Transparent Interconnection of Lots of Links (TRILL): MTU Negotiation
RFC 8249
Internet Engineering Task Force (IETF) M. Zhang
Request for Comments: 8249 X. Zhang
Updates: 6325, 7177, 7780 D. Eastlake 3rd
Category: Standards Track Huawei
ISSN: 2070-1721 R. Perlman
Dell EMC
S. Chatterjee
Cisco
September 2017
Transparent Interconnection of Lots of Links (TRILL):
MTU Negotiation
Abstract
The base IETF TRILL (Transparent Interconnection of Lots of Links)
protocol has a TRILL campus-wide MTU feature, specified in RFCs 6325
and 7177, that assures that link-state changes can be successfully
flooded throughout the campus while being able to take advantage of a
campus-wide capability to support jumbo packets. This document
specifies recommended updates to that MTU feature to take advantage,
for appropriate link-local packets, of link-local MTUs that exceed
the TRILL campus MTU. In addition, it specifies an efficient
algorithm for local MTU testing. This document updates RFCs 6325,
7177, and 7780.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc8249.
Zhang, et al. Standards Track [Page 1]
RFC 8249 MTU Negotiation September 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
(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 extracted from this document must
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 ....................................................3
1.1. Conventions Used in This Document ..........................3
2. Link-Wide TRILL MTU Size ........................................4
2.1. Operations .................................................5
3. Testing Link MTU Size ...........................................6
4. Refreshing Sz ...................................................8
5. Relationship between Port MTU, Lz, and Sz .......................9
6. LSP Synchronization ............................................10
7. Recommendations for Traffic Link Testing of MTU Size ...........10
8. Backward Compatibility .........................................11
9. Security Considerations ........................................11
10. Additions to Configuration ....................................12
10.1. Per-RBridge Configuration ................................12
10.2. Per-RBridge Port Configuration ...........................12
11. IANA Considerations ...........................................12
12. References ....................................................12
12.1. Normative References .....................................12
12.2. Informative References ...................................14
Acknowledgements ..................................................14
Authors' Addresses ................................................14
Zhang, et al. Standards Track [Page 2]
RFC 8249 MTU Negotiation September 2017
1. Introduction
[RFC6325] describes the way RBridges agree on the campus-wide minimum
acceptable inter-RBridge MTU (Maximum Transmission Unit) size (called
"Sz") to ensure that link-state flooding operates properly and all
RBridges converge to the same link state. For the proper operation
of TRILL (Transparent Interconnection of Lots of Links) IS-IS, all
RBridges format their Link State Protocol Data Units (LSPs) to fit
in Sz.
[RFC7177] diagrams the state transitions of an adjacency. If MTU
Show full document text