefix2 Speaker1 IGW2 Speaker1
Prefix2 Speaker2 IGW2 Speaker2
...
4. IGW2 gets the matching criteria from the BGP Policy Attribute:
Local BGP Speaker IGW2, Remote BGP Peer Speaker1;
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5. IGW2 gets the action from the BGP Policy Attribute: Route-
Preference;
So IGW2 chooses the BGP route received from Speaker1 instead of
Speaker2 as the best route and the outbound traffic destined for
Prefix2 can be scheduled to link L3 for transmission.
5.3. Option 2: BGP Wide Community
This section describes the option 2 for protocol extensions, which is
completely different from section 5.2 by reusing BGP Wide Community
introduced in [I-D.ietf-idr-wide-bgp-communities].
BGP Wide Community Attribute is a very useful tool that it can be
used to convey different kinds of routing policies.
5.3.1. New Wide Community Atoms
Wide Community Atoms define in [I-D.ietf-idr-wide-bgp-communities] ,
in that draft it defines Type 1 to Type 8.
New wide community atoms have to be introduced since the entrance and
exit of traffic need to be designated precisely.
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
+-+-+-+-+-+-+-+-+
| Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Value (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 8: Wide Community Atoms
Supported format of the TLVs can be:
o Type 1: Autonomous System number list
o Type 2: IPv4 prefix (1 octet prefix length + prefix) list
o Type 3: IPv6 prefix (1 octet prefix length + prefix) list
o Type 4: Integer list
o Type 5: IEEE Floating Point Number list
o Type 6: Neighbor Class list
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o Type 7: User-defined Class list7
o Type 8: UTF-8 String
o Type TBD: BGP IPv4 neighbor --- Newly introduced in this draft,
which contains the BGP session IPv4 local address and the BGP
session IPv4 peer address.
o Type TBD: BGP IPv6 neighbor --- Newly introduced in this draft,
which contains the BGP session IPv6 local address and the BGP
session IPv6 peer address.
5.3.2. Operation examples
5.3.2.1. Inbound Traffic Control
As required in the case, traffic from PE1 to Prefix1 need to enter
through L3, so IGWs except IGW2 should prepend ASN list to Prefix1
when populating to AS100. As shown in figure below, community
"PREPEND N TIMES BY AS" and "Exclude Target(s) TLV" are be used.
The encoding example using BGP Wide Community:
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Container Type 1 (1) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1 0 0 0 0 0 0 0|
+-+-+-+-+-+-+-+-+
| Hop Count: 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length: 36 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Community: PREPEND N TIMES BY AS 17 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Own ASN 100 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Context ASN# 100 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|ExcTargetTLV(2)| Length: 11 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4Neig(TBD)| Length: 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local Speaker #IGW2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remote Speaker #Speaker1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Param TLV (3) | Length: 7 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Integer (4) | Length: 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Prepend # 5 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 9: Example encoding for Inbound Traffic Control case
"PREPEND N TIMES BY AS" Wide Community has been defined in
[I-D.ietf-idr-registered-wide-bgp-communities].
The traffic destined for Prefix1 needs to be scheduled to link
Speaker1 -> IGW2 for transmission.
The Policy Controller constructs a BGP-FS RPD route and pushes it to
all the IGW routers, the route carries:
1. Prefix1 in the Destination Prefix component of the BGP-FS NLRI;
2. Flow Specification Traffic Action Extended Community with the
Route Policy Distribution Flag(Bit 45) set. When this bit is
set, the corresponding filtering rules will be used as Routing
Policies.
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3. NO_ADVERTISE Community [RFC1997]
4. Wide BGP Community Attribute:
PREPEND N TIMES BY AS:
Type: 0x0001 S = src AS #
F = 0x80 C = 0x00000000
H = 0 T = none
L = 36 octets E = Type_TBD (BGP IPv4 neighbor)
R = 17 P = Type_4 (0x05)
Where "BGP IPv4 neighbor" Atom TLV contains:
The BGP session IPv4 local address: Local BGP Speaker IGW2
The BGP session IPv4 peer address: Remote BGP Peer Speaker1
IGW1 processes the received BGP-FS RPD route as follows:
1. IGW1 gets the target prefix Prefix1 from the Destination Prefix
component in the BGP FS NLRI of the BGP FS RPD route;
2. IGW1 identifies the Route Policy Distribution Flag carrying in
the Flow Specification Traffic Action Extended Community, then
IGW1 knows that the corresponding filtering rules will be used as
Routing Policies.
