BGP Dissemination of Flow Specification Rules for Tunneled Traffic
draft-ietf-idr-flowspec-nvo3-17
| Document | Type | Active Internet-Draft (idr WG) | |
|---|---|---|---|
| Authors | Donald E. Eastlake 3rd , Hao Weiguo , Shunwan Zhuang , Zhenbin Li , Rong Gu | ||
| Last updated | 2023-01-04 | ||
| Replaces | draft-hao-idr-flowspec-nvo3 | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Intended RFC status | Proposed Standard | ||
| Formats | |||
| Additional resources | Mailing list discussion | ||
| Stream | WG state | Waiting for Implementation | |
| Document shepherd | (None) | ||
| IESG | IESG state | I-D Exists | |
| Consensus boilerplate | Yes | ||
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
draft-ietf-idr-flowspec-nvo3-17
INTERNET-DRAFT D. Eastlake
Intended Status: Proposed Standard Futurewei Technologies
W. Hao
S. Zhuang
Z. Li
Huawei Technologies
R. Gu
China Mobile
Expires: July 3, 2023 January 4, 2023
BGP Dissemination of
Flow Specification Rules for Tunneled Traffic
draft-ietf-idr-flowspec-nvo3-17
Abstract
This draft specifies a Border Gateway Protocol (BGP) Network Layer
Reachability Information (NLRI) encoding format for flow
specifications (RFC 8955) that can match on a variety of tunneled
traffic. In addition, flow specification components are specified for
certain tunneling header fields.
Status of This Document
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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
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to this document. Code Components extracted from this document must
include Revised BSD License text as described in Section 4.e of the
Trust Legal Provisions and are provided without warranty as described
in the Revised BSD License.
Distribution of this document is unlimited. Comments should be sent
to the authors or the IDR Working Group mailing list <idr@ietf.org>.
Internet-Drafts are working documents of the Internet Engineering
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other groups may also distribute working documents as Internet-
Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
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The list of current Internet-Drafts can be accessed at
https://www.ietf.org/1id-abstracts.html. The list of Internet-Draft
Shadow Directories can be accessed at
https://www.ietf.org/shadow.html.
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Table of Contents
1. Introduction............................................4
1.1 Terminology............................................4
2. Tunneled Traffic Flow Specification NLRI................6
2.1 The SAFI Code Point....................................9
2.2 Tunnel Header Component Code Points....................9
2.3 Specific Tunnel Types.................................11
2.3.1 VXLAN...............................................11
2.3.2 VXLAN-GPE...........................................12
2.3.3 NVGRE...............................................13
2.3.4 L2TPv3..............................................13
2.3.4.1 L2TPv3 Data Messages..............................13
2.3.4.2 L2TPv3 Control Messages...........................14
2.3.5 GRE.................................................14
2.3.6 IP-in-IP............................................15
2.3.7 Geneve..............................................15
2.4 Tunneled Traffic Actions..............................16
3. Order of Traffic Filtering Rules.......................17
4. Flow Spec Validation...................................18
5. Security Considerations................................18
6. IANA Considerations....................................19
Normative References......................................20
Informative References....................................21
Acknowledgments...........................................22
Authors' Addresses........................................22
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1. Introduction
BGP Flow Specification (flowspec [RFC8955]) is an extension to BGP
that supports the dissemination of traffic flow specification rules
and actions to be taken on packets matching such specifications. It
uses the BGP control plane to simplify the distribution of Access
Control Lists (ACLs) and allows new filter rules to be injected to
all BGP peers simultaneously without changing router configuration. A
typical application of BGP flowspec is to automate the distribution
of traffic filter lists to routers for Distributed Denial of Service
(DDOS) mitigation.
BGP flowspec defines BGP Network Layer Reachability Information
(NLRI) formats used to distribute traffic flow specification rules.
AFI=1/SAFI=133 is for IPv4 unicast filtering. AFI=1/SAFI=134 is for
IPv4 BGP/MPLS VPN filtering [RFC8955]. [RFC8956] and [FlowSpecL2]
extend the flowspec rules for IPv6 and Layer 2 Ethernet packets
respectively. None of these previously defined flow specifications
are suitable for matching packets in cases of tunneling or
encapsulation where there might be duplicates of a layer of header
such as two IPv6 headers in IP-in-IP [RFC2003] or a nested header
sequence such as the Layer 2 and 3 headers encapsulated in VXLAN
[RFC7348].
