In-situ OAM Data Validation Option
draft-song-ippm-ioam-data-validation-option-00
The information below is for an old version of the document.
| Document | Type | Active Internet-Draft (individual) | |
|---|---|---|---|
| Authors | Haoyu Song , Tianran Zhou | ||
| Last updated | 2017-10-18 | ||
| Stream | (None) | ||
| Formats | plain text xml pdf htmlized pdfized bibtex | ||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
| IESG | IESG state | I-D Exists | |
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
draft-song-ippm-ioam-data-validation-option-00
ippm H. Song, Ed.
Internet-Draft T. Zhou
Intended status: Standards Track Huawei
Expires: December 3, 2017 June 2017
In-situ OAM Data Validation Option
draft-song-ippm-ioam-data-validation-option-00
Abstract
This document describes several potential performance scalability and
capability issues when implementing in-situ OAM on heterogenous
target network elements. The document proposes the corresponding
solutions and modifications to the current in-situ OAM specification
to mitigate the issues. Specifically, in-situ OAM is extended with
data validation fields to cope with the node processing capability.
We provide use cases to motivate our proposal and base the
modifications on the current in-situ OAM header format specification.
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 3, 2017.
Copyright Notice
Copyright (c) 2017 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
Song & Zhou Expires December 3, 2017 [Page 1]
Internet-Draft IOAM Data Validation June 2017
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 . . . . . . . . . . . . . . . . . . . . . . . . 2
2. In-situ OAM Sampling and Data Validation . . . . . . . . . . 3
2.1. Valid Node Bitmap and Valid Data Bitmap . . . . . . . . . 3
2.2. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Security Considerations . . . . . . . . . . . . . . . . . . . 5
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
5. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 5
6. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 5
7. Informative References . . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
In-situ OAM (iOAM) [I-D.brockners-inband-oam-requirements] records
OAM information within user packets while the packets traverse a
network. The data types and data formats for in-situ OAM data
records have been defined in [I-D.ietf-ippm-ioam-data]. We identify
several scalability issues for implementing the current iOAM
specification and propose solutions in this draft.
iOAM can designate the flow to add the iOAM header and collect data
on the flow forwarding path. The flow can have arbitrary
granularity. However, processing the data can be a heavy burden for
the network nodes, especially when some data needs to be calculated
by the node (e.g., the transit delay). If the flow traffic is heavy,
the node may not be able to handle the iOAM processing so many
performance issues may occur, such as long latency and packet drop.
Although it is good for the OAM applications to gain the detailed
information on every packet at every node, in many cases, such
information is often repetitive and redundant. The large quantity of
data would also burden the management plane which needs to collect
and stream the data for analytics. It is also possible that some
nodes cannot provide the requested data at all or are unwilling to
provide some data for security or privacy concerns. So a trade-off
is needed to balance the performance impact and the data availability
and completeness.
We provide several motivating examples. To minimize the network
impact, a network operator decides to collect the iOAM data only for
initial and last flow packets (e.g., TCP packets with SYN, FIN, and
RST flags).
Song & Zhou Expires December 3, 2017 [Page 2]
Internet-Draft IOAM Data Validation June 2017
In another example, a head node alternates two iOAM headers with each
requesting a subset of iOAM data. Hence, each node on the flow path
only needs to handle partial data. The requests can be balanced
without exhausting the network nodes.
The above two cases can be realized by manipulating the iOAM header
at the domain edge. It is also possible that a node is temporarily
under heavy traffic load. It is in danger of dropping packets if it
tries to satisfy all the iOAM data requests. In this case, it would
rather deny some requests than drop user traffic. This case can be
realized by adding some auxiliary fields in the iOAM header.
More examples are listed in Section 2.2.
2. In-situ OAM Sampling and Data Validation
Based on the observation in Section 1, the source edge node should be
able to define either the period or the probability to add the iOAM
header to the selected flow packet. In this way, only a subset of
the flow/sec packets would carry the OAM data, which not only reduces
the overall iOAM data quantity but also reduces the processing work
load of the network nodes.
2.1. Valid Node Bitmap and Valid Data Bitmap
It is possible that even an iOAM capable node will not add data to
the node data list as requested. In some cases, a node can be too
busy to handle the data request or some types of the requested data
is not available. Therefore, we propose to add two bitmaps, a valid
node bitmap and a valid data bitmap, to the iOAM specification.