3. IGW1 uses the target prefix Prefix1 to choose the matching
routes, in this case, IGW1 will choose the current best route of
Prefix1;
4. IGW1 gets the action type from the Wide BGP Community Attribute:
PREPEND N TIMES BY AS;
5. IGW1 gets the matching criteria from the Wide BGP Community
Attribute: Exclude the BGP IPv4 neighbor: <Local BGP Speaker
IGW2, Remote BGP Speaker1>;
6. IGW1 gets the parameter for "PREPEND N TIMES BY AS" from the Wide
BGP Community Attribute: 5 times;
IGW1 checks the matching criteria and finds that it doesn't hits the
exclude matching criteria: Local BGP Speaker IGW2, Remote BGP
Speaker1, so IGW1 sends the best route of Prefix1 to Speaker1 and
Speaker2 with performing the Action instructions from the BGP-FS RPD
route: Prepend Local AS 5 times.
IGW2 processes the received BGP FS RPD route as follows:
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1. IGW2 gets the target prefix Prefix1 from the Destination Prefix
component in the BGP-FS NLRI of the BGP FS RPD route;
2. IGW2 identifies the Route Policy Distribution Flag carrying in
the Flow Specification Traffic Action Extended Community, then
IGW2 knows that the corresponding filtering rules will be used as
Routing Policies.
3. IGW2 uses the target prefix Prefix1 to choose the matching
routes, in this case, IGW2 will choose the current best route of
Prefix1;
4. IGW2 gets the action type from the Wide BGP Community Attribute:
PREPEND N TIMES BY AS;
5. IGW2 gets the matching criteria from the BGP Policy Attribute:
Exclude the BGP IPv4 neighbor: <Local BGP Speaker IGW2, Remote
BGP Speaker1>;
6. IGW2 gets the parameter for "PREPEND N TIMES BY AS" from the Wide
BGP Community Attribute: 5 times;
IGW2 checks the matching criteria and finds that there is a speaker
which hits the exclude matching criteria: Local BGP Speaker IGW2,
Remote BGP Peer Speaker1, so IGW2 sends the best route of Prefix1 to
Speaker1 without performing the Action instructions from the BGP-FS
RPD route, at the same time, IGW2 sends the best route of Prefix1 to
Speaker2 with performing the Action instructions from the BGP-FS RPD
route: Prepend Local AS 5 times.
In the similar manner, other IGWs will perform the same Action
instructions as IGW1. Then the traffic destined for Prefix1 has been
be scheduled to link L3 for transmission.
5.3.2.2. Outbound Traffic Control
As required in the case, traffic from PE2 to Prefix2 need to exit
through L3, so IGWs should perfer the route from IGW2 to Speaker1.
As shown in figure below, community "LOCAL PREFERENCE" and "Target(s)
TLV" are be used.
The encoding example using BGP Wide Community:
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Container Type 1 (1) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1 0 0 0 0 0 0 0|
+-+-+-+-+-+-+-+-+
| Hop Count: 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length: 36 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Community: LOCAL PREFERENCE 20 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Own ASN 100 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Context ASN# 100 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TargetTLV(1) | Length: 11 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4Neig(TBD)| Length: 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local Speaker #IGW2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remote Speaker #Speaker1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Param TLV (3) | Length: 7 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Integer (4) | Length: 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Increment # 100 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 10: Example encoding for Outbound Traffic Control case
"LOCAL PREFERENCE" Wide Community has been defined in
[I-D.ietf-idr-registered-wide-bgp-communities]
In this scenario, if the bandwidth usage of a link exceeds the
specified threshold, the Policy Controller automatically identifies
which traffic needs to be scheduled and the Policy Controller
automatically calculates traffic control paths based on network
topology and traffic information.
