Configuring ISL Trunks on Cisco Routers

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Updated:August 30, 2005

Document ID:17051

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Introduction

Prerequisites

Requirements

Components Used

Conventions

Background Information

Configurations

Debug and Troubleshoot

Related Information

Introduction

This document discusses the configuration of Inter-Switch Link Protocol (ISL) trunks on external Cisco routers like the 7500/7000, 3600, 4500, or 2500 series. This document does not discuss the configuration of ISL trunks on Layer 2 (L2)/Layer 3 (L3) switches like the Cisco Catalyst 6500 or 4500.

For information on configuring ISL and 802.1Q trunks between Catalyst L2 and L3 switches that run Catalyst OS (CatOS) or Cisco IOS® Software, refer to either of these: