Internet DRAFT - draft-li-rtgwg-protocol-assisted-protocol
draft-li-rtgwg-protocol-assisted-protocol
Network Working Group Z. Li
Internet-Draft S. Chen
Intended status: Standards Track Z. Tan
Expires: 12 September 2023 Huawei
Y. Qu
Futurewei
Y. Gu
Huawei
11 March 2023
Protocol Assisted Protocol (PASP)
draft-li-rtgwg-protocol-assisted-protocol-05
Abstract
For routing protocol troubleshooting, different approaches exibit
merits w.r.t. different situations. They can be generally divided
into two categories, the distributive way and the centralized way. A
very commonly used distributive approach is to log in possiblly all
related devices one by one to check massive data via CLI. Such
approach provides very detailed device information, however it
requires operators with high NOC (Network Operation Center)
experience and suffers from low troubleshooting efficiency and high
cost. The centralized approach is realized by collecting data from
devices via approaches, like the streaming Telemetry or BMP( BGP
Monitoring Protocol), for the centralized server to analyze all
gathered data. Such approach allows a comprehensive view fo the
whole network and facilitates automated troubleshooting, but is
limited by the data collection boundary set by different management
domains, as well as high network bandwidth and CPU computation costs.
This document proposes a semi-distributive and semi-centralized
approach for fast routing protocol troubleshooting, localizing the
target device and possibly the root cause, more precisely. It
defines a new protocol, called the PASP (Protocol assisted Protocol),
for devices to exchange protocol related information between each
other in both active and on-demand manners. It allow devices to
request specific information from other devices and receive replies
to the requested data. It also allows actively transmission of
information without request to inform other devices to better react
w.r.t. network issues.
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].
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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
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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 12 September 2023.
Copyright Notice
Copyright (c) 2023 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 (https://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
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provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . 4
1.2. PASP Use cases . . . . . . . . . . . . . . . . . . . . . 5
1.2.1. Use Case 1: BGP Route Oscillation . . . . . . . . . . 6
1.2.2. Use Case 2: RSVP-TE Set Up Failure . . . . . . . . . 6
1.2.3. Use Cases 3: Peer Disconnection (for IGP/BGP/LDP/
BFD) . . . . . . . . . . . . . . . . . . . . . . . . 6
1.2.4. Use Cases 4: Detecting Route Interruption . . . . . . 7
1.2.5. Use Cases 5: BGP Route No-advertise . . . . . . . . . 7
1.2.6. Use Cases 6: Route Abnormal . . . . . . . . . . . . . 7
1.2.7. Use Cases 7: Management protocol failures . . . . . . 7
1.2.8. Use Cases 8: Collecting other O&M Events . . . . . . 8
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 8
3. PASP Overview . . . . . . . . . . . . . . . . . . . . . . . . 8
3.1. PASP Encapsulation . . . . . . . . . . . . . . . . . . . 8
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3.2. PASP Speaker and PASP Agent . . . . . . . . . . . . . . . 9
3.3. PASP Event . . . . . . . . . . . . . . . . . . . . . . . 9
3.4. Summary of Operation . . . . . . . . . . . . . . . . . . 9
3.4.1. PASP Capability Negotiation Process . . . . . . . . . 10
3.4.2. PASP Request and Reply Process . . . . . . . . . . . 10
3.4.3. PASP Notification Process . . . . . . . . . . . . . . 11
4. PASP Message Format . . . . . . . . . . . . . . . . . . . . . 11
4.1. Common Header . . . . . . . . . . . . . . . . . . . . . . 11
4.1.1. Capability Negotiation Message . . . . . . . . . . . 12
4.2. Request Message . . . . . . . . . . . . . . . . . . . . . 13
4.3. Reply Message . . . . . . . . . . . . . . . . . . . . . . 14
4.4. Notification Message . . . . . . . . . . . . . . . . . . 15
4.5. ACK Message . . . . . . . . . . . . . . . . . . . . . . . 15
5. PASP Operations . . . . . . . . . . . . . . . . . . . . . . . 15
5.1. Capability Negotiation Process . . . . . . . . . . . . . 15
5.1.1. PASP Peering Relation Establish Process . . . . . . . 16
5.1.2. PASP Capability Enabling Notification Process . . . . 17
5.1.3. PASP Capability Disabling Notification Process . . . 17
5.2. PASP Request and Reply Process . . . . . . . . . . . . . 18
5.3. PASP Notification Process . . . . . . . . . . . . . . . . 20
6. PASP Error Handling . . . . . . . . . . . . . . . . . . . . . 20
7. Discussion . . . . . . . . . . . . . . . . . . . . . . . . . 20
8. Security Considerations . . . . . . . . . . . . . . . . . . . 21
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21
10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 21
11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 22
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 22
12.1. Normative References . . . . . . . . . . . . . . . . . . 22
12.2. References . . . . . . . . . . . . . . . . . . . . . . . 23
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23
1. Introduction
A healthy control plane, providing network connectivity, is the
foundation of a well-functioning network. There have been rich
routing and signaling protocols designed and used for IP networks,
such as IGP (ISIS,OSPF), BGP, LDP, RSVP-TE and so on. The health
issues of these protocols, such as neighbor/peer disconnect/set up
failure, LSP set up failure, route flapping and so on, have been
devoted with ongoing efforts for diagnosing and remediation.