The Node Valid Bitmap (NVB) is inserted before the Node Data List as
shown in Figure 1. Each bit in the NVB corresponds to a hop on the
packet's forwarding path. The bits are listed in the same order as
the hop on the packet's forwarding path. The bitmap is cleared to
all zero at first. If a hop can add data to the Node Data List, the
corresponding bit in the NVB is set to 1. The bit location for a hop
can be calculated from the length field (e.g, the bit index is equal
to SSize-RHop).The valid node data items in the node data list is
equal to the number of 1's in the NVB.
Song & Zhou Expires December 3, 2017 [Page 3]
Internet-Draft IOAM Data Validation June 2017
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Base OAM Trace Type |NodeLen| Flags | Octets-left |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Node Valid Bitmap (NVB) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Node Data List [] |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: iOAM Header Format with Node Valid Bitmap (NVB)
In addition to NVB, for each node data in the node data list, a Data
Valid Bitmap (DVB) is added before the node data. The number of bits
in the DVB is equal to the number of 1's in the OAM Trace Type
bitmaps (excluding the next trace type bitmap indicator bits). When
the bit is set, the corresponding data is valid in the node;
otherwise, the corresponding data is invalid so the management plane
should ignore it after the data is collected.
The size of the DVB can be padded to two or four bytes, which allow
up to 16 or 32 types of data to be included in a node. The node data
list format with the enhanced DVB is shown in Figure 2.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Valid Bitmap (DVB) | Padding |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Node Data List [i] |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: iOAM Node Data with Data Valid Bitmap (DVB)
2.2. Use Cases
We give some examples to show the usefulness of in-situ OAM sampling
and data validation features.
o An application needs to track a flow's forwarding path and knows
the path will not change frequently, so it sets a low sampling
Song & Zhou Expires December 3, 2017 [Page 4]
Internet-Draft IOAM Data Validation June 2017
rate to periodically insert the iOAM header to request the node
ID.
o In a heterogeneous data plane, some nodes support to provide data
x but the other nodes do not support it. However, an application
is still interested in collecting data x if available. In this
case, iOAM header can still be configured to ask for data x but
the nodes that cannot provide the data simply invalidates it by
resetting the corresponding bit in the valid data bitmap.
o Multiple sampling rate and multiple data request schema can be
defined for a flow based on applications requirements and the data
property, so for a flow packet, there can be no iOAM header or
different iOAM headers. The node does not need to process all
data all the time.
o For security reason, a node decides to not participate in the iOAM
data collection. While it processes the other iOAM header fields
as usual, it does not set the node valid bit in the Node Valid
Bitmap and add node data to the Node Data List.
3. Security Considerations
There is no extra security considerations beyond those have been
identified by in-situ OAM protocol.
4. IANA Considerations
This memo includes no request to IANA.
5. Acknowledgments
We would like to thank Frank Brockners, Carlos Pignataro, Shwetha
Bhandari, and Tal Mizrahi for helpful comments and suggestions.
6. Contributors
The document is inspired by numerous discussions with James N.
Guichard. He also provided significant comments and suggestions to
help improve this document.
7. Informative References
Song & Zhou Expires December 3, 2017 [Page 5]
Internet-Draft IOAM Data Validation June 2017
[I-D.brockners-inband-oam-requirements]
Brockners, F., Bhandari, S., Dara, S., Pignataro, C.,
Gredler, H., Leddy, J., Youell, S., Mozes, D., Mizrahi,
T., <>, P., and r. remy@barefootnetworks.com,
"Requirements for In-situ OAM", draft-brockners-inband-
oam-requirements-02 (work in progress), October 2016.
[I-D.ietf-ippm-ioam-data]
Brockners, F., Bhandari, S., Pignataro, C., Gredler, H.,
Leddy, J., Youell, S., Mizrahi, T., Mozes, D., Lapukhov,
P., Chang, R., and d. daniel.bernier@bell.ca, "Data Fields
for In-situ OAM", draft-ietf-ippm-ioam-data-00 (work in
progress), September 2017.
Authors' Addresses
Haoyu Song (editor)
Huawei
2330 Central Expressway
Santa Clara, 95050
USA
Email: haoyu.song@huawei.com
Tianran Zhou
Huawei
156 Beiqing Road
Beijing, 100095
P.R. China
Email: zhoutianran@huawei.com
Song & Zhou Expires December 3, 2017 [Page 6]