Internet DRAFT - draft-yue-lsr-loop-detection-for-imported-routes
draft-yue-lsr-loop-detection-for-imported-routes
Network Working Group Z. Yue
Internet-Draft G. Xu
Intended status: Standards Track C. Li
Expires: 27 March 2023 H. Li
Huawei
23 September 2022
Loop detection for imported routes
draft-yue-lsr-loop-detection-for-imported-routes-00
Abstract
Mutual route import between two IGP instances is often involved in
networking solutions. However, routing loops may occur when route
are imported to an instance from another and cause critical problem.
This document provides a way to detect routing loop and introduces
new sub-TLVs to support advertisement IPv4 and IPv6 prefix extended
attribute flags and the source router ID of the router which import
the route and redistribute the route.
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 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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Drafts is at https://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 27 March 2023.
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Copyright Notice
Copyright (c) 2022 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 Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Prefix Redistribute-list Sub-TLV Details . . . . . . . . . . 3
2.1. The IS-IS Prefix Redistribute-list Sub-TLV . . . . . . . 3
2.2. The OSPF Prefix Redistribute-list Sub-TLV . . . . . . . . 4
3. Enabling and Disabling Sub-TLVs . . . . . . . . . . . . . . . 4
4. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
6. Security Considerations . . . . . . . . . . . . . . . . . . . 4
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 4
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
As dynamic routing protocols, IS-IS and OSPF are widely used on live
networks. Mutual route import between two IGP instances is often
involved in networking solutions. However, restricted routing policy
need to be configred on the router, otherwise, routing loops may
occur and cause critical problem.
When a route is imported to an IGP instance, if the IGP instance can
recognize the route has already been redistributed by itself and
notice that there might be routing loops in the network, the router
can take some actions to avoid or fix futher potential routing
problems.
Therefore, new sub-TLVs are introduced to support advertisement IPv4
and IPv6 prefix extended attribute flags and the source router ID of
the router which has redistributed the prefix.
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2. Prefix Redistribute-list Sub-TLV Details
When a routing prefix is imported to an IGP instance and
redistributed by the instance to other IGP areas, the router ID of
this IGP instance will be added to the redistribute list of the
prefix and advertised in IGP areas.
The following sections describe how the redistribute list for a route
prefix is advertised in IGP areas.
2.1. The IS-IS Prefix Redistribute-list Sub-TLV
This document registers a new IS-IS sub-TLV in the "Sub-TLVs for TLVs
135, 235, 236 and 237" registry. This new sub-TLV provides ways to
advertise IPv4 and IPv6 prefix extended attribute flags and the
router ID of the router which redistributed the prefix.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ Router ID +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Prefix Redistribute-list Sub-TLV
Type: 10
Length: 1 + Router-ID length.
Flags: 1 octet. The following flags are defined:
0
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|S|R| Reserved |
+-+-+-+-+-+-+-+-+
Figure 2: Flags
where:
S-flag: If set, the prefix has be redistributed by the router that
generate the current LSP.
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R-flag: If set, the prefix has be redistributed by the router other
than the router that generate current LSP.
Router ID: 6 octets. IS-IS System-ID as defined in [ISO10589].
This sub-TLV is optional.
If the sub-Tlv length is equal to one, R-flag MUST be treated as if
it is set to 0 on receipt. Undefined bits that are transmitted MUST
be transmitted as 0 and MUST be ignored on receipt.
2.2. The OSPF Prefix Redistribute-list Sub-TLV
TBD.
3. Enabling and Disabling Sub-TLVs
Implementations MUST make it possible to enable or disable the sub-
TLV based on configuration.
4. Acknowledgements
TBD.
5. IANA Considerations
This document requests that IANA allocates new sub-TLV types from the
IS-IS "Sub-TLVs for TLVs 135, 235, 236 and 237)" registry as
specified.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ Router ID +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: IS-IS Prefix Redistribute-list Sub-TLV
6. Security Considerations
These extensions to IS-IS do not add any new security issues to the
existing IGP.
7. References
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Authors' Addresses
Zhuo Yue
Huawei
Huawei Bld., No.156 Beiqing Rd.
Beijing
100095
China
Email: yuezhuo@huawei.com
GuoQi Xu
Huawei
Huawei Bld., No. 156 Beiqing Rd.
Beijing
100095
China
Email: xuguoqi@huawei.com
ChenXi Li
Huawei
Huawei Bld., No. 156 Beiqing Rd.
Beijing
100095
China
Email: lichenxi1@huawei.com
HaiChao Li
Huawei
Huawei Bld., No.156 Beiqing Rd.
Beijing
100095
China
Email: tide.li@huawei.com
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