© 1999, Cisco Systems, Inc. 4-1 Chapter 10 Controlling Campus Device Access Chapter 4 Defining Common Workgroups © 1999, Cisco Systems, Inc. 10-1

© 1999, Cisco Systems, Inc. BCMSN—4-2 Objectives Upon completion of this chapter, you will be able to perform the following tasks: Given a network diagram of your switch block, correctly associate VLANs and port numbers Enable a single physical connection to carry multiple VLANs Ensure broadcast integrity by establishing VLANs in the switch block Maintain VLAN configuration consistency using VTP domains

© 1999, Cisco Systems, Inc. BCMSN—4-3 Defining the Common Workgroup In this chapter, we discuss the following topics: VLANs VLAN identification VLAN Trunk Protocol

© 1999, Cisco Systems, Inc. BCMSN—4-4 Defining the Common Workgroup (cont.) In this section we discuss the following topics: VLANs –VLAN Review –VLAN Boundaries –Establishing VLAN membership –Configuring VLANs VLAN Identification VLAN Trunk Protocol

© 1999, Cisco Systems, Inc. BCMSN—4-5 Ethernet Broadcast Domain In a flat network, every device sees every transmitted packet

© 1999, Cisco Systems, Inc. BCMSN—4-6 VLANs A VLAN is a broadcast domain

© 1999, Cisco Systems, Inc. BCMSN—4-7 VLANs Establish Broadcast Domains VLANs plus routers limit broadcasts to the domain of origin Broadcast Domain 1 Broadcast Domain 2

© 1999, Cisco Systems, Inc. BCMSN—4-8 Scaling the Switch Block with VLANs Decisions include how many VLANs there are in a switch block and where these devices are placed Server BlockCore

© 1999, Cisco Systems, Inc. BCMSN—4-9 Layer 2 End-to-End VLANs Distribution Layer Core Layer Fast or Gigabit Ethernet Wiring Closet Fast Ethernet Workgroup Servers Switched Ethernet Enterprise Servers Inter-VLAN Routing End-to-end VLANs span the switch fabric

© 1999, Cisco Systems, Inc. BCMSN—4-10 Local VLANs STP Blocked Links Redundant Uplinks Redundant Uplinks Redundant Uplinks HSRP Peers HSRP Peers Local VLANs generally reside in the wiring closet

© 1999, Cisco Systems, Inc. BCMSN—4-11 Establishing VLAN Membership Approaches Can Affect Performance Port-Based VLAN1 VLAN2 VLAN3 MAC Addresses VLAN2 MAC-Based VLAN1 MAC Address Driven (Layer 2) Port-Driven VLAN membership can either be static or dynamic

© 1999, Cisco Systems, Inc. BCMSN—4-12 Membership by Port Maximizes Forwarding Performance VLAN 2VLAN 1 VLAN 3

© 1999, Cisco Systems, Inc. BCMSN—4-13 Configuring Static VLANs Engineering VLAN Marketing VLAN Sales VLAN Floor #1 Floor #2 Floor #3 Physical Layer LAN Switch Human Layer Network Layer Routing Function Interconnects VLANs Data Link Layer Broadcast Domains All users attached to same switch port must be in the same VLAN x

© 1999, Cisco Systems, Inc. BCMSN—4-14 The set vlan command associates VLAN number with name, type, mtu, SAID, and status Configuring VLANs switch> (enable)set vlan 41 name engineering VTP: vlan addition successful

© 1999, Cisco Systems, Inc. BCMSN—4-15 Verifying VLAN Configuration switch>(enable) show vlan VLAN Name Type Status Mod/Ports default enet active1/1-2 2/2-12 3/1-12 4/ engineering enet active 1002 fddi-default fddi active 1003 token-ring-default tring active 1004 fddinet-default fdnet active 1005 trnet-default trnet active VLAN SAID MTU RingNo BridgeNo StpNo Parent Trans1 Trans