In the cloud computing era, multi-tenancy has become a core
requirement for data centers. It is increasingly common to see
tunneled traffic with a field to distinguish tenants. An example is
the Network Virtualization Over Layer 3 (NVO3 [RFC8014]) overlay
technology that can satisfy multi-tenancy key requirements. VXLAN
[RFC7348] and NVGRE [RFC7637] are two typical NVO3 encapsulations.
Other encapsulations such as IP-in-IP or GRE may be encountered.
Because these tunnel / overlay technologies involving an additional
level of encapsulation, flow specification that can match on the
inner header as well as the outer header and fields in any tunneling
header are needed.
In summary, Flow Specifications should be able to include inner
nested header information as well as fields specific to the type of
tunneling in use such as virtual network / tenant ID. This draft
specifies methods for accomplishing this using SAFI=77 and a new NLRI
encoding. In addition, flow specification components are specified
for certain tunneling header fields.
1.1 Terminology
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
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14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
The reader is assumed to be familiar with BGP terminology [RFC4271]
[RFC4760]. The following terms and acronyms are used in this document
with the meaning indicated:
ACL - Access Control List
DDoS - Distributed Denial of Service (Attack)
DSCP - Differentiated Services Code Point [RFC2474]
GRE - Generic Router Encapsulation [RFC2890]
L2TPv3 - Layer Two Tunneling Protocol - Version 3 [RFC3931]
NLRI - Network Layer Reachability Information [RFC4271] [RFC4760]
NVGRE - Network Virtualization Using Generic Routing Encapsulation
[RFC7637]
NVO3 - Network Virtual Overlay Layer 3 [RFC8014]
PE - Provider Edge
VN - virtual network
VXLAN - Virtual eXtensible Local Area Network [RFC7348]
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2. Tunneled Traffic Flow Specification NLRI
The Flowspec rules specified in [RFC8955], [RFC8956], and
[FlowSpecL2] cannot match or filter tunneled traffic based on the
tunnel type, tunnel header fields, or headers past the tunnel header.
To enable flow specification of tunneled traffic, a new SAFI (77) and
NLRI encoding are specified. This encoding, shown in Figure 1,
enables flow specification of more than one layer of header when
needed.
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+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| Length 2 octets |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| Tunnel Type 2 octets |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
Flags:
+--+--+--+--+--+--+--+--+
| D| I| Reserved | 1 octet
+--+--+--+--+--+--+--+--+
Optional Routing Distinguisher:
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| |
+ +
| |
+ Routing Distinguisher 8 octets +
| |
+ +
| |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
Outer Flowspec:
+--+--+--+--+--+--+--+--+
| Outer Flowspec Length ... 1 or 2 octets
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| Outer Flowspec variable :
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
Tunnel Header Flowspec:
+--+--+--+--+--+--+--+--+
| Tunnel Flowspec Length ... 1 or 2 octets
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| Tunnel Header Flowspec variable :
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
Optional Inner Flowspec:
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| Inner AFI 2 octets |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| Inner Flowspec Length ... 1 or 2 octets
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| Inner Flowspec variable :
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
Figure 1. Tunneled Traffic Flowspec NLRI
Length - The NLRI Length encoded as an unsigned integer including the
Tunnel Type.
Tunnel Type - The type of tunnel using a value from the IANA BGP
Tunnel Encapsulation Attribute Tunnel Types registry.
Flags: D bit - Indicates the presence of the Routing Distinguisher
(see below).
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Flags: I bit - Indicates the presence of the Inner AFI and the Inner
Flowspec (see below).
Flags: Reserved - Six bits that MUST be sent as zero and ignored on
receipt.
Routing Distinguisher - If the outer Layer 3 address belongs to a
BGP/MPLS VPN, the routing distinguisher is included to indicate
traffic filtering within that VPN. Because NVO3 outer layer
addresses normally belong to a public network, a Route
Distinguisher field is normally not needed for NVO3.
Outer Flowspec / Length - The flow specification for the outer
header. The length is encoded as provided in Section 4.1 of
[RFC8955]. The AFI for the Outer Flowspec is the AFI at the
beginning of the BGP multiprotocol MP_REACH_NLRI or
MP_UNREACH_NLRI containing the tunneled traffic flow
specification NLRI.