For example, the outbound traffic destined for Prefix2 needs to be
scheduled to link IGW2 -> Speaker1 for transmission.
The Policy Controller sends a BGP-FS RPD route to IGW2, the route
carries:
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1. Prefix2 in the Destination Prefix component of the BGP-FS NLRI;
2. Flow Specification Traffic Action Extended Community with the
Route Policy Distribution Flag(Bit 45) set. When this bit is
set, the corresponding filtering rules will be used as Routing
Policies.
3. NO_ADVERTISE Community [RFC1997]
4. Wide BGP Community Attribute:
LOCAL PREFERENCE:
Type: 0x0001 S = src AS #
F = 0x80 C = 0x00000000
H = 0 T = Type_TBD (BGP IPv4 neighbor)
L = 36 octets E = none
R = 20 P = Type_4 (0x64)
Where "BGP IPv4 neighbor" Atom TLV contains:
The BGP session IPv4 local address: Local BGP Speaker IGW2
The BGP session IPv4 peer address: Remote BGP Peer Speaker1
IGW2 processes the received BGP FS RPD route as follows:
1. IGW2 gets the target prefix Prefix2 from the Destination Prefix
component in the BGP-FS NLRI of the BGP FS RPD route;
2. IGW2 identifies the Route Policy Distribution Flag carrying in
the Flow Specification Traffic Action Extended Community, then
IGW2 knows that the corresponding filtering rules will be used as
Routing Policies.
3. IGW2 uses the target prefix Prefix2 to choose the matching
routes, in this case, the prefix Prefix2 has two more routes:
Prefix Next-Hop Local BGP Speaker Remote BGP Peer
--------------------------------------------------------
Prefix2 Speaker1 IGW2 Speaker1
Prefix2 Speaker2 IGW2 Speaker2
...
4. IGW2 gets the action type from the Wide BGP Community Attribute:
LOCAL PREFERENCE;
5. IGW2 gets the matching criteria from the Wide BGP Community
Attribute: Local BGP Speaker IGW2, Remote BGP Peer Speaker1;
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6. IGW2 gets the parameter for "LOCAL PREFERENCE" from the Wide BGP
Community Attribute: increment 100;
So IGW2 chooses the BGP route received from Speaker1 instead of
Speaker2 as the best route and the outbound traffic destined for
Prefix2 can be scheduled to link L3 for transmission.
5.4. Capability Negotiation
It is necessary to negotiate the capability to support BGP FlowSpec
Extensions for Route Policy Distribution (RPD). The BGP FS RPD
Capability is a new BGP capability [RFC5492]. The Capability Code
for this capability is to be specified by the IANA. The Capability
Length field of this capability is variable. The Capability Value
field consists of one or more of the following tuples:
+--------------------------------------------------+
| Address Family Identifier (2 octets) |
+--------------------------------------------------+
| Subsequent Address Family Identifier (1 octet) |
+--------------------------------------------------+
| Send/Receive (1 octet) |
+--------------------------------------------------+
Figure 11: BGP FS RPD Capability
The meaning and use of the fields are as follows:
Address Family Identifier (AFI): This field is the same as the one
used in [RFC4760].
Subsequent Address Family Identifier (SAFI): This field is the same
as the one used in [RFC4760].
Send/Receive: This field indicates whether the sender is (a) willing
to receive Route Policies via BGP FLowSpec from its peer (value 1),
(b) would like to send Route Policies via BGP FLowSpec to its peer
(value 2), or (c) both (value 3) for the <AFI, SAFI>.
6. Consideration
6.1. Route-Policy
Routing policies are used to filter routes and control how routes are
received and advertised. If route attributes, such as reachability,
are changed, the path along which network traffic passes changes
accordingly.
