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

2. © 1999, Cisco Systems, Inc. www.cisco.com 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

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

4. © 1999, Cisco Systems, Inc. www.cisco.com 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

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

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

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

8. © 1999, Cisco Systems, Inc. www.cisco.com BCMSN—4-8 Scaling the Switch Block with VLANs 3 4 1 2 5 6 7 8 9 10 Decisions include how many VLANs there are in a switch block and where these devices are placed Server BlockCore

9. © 1999, Cisco Systems, Inc. www.cisco.com 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

10. © 1999, Cisco Systems, Inc. www.cisco.com 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

11. © 1999, Cisco Systems, Inc. www.cisco.com 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

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

13. © 1999, Cisco Systems, Inc. www.cisco.com 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 192.20.24.0 Routing Function Interconnects VLANs 192.20.21.0192.30.20.0 Data Link Layer Broadcast Domains All users attached to same switch port must be in the same VLAN x

14. © 1999, Cisco Systems, Inc. www.cisco.com 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

15. © 1999, Cisco Systems, Inc. www.cisco.com BCMSN—4-15 Verifying VLAN Configuration switch>(enable) show vlan VLAN Name Type Status Mod/Ports ---- -------------------------- ----- --------- ---------------1 default enet active1/1-2 2/2-12 3/1-12 4/1-48 41 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 Trans2 ---- ---------- --- ------ -------- ----- ------ ------ ------ 1 1 1500 0 0 0 0 00 41 41 1500 0 0 0 0 00 1002 1002 1500 0 0 0 0 00 1003 1003 1500 0 0 0 0 00 1004 1004 1500 0 0 0 0 00

16. © 1999, Cisco Systems, Inc. www.cisco.com 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

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

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

19. © 1999, Cisco Systems, Inc. www.cisco.com 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

20. © 1999, Cisco Systems, Inc. www.cisco.com 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

21. © 1999, Cisco Systems, Inc. www.cisco.com 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

22. © 1999, Cisco Systems, Inc. www.cisco.com 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

23. © 1999, Cisco Systems, Inc. www.cisco.com 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

24. © 1999, Cisco Systems, Inc. www.cisco.com 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

25. © 1999, Cisco Systems, Inc. www.cisco.com 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

26. © 1999, Cisco Systems, Inc. www.cisco.com BCMSN—4-26 switch (enable) clear trunk 1/1 1-1000 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

27. © 1999, Cisco Systems, Inc. www.cisco.com BCMSN—4-27 Verifying the Trunk Link Configuration switch (enable) show trunk 1/1 Port Mode Encapsulation Status Native vlan -------- ----------- ------------- ------------ ----------- 1/1 desirable isl trunking 1 Port Vlans allowed on trunk -------- -------------------------------------------------------- 1/1 1-100,250,500-1005 Port Vlans allowed and active in management domain -------- -------------------------------------------------------- 1/1 1,521-524 Port Vlans in spanning tree forwarding state and not pruned -------- -------------------------------------------------------- 1/1 1,521-524 Console> (enable)

28. © 1999, Cisco Systems, Inc. www.cisco.com 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

29. © 1999, Cisco Systems, Inc. www.cisco.com 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

30. © 1999, Cisco Systems, Inc. www.cisco.com 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 C5000-1C5000-2 C5000-3 C5000-4 C5000-6 VTP Ensures VLAN Consistency throughout the Domain C5000-5

31. © 1999, Cisco Systems, Inc. www.cisco.com BCMSN—4-31 BCMSN domain ce_ domain 3/13/2 1/12/2 1/22/1 4/14/2 5/11/1 C5000-1C5000-2 C5000-3 C5000-4 C5000-6 C5000-5 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

32. © 1999, Cisco Systems, Inc. www.cisco.com 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

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

34. © 1999, Cisco Systems, Inc. www.cisco.com 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

35. © 1999, Cisco Systems, Inc. www.cisco.com 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) 0 1 2 3 Summary-Advert Subset-Advert Advert-Request VLAN-info field N Start Value VLAN-info field 1 VTP Advertisement Content 0 1 2 3

36. © 1999, Cisco Systems, Inc. www.cisco.com BCMSN—4-36 Version Code Seq-Num MgmtD Len Management Domain Name (zero-padded to 32 bytes) Configuration Revision Number 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 VLAN-info field N VLAN-info field 1 V-info-len Status VLAN-Type MgmtD Len 802.10 index ISL VLAN-id MTU Size VLAN-name (padded with zeros to multiple of of 4 bytes) Rsvd VTP Subset Advertisement

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

38. © 1999, Cisco Systems, Inc. www.cisco.com 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 C5000-1C5000-2 C5000-3 C5000-4 C5000-6 C5000-5 VTP Domain Name VTP Mode – Server – Client – Transparent

39. © 1999, Cisco Systems, Inc. www.cisco.com BCMSN—4-39 BCMSN Domain ce_ Domain 3/13/2 1/12/2 1/22/1 4/14/2 5/11/1 C5000-1C5000-2 C5000-3 C5000-4 C5000-6 C5000-5 VTP Mode – Server – Client – Transparent Choose VTP Version VTP v2 All switches in a management domain must run the same version

40. © 1999, Cisco Systems, Inc. www.cisco.com 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 C5000-1C5000-2 C5000-3 C5000-4 C5000-6 C5000-5 VTP Domain Name VTP Mode – Server – Client – Transparent

41. © 1999, Cisco Systems, Inc. www.cisco.com 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

42. © 1999, Cisco Systems, Inc. www.cisco.com 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 ---------- ---------------- --------------- ------------- 5 256 4 enabled Last Updater V2 Mode Pruning PruneEligible on Vlans --------------- ------- ------- ---------------------- 172.20.25.130 disabled disabled 2-1000

43. © 1999, Cisco Systems, Inc. www.cisco.com 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

44. © 1999, Cisco Systems, Inc. www.cisco.com 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 C5000-6C5000-3C5000-1 C5000-5C5000-2 C5000-4

45. © 1999, Cisco Systems, Inc. www.cisco.com 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 C5000-6C5000-3C5000-1 C5000-5C5000-2 C5000-4 Host A Host B Green VLAN Broadcast Traffic Pruned Here Port 4

46. © 1999, Cisco Systems, Inc. www.cisco.com BCMSN—4-46 Verify VTP Pruning switch (enable) show trunk 1/1 Port Mode Encapsulation Status Native vlan -------- ----------- ------------- ------------ ----------- 1/1 desirable isl trunking 1 Port Vlans allowed on trunk -------- --------------------------------------------------------------------- 1/1 1-100,250,500-1005 Port Vlans allowed and active in management domain -------- --------------------------------------------------------------------- 1/1 1,521-524 Port Vlans in spanning tree forwarding state and not pruned -------- --------------------------------------------------------------------- 1/1 1,521-524

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

48. © 1999, Cisco Systems, Inc. www.cisco.com 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

49. © 1999, Cisco Systems, Inc. www