Tunnel Header Flowspec / Length - The flow specification for the
tunneling header. The length is encoded as provided in Section
4.1 of [RFC8955]. This specifies matching criterion on tunnel
header fields as well as, implicitly, on the tunnel type which
is indicated by the Tunnel Type field above. For some types of
tunneling, such as IP-in-IP, there may be no tunnel header
fields. For other types of tunneling, there may be several
tunnel header fields on which matching can be specified with
this flowspec. If a Tunnel Type has no tunnel header fields or
it is not desired to filter on header fields, the Tunnel
Flowspec length field is present but has value zero.
Inner AFI - Depending on the Tunnel Type, there may be an Inner AFI
that indicate the type of inner flow specification. The "Inner
SAFI" is implicitly 133 for flowspec.
Inner Flowspec / Length - Depending on the Tunnel Type, there may be
an inner flowspec for the header level encapsulated within the
outer header. The length is encoded as provided in Section 4.1
of [RFC8955].
A Tunneled Traffic Flowspec matches if the Outer Flowspec, Tunnel
Type, and Tunnel Header Flowspec match and, in addition, each of the
following optional items matches if it is present:
- Inner Flowspec, and
- Routing Distinguisher.
An omitted (as can be done for the Inner Flowspec) or null flowspec
is considered to always match.
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2.1 The SAFI Code Point
Use of the tunneled traffic flow specification NLRI format is
indicated by SAFI=77. This is used in conjunction with the AFI for
the outer header, that is AFI=1 for IPv4, AFI=2 for IPv6, and AFI=6
for Layer 2.
2.2 Tunnel Header Component Code Points
For most cases of tunneled traffic, there are tunnel header fields
that can be tested by components that appear in the Tunnel Header
Flowspec field. The types for these components are specified in a
Tunnel Header Flowspec component registry (see Section 6) and the
initial entries in this registry are specified below.
All Tunnel Header field components defined below and all such
components added in the future have a TLV structure as follows:
- one octet of type followed by
- one octet giving the length of the value part as an unsigned
integer number of octets followed by
- the specific matching operations/values as determined by the
type.
Type 1 - VN ID
Encoding: <type (1 octet), length (1 octet), [op, value]+>.
Defines a list of {operation, value} pairs used to match the
24-bit VN ID (Virtual Network Identifier) that is used as the
tenant identification in some tunneling headers. For VXLAN and
Geneve encapsulation, the VN ID field is the VNI. For NVGRE
encapsulation, the VN ID is the VSID. op is encoded as
specified in Section 4.2.3 of [RFC8955]. Values are encoded as
a 1, 2, or 4 octet quantity. If value is 24-bits, it is left-
justified in the first 3 octets of the value and the last value
octet MUST be sent as zero and ignored on receipt.
Type 2 - Flow ID
Encoding: <type (1 octet), length (1 octet), [op, value]+>
Defines a list of {operation, value} pairs used to match 8-bit
Flow ID fields which are currently only useful for NVGRE
encapsulation. op is encoded as specified in Section 4.2.3 of
[RFC8955]. Values are encoded as a 1-octet quantity.
Type 3 - Session
Encoding: <type (1 octet), length (1 octet), [op, value]+>
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Defines a list of {operation, value} pairs used to match a
32-bit Session field. This field is called Key in GRE [RFC2890]
encapsulation and Session ID in L2TPv3 encapsulation. op is
encoded as specified in Section 4.2.3 of [RFC8955]. Values are
encoded as a 1, 2, or 4 octet quantity; if 1 or 2 octets are
provided, these are right justified and padded on the left with
zeros.
Type 4 - Cookie
Encoding: <type (1 octet), length (1 octet), [op, value]+>
Defines a list of {operation, value} pairs used to match a
variable length Cookie field. This is only useful in L2TPv3
encapsulation. op is encoded as specified in Section 4.2.3 of
[RFC8955]. Values are encoded as a 1, 2, 4, or 8 octet
quantity. If the Cookie does not fit exactly into the value
length, it is left justified and padded with following octets
that MUST be sent as zero and ignored on receipt.
