| Interdomain Routing Working Group | M. Liu, Ed. |
| Internet-Draft | Y. Wang, Ed. |
| Intended status: Standards Track | Huawei |
| Expires: August 31, 2020 | February 28, 2020 |
A New Definition of the Flowspec IFIT Wide Community
draft-liu-idr-flowspec-ifit-00
BGP Flowspec mechanism propogates both flow specification information and traffic filtering actions by making use of the BGP policy framework. In this document, authors only add the requirements of one new IFIT application [I-D.song-opsawg-ifit-framework] and specify the encoding format of a new BGP Extended Community to propagate In-situ flow information telemetry(IFIT) actions so as to address the deployment challenges of IPv6 unicast and VPNv6 unicast on-path flow information telemetry automatically.
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 [RFC2119].
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A family of on-path flow telemetry techniques being referred in [I-D.song-opsawg-ifit-framework], are emerging, which can provide flow information on the entire forwarding path on a per-packet basis in real time. we categorize these on-path telemetry echniques as the hybrid OAM type I according to the classification defined in [RFC7799]. These techniques are invaluable for application-aware network operations not only in data center and enterprise networks but also in carrier networks which may cross multiple domains, which are important for user SLA compliance, service path enforcement, fault diagnosis, and network resource optimization. In IFIT reflection-loop architecture [I-D.song-opsawg-ifit-framework], an IFIT application would pick a suite of telemetry tecchniques based on its requirements and apply an initial technique to the data plane. Then the IFIT head nodes are configured to decide the initial target flows/packets and telemetry data set, the encapsulation and tunneling scheme based on the underlying network architecture. And the IFIT-capable nodes are configured to decide the inital telemetry data export policy.
As we know, Dissemination of Flow Specification Rules [I-D.ietf-idr-rfc5575bis] provides a protocol extension for propagation of traffic flow information for the purpose of rate limiting, filtering, shaping, classifying or redirecting. BGP extended community encoding formats can be used to propagate traffic filtering actions along with the flow specification NLRI. Those traffic filtering actions encode actions a routing system can take if the packet matches the flow specifications. Meanwhile, the other document [I-D.ietf-idr-flow-spec-v6] extends [I-D.ietf-idr-rfc5575bis] and defines changes to it in order to make it also usable and applicable to IPv6 data packets.
From an operational perspective, the utilization of BGP Flowspec as the carrier for the specific flow information allows a network service provider to reuse BGP route distribute infrastructure.
But the former document defines these traffic filter actions by extending the BGP extended community value which are formatted into only 6-octet fixed length of data. Concerning actions of variable IFIT option-types and different parameters, this document extends the wide BGP communities [I-D.ietf-idr-wide-bgp-communities-05] to define the IFIT action.
IFIT: in-situ Flow Information Telemetry
NLRI: Network Layer Reachability Information
The IFIT applications, which enable the future autonomous network operation, will pick one of proper in-situ telemetry techniques and apply a flow, packet, and data selection policy to monitor the specific traffic flow for application-aware network operation. In current deployments, there have been relatively static methods, ACL-like CLI and Netconf with YANG model to enable the specific flow or packets from the target flow to be monitored on the relevant IFIT-capable nodes.
With the evolution of intent-based and automatic network operation, and the trends of network virtualization, network convergence, and packet-optical integration, future data plane telemetry will support an on-demand and interactive fashion. Flexibility and extensibility of data defining and acquiring must be considered. Therefore, flexible configurations and actions need to be deployed based on the real-time telemetry data analysis results and different application requirements.
Then BGP Flowspec dynamic mechanism is preferred in the closed-loop network telemetry system, which is going to add a new Traffic IFIT Action value of BGP Wide Community to closely monitor the relevant flows in real time that matches the flow specification's Network Layer Reachability Information (NLRI) defined in [I-D.ietf-idr-rfc5575bis] and [I-D.ietf-idr-flow-spec-v6].
In most cases, the IFIT application does not require Next Hop information that shall be encoded as a 0-octet length Next Hop in the MP_REACH_NLRI attribute.
According to the IOAM attribute, there is no disagreement between IFIT action and the other defined traffic filtering actions.
This section defines a new community value in BGP wide community for IFIT action and extends optional lists of Atoms that encode parameters of IFIT actions in accordance with different IFIT option types.
