... © 2002, Cisco Systems, Inc. All rights reserved. ICND v2.0— 4-1 0Importance of Native VLANs© 2002, Cisco Systems, Inc. All rights reserved. ICND v2.0— 4-1 1802.1Q Frame© 2002, Cisco Systems, ... switches, and between routers and switchesISL trunks enable VLANs across a backbone.ISL Tagging© 2002, Cisco Systems, Inc. All rights reserved. ICND v2.0— 4-1 4ISL Encapsulation© 2002, Cisco Systems, ... routers, and for defining VLAN topologies. © 2002, Cisco Systems, Inc. All rights reserved.© 2002, Cisco Systems, Inc. All rights reserved. ICND v2.0— 4-2 0Summary (Cont.)•ISL is a Cisco proprietary...