IS-IS Flooding Scale Considerations
draft-ginsberg-lsr-isis-flooding-scale-01
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Networking Working Group L. Ginsberg
Internet-Draft P. Psenak
Intended status: Informational A. Lindem
Expires: May 24, 2020 Cisco Systems
November 21, 2019
IS-IS Flooding Scale Considerations
draft-ginsberg-lsr-isis-flooding-scale-01
Abstract
Link State PDU flooding rates in use are much slower than what modern
networks can support. The use of IS-IS at larger scale requires
faster flooding rates to achieve desired convergence goals. This
document discusses issues associated with increasing flooding rates
and some recommended practices which allow faster flooding rates to
be used safely.
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.
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 May 24, 2020.
Ginsberg, et al. Expires May 24, 2020 [Page 1]
Internet-Draft draft-ginsberg-lsr-isis-flooding-scale November 2019
Copyright Notice
Copyright (c) 2019 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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Historical Behavior . . . . . . . . . . . . . . . . . . . . . 3
3. Flooding Rate and Convergence . . . . . . . . . . . . . . . . 4
3.1. Flow Control . . . . . . . . . . . . . . . . . . . . . . 5
3.2. Bandwidth Utilization . . . . . . . . . . . . . . . . . . 6
3.3. Packet Prioritization on Receive . . . . . . . . . . . . 7
4. Minimizing LSP Generation . . . . . . . . . . . . . . . . . . 7
5. Redundant Flooding . . . . . . . . . . . . . . . . . . . . . 9
6. Use of Jumbo Frames . . . . . . . . . . . . . . . . . . . . . 9
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
8. Security Considerations . . . . . . . . . . . . . . . . . . . 10
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
10.1. Normative References . . . . . . . . . . . . . . . . . . 10
10.2. Informative References . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction
Link state IGPs such as Intermediate-System-to-Intermediate-System
(IS-IS) depend upon having consistent Link State Databases (LSDB) on
all Intermediate Systems (ISs) in the network in order to provide
correct forwarding of data packets. When topology changes occur,
new/updated Link State PDUs (LSPs) are propagated network-wide. The
speed of propagation is a key contributor to convergence time.
Historically, flooding rates have been conservative - on the order of
10s of LSPs/second. This derives from guidance in the base
specification [ISO10589] and early deployments when both CPU speeds
and interface speeds were much slower than they are today and the
scale of an IS-IS area was smaller than it may be today.
Ginsberg, et al. Expires May 24, 2020 [Page 2]
Internet-Draft draft-ginsberg-lsr-isis-flooding-scale November 2019
As IS-IS is deployed in greater scale (larger number of nodes in an
area and larger number of neighbors/node) the impact of the historic
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