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When advertising, receiving, and importing routes, the router
implements certain policies based on actual networking requirements
to filter routes and change the attributes of the routes. Routing
policies serve the following purposes:
o Control route advertising: Only routes that match the rules
specified in a policy are advertised.
o Control route receiving: Only the required and valid routes are
received. This reduces the size of the routing table and improves
network security.
o Filter and control imported routes: A routing protocol may import
routes discovered by other routing protocols. Only routes that
satisfy certain conditions are imported to meet the requirements
of the protocol.
o Modify attributes of specified routes Attributes of the routes:
that are filtered by a routing policy are modified to meet the
requirements of the local device.
o Configure fast reroute (FRR): If a backup next hop and a backup
outbound interface are configured for the routes that match a
routing policy, IP FRR, VPN FRR, and IP+VPN FRR can be
implemented.
Routing policies are implemented using the following procedures:
1. Define rules: Define features of routes to which routing policies
are applied. Users define a set of matching rules based on
different attributes of routes, such as the destination address
and the address of the router that advertises the routes.
2. Implement the rules: Apply the matching rules to routing policies
for advertising, receiving, and importing routes.
7. Contributors
The following people have substantially contributed to the definition
of the BGP-FS RPD and to the editing of this document:
Peng Zhou
Huawei
Email: Jewpon.zhou@huawei.com
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8. IANA Considerations
TBD.
9. Security Considerations
TBD.
10. Acknowledgements
The authors would like to thank Acee Lindem, Jeff Haas, Jie Dong,
Haibo Wang, Lucy Yong, Qiandeng Liang, Zhenqiang Li for their
comments to this work.
11. References
11.1. Normative References
[I-D.ietf-idr-wide-bgp-communities]
Raszuk, R., Haas, J., Lange, A., Amante, S., Decraene, B.,
Jakma, P., and R. Steenbergen, "Wide BGP Communities
Attribute", draft-ietf-idr-wide-bgp-communities-02 (work
in progress), May 2016.
[RFC1997] Chandra, R., Traina, P., and T. Li, "BGP Communities
Attribute", RFC 1997, DOI 10.17487/RFC1997, August 1996,
<http://www.rfc-editor.org/info/rfc1997>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Border Gateway Protocol 4 (BGP-4)", RFC 4271,
DOI 10.17487/RFC4271, January 2006,
<http://www.rfc-editor.org/info/rfc4271>.
[RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
"Multiprotocol Extensions for BGP-4", RFC 4760,
DOI 10.17487/RFC4760, January 2007,
<http://www.rfc-editor.org/info/rfc4760>.
[RFC5492] Scudder, J. and R. Chandra, "Capabilities Advertisement
with BGP-4", RFC 5492, DOI 10.17487/RFC5492, February
2009, <http://www.rfc-editor.org/info/rfc5492>.
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[RFC5575] Marques, P., Sheth, N., Raszuk, R., Greene, B., Mauch, J.,
and D. McPherson, "Dissemination of Flow Specification
Rules", RFC 5575, DOI 10.17487/RFC5575, August 2009,
<http://www.rfc-editor.org/info/rfc5575>.
11.2. Informative References
[I-D.ietf-idr-registered-wide-bgp-communities]
Raszuk, R. and J. Haas, "Registered Wide BGP Community
Values", draft-ietf-idr-registered-wide-bgp-communities-02
(work in progress), May 2016.
Authors' Addresses
Zhenbin Li
Huawei
Huawei Bld., No.156 Beiqing Rd.
Beijing 100095
China
Email: lizhenbin@huawei.com
Liang Ou
China Telcom Co., Ltd.
109 West Zhongshan Ave,Tianhe District
Guangzhou 510630
China
Email: oul@gsta.com
Yujia Luo
China Telcom Co., Ltd.
109 West Zhongshan Ave,Tianhe District
Guangzhou 510630
China
Email: luoyuj@gsta.com
Sujian Lu
Tencent
Tengyun Building,Tower A ,No. 397 Tianlin Road
Shanghai, Xuhui District 200233
China
Email: jasonlu@tencent.com
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Shunwan Zhuang
Huawei
Huawei Bld., No.156 Beiqing Rd.
Beijing 100095
China
Email: zhuangshunwan@huawei.com
Nan Wu
Huawei
Huawei Bld., No.156 Beiqing Rd.
Beijing 100095
China
Email: eric.wu@huawei.com
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