Container Type 1, BGP Wide Community is defined in [I-D.ietf-idr-wide-bgp-communities-05] .
The Type 1 BGP Community Container, the BGP Wide Community, is of variable size (but minimum length 12). The Community Value, in the first 4-octets of a fixed 12-octets Wide Community header, indicates what set of actions a router is requested to take upon reception of a route containing this community. Then for this new type-IFIT action, IANA is requested to allocate a new value in the corresponding registry:
Name Community Value
---- ----------
IFIT Action TBD
The BGP Wide Community Parameter(s) TLV (Sub-Type 3) contains a list of Atoms. Atoms are encoded as TLVs described in section 5 of [I-D.ietf-idr-wide-bgp-communities-05]. The TLV types are to be assigned by IANA registry. The Length represents the length of the "Value" field in octets. The Value field contains the TLV value.
In IFIT architecture, there are a few of option types available for the specified traffic flow, e.g. IOAM pre-allocated/incremental trace, IOAM DEX trace, E2E ,POT etc. As different IFIT option types have different formats of parameters, following defines new Atoms in accordance with different IFIT option types.
Supported format of the IFIT action TLVs can be:
Type xx: IOAM Pre-allocated Trace Option
Type xx: IOAM Incremental Trace Option
Type xx: IOAM DEX Trace Option
Type xx: IOAM Edge-to-Edge Option
Type xx: Enhanced Alternate Marking Option
In the following sections, the different IFIT action option types of Atoms will be presented.
The IOAM tracing data is expected to be collected at every node that a packet traverses to ensure visibility into the entire path a packet takes within an IOAM domain. The pre-allocated tracing option will create pre-allocated space for each node to populate its information.
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 | NamespaceID |
| | | high |
+---------------------------------------------------------------+
| NamespaceID | IOAM Trace Type |
| Low | |
+---------------------------------------------------------------+
| Flags | Rsvd |
| | |
+---------------+
Fig. 1 IOAM Pre-allocated Trace Option Sub-TLV
The format of IOAM pre-allocated trace option sub-TLV is defined as follows:
Type: to be assigned by IANA.
Length: the total length of the value field not including Type and Length fields.
Namespace ID: A 16-bit identifier of an IOAM-Namespace. The definition is the same as described in section 4.4 of[I-D.ietf-ippm-ioam-data] .
IOAM Trace Type: A 24-bit identifier which specifies which data types are used in the node data list. The definition is the same as described in section 4.4 of [I-D.ietf-ippm-ioam-data].
Flags: A 4-bit field. The definition is the same as described in [I-D.ietf-ippm-ioam-flags] and section 4.4 of [I-D.ietf-ippm-ioam-data].
Rsvd: A 4-bit field reserved for further usage. It MUST be zero.
The incremental tracing option contains a variable node data fields where each node allocates and pushes its node data immediately following the option header.
The format of IOAM incremental trace option sub-TLV is defined as follows:
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 | NamespaceID |
| | | high |
+---------------------------------------------------------------+
| NamespaceID | IOAM Trace Type |
| Low | |
+---------------------------------------------------------------+
| Flags | Rsvd |
| | |
+---------------+
Fig. 2 IOAM Incremental Trace Option Sub-TLV
Type: to be assigned by IANA.
Length: the total length of the value field not including Type and Length fields.
All the other fields definistion is the same as the pre-allocated trace option sub-TLV in section 3.2.1.
The DEX option is used as a trigger to export IOAM data to a collector. Moreover, IOAM nodes MAY send exported data for all traversing packets that carry the DEX option, or MAY selectively export data only for a subset of these packets. The DEX option specifies which data fields should be exported to the collector, as specified in Section 3.2 of [I-D.ioamteam-ippm-ioam-direct-export].
The format of IOAM DEX Trace option sub-TLV is defined as follows:
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 |
| | |
+---------------------------------------------------------------+
| NamespaceID | Flags |
| | |
+---------------------------------------------------------------+
| IOAM-Trace-Type | Rsvd |
| | |
+---------------------------------------------------------------+
| FlowID(Optional) |
| |
+---------------------------------------------------------------+
| Sequence Number(Optional) |
| |
+---------------------------------------------------------------+
Fig. 3 IOAM DEX Trace Option Sub-TLV
Type: to be assigned by IANA.
Length: the total length of the value field not including Type and Length fields.
