1-Apricot 2015-Cisco ISIS Fundamentals & Troubleshooting.pptx

126 Pages·2015·3.29 MB·English

MPLS
Workshop
ISIS Fundamentals and
Troubleshooting
BRKRST-2327

MPLS
Workshop
ISIS Fundamentals and Troubleshooting
Agenda
•  Overview
Reference slide
•  Hierarchical Areas
•  Addressing
•  MTU and Hello Padding
•  Attach-bit and Route Leaking
•  LSP Flooding and Convergence
•  SPF and Network Stability
•  Route Redistribution

•  Narrow and Wide Metrics MPLS
Workshop
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What Is IS-IS?
•  Intermediate System to Intermediate System
•  An “IS” is ISO terminology for a router
•  IS-IS was originally designed as a dynamic routing protocol for ISO CLNP,
defined in the ISO 10589 standard
•  Also called as “Integrated IS-IS” or “Dual IS-IS”

MPLS
•  Encodes the packet(s) in TLV ( Type, Length, Value ) format
Workshop
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IS-IS for IP Routing
•  Easily adapted to carry IP prefix information, as specified in RFC1195
•  Flexible protocol in terms of tuning and easily extensible with to new features with
TLVs
- IS-IS extensions for MPLS -TE, IPv6
•  It runs directly over Layer 2
•  Proven to be a very stable and scalable, with very fast convergence

MPLS
Workshop
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Encapsulation of IS-IS
§  IS-IS is not encapsulated in IP!
§  Encapsulated directly in the data link layer
§  Protocol family is OSI: 0xFEFE is used in layer 2 headers to identify it

Data-link header IS-IS fixed header
IS-IS:
IS-IS TLVs
(OSI family 0xFEFE) (first byte is 0x83)

MPLS
Workshop
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ISIS Fundamentals and Troubleshooting
Agenda
§  Overview
§  IS-IS Hierarchical Areas
§  Addressing
§  MTU and Hello Padding
§  Attach-bit and Route Leaking
§  LSP Flooding and Convergence
§  SPF and Network Stability
§  Route Redistribution

MPLS
§  Narrow and Wide Metrics
Workshop
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ISIS Fundamentals and Troubleshooting
Flow of the presentation
Troubleshooting Scenario Solution to the Scenario
Related Fundamentals

MPLS
Workshop
LTRARC-2002 © 2015 Cisco and/or its affiliates. All rights reserved. Cisco Public 8
Scenario 1 :
R2 and R4 Peering showing as ES-IS instead of IS-IS?
area 49.0001
area 49.0002
L1L2 L1 L1L2 L1L2
R1 E0/0 E0/0 R2 S3/0 S3/0 R4 E1/0 E1/0 R5
R2#show clns neighbors
System Id Interface SNPA State Holdtime Type
Protocol
R1 Et0/0 00d0.58eb.ff01 Up 26 L1 IS-IS
R4 Se3/0 *HDLC* Up 280 IS ES-IS

MPLS
Workshop
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Hierarchy Levels
•  IS-IS presently has a two-layer hierarchy
– The backbone (level 2)
– The areas (level 1)

•  An IS (router) can be either:
– Level 1 router (intra-area routing)
– Level 2 router (inter-area routing)
– Level 1–2 router (intra and inter-area routing)

MPLS
Workshop
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