Type 5 - Tunnel Header Flags
Encoding: <type (1 octet), length (1 octet), [op, bitmask]+>
Defines a list of {operation, bitmask} pairs used to match
against the tunnel header flags field. op is encoded as in
Section 4.2.9 of [RFC8955]. bitmask is encoded as 1 octet for
VXLAN-GPE and Geneve and as 2 octets for L2TPv3 control
messages. When matching on L2TPv3 control message flags, the
3-bit Version subfield is treated as if it was zero.
Type 6 - L2TP Control Version
Encoding: <type (1 octet), length (1 octet), [op, value]+>
Defines a list of {operation, value} pairs used to match
against the L2TP Control Message Version. op is encoded as in
Section 4.2.3 of [RFC8955]. Value is encoded as 1 octet.
Type 7 - L2TPv3 Control Connection ID
Encoding: <type (1 octet), length (1 octet), [op, value]+>
Defines a list of {operation, value} pairs used to match
against the L2TPv3 Control Connection ID. op is encoded as in
Section 4.2.3 of [RFC8955]. Value is encoded as 4 octets.
Type 8 - L2TPv3 Ns
Encoding: <type (1 octet), length (1 octet), [op, value]+>
Defines a list of {operation, value} pairs used to match
against the L2TPv3 control message Ns field. op is encoded as
in Section 4.2.3 of [RFC8955]. Value is encoded as 2 octets.
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Type 9 - L2TPv3 Nr
Encoding: <type (1 octet), length (1 octet), [op, value]+>
Defines a list of {operation, value} pairs used to match
against the L2TPv3 control message Nr field. op is encoded as
in Section 4.2.3 of [RFC8955]. Values are encoded as 2 octets.
Type 10 - Protocol Type
Encoding: <type (1 octet), length (1 octet), [op, value]+>
Defines a list of {operation, value} pairs used to match
against the GRE and Geneve Protocol Type fields. op is encoded
as in Section 4.2.3 of [RFC8955]. Values are encoded as 2
octets.
Type 11 - GRE Sequence
Encoding: <type (1 octet), length (1 octet), [op, value]+>
Defines a list of {operation, value} pairs used to match
against the GRE Sequence field. op is encoded as in Section
4.2.3 of [RFC8955]. Values are encoded as a 1, 2, or 4 octet
quantity; if 1 or 2 octets are provided, these are right
justified and padded on the left with zeros.
2.3 Specific Tunnel Types
The following subsections describe how to handle flow specification
for several specific tunnel types.
2.3.1 VXLAN
The headers on a VXLAN [RFC7348] data packet are an outer Ethernet
header, an outer IP header, a UDP header, the VXLAN header, and an
inner Ethernet header. This inner Ethernet header is frequently, but
not always, followed by an inner IP header. If the tunnel type is
VXLAN, the I flag MUST be set in the Tunneled Traffic Flow
Specification.
If the outer Ethernet header is not being matched, the version (IPv4
or IPv6) of the outer IP header is indicated by the AFI at the
beginning of the multiprotocol MP_REACH_NLRI or MP_UNREACH_NLRI
containing the Tunneled Traffic Flow Specification NLRI. The outer
Flowspec is used to filter the outer headers including, if desired,
the UDP header.
If the outer Ethernet header is being matched, then the initial AFI
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is 6 [FlowSpecL2] and the Outer Flowspec can match the outer Ethernet
header, specify the IP version of the outer IP header, and match that
IP header including, if desired, the UDP header.
The Tunnel Header Flowspec can be used to filter on the VXLAN header
VN ID (VNI).
The Inner Flowspec can be used on the Inner Ethernet header
[FlowSpecL2] and any following IP header. If the inner AFI is 6,
then the inner Flowspec provides filtering of the Layer 2 header,
indicates whether filtering on a following IPv4 or IPv6 header is
desired, and if it is desired provides the Flowspec components for
that filtering. If the Inner AFI is 1 or 2, the Inner Ethernet
header is not matched and to match the Flowspec the Inner Ethernet
header must be followed by an IPv4 or IPv6 header, respectively, and
the inner Flowspec is used to filter that inner IP header.
The inner MAC/IP address is associated with the VN ID. In the NVO3
terminating into a VPN scenario, if multiple access VN IDs map to one
VPN instance, one shared VN ID can be carried in the flowspec rule to
enforce the rule on the entire VPN instance and the shared VN ID and
VPN correspondence should be configured on each VPN PE beforehand. In
this case, the function of the Layer 3 VN ID is the same as a Route
Distinguisher: it acts as the identification of the VPN instance.
2.3.2 VXLAN-GPE
VXLAN-GPE [GPE] is similar to VXLAN. The VXLAN-GPE header is the same
size as the VXLAN header but has been extended from the VXLAN header
by specifying a number of bits that are reserved in the VXLAN header.
In particular, a number of additional flag bits are specified and a
Next Protocol field is added that is valid if the P flag bit is set
in the VXLAN-GPE header. These flags bits can be tested using the
Tunnel Header Flags flowspec component defined above. VXLAN and
VXLAN-GPE are distinguished by the port number in the UDP header that
precedes the VXLAN or VXLAN-GPE headers.
If the VXLAN-GPE header P flag is zero, then that header is followed
by the same sequence as for VXLAN and the same flowspec choices apply
(see Section 2.3.1).
If the VXLAN-GPE header P flag is one and that header's next protocol
field is 1, then the VXLAN-GPE header is followed by an IPv4 header
(there is no Inner Ethernet header). The Inner Flowspec matches only
if the Inner AFI is 1 and the Inner Flowspec matches.
If the VXLAN-GPE header P flag is one and that header's next protocol
field is 2, then the VXLAN-GPE header is followed by an IPv6 header
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(there is no Inner Ethernet header). The Inner Flowspec match only
if the Inner AFI is 2 and the Inner Flowspec matches.
2.3.3 NVGRE
NVGRE [RFC7637] is similar to VXLAN except that the UDP header and
VXLAN header immediately after the outer IP header are replaced by a
GRE (Generic Router Encapsulation) header. The GRE header as used in
NVGRE has no Checksum or Reserved1 field as shown in [RFC2890] but
there are Virtual Subnet ID and Flow ID fields in place of what is
labeled in [RFC2890] as the Key field. Processing and restrictions
for NVGRE are as in Section 2.3.1 eliminating references to a UDP
header and replacing references to the VXLAN header and its VN ID
with references to the GRE header and its VN ID (VSID) and Flow ID.
2.3.4 L2TPv3
The headers on an L2TPv3 [RFC3931] packets are an outer Ethernet
header, an outer IP header, the L2TPv3 header, an inner Ethernet
header, and possibly an inner IP header if indicated by the inner
Ethernet header EtherType. The Outer Flowspec operates on the outer
headers that precede the L2TPv3 Session Header. The version of IP in
the outer IP header is specified by either the outer AFI at the
beginning of the MP_REACH_NLRI or MP_UNREACH_NLRI or, if that AFI is
6 (L2), optionally specified by the inner AFI within that L2
flowspec.
L2TPv3 data messages and control messages both start with a Session
ID and are distinguished by whether the Session ID is non-zero or
zero, respectively. Data message filtering is further specified in
Section 2.3.4.1 and control message filtering is further specified in
Section 2.3.4.2.
2.3.4.1 L2TPv3 Data Messages
For data messages, the L2TPv3 Session Header consists of a 32-bit
non-zero Session ID followed by a variable length Cookie (maximum
length 8 octets). A Tunnel Header flowspec is assumed to apply to
data messages unless the first component requires a zero Session ID.
The Session ID and Cookie can be filtered on by using the Session and
Cookie flowspec components in the Tunnel Header Flowspec. To filter
on Cookie or even be able to bypass Cookie and parse the remainder of
the L2TPv3 packet, the node implementing tunneled traffic flowspec
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needs to know the length and/or value of the Cookie fields of
interest. This is negotiated at L2TPv3 session establishment and it
is out of scope for this document how the node would learn this
information. Of course, if flowspec is being used for DDOS
mitigation and the Cookie has a fixed length and/or value in the DDOS
traffic, this could be learned by inspecting that traffic.
If the I flag bit is zero, then no filtering is done on data beyond
the L2TPv3 header. If the I flag is one, indicating the presence of
an Inner Flowspec, and the node implementing flowspec does not know
the length of the L2TPv3 header Cookie, the match fails. If that node
does know the length of that Cookie, the Inner Flowspec if matched
against the headers at the beginning of that data using the Inner
AFI. If that Inner AFI is 1 or 2, then an inner IP header is required
and filtering can be done on that IPv4 or IPv6 header respectively.