Namespace-ID: a 16-bit identifier of the IOAM namespace, as defined in section 4.4 of [I-D.ietf-ippm-ioam-data] .
Flags: a 16-bit field, comprised of 16 one-bit subfields. Flags are allocated by IANA, as defined in Section 4.2 of [I-D.ioamteam-ippm-ioam-direct-export] .
IOAM-Trace-Type: a 24-bit identifier which specifies which data fields should be exported. The format of this field is as defined in section 4.4 of[I-D.ietf-ippm-ioam-data]
Rsvd: this field SHOULD be ignored by the receiver.
Flow ID: a 32-bit flow identifier, as defined in section 3.2 of [I-D.ioamteam-ippm-ioam-direct-export]
Sequence Number: a 32-bit sequence number , as defined in section 3.2 of [I-D.ioamteam-ippm-ioam-direct-export] .
The IOAM edge to edge option is to carry data that is added by the IOAM encapsulating node and interpreted by IOAM decapsulating node.
The format of IOAM edge-to-edge option sub-TLV is defined as follows:
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 |
| | |
+---------------------------------------------------------------+
| NamespaceID | IOAM E2E Type |
| | |
+---------------------------------------------------------------+
Fig. 4 IOAM Edge-to-Edge Option Sub-TLV
Type: to be assigned by IANA.
Length: the total length of the value field not including Type and Length fields.
Namespace ID: A 16-bit identifier of an IOAM-Namespace. The definition is the same as described in section 4.6 of[I-D.ietf-ippm-ioam-data].
IOAM E2E Type: A 16-bit identifier which specifies which data types are used in the E2E option data. The definition is the same as described in section 4.6 of [I-D.ietf-ippm-ioam-data].
The Alternate Marking [RFC8321]technique is an hybrid performance measurement method and can be used to measure packet loss, latency, and jitter on live traffic because it is based on marking consecutive batches of packets.
The Enhanced Alternate Marking (EAM) [I-D.zhou-ippm-enhanced-alternate-marking] defines data fields for the alternate marking with enough space, in particular for Postcard- based Telemetry. More information can be considered within the alternate marking field to facilitate the efficiency and ease the deployment.
The format of EAM sub-TLV is defined as follows:
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 | | | | +---------------+-----------------------+-------+-------+-------+ | FlowMonID | Period | Rsvd | | | | | +---------------------------------------+---------------+-------+
Fig. 5 Enhanced Alternate Marking Option Sub-TLV
Length: the total length of the value field not including Type and Length fields.
FlowMonID: A 20-bit identifier to uniquely identify a monitored flow within the measurement domain. The definition is the same as described in section 2 of [I-D.zhou-ippm-enhanced-alternate-marking].
Period: Time interval between two alternate marking period. The unit is second.
Rsvd: A 4-bit field reserved for further usage. It MUST be zero.
For the new type-IFIT action, this document requests IANA to allocate a new value in the corresponding registry named " Registered Type 1 BGP Wide Community Community Types":
| Name | Community Type |
|---|---|
| IFIT Action | TBD |
This document requests IANA to define new Atoms types for IFIT action option types in registry named: "BGP Community Container Atom Types":
Name Type Value
----- ----------
IOAM Pre-allocated Trace Option TBD
IOAM Incremental Trace Option TBD
IOAM DEX Trace Option TBD
IOAM Edge-to-Edge Option TBD
Enhanced Alternate Marking TBD
No new security issues are introduced to the BGP protocol by this specification over the security considerations in [I-D.ietf-idr-rfc5575bis].
| [RFC2119] | Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997. |
| [RFC7799] | "Active and Passive Metrics and Methods (with Hybrid Types In-Between)" |
| [I-D.ietf-idr-flow-spec-v6] | "Dissemination of Flow Specification Rules for IPv6" |
| [I-D.ietf-idr-rfc5575bis] | "Dissemination of Flow Specification Rules" |
| [I-D.ietf-idr-wide-bgp-communities-05] | "BGP Community Container Attribute" |
| [I-D.ietf-ippm-ioam-data] | "Data Fields for In-situ OAM" |
| [I-D.ioamteam-ippm-ioam-direct-export] | "In-situ OAM Direct Exporting" |
| [I-D.song-opsawg-ifit-framework] | "In-situ Flow Information Telemetry Framework" |
| [I-D.zhou-ippm-enhanced-alternate-marking] | "Enhanced Alternate Marking Method" |