Passive Interface Attribute
draft-wang-lsr-passive-interface-attribute-06
LSR Working Group A. Wang
Internet-Draft China Telecom
Intended status: Standards Track Z. Hu
Expires: May 19, 2021 Huawei Technologies
G. Mishra
Verizon Inc.
November 15, 2020
Passive Interface Attribute
draft-wang-lsr-passive-interface-attribute-06
Abstract
This document describes the mechanism that can be used to
differentiate the passive interfaces from the normal interfaces
within ISIS or OSPF domain.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions used in this document . . . . . . . . . . . . . . 3
3. Consideration for flagging passive interface . . . . . . . . 3
4. Passive Interface Attribute . . . . . . . . . . . . . . . . . 4
4.1. OSPFv2 Extended Stub-Link TLV . . . . . . . . . . . . . . 4
4.2. OSPFv3 Router-Stub-Link TLV . . . . . . . . . . . . . . . 5
4.3. ISIS Stub-link TLV . . . . . . . . . . . . . . . . . . . 6
4.4. Stub-Link Prefix Sub-TLV . . . . . . . . . . . . . . . . 6
5. Security Considerations . . . . . . . . . . . . . . . . . . . 7
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
7. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 8
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
8.1. Normative References . . . . . . . . . . . . . . . . . . 8
8.2. Informative References . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction
Passive interfaces are used commonly within an operators enterprise
or service provider networks. One of the most common use cases for
passive interface is in a data center Layer 2 and Layer 3 Top of
Rack(TOR) switch where the inter connected links between the TOR
switches and uplinks to the Core switch are only a few links and a
majority of the links are Layer 3 VLAN switched virtual interface
trunked between the TOR switches serving Layer 2 broadcast domains.
In this scenario all the VLANs are made passive as it is recommended
to limit the number of network LSAs between routers and switches to
avoid unnecessary hello processing overhead.
Another common use case is an inter-as routing scenario where the
same routing protocol but different IGP instance is running between
the adjacent BGP domains. Using passive interface on the inter-as
connections can ensure that prefixes contained within a domain are
only reachable within the domain itself and not allow the link state
database to be merged between domain which could result in
undesirable consequences.
For operator which runs different IGP domains that interconnect with
each other via the passive interfaces, there is desire to obtain the
inter-as topology information as described in
[I-D.ietf-idr-bgpls-inter-as-topology-ext]. If the router that runs
BGP-LS within one IGP domain can distinguish passive interfaces from
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