If the Inner AFI is 6, filtering is done on the inner Ethernet header
and, if an IPv4 or IPv6 inner AFI is specified within the inner L2
flowspec, done on the following IP header [FlowSpecL2].
2.3.4.2 L2TPv3 Control Messages
Control messages are distinguished by starting with a zero value
32-bit Session ID. L2TPv3 control message flowspecs MUST start with a
Session component that requires Session to be zero. For L2TPv3
control messages, there is no Cookie but there are L2TPv3 flags, a
3-bit Version field, a 32-bit Control Connection ID, and 16-bit Ns
and Nr sequence numbers. These can be tested using the Tunnel Header
Flags, L2TP Control Version, L2TPv3 Control Connection ID, L2TPv3 Ns,
and L2TPv3 Nr flowspec components in the Tunnel Header Flowspec.
2.3.5 GRE
Generic Router Encapsulation (GRE [RFC2890]) is another type of
encapsulation. The Outer Flowspec operates on the outer headers that
precede the GRE header. The version of IP is specified by the outer
AFI at the beginning of the MP_REACH_NLRI or MP_UNREACH_NLRI.
The Tunnel Header Flags component can be used to match the first two
octets of the GRE header. The Protocol Type component can be used to
match the corresponding GRE header field. The Session and GRE
Sequence components can be used to match on the GRE Key and GRE
Sequence fields if those fields are present respectively. If either
of those fields is not present, a component to match on that field
fails.
If the I flag bit is zero, no filtering is done on data after the GRE
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header. If the I flag bit is one in the tunnel flowspec, then there
is an inner AFI and inner flowspec and the Protocol Type field of the
GRE header must correspond to the Inner AFI as follows for the tunnel
Flowspec to match. Otherwise, the match fails.
GRE Protocol Type Inner AFI
------------------- -----------
0x0800 (IPv4) 1
0x86DD (IPv6) 2
0x6558 6
With the I flag a one and the Inner AFI and GRE Protocol Type fields
correspond, the Inner Flowspec is used to filter the inner IP headers
(Inner AFI=1 or 2) or the inner Ethernet header and optionally a
following IP header (Inner AFI=6).
2.3.6 IP-in-IP
IP-in-IP encapsulation [RFC2003] is indicated when an outer IP header
indicates an inner IP IPv4 or IPv6 header by the value of the outer
IP header's Protocol (IPv4) or Next Protocol (IPv6) field.
The IP version of the outer IP header (IPv4 or IPv6) matched is
indicated by an AFI of 1 or 2 at the beginning of the MP_REACH_NLRI
or MP_UNREACH_NLRI while if that AFI is 6, it indicates a match on
the outer Ethernet header and, optionally, the following IP Header
[FlowSpecL2]. The IP version of the inner IP header is indicated by
the Inner AFI and the Inner Flowspec applies to the inner IP header.
There is no tunnel header so there are no fields that can be matched
by the Tunnel Header Flowspec in the case of IP-in-IP.
2.3.7 Geneve
The headers on a Geneve [RFC8926] encapsulated packet are an outer
Ethernet header, an outer IP header, a UDP header, the Geneve header,
and subsequent headers depending on the Geneve header Protocol Type
field.
If the outer Ethernet header is not being matched, the version (IPv4
or IPv6) of the outer IP header is indicated by the AFI at the
beginning of the multiprotocol MP_REACH_NLRI or MP_UNREACH_NLRI
containing the Tunneled Traffic Flow Specification NLRI. The outer
Flowspec is used to filter the outer headers including, if desired,
the UDP header.
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If the outer Ethernet header is being matched, then the initial AFI
is 6 [FlowSpecL2] and the Outer Flowspec can match the outer Ethernet
header, specify the IP version of the outer IP header, and match that
IP header including, if desired, the UDP header.
The Tunnel Header Flowspec can be used to filter on the Protocol Type
field and/or the VNI field in the Geneve header. The flags octet of
the Geneve header, the second octet of that header, can be filtered
using the Tunnel Header Flags component.
If an Inner Flowspec is present, it is used to match the header(s)
after the Geneve header. The Protocol Type field in the Geneve header
must correspond to the Inner AFI as shown in the table in Section
2.3.5 above or the match fails. If the Inner AFI and GRE Protocol
Type fields correspond, the Inner Flowspec is used to filter the
inner IP headers (Inner AFI=1 or 2) or the inner Ethernet header and
optionally a following IP header (Inner AFI=6).