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1.1. Motivation
The distributive protocol troubleshooting approach is typically
realized through manual per-device check. It's both time- and labor-
consuming, and requires NOC experience of the operators. Amongst
all, localizing the target device is usually the most diffcult and
time-consuming part. For example, in the case of route loop,
operators first log in a random deivce that reports TTL alarms, and
then check the looped route in the Forwarding Information Base (FIB)
and/or the Routing Information Base (RIB). It requires device by
device check, as well as manul data correlation, to pin point to the
exact responsible device, since the information retrival and analysis
of such distributive way is fragmented. In addition, the low
efficiency and manul troubleshooting activities may further impact
new network services and/or enlarge affected areas.
The centralized network OAM, by collecting network-wide data from
devices, enables automatic routing protocol troubleshooting. Date
collection protocols, such as SNMP (Simple Network Management
Protocol) [RFC1157], NETCONF (Network Configuration Protocol)
[RFC6241], and (BMP) [RFC7854], can provide various information
retrival, such as network states, routing data, configurations and so
on. Such centrazlized way relies on the existence of a centralized
server/controller, which is not supported by some legacy networks.
What's more, even with the existence of a centralized server/
controller, it can only collect the data within its own management
domain, while the cross-domain data are not available due to
independent managment of different ISPs. Thus, the lack of such
information may lead to troubleshooting failure. In addition,
centralized approaches may suffer from high network bandwidth and CPU
computation consumptions.
Another way of protocol troubleshooting is utilzing the protocol
itself to convey diagnosing information. For example, some reason
codes are carried in the Path-Err/ResvErr messages of RSVP-TE, so
that to other nodes may know the why the tunnel fails to be set up.
Such approaches is semi-distributive and semi-centralized. It does
not rely on the deployment of a centralized server, but still gets
partial global view of the network. However, there still requires
non-trivial augementation works to existing routing protocols in
order to support troubleshooting. This then raises the question that
whether such non-routing data is suitable to be carried in these
routing protocols. The extra encapsulation, parsing and analyzing
work for the non-routing data would further slow down the network
convergence. Thus, it's better to separate the routing and non-
routing data transmission as well as data parsing. In addition,
coexisting with legacy devices may cause interop issues. Thus,
relying on augumenting existing routing protocols without network-
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wide upgrading may not only fail to provide the truobleshooting
benefit, but further affect the operation of the existing routing
system. What's more, the failure of routing protocol instance would
lead to the failure of diagnosing itself. All in all, it's
reasonable to separate the protocol diagnosing data
generation/encapsulation/transmission/parsing from the protocol
itself.
This document proposes a new protocol, called the PASP (Protocol
assisted Protocol), for devices to exchange protocol related
information between each other. It allows both active and on-demand
data exchange. Considering that massiveness of protocol/routing
related data, the intuitive of designing PASP is not to exchange the
comprehensive protocol/routing status between devices, but to provide
very specific information required for fast troubleshooting. The
benefits of such a semi-distributive and semi-centralized approach
are summarized as follows:
1. It facilitates automatic troubleshooting without requiring manul
device by device check.
2. It allows individual device to have a more global view by
requesting data from other devices.
3. It does not rely on the deployement of a centralized server/
controller.
4. It passes the data collection boundary set by different
management domains by cross-domain data exchange between devices.
5. It relieves the bandwidth pressure of network-wide data
collection, and the processing pressure of the centralized
server.
6. It does not affect the running of existing routing protocols.
1.2. PASP Use cases
PASP allows both data request/reply and data notification between
devices. PASP speakers use the exchanged PASP data to help quickly
localize the network issues.
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1.2.1. Use Case 1: BGP Route Oscillation
A BGP route oscillation can be caused by various reasons, and usually
leaves network-wide impact. In order to find the root cause and take
remediation actions, the first step is to localize the oscillation
source. In this case, a BGP speaker can send a PASP Request Message
to the next hop device of the oscillating route asking " Are you the
oscillation source?". If the BGP speaker is the oscillation source,
possiblly knows by running a device diagnosing system, replies with a
PASP Reply Message saying that "I'm the oscillation source!" to the
device who sends the PASP Request Message. If the BGP speaker is not
the oscillation source, it further asks the same question with a PASP
Request Message to its next hop device of the oscillating route.
This request and reply process continues util the request has reached
the oscillation source. The source device then sends a PASP Reply
Message to tell its upstream device along the PASP request path that
" I am the oscillation source!", and then "xx is the oscillation
source!" information is further sent back hop by hop to the device
who originates the request.
1.2.2. Use Case 2: RSVP-TE Set Up Failure
The MPLS label switch path set up, either using RSVP-TE or LDP, may
fail due to various reasons. Typical troubleshooting procedures are
to log in the device, and then check if the failure lies on the
configuration, or path computation error, or link failure.
Sometimes, it requires the check of multiple devices along the
tunnel. Certain reason codes can be carried in the Path-Err/ResvErr
messages of RSVP-TE, while other data are currently not supported to
be transmitted to the path ingress/egress node, such as the
authentication failure. Using PASP, the device, which is reponsible
for the tunnel set up failure, can send the PASP Notification Message
to the ingress device, and possibly with some reason codes so that
the ingress device can not only localize the target device but also
the root cause.