© 1999, Cisco Systems, Inc. BCMSN—4-16 Defining the Common Workgroup In this section, we discuss the following topics: VLANs VLAN Identification –Link Types –VLAN Identification Methods –ISL –802.1Q VLAN Trunk Protocol

© 1999, Cisco Systems, Inc. BCMSN—4-17 Link Types Access Links An access link is a link that is a member of only one VLAN

© 1999, Cisco Systems, Inc. BCMSN—4-18 Link Types (Cont.) Trunk Links A trunk link is capable of carrying multiple VLANs

© 1999, Cisco Systems, Inc. BCMSN—4-19 VLAN Frame Identification Specifically developed for multi-VLAN, inter-switch communications Places a unique identifier in header of each frame Functions at Layer 2 VLAN1 VLAN2 VLAN3 Backbone VLAN1VLAN2VLAN3

© 1999, Cisco Systems, Inc. BCMSN—4-20 Red RED VLAN Blue Green Blue Green BlueRed VLAN Identification Methods VLAN Identification Options: Cisco ISL IEEE 802.1Q Fast Ethernet Packets traversing a shared backbone carry VLAN identification within the packet header RED VLAN

© 1999, Cisco Systems, Inc. BCMSN—4-21 VLAN Identification Using ISL Trunk Link VLAN100 VLAN200 (Port C) VLAN200 (Port A) Legend: Trunk Links VLAN200 (Access Link) X Z Y W Trunk Link Frame 1 ISL Frame 2 Frame 3 VLAN200 (Port B) ISL maintains VLAN information as frames travel between switches on trunk links Y

© 1999, Cisco Systems, Inc. BCMSN—4-22 VLAN Identification Using IEEE 802.1Q 2-byte tag protocol identifier (TPID) –A fixed value of 0x8100. This TPID value indicates that the frame carries the 802.1Q/802.1p tag information. 2-byte tag control information (TCI) Initial MAC Address Initial Type/DataNew CRC 2-Byte TPID 2-Byte TCI

© 1999, Cisco Systems, Inc. BCMSN—4-23 BCMSN Domain 3/13/2 1/12/2 1/22/1 1/1 Trunk Negotiation Dynamic Trunk Protocol (DTP) handles the negotiation of trunk links C5000-1

© 1999, Cisco Systems, Inc. BCMSN—4-24 Configuring a Trunk Link Switch (enable) set trunk 1/1 on type isl Port(s) 1/1 trunk mode set to on. Console>(enable) 04/05/1999, 10:45:39:DTP-5:Port 1/1 has become isl trunk 04/05/1999, 10:45:40:PAGP-5:Port 1/1 left bridge port 1/1. 04/05/1999, 10:45:40:PAGP-5:Port 1/1 joined bridge port 1/1. On an Cisco IOS™ command-based switch, enter the trunk on command in interface configuration mode

© 1999, Cisco Systems, Inc. BCMSN—4-25 BCMSN Domain 3/1 3/2 1/1 2/2 1/22/1 1/1 Clearing VLANs from Trunk Links Which VLANs Should Be on the Trunk? Not all VLANs should be carried on a trunk link

© 1999, Cisco Systems, Inc. BCMSN—4-26 switch (enable) clear trunk 1/ switch (enable) set trunk 1/1 on 40,41 type isl Clearing VLANs from Trunk Links Clear all of the VLANs off the trunk link in order to configure only a few VLANs to be transported on the trunk link

© 1999, Cisco Systems, Inc. BCMSN—4-27 Verifying the Trunk Link Configuration switch (enable) show trunk 1/1 Port Mode Encapsulation Status Native vlan /1 desirable isl trunking 1 Port Vlans allowed on trunk / ,250, Port Vlans allowed and active in management domain /1 1, Port Vlans in spanning tree forwarding state and not pruned /1 1, Console> (enable)