2.4 Tunneled Traffic Actions
The traffic filtering actions previously specified in [RFC8955] and
[FlowSpecL2] are used for tunneled traffic. For Traffic Marking in
NVO3, only the DSCP in the outer header can be modified.
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3. Order of Traffic Filtering Rules
The following rules determine which flowspec takes precedence where
one or more are applicable and at least one of the applicable
flowspecs is a tunneled traffic flowspec:
- In comparing an applicable tunneled traffic flow specification
with an applicable non-tunneled flow specification, the tunneled
specification has precedence.
- If comparing tunneled traffic flow specifications, if all are
applicable, the tunnel types will be the same. Any that have a
Routing Distinguisher will take precedence over those without a
Routing Distinguisher. Of those with a Routing Distinguisher, all
applicable flowspecs will have the same Routing Distinguisher.
- At this point in the process, all remaining contenders for the
highest precedence will either not have a Routing Distinguisher or
have equal Routing Distinguishers. If more than one contender
remain, those with an L2 Outer Flowspec take precedence over those
with an L3 Outer Flowspec. If the Outer Flowspec AFI is the same,
their order of precedence is determined by comparing the Outer
Flowspecs as described in [RFC8955] and [RFC8956] for AFI for 1 or
2 respectively or [FlowSpecL2] for AFI=6.
- If the Outer Flowspecs are equal, then the Tunnel Header Flowspecs
are compared using the usual sequential component comparison
process [RFC8955].
- If the Tunnel Header Flowspecs are equal then compare the "I"
flag. Those with an Inner Flowspec take precedence over those
without an Inner Flowspec. If you get to this stage in the
ordering process, those without an Inner Flowspec are equal. For
those with an Inner Flowspec, check the Inner AFI. An L2 Inner AFI
(AFI=6) takes precedence over an L3 Inner AFI.
- If the Inner AFIs are equal, precedence is determined by comparing
the Inner Flowspecs as described in [FlowSpecL2] for L2 or
[RFC8955] for L3.
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4. Flow Spec Validation
Flowspecs received over AFI=1/SAFI=77 or AFI=2/SAFI=77 are validated,
using only the Outer Flowspec, against routing reachability received
over AFI=1/SAFI=133 and AFI=2/SAFI=133 respectively, as modified by
[RFC9117].
5. Security Considerations
No new security issues are introduced to the BGP protocol by this
specification.
For general Flowspec security considerations, see [RFC8955].
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6. IANA Considerations
IANA has assigned the following SAFI:
Value Description Reference
----- ------------------------------------------ ---------------
77 Tunneled Traffic Flowspec [This document]
IANA is requested to create a Tunnel Header Flow Spec Component Type
registry on the Flow Spec Component Types registries web page as
follows:
Name: Tunnel Flow Spec Component Types
Reference: [this document]
Registration Procedures:
0 Reserved
1-127 Specification Required
128-254 First Come First Served
255 Reserved
Initial contents:
Type Name Reference
------ -------------- -----------------
0 reserved [this document]
1 VN ID [this document]
2 Flow ID [this document]
3 Session [this document]
4 Cookie [this document]
5 Tunnel Header Flags [this document]
6 L2TP Control Version [this document]
7 L2TPv3 Control Connection ID
[this document]
8 L2TPv3 Ns [this document]
9 L2TPv3 Nr [this document]
10 Protocol Type [this document]
11 GRE Sequence [this document]
12-254 unassigned [this document]
255 reserved [this document]
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Normative References
[RFC2003] - Perkins, C., "IP Encapsulation within IP", RFC 2003, DOI
10.17487/RFC2003, October 1996, <https://www.rfc-
editor.org/info/rfc2003>.
[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>.
[RFC2474] - Nichols, K., Blake, S., Baker, F., and D. Black,
"Definition of the Differentiated Services Field (DS Field) in
the IPv4 and IPv6 Headers", RFC 2474, DOI 10.17487/RFC2474,
December 1998, <https://www.rfc-editor.org/info/rfc2474>.
[RFC2890] - Dommety, G., "Key and Sequence Number Extensions to GRE",
RFC 2890, DOI 10.17487/RFC2890, September 2000,
<https://www.rfc-editor.org/info/rfc2890>.