1.2.3. Use Cases 3: Peer Disconnection (for IGP/BGP/LDP/BFD)
In a peer disconnected situation, a typical troubleshooting procedure
is to login to both devices and check the error log of specific
protocols. This is quite difficult if those devices are far away
from each other, either geometrically or administratively. Using
PASP, a device that suffers the disconnection could send a PASP
Request to the disconneted peer. The device that triggers the
disconnection could send a PASP Reply with the reason of
disconnection, including manual shutdown, TCP down and so on.
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1.2.4. Use Cases 4: Detecting Route Interruption
Route Interruption could occur randomly on devices. It is typically
short-lived and threfore difficult to be catched in time. Often,
when an O&M personnel reaches to the device, the interruption had
recovered and the real causes remain uncovered. The distance problem
could also exist in this scenario. PASP could collecting route
change history, so that rapid route interruptions can be detected and
logged. Certain data could be fetched up on request, with a PASP
Request message from a trusted source.
1.2.5. Use Cases 5: BGP Route No-advertise
After a BGP peer relationship is established, expected routes may not
be advertised or may be withdrawn unexpectedly. Troubleshooting for
these situations need the O&M personnel login to both devices and
check the status of the routes and peer to determine the cause. Due
to the time validity issue, O&M personnel may need to check both BGP
speaker simultaneously. Using PASP, device that suffers from a no-
advertise situation could send a PASP Request with specific IP
address. Receiver could send an PASP Reply with reason of no-
advertise, including egress filters, no-advertise attribute and so
on.
1.2.6. Use Cases 6: Route Abnormal
Traffic interruption caused by abnormal routes is a common network
problem, which could have a great impact on users. It usually takes
a lot of time and energy for O&M personnel to locate the device where
traffic is interrupted, especially on a large-scale network. With
PASP depolyed, an O&M personnel could send a PASP Request message
with the specific IP address on any connected device to another
device. Receiver could send a PASP Reply with situation codes
including nexthop unreachable, outbound interface down, suppression
and others.
1.2.7. Use Cases 7: Management protocol failures
Many North-South management protocols, such as SNMP and SSH, are
widely used to manage devices. The failure of the management
protocol itself could result in a login error or others, which could
bring great difficulties in O&M. An O&M personnel could send a PASP
Request on a neighbour device to the target device, asking for the
reason of failure of a management protocol. In this scenario, PASP
can provide another channel for obtaining O&M information of
management protocols.
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1.2.8. Use Cases 8: Collecting other O&M Events
PASP could record O&M events, such as IP-address conflict, memory
leak and so on. Certain data could be fetched up on request, with a
PASP Request message from a trusted source. Therefore O&M personnel
could obtain those information without repeatedly checking every
device in the network.
2. Terminology
IGP: Interior Gateway Protocol
IS-IS: Intermediate System to Intermediate System
OSPF: Open Shortest Path First
BGP: Boarder Gateway Protocol
BGP-LS: Boarder Gateway Protocol-Link State
MPLS: Multi-Protocol Label Switching
RSVP-TE: Resource Reservation Protocol-Traffic Engineering
LDP: Label Distribution Protocol
BMP: BGP Monitoring Protocol
LSP: Link State Packet
IPFIX: Internet Protocol Flow Information Export
PASP: Protocol assisted Protocol
UDP: User Datagram Protocol
3. PASP Overview
3.1. PASP Encapsulation
PASP uses UDP as its transport protocol, which is connectionless.
The reason that UDP is selected over TCP is because PASP is intended
for on-demand communications. The PASP packet is defined as follows.
This document requires the assignment of a User Port registry for the
UDP Destination Port.
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+-------------+-------------+-------------+-------------+-------------+
| ETH. Header | IP Header | UDP Header | PASP Header| PASP Payload|
+-------------+-------------+-------------+-------------+-------------+
Figure 1. Encapsulation in UDP
3.2. PASP Speaker and PASP Agent
This document uses PASP speakers to refer to routing devices that
communicate with each other using PASP. PASP speakers SHOULD be
implemented with a supporting module (or multiple modules) to
receive, parse, analyze, generate, and send PASP messages. For
example, a BGP diagnosing module used for BGP related PASP message
handling functions as a PASP agent. A PASP Agent is the union of
multiple such modules regarding different protocols, or one module
for all protocols. Such supporting module is called PASP Agent in
this document. PASP Agent, standalone, SHOULD be able to provide
protocol troubleshooting capability with local information. Enabling
PASP exchange capability, PASP agent gains information from remote
PASP speakers to improve diagnosing accuracy . The primary function
of PASP is to provide a unfied tunnel for protocol diagnosing
information exchange without augumenting each specific protocol.
3.3. PASP Event
A PASP Event is referred to as the a troubleshooting instance running
within a PASP Agent. A PASP Agent may instantiate one or multiple
PASP Events for each protocol at the same time depending on the
configured troubleshooting triggering condition. For example, an
PASP Event is intiated automatically when device CPU is over high, or
manually with related command line input from a device operator.
Once a PASP Event is generated, corresponding PASP processes are to
be called on demand. Notice, the initiation of PASP Capability
Negotiation does not require the existance of a PASP Event.
