Configuring Basic Ipv4 Is-Is Functions - Huawei Quidway NetEngine80E Configuration Manual

HUAWEI NetEngine80E/40E Router
Configuration Guide - IP Routing
IS-IS Three-Way Handshake
A reliable link layer protocol is required when IS-IS runs on a point-to-point (P2P) link. Based
on ISO 10589, the two-way handshake mechanism of IS-IS uses Hello packets to set up P2P
adjacencies between neighboring routers. Once the router receives a Hello packet from its peer,
it regards the status of the peer as Up and sets up an adjacency with the peer.
This mechanism has obvious defects. For example, when an adjacency is set up, the unstable
link status causes the loss of Complete Sequence Number Packets (CSNPs). As a result, the
LSDB fails to be synchronized during the update period of an LSP. If two or more links exist
between two routers, an adjacency can still be set up when one link is Down and the other is Up
in the same direction. The parameters of the other link, however, are also used in SPF calculation.
Therouter does not detect any fault of the link that is in the Down state and still tries to forward
packets over this link.
The three-way handshake mechanism addresses the problem on the unreliable P2P link. In three-
way handshake mode, the router regards the neighbor as Up only after confirming that the
neighbor receives the packet that it sends and then sets up an adjacency with the neighbor. In
addition, a 32-bit circuit ID is used in the three-way handshake mechanism, which is an extension
of the local 8-bit circuit ID that defines 255 P2P links.

7.2 Configuring Basic IPv4 IS-IS Functions

This section describes the procedures for configuring basic IPv4 IS-IS functions, including the
procedures for configuring IS-IS processes and interfaces, to implement communication
between nodes on an IPv4 IS-IS network.
7.2.1 Before You Start
Before configuring basic IPv4 IS-IS functions, familiarize yourself with the usage scenario,
complete the pre-configuration tasks, and obtain the required data.
Applicable Environment
To deploy IS-IS on an IPv4 network, configure basic IS-IS functions to implement
communication between different nodes on the network.
Other IS-IS functions can be configured only after basic IS-IS functions are configured.
Configuring basic IPv4 IS-IS functions includes the following operations:
1.
2.
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IS, but helps IS-IS to detect the faults on neighbors or links more quickly, and instruct IS-
IS to recalculate routes to correctly guide packet forwarding.
The NE80E/40E supports dynamic IPv4 and IPv6 BFD for IS-IS.
NOTE
For details about IS-IS GR, see the "IS-IS" chapter in the HUAWEI NetEngine80E/40E Router
Feature Description-IP Routing.
Create IPv4 IS-IS processes.
Configure IPv4 IS-IS interfaces.
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