[RFC3931] - Lau, J., Ed., Townsley, M., Ed., and I. Goyret, Ed.,
"Layer Two Tunneling Protocol - Version 3 (L2TPv3)", RFC 3931,
DOI 10.17487/RFC3931, March 2005, <https://www.rfc-
editor.org/info/rfc3931>.
[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, <https://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, <https://www.rfc-
editor.org/info/rfc4760>.
[RFC7348] - Mahalingam, M., Dutt, D., Duda, K., Agarwal, P., Kreeger,
L., Sridhar, T., Bursell, M., and C. Wright, "Virtual
eXtensible Local Area Network (VXLAN): A Framework for
Overlaying Virtualized Layer 2 Networks over Layer 3 Networks",
RFC 7348, DOI 10.17487/RFC7348, August 2014, <https://www.rfc-
editor.org/info/rfc7348>.
[RFC7637] - Garg, P., Ed., and Y. Wang, Ed., "NVGRE: Network
Virtualization Using Generic Routing Encapsulation", RFC 7637,
DOI 10.17487/RFC7637, September 2015, <https://www.rfc-
editor.org/info/rfc7637>.
[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>.
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[RFC8926] - Gross, J., Ed., Ganga, I., Ed., and T. Sridhar, Ed.,
"Geneve: Generic Network Virtualization Encapsulation", RFC
8926, DOI 10.17487/RFC8926, November 2020, <https://www.rfc-
editor.org/info/rfc8926>.
[RFC8955] - Loibl, C., Hares, S., Raszuk, R., McPherson, D., and M.
Bacher, "Dissemination of Flow Specification Rules", RFC 8955,
DOI 10.17487/RFC8955, December 2020, <https://www.rfc-
editor.org/info/rfc8955>.
[RFC8956] - Loibl, C., Ed., Raszuk, R., Ed., and S. Hares, Ed.,
"Dissemination of Flow Specification Rules for IPv6", RFC 8956,
DOI 10.17487/RFC8956, December 2020, <https://www.rfc-
editor.org/info/rfc8956>.
[RFC9117] - Uttaro, J., Alcaide, J., Filsfils, C., Smith, D., and P.
Mohapatra, "Revised Validation Procedure for BGP Flow
Specifications", RFC 9117, DOI 10.17487/RFC9117, August 2021,
<https://www.rfc-editor.org/info/rfc9117>.
[FlowSpecL2] - W. Hao, et al, "Dissemination of Flow Specification
Rules for L2 VPN", draft-ietf-idr-flowspec-l2vpn, work in
progress.
Informative References
[RFC8014] - Black, D., Hudson, J., Kreeger, L., Lasserre, M., and T.
Narten, "An Architecture for Data-Center Network Virtualization
over Layer 3 (NVO3)", RFC 8014, DOI 10.17487/RFC8014, December
2016, <https://www.rfc-editor.org/info/rfc8014>.
[GPE] - P. Quinn, et al, "Generic Protocol Extension for VXLAN",
draft-ietf-nvo3-vxlan-gpe, work in progress.
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Acknowledgments
The authors wish to acknowledge the important contributions of the
following listed in alphabetic order:
Jeff Haas, Susan Hares, Yizhou Li, Qiandeng Liang, Greg Mirsky,
Nan Wu, Robert Raszuk, and Lucy Yong
Authors' Addresses
Donald Eastlake
Futurewei Technologies
2386 Panoramic Circle
Apopka, FL 32703 USA
Tel: +1-508-333-2270
Email: d3e3e3@gmail.com
Weiguo Hao
Huawei Technologies
101 Software Avenue,
Nanjing 210012 China
Email: haoweiguo@huawei.com
Shunwan Zhuang
Huawei Technologies
Huawei Bld., No.156 Beiqing Rd.
Beijing 100095 China
Email: zhuangshunwan@huawei.com
Zhenbin Li
Huawei Technologies
Huawei Bld., No.156 Beiqing Rd.
Beijing 100095 China
Email: lizhenbin@huawei.com
Rong Gu
China Mobile
Email: gurong_cmcc@outlook.com
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Copyright, Disclaimer, and Additional IPR Provisions
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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
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include Revised BSD License text as described in Section 4.e of the
Trust Legal Provisions and are provided without warranty as described
in the Revised BSD License.
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