3.4. Summary of Operation
The communications between two PASP speakders should follow three
major processes, i.e., the Capability Negotiation Process, the
Request and Reply Process, and the Notification Process. This
document defines 5 PASP Message types, i.e., Negotiation Message,
Request Message, Reply Message, Notification Message, and ACK
Message, which are used in the above PASP processes.
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3.4.1. PASP Capability Negotiation Process
The purpose of the Capability Negotiation process is to inform two
PASP speakers of each other's PASP capabilties. The PASP capability
indicates, for which specific protocol(s), that PASP supports its/
their diagnosing information exchange. The process can be further
divided into three procudures: 1) PASP Peering Relations Establish
process, 2) PASP Capability Enabling Notification Process, 3) PASP
Capability Disabling Notification Process. The Capability
Negotiation Process is realized by the exchange of PASP Capability
Negotiation Message, which is defined in Section 4.
Although PASP is connectionless, a successful PASP Peering Relations
Establish Process is required to be successfully performed before any
other PASP process. This process can be initiated by either the
local or remote PASP speaker through sending out a PASP Capability
Negotiation Message. The Negotiation Message may or may not require
an ACK Message, as indicated in the Negotiation Message. A
successful Peering is established if both PASP speakers have
correctly received the other speaker's Capability Negotiation
Message. After a successful negotiation, two PASP speakers can
exchange any PASP Message on-demand. The PASP Capability Enabling
Notification Process is used to inform the PASP peer its newly
supported capability, which can be intiated by the PASP speaker at
any moment after a PASP Peering is established with the respective
PASP Peer. The PASP Capability Disabling Notification Process is
used to inform the PASP peer its newly unsupported capability, which
can be intiated by the PASP speaker at any moment after a PASP
Peering is established with the respective PASP Peer.
3.4.2. PASP Request and Reply Process
The purpose of the PASP Request and Reply Process is to acquire
information needed by a PASP speaker from other PASP speakers for a
specific PASP Event. The Request and Reply Messages can be
customized for different events. The process is triggered by the
instantiation of a PASP Event, and starts with sending a Request
Message to a target PASP peer. The target PASP peer is selected by
the PASP agent regarding the current PASP Event, which is out of the
scope of this document. The remote PASP speaker, after receiving the
Request Message, sends out a Reply Message to the request sender.
ACK is required or not as indicated in the Message Flag.
One Request Message received at the local PASP speaker from a PASP
peer may further results in a new Request Message generation
regarding a third PASP speaker, if the local PASP speaker does not
have the right Reply to this PASP peer. This local PASP speaker does
not send Reply Message to the requesting PASP peer until it receives
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a new Reply Message from this third PASP speaker. So the whole
process In order to avoid Request/Reply loops, a Residua Hop value is
used to limit the Request/Reply rounds.
3.4.3. PASP Notification Process
The Notification Process is used by a PASP speaker voluntarily to
notify other PASP speakers of certain information regarding a PASP
Event. The process is triggered by the instantiation of a PASP
Event, and starts with sending a Notification Message to one or
multiple target PASP peer(s). The target PASP peer(s) is/are
selected by the PASP agent regarding the current PASP Event, which is
out of the scope of this document. The Notification Message may or
may not require an ACK Message, as indicated in the Notification
Message.
4. PASP Message Format
4.1. Common Header
The common header is encapsulated in all PASP messages. It 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
+---------------+----------------+------------------------------+
|V| Flag | Msg. Type | Length |
+---------------+----------------+------------------------------+
+ Peer Address (16 bytes) +
~ ~
+--------------------------------+------------------------------+
| Msg. Sequence |
+--------------------------------+
Figure 2. PASP Common Header
* Flag (1 byte): The V flag indicates that the source IP address is
an IPv6 address. For IPv4 address, this is set to 0.
* Message Type (1 byte): This indicates the PASP message type.The
following types are defined, and listed as follows.
- Type = TBD1: Capability Negotiation Message. It is used for
two devices to inform each other of the capabilties they
support and no longer support.
- Type = TBD2: Request Message.
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- Type = TBD3: Reply Message.
- Type = TBD4: Notification Message.
- Type = TBD5: ACK Message. It is used to confirm to the local
device that the remote device has received a previous sent PASP
message, which can be either a Negotiation Message, a Request
Message, a Reply Message or an Notification Message.
* Length (2 bytes): Length of the message in bytes, including the
Common Header and the following Message.
* Souece IP Address (16 bytes): It indicates the IP address who
initiates the PASP message. It is 4 bytes long if an IPv4 address
is carried in this field (with the 12 most significant bytes zero-
filled) and 16 bytes long if an IPv6 address is carried in this
field.
* Message Sequence (2 bytes): It indicates the sequence number of
each PASP message.
4.1.1. Capability Negotiation Message
The Negotiation Message is used in the PASP Capability Negotiation
Process. It 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
+--------------------------------+------------------------------+
| Version |A|E| Flag |
+--------------------------------+------------------------------+
| Protocol Capacity |
+---------------------------------------------------------------+
Figure 3. PASP Negotiation Message
* Version (1 byte): It indicates the PASP version. The current
version is 0.
* Flags (1 bytes): Two flag bits are currently defined.
- The A bit is used to indicate if an ACK Message from the remote
PASP speaker is required for each Negotiation Message sent. If
an ACK is required, then the A bit SHOULD be set to "1", and
"0" otherwise.
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- The E bit is used to indicate the enabling/disabling of the
capabilities that carried in the Protocol Capability field. If
the local device wants to inform the remote device of enabling
one or more capabilities, the E bit SHOULD be set to "1". If
the local device wants to inform the remote device of disabling
one or more capabilities, the E bit SHOULD be set to "0".
* Protocol Capability (4 bytes): It is 4-byte bitmap that indicates
the capability of inforamtion exchange regarding various
protocols. Each bit represents one protocol. The following
protocol capability is defined (from the rightmost bit).
- Bit 0: ISIS
- Bit 1: OSPF
- Bit 2: BGP
- Bit 3: LDP
4.2. Request Message
The Request Message is used for the local device to request specific
data regarding one specific protocol or application from the remote
device. It MUST be sent after a successful Capability Negotiation
Process (described in Section 5.1), and the requested protocol/
application MUST be supported by both the local and remote devices,
as indicated in the Negotiation Messages exchanged between the local
and remote devices. It 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
+---------------+----------------+------------------------------+
|A| Flag | Prot. Capb. | Event ID |
+--------------------------------+------------------------------+
| Res. Hop |
+---------------+-----------------------------------------------+
+ Request Data +
~ ~
+---------------------------------------------------------------+
Figure 4. PASP Request Message
* Flags (1 byte): It is currently reserved. The A bit is used to
indicate if an ACK Message from the remote PASP speaker is
required for each Request Message sent. If an ACK is required,
then the A bit SHOULD be set to "1", and "0" otherwise.
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* Capability (1 byte): It represents the bit index of the protocol,
which the Request Message is requesting data for.
* Event ID (2 bytes): It indicates the event number that this
Request message is regarding.
* Residua hop (1 byte): it indicates the residua Request hops of the
current PASP Event. It is reduced by 1 at each PASP speaker when
generating a further PASP Request to a third PASP speaker.
* Request Data (Variable): Specifies information of the data that
the local device is requesting. The specific format remains to be
determined per each protocol, as well as each use case.
4.3. Reply Message
The Reply Message is used to carry the information that the local
device requests from the remote device through the Request Message.
It 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
+---------------+----------------+------------------------------+
|A| Flag | Prot. Capb. | Event ID |
+---------------+----------------+------------------------------+
+ Reply Data +
~ ~
+---------------------------------------------------------------+
Figure 5. PASP Reply Message
* Flags (1 byte): It is currently reserved. The A bit is used to
indicate if an ACK Message from the remote PASP speaker is
required for each Reply Message sent. If an ACK is required, then
the A bit SHOULD be set to "1", and "0" otherwise.
* Capability (1 byte): It represents the bit index of the protocol,
which the Reply Message is replying data for.
* Event ID (2 bytes): It indicates the event number that this Reply
message is regarding.
* Reply Data (Variable): Specifies information of the data that the
local device is replying. The specific format remains to be
determined per each protocol, as well as each use case.
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4.4. Notification Message
The Notification Message is used to carry the information that the
local device sends to the remote device.
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
+---------------+----------------+------------------------------+
|A| Flag | Prot. Capb. | Event ID |
+---------------+----------------+------------------------------+
+ Notification Data +
~ ~
+---------------------------------------------------------------+
Figure 6. PASP Notification Message
* Flags (1 byte): It is currently reserved. The A bit is used to
indicate if an ACK Message from the remote PASP speaker is
required for each Notification Message sent. If an ACK is
required, then the A bit SHOULD be set to "1", and "0" otherwise.
* Capability (1 byte): It represents the bit index of the protocol,
which the Notification Message is notifying for.
* Event ID (2 bytes): It indicates the event number that this
Notification Message is regarding.
* Notification Data (Variable): Specifies information of the data
that the local device is notifying. The specific format remains
to be determined per each protocol, as well as each use case.
4.5. ACK Message
The ACK Message is used to confirm that the remote device has
received a PASP Message with the A bit set to "1". The ACK Message
includes only the PASP Common Header. The Msg. Sequence MUST be set
to the sequence number carried in the received PASP message, which
requires this ACK.
5. PASP Operations
The PASP operations include the following 3 major processes, the
Capability Negotiation Process, the Data Request and Reply Process,
and the Data Notification Process.
5.1. Capability Negotiation Process
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5.1.1. PASP Peering Relation Establish Process
A successful PASP Peering relation MUST be Established between two
PASP speakers before any other PASP process.
As the first step, a Capability Negotiation Message can be initiated
at any time by a PASP speaker,as long as the target PASP peer is IP
reachable. It usually companies the establishment of neighboring/
peering relation between two routing devices. The "A" bit in the
Negotiation Message MUST be set as 1 during the PASP Peering
Establish Process, meaning ACK required. The "E" in the Negotiation
Message MUST be set to 1 during this process, meaning the
capabilities indicated in the Protocol Capability field are enabled
by default. The Protocol Capability field SHOULD indicate all the
protocol capabilities that are supported by the local PASP Agent and
currently enabled. After the first Negotiation Message is sent, the
local device SHUOLD wait for the ACK Message from the remote device
for a certain time period before taking further actions, and if no
ACK Message is received within this time frame, the local device
SHOULD resend the Negotiation Message to the remote device. The
waiting period can be configured locally. This send and wait process
CAN be repeated for at most 3 times before receiving a ACK Message
from the remote device. If after 3 times of resending the
Negotiation Message, still no ACK received, then this peering
establishment is treated as unsuccessful.