© 1999, Cisco Systems, Inc. BCMSN—4-28 Defining the Common Workgroup In this section, we discuss the following topics: VLANs VLAN Identification VLAN Trunk Protocol –VTP Overview –VTP Configuration Tasks and Guidelines –VTP Pruning

© 1999, Cisco Systems, Inc. BCMSN—4-29 What Is VTP? Each VLAN spans the switch fabric Mapping tables from one trunking technology to another needed at end switches ISL VTP Shares Attributes with All Switches “I just created VLAN 2” ISL

© 1999, Cisco Systems, Inc. BCMSN—4-30 BCMSN Domain ce_ domain 3/13/2 1/12/2 1/22/1 4/14/2 5/11/1 Switches listen to VTP advertisements from their own domain and ignore advertisements from other domains A switch resides in only one domain A router does not propagate VTP information NN N ADMIN1 CONFIG-REV# N 1 default 1002 fddi-default 1003token-ring-default 1004fddinet-default 1003 trnet-default C5000-1C C C C VTP Ensures VLAN Consistency throughout the Domain C5000-5

© 1999, Cisco Systems, Inc. BCMSN—4-31 BCMSN domain ce_ domain 3/13/2 1/12/2 1/22/1 4/14/2 5/11/1 C5000-1C C C C C BCMSN CONFIG-REV# N+1 1 default 1002 fddi-default 1003token-ring-default 1004fddinet-default 1003 trnet-default 2 first-vtp-vlan N+1 VTP Advertisements Update Other Switches in Domain

© 1999, Cisco Systems, Inc. BCMSN—4-32 Server Mode= Create/delete global VLANs Client Mode= Can not change any VLANs Transparent= Create/delete local VLANs, ignore VTP updates Server Mode Client ModeTransparent Mode VTP Modes of Operation Client Mode

© 1999, Cisco Systems, Inc. BCMSN—4-33 Adding a Switch to an Existing VTP Domain Switch B Switch A Added Switch VTP Domain BCMSN

© 1999, Cisco Systems, Inc. BCMSN—4-34 Summary-Advert and Subset-Advert Subset-advert follows summary-advert and contains all information for one or more VLANs (generally in response to an advert-request) Server Mode Client ModeTransparent Mode Summary-Advert and Subset-Advert VTP Advertisements Advert-Request

© 1999, Cisco Systems, Inc. BCMSN—4-35 Version Code Seq-Num MgmtD Len Management Domain Name (zero-padded to 32 bytes) Configuration Revision Number Version Code Followers MgmtD Len Management Domain Name (zero-padded to 32 bytes) Updater Timestamp (12 bytes) Configuration Revision Number MD5 Digest (16 bytes) Updater Identity Version Code Rsvd MgmtD Len Management Domain Name (zero-padded to 32 bytes) Summary-Advert Subset-Advert Advert-Request VLAN-info field N Start Value VLAN-info field 1 VTP Advertisement Content

© 1999, Cisco Systems, Inc. BCMSN—4-36 Version Code Seq-Num MgmtD Len Management Domain Name (zero-padded to 32 bytes) Configuration Revision Number VLAN-info field N VLAN-info field 1 V-info-len Status VLAN-Type MgmtD Len index ISL VLAN-id MTU Size VLAN-name (padded with zeros to multiple of of 4 bytes) Rsvd VTP Subset Advertisement

© 1999, Cisco Systems, Inc. BCMSN—4-37 Configuration Revision Number Review VLAN added/modified/deleted N N N +1

© 1999, Cisco Systems, Inc. BCMSN—4-38 Trunk Ports Configuration Tasks and Guidelines BCMSN domain ce_ Domain 3/13/2 1/12/2 1/22/1 4/14/2 5/11/1 C5000-1C C C C C VTP Domain Name VTP Mode – Server – Client – Transparent

