Link State Routing A. Retana
Internet-Draft L. Han
Intended status: Standards Track Futurewei Technologies, Inc.
Expires: 8 September 2022 7 March 2022
OSPF Monitor Node
draft-retana-lsr-ospf-monitor-node-00
Abstract
This document specifies mechanisms that allow a node to monitor an
OSPF network actively without influencing the topology or affecting
its stability.
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Router Interface Parameters . . . . . . . . . . . . . . . . . 3
3. Monitoring Interface . . . . . . . . . . . . . . . . . . . . 3
4. The Monitor Node Option . . . . . . . . . . . . . . . . . . . 4
5. Operational Considerations . . . . . . . . . . . . . . . . . 4
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
8. Security Considerations . . . . . . . . . . . . . . . . . . . 5
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
9.1. Normative References . . . . . . . . . . . . . . . . . . 5
9.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
Monitoring the control plane activity in a network is essential to
designing and maintaining a robust and stable network. Passive
(listen- only) devices deployed in broadcast or non-broadcast multi-
access (NBMA) networks have typically satisfied the need. However,
passive devices depend on more than two routers being present in the
network and are not visible to the network operator -- anyone can
listen.
An alternative implementation, primarily used in point-to-point
interfaces, or in cases where the listening device is the only other
node on the interface, is to participate fully in the protocol:
create a full adjacency with the closest router, participate in
designated router (DR) election, etc. The node is now visible in the
network, can advertise control plane information, and any changes in
its status are flooded throughout the network. Many link state
advertisements (LSA) or state changes can cause instability in the
network, and additional configuration is usually needed to avoid the
device becoming a transit node.
This document specifies mechanisms that allow a node to monitor OSPF
activity without influencing the topology or affecting its stability
while being fully adjacent and known to the network operator. These
nodes are referred to as a Monitor Node. Two such mechanisms are
introduced:
Section 3 describes a local implementation to be used in the case
where the Monitor Node is the only other router on an interface.
Section 4 specifies signaling in the Hello message for a node to
communicate its intention to become a Monitor Node.
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The mechanisms presented apply to both OSPFv2 [RFC2328] and OSPFv3
[RFC5340]. The term OSPF is used to refer to both versions.
1.1. Requirements Language
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
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. Router Interface Parameters
This document defines the following router interface configurable
parameters:
DoNotAdvertiseLink
Indicates whether or not the link is advertised on the local
router-LSA. If set to "enabled," the router MUST NOT include
a corresponding interface description in its router-LSA. The
router MUST NOT originate other LSAs related to the link or
its addresses. Enabling this interface parameter overrides
the setting of LinkLSASuppression [RFC5340].
DoNotRequestAndIgnoreLSAs
Indicates whether or not the router should request and use
LSAs from other routers on this interface. If set to
"enabled," the router MUST consider its Link state request
list empty. Also, the router MUST consider the LS age of any
received LSA to be equal to MaxAge and process it according
to Section 13 of [RFC2328].
3. Monitoring Interface
By using the interface parameters specified in Section 2, a router
can treat all neighbors on the interface as Monitor Nodes. To do so,
DoNotAdvertiseLink and DoNotRequestAndIgnoreLSAs SHOULD be configured
simultaneously. If either parameter is configured on a broadcast or
NBMA interface, the router MUST NOT participate in the Designated
Router (DR) selection process.
Enabling DoNotAdvertiseLink by itself results in any LSAs originated
by the Monitor Node not being resolved in the routing table.
If only DoNotRequestAndIgnoreLSAs is enabled, the router MUST treat
the link as a stub network. Note that the neighbor information
(corresponding to the Monitor Node) is not advertised.
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4. The Monitor Node Option
This document defines a new Option in the Extended Options and Flags
(EOF) Link-Local Signaling (LLS) TLV [RFC5613]. The new option is
called Monitor (M-bit) and has a value of TBD.
When set, the M-bit indicates that the originating router is a
Monitor Node. Other routers on the same link MUST:
* Consider the Monitor Node ineligible for the DR selection process.