The next step for the local PASP speaker is to wait for the
Negotiation Message from the remote PASP speaker. If no Negotiation
Message is received from the remote PASP speaker within a time frame
after its own Negotiation Message is sent , the local PASP speaker
CAN resend the Negotiation Message. This time frame is also
configured locally. This send and wait process CAN be repeated for
at most 3 times before receiving a Negotiation Message from the
remote PASP speaker. If after 3 times of resending the Negotiation
Message, still no Negotiation Message received, then this negotiation
is treated as unsuccessful. If a Negotiation Message is received and
parsed correctly, an ACK MUST be sent to the remote PASP speaker.
Once an ACK Message and a Negotiation Message are received from the
remote PASP speaker and correctly parsed, a PASP Peering relation is
considered as successfully established. The local PASP speaker
maintains locally the protocol capabilities of the remote PASP
speaker, and uses them during other PASP processes.
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5.1.2. PASP Capability Enabling Notification Process
Once the PASP Peering relation is set up between two PASP speakers,
they become PASP peers. Thereafter, any PASP speaker supports a new
protocol capability, it SHOULD call the Capability Enabling
Notification Process to inform all its PASP peers.
When the local PASP speaker initates a PASP Capability Enabling
Notification Process: The "A" bit in the Negotiation Message MUST be
set as 1 during the PASP Capability Enabling Notification Process,
meaning ACK required. The "E" in the Negotiation Message MUST be set
to 1 during this process, meaning the capabilities indicated in the
Protocol Capability field are enabled. The Protocol Capability field
SHOULD indicate all the protocol capabilities that are supported by
the local PASP Agent and currently enabled. After the Negotiation
Message is sent, the local PASP speaker SHUOLD wait for the ACK
Message from the PASP peer for a certain time period before taking
further actions, and if no ACK Message is received within this time
frame, the local device SHOULD resend the Negotiation Message to the
remote device. The waiting period can be configured locally. This
send and wait process CAN be repeated for at most 3 times before
receiving a ACK Message from the remote device. If after 3 times of
resending the Negotiation Message, still no ACK received, then this
Capability Enabling Notification Process is treated as unsuccessful.
This process MAY be intiated at another time thereafter. If a ACK is
received, the Capability Enabling Notification Process is considered
successful.
When a PASP peer initates a PASP Capability Enabling Notification
Process: The local PASP speaker, after receiving the PASP Negotiation
Message and correctly parsing it, sends out an ACK. This Capability
Enabling Notification Process is considered successful. The local
PASP speaker updates the capability status maintained accordingly.
5.1.3. PASP Capability Disabling Notification Process
Whenever a PASP speaker disables a PASP capability, it SHOULD
initiate a PASP Capability Disabling Notification Process to inform
all its PASP peers.
When the local PASP speaker initates a PASP Capability Disabling
Notification Process: The "A" bit in the Negotiation Message MUST be
set as 1 during the PASP Capability Disabling Notification Process,
meaning ACK required. The "E" in the Negotiation Message MUST be set
to 0 during this process, meaning the capabilities indicated in the
Protocol Capability field are disabled. The Protocol Capability
field SHOULD indicate all the protocol capability that is disabled.
After the Negotiation Message is sent, the local PASP speaker SHUOLD
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wait for the ACK Message from the PASP peer for a certain time period
before taking further actions, and if no ACK Message is received
within this time frame, the local device SHOULD resend the
Negotiation Message to the remote device. The waiting period can be
configured locally. This send and wait process CAN be repeated for
at most 3 times before receiving a ACK Message from the remote
device. If after 3 times of resending the Negotiation Message, still
no ACK received, then this Capability Disabling Notification Process
is treated as unsuccessful. This process MAY be intiated at another
time thereafter.
When a PASP peer initates a PASP Capability Disabling Notification
Process: The local PASP speaker, after receiving the PASP Negotiation
Message and correctly parsing it, sends out an ACK. This Capability
Disabling Notification Process is considered successful. The local
PASP speaker updates the capability status maintained accordingly.
5.2. PASP Request and Reply Process
When a local PASP Event triggers a PASP Request and Reply Process,
the local PASP speaker initates a Request Message, and send to a
target PASP peer as indicated by PASP Agent per this PASP Event.
This local PASP speaker is called the Request and Reply Process
Starter. It sets the Residua Hop as the maximum number of Request/
Reply rounds (e.g., 10) it will wait in order to receive the final
Reply. The Event ID and the Request are set by the local PASP Agent.
The A bit of the Request Message MUST be set to "1" (i.e., ACK is
required). The local device waits for the ACK Message from the
remote device for a certain time period before taking further
actions, and if no ACK Message is received within this time frame,
the local device SHOULD resend the Request Message to the remote
device. The waiting period can be configured locally. This send and
wait process CAN be repeated for at most 3 times before receiving a
ACK Message from the remote device. If after 3 times of resending
the Request Message, still no ACK received, then this Request and
Reply Process is treated as unsuccessful. If ACK received, the local
device waits for the Reply Message. If no Reply Message is received
from the remote device within a time frame, the local device can
resend the Request Message. This send and wait process CAN be
repeated for at most 3 times before receiving a Reply Message from
the remote device. If after 3 times of resending the Request
Message, still no Reply Message received, then this Request and Reply
Process is treated as unsuccessful. The waiting period can be
configured locally, and SHOULD take into consideration of the Residua
Hop value. If the Request and Reply Process Starter receives the
Reply Message within the time frame, and the Event ID is matched to
the local PASP Event, the PASP Request and Reply Process is
considered as successful.
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When a local PASP speaker receives a Request Message from its PASP
peer (i.e., it is not the Pequest and Reply Process Starter), it
sends back an ACK Message. With the received Request Message, a new
PASP event it instantiated at the local PASP Agent. The PASP event
triggers the troubleshooting analysis of the received Request
Message, and then generate the Reply Message if the Reply condition
is met, or generate a new Request Message when the Reply condition is
not met. The Reply condition and the troubleshooting analysis of the
PASP Agent is out of the scope of this document.
If the Reply condition is met, the local PASP speaker is called the
Request and Reply Process Terminator. It generates the Reply Message
and send the message back to the requesting PASP peer. The Event ID
is set to be the same as the Event ID of the received Request
Message. The Reply Data is set by the local PASP Agent per this
generated event. The A bit of the Reply Message MUST be set to "1"
(i.e., ACK is required). The local device waits for the ACK Message
from the remote device for a certain time period before taking
further actions, and if no ACK Message is received within this time
frame, the local device SHOULD resend the Reply Message to the remote
device. The waiting period can be configured locally. This send and
wait process CAN be repeated for at most 3 times before receiving a
ACK Message from the remote device. If after 3 times of resending
the Request Message, still no ACK received, then this Request and
Reply Process is treated as unsuccessful.
If the Reply condition is not met, the local PASP speaker is called
the Request and Reply Process mid-handler. It generates a new
Request Message and send the message to a third PASP speaker per
indicated by the local PASP Agent per this generated event. In the
new generated Request Message, the Residua Hop value by MUST be
reduced by 1. The A bit of the Request Message MUST be set to "1"
(i.e., ACK is required). The local device waits for the ACK Message
from the remote device for a certain time period before taking
further actions, and if no ACK Message is received within this time
frame, the local device SHOULD resend the Request Message to the
remote device. The waiting period can be configured locally. This
send and wait process CAN be repeated for at most 3 times before
receiving a ACK Message from the remote device. If after 3 times of
resending the Request Message, still no ACK received, then this
Request and Reply Process is treated as unsuccessful. If ACK
received, the local device waits for the Reply Message. If no Reply
Message is received from the remote device within a time frame, the
local device can resend the Request Message. This send and wait
process CAN be repeated for at most 3 times before receiving a Reply
Message from the remote device. If after 3 times of resending the
Request Message, still no Reply Message received, then this Request
and Reply Process is treated as unsuccessful. The waiting period can
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be configured locally, and SHOULD take into consideration of the
Residua Hop value. If the local device receives the Reply Message
within the time frame, it generates a new Reply Message and sends
back to it requesting PASP peer. The Event ID of the new Reply
Message is set to be the same as the Event ID of the received Request
Message.
5.3. PASP Notification Process
When a local PASP Event triggers a PASP Notification Process, the
local PASP speaker initates a Notification Message. The target PASP
peer(s) is/are selected by the PASP agent regarding the current PASP
Event, which is out of the scope of this document. The Notification
Message may or may not require an ACK Message, as indicated in the
Notification Message. If the A bit is set to 1 (meaning ACK
required), the local device waits for the ACK Message from the remote
device for a certain time period before taking further actions, and
if no ACK Message is received within this time frame, the local
device SHOULD resend the Notification Message to the remote device.
The waiting period can be configured locally. This send and wait
process CAN be repeated for at most 3 times before receiving a ACK
Message from the remote device. If after 3 times of resending the
Request Message, still no ACK received, then this Request and Reply
Process is treated as unsuccessful. The waiting period can be
configured locally. If ACK is received within the time frame, the
Notification Process is considered to be successful. If the A bit is
set to 0 (meaning no ACK required), after sending the Notification
Message, the Notification Process is considered successful.
6. PASP Error Handling
When any PASP process is unsuccessful, information is recorded or not
by local PASP Agent. No further action is taken.
7. Discussion
In addition to the preceding message definition and process
description, the security and reliability requirements of the PASP
need to be considered. There are two possible options to implement
PASP.
- Option 1: PASP is developed independently as a new protocol.
- Option 2: PASP reuses the existing protocol Generic Autonomic
Signaling Protocol(GRASP) [RFC8990] .
Option1:
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1. Definition of the Message Format and Interaction Process: It can
be defined independently in the PASP.
2. Reliability: The transmission mode of PASP is based on UDP mainly
considering that the collected information is the auxiliary
information to help locate the protocol fault, and the information
loss has no impact on the service. In addition, if TCP mode is
adopted, the resource consumption of the device may be large,
especially when there area large number of neighbors. If it is
considered that PASP must ensure reliability, it can done in the
application layer, such as adding the sequence number to the message.
3. Security: MD5 authentication can be introduced for PASP security.
Option2:
ANIMA GRASP is a signaling protocol used for dynamic peer discovery,
status synchronization, and parameter negotiation between AS nodes or
AS service agents. GRASP specifies that unicast packets must be
transmitted based on TCP, and multicast packets (Discovery and Flood)
must be transmitted based on UDP.
1. Message format and interaction process: PASP can reuse the
defined messages and procedures of the GRASP. Messages defined in
the PASP include Capability Negotiation Message, Request Message,
Reply Message, and Negotiation Message. These message types are also
defined in GRASP.
2. Reliability: TCP mode of GRASP can be used to ensure reliability
for PASP. But there may be some challenges for the equipment
resources.
3. Security: Autonomic Control Plane(ACP) [RFC8994] can be reused.
8. Security Considerations
TBD
9. IANA Considerations
TBD
10. Contributors
We thank Jiaqing Zhang (Huawei), Tao Du (Huawei) and Lei Li (Huawei)
for their contributions.
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11. Acknowledgments
12. References
12.1. Normative References
[RFC1191] Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191,
DOI 10.17487/RFC1191, November 1990,
<https://www.rfc-editor.org/info/rfc1191>.
[RFC1195] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and
dual environments", RFC 1195, DOI 10.17487/RFC1195,
December 1990, <https://www.rfc-editor.org/info/rfc1195>.
[RFC1213] McCloghrie, K. and M. Rose, "Management Information Base
for Network Management of TCP/IP-based internets: MIB-II",
STD 17, RFC 1213, DOI 10.17487/RFC1213, March 1991,
<https://www.rfc-editor.org/info/rfc1213>.
[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>.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001,
<https://www.rfc-editor.org/info/rfc3209>.
[RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
and A. Bierman, Ed., "Network Configuration Protocol
(NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
<https://www.rfc-editor.org/info/rfc6241>.
[RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and
S. Ray, "North-Bound Distribution of Link-State and
Traffic Engineering (TE) Information Using BGP", RFC 7752,
DOI 10.17487/RFC7752, March 2016,
<https://www.rfc-editor.org/info/rfc7752>.
[RFC7854] Scudder, J., Ed., Fernando, R., and S. Stuart, "BGP
Monitoring Protocol (BMP)", RFC 7854,
DOI 10.17487/RFC7854, June 2016,
<https://www.rfc-editor.org/info/rfc7854>.
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[RFC8641] Clemm, A. and E. Voit, "Subscription to YANG Notifications
for Datastore Updates", RFC 8641, DOI 10.17487/RFC8641,
September 2019, <https://www.rfc-editor.org/info/rfc8641>.
[RFC8990] Bormann, C., Carpenter, B., Ed., and B. Liu, Ed., "GeneRic
Autonomic Signaling Protocol (GRASP)", RFC 8990,
DOI 10.17487/RFC8990, May 2021,
<https://www.rfc-editor.org/info/rfc8990>.
[RFC8994] Eckert, T., Ed., Behringer, M., Ed., and S. Bjarnason, "An
Autonomic Control Plane (ACP)", RFC 8994,
DOI 10.17487/RFC8994, May 2021,
<https://www.rfc-editor.org/info/rfc8994>.
12.2. References
[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. L., and remy@barefootnetworks.com,
"Requirements for In-situ OAM", Work in Progress,
Internet-Draft, draft-brockners-inband-oam-requirements-
03, 13 March 2017, <https://datatracker.ietf.org/doc/html/
draft-brockners-inband-oam-requirements-03>.
[I-D.song-ntf]
Song, H., Zhou, T., Li, Z., Fioccola, G., Li, Z.,
Martinez-Julia, P., Ciavaglia, L., and A. Wang, "Toward a
Network Telemetry Framework", Work in Progress, Internet-
Draft, draft-song-ntf-02, 2 July 2018,
<https://datatracker.ietf.org/doc/html/draft-song-ntf-02>.
[RFC1157] Case, J., Fedor, M., Schoffstall, M., and J. Davin,
"Simple Network Management Protocol (SNMP)", RFC 1157,
DOI 10.17487/RFC1157, May 1990,
<https://www.rfc-editor.org/info/rfc1157>.
[RFC3988] Black, B. and K. Kompella, "Maximum Transmission Unit
Signalling Extensions for the Label Distribution
Protocol", RFC 3988, DOI 10.17487/RFC3988, January 2005,
<https://www.rfc-editor.org/info/rfc3988>.
Authors' Addresses
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Zhenbin Li
Huawei
156 Beiqing Rd
Beijing
China
Email: lizhenbin@huawei.com
Shuanglong Chen
Huawei
156 Beiqing Road
Beijing,100095
China
Email: chenshuanglong@huawei.com
Zhen Tan
Huawei
156 Beiqing Rd
Beijing
China
Email: tanzhen6@huawei.com
Yingzhen Qu
Futurewei
Email: yingzhen.qu@futurewei.com
Yunan Gu
Huawei
156 Beiqing Rd
Beijing
China
Email: guyunan@huawei.com
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