© 1999, Cisco Systems, Inc. BCMSN—4-39 BCMSN Domain ce_ Domain 3/13/2 1/12/2 1/22/1 4/14/2 5/11/1 C5000-1C C C C C VTP Mode – Server – Client – Transparent Choose VTP Version VTP v2 All switches in a management domain must run the same version

© 1999, Cisco Systems, Inc. BCMSN—4-40 Determine VTP Management Domain and Mode Trunk Ports BCMSN Domain ce_ Domain 3/13/2 1/12/2 1/22/1 4/14/2 5/11/1 C5000-1C C C C C VTP Domain Name VTP Mode – Server – Client – Transparent

© 1999, Cisco Systems, Inc. BCMSN—4-41 Configuring VTP Switch (enable) set vtp domain bcmsn_block2 mode server passwd cisco VTP : domain ce-domain modified Switch (enable) set vtp domain bcmsn_block2 mode server passwd cisco VTP : domain ce-domain modified

© 1999, Cisco Systems, Inc. BCMSN—4-42 show vtp domain Command switch (enable) show vtp domain Domain Name Domain Index VTPVersion Local Mode bcmsn_block2 1 1 server Vlan-count Max-vlan-storage Config Revision Notifications enabled Last Updater V2 Mode Pruning PruneEligible on Vlans disabled disabled

© 1999, Cisco Systems, Inc. BCMSN—4-43 switch (enable) show vtp statistics VTP statistics: summary advts received 0 subset advts received 0 request advts received 0 summary advts transmitted 0 subset advts transmitted 0 request advts transmitted 10 No of config revision errors 0 No of config digest errors 0 switch (enable) clear vtp statistics vtp statistics cleared switch (enable) show vtp statistics VTP statistics: summary advts received 0 subset advts received 0 request advts received 0 summary advts transmitted 0 subset advts transmitted 0 request advts transmitted 10 No of config revision errors 0 No of config digest errors 0 switch (enable) clear vtp statistics vtp statistics cleared Verifying VTP Traffic/Operation

© 1999, Cisco Systems, Inc. BCMSN—4-44 Flooded Traffic with VTP Pruning Disabled Port 2 Port 1 Port 5 Port 4 Every switch has to receive the broadcast, even if no ports on the switch participate in the VLAN C5000-6C5000-3C C5000-5C C5000-4

© 1999, Cisco Systems, Inc. BCMSN—4-45 Flooded Traffic with VTP Pruning Enabled VTP pruning limits VLAN traffic to those links that support the VLAN Port 2 Port 1 Port 5 C5000-6C5000-3C C5000-5C C Host A Host B Green VLAN Broadcast Traffic Pruned Here Port 4

© 1999, Cisco Systems, Inc. BCMSN—4-46 Verify VTP Pruning switch (enable) show trunk 1/1 Port Mode Encapsulation Status Native vlan /1 desirable isl trunking 1 Port Vlans allowed on trunk / ,250, Port Vlans allowed and active in management domain /1 1, Port Vlans in spanning tree forwarding state and not pruned /1 1,

© 1999, Cisco Systems, Inc. BCMSN—4-47 Laboratory Exercise: Visual Objective To the Core VLAN Switch Block VLAN

© 1999, Cisco Systems, Inc. BCMSN—4-48 After completing this chapter, you should be able to perform the following tasks: VLANs solve many issues of large Layer 2 environments VLAN identification enables user/VLAN association across the campus network VTP enables dynamic VLAN reporting across the campus network VTP must be enabled and configured prior to configuring VLANs Summary

© 1999, Cisco Systems, Inc. BCMSN—4-49 Review Questions Explain how VTP enables propagation of VLAN data across the network. Discuss how frame identification enables VLAN membership association. Define the three VTP modes of operation and describe how they work. Describe the use of VTP pruning. Explore the same solution without VTP pruning.

© 1999, Cisco Systems, Inc. BCMSN—4-50 Review Questions (Text only)

© 1999, Cisco Systems, Inc. BCMSN—4-51 Network Diagram (Text Only)