* Consider its Link state request list empty with respect to the
Monitor Node.
* Consider the LS age of any LSA received from the Monitor Node is
equal to MaxAge.
If the Monitor Node is one of only two routers on an interface, the
other router MUST NOT include a corresponding interface description
in its router-LSA. Furthermore, other LSAs related to the link or
its addresses MUST NOT be originated. This situation overrides the
setting of LinkLSASuppression.
5. Operational Considerations
The use of the monitoring interface (Section 3) applies to all other
routers on the same interface. While the Monitor Node option
(Section 4) applies to only the router signaling the M-bit. Network
administrators should use the Monitor Node option in transit
interfaces where one router is a Monitor Node.
If the Monitor Node is the only other router on an interface, the
link information can be advertised (as a stub link) if only
DoNotRequestAndIgnoreLSAs is enabled.
The deployment of the Monitoring Interface (Section 3) requires that
only the non-Monitor Node supports this specification. On the other
hand, the Monitor Node Option (Section 4) requires all nodes on the
interface to support the functionality. If support is not present in
all the routers on the link, the Monitor Node will be eligible to be
a DR, and its information may be flooded through the network.
6. Acknowledgements
TBD
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7. IANA Considerations
IANA is requested to allocate a value (TBD) from the "LLS Type 1
Extended Options and Flags" registry for the M-bit (Section 4).
8. Security Considerations
The security considerations documented in [RFC2328], [RFC5340], and
[RFC5613] apply to this extension.
This document defines a new type of node, called a Monitor Node,
intended only to receive information from its neighbors and not send
any. If the LSAs from the Monitor Node are not ignored, they will be
flooded throughout the network. A rouge Monitor Node may advertise
LSAs with an Advertising Router field that doesn't correspond to its
router ID. This type of vulnerability is not new, but it is already
present in the base specification.
Even though it is expected that the local network operator deploys
any Monitor Node, authentication mechanisms such as those specified
in [RFC5709], [RFC7474], [RFC4552], or [RFC7166] SHOULD be used.
9. References
9.1. Normative References
[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>.
[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328,
DOI 10.17487/RFC2328, April 1998,
<https://www.rfc-editor.org/info/rfc2328>.
[RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF
for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008,
<https://www.rfc-editor.org/info/rfc5340>.
[RFC5613] Zinin, A., Roy, A., Nguyen, L., Friedman, B., and D.
Yeung, "OSPF Link-Local Signaling", RFC 5613,
DOI 10.17487/RFC5613, August 2009,
<https://www.rfc-editor.org/info/rfc5613>.
[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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9.2. Informative References
[RFC4552] Gupta, M. and N. Melam, "Authentication/Confidentiality
for OSPFv3", RFC 4552, DOI 10.17487/RFC4552, June 2006,
<https://www.rfc-editor.org/info/rfc4552>.
[RFC5709] Bhatia, M., Manral, V., Fanto, M., White, R., Barnes, M.,
Li, T., and R. Atkinson, "OSPFv2 HMAC-SHA Cryptographic
Authentication", RFC 5709, DOI 10.17487/RFC5709, October
2009, <https://www.rfc-editor.org/info/rfc5709>.
[RFC7166] Bhatia, M., Manral, V., and A. Lindem, "Supporting
Authentication Trailer for OSPFv3", RFC 7166,
DOI 10.17487/RFC7166, March 2014,
<https://www.rfc-editor.org/info/rfc7166>.
[RFC7474] Bhatia, M., Hartman, S., Zhang, D., and A. Lindem, Ed.,
"Security Extension for OSPFv2 When Using Manual Key
Management", RFC 7474, DOI 10.17487/RFC7474, April 2015,
<https://www.rfc-editor.org/info/rfc7474>.
Authors' Addresses
Alvaro Retana
Futurewei Technologies, Inc.
2330 Central Expressway
Santa Clara, CA 95050
United States of America
Email: aretana@futurewei.com
Lin Han
Futurewei Technologies, Inc.
2330 Central Expressway
Santa Clara, CA 95050
United States of America
Email: lin.han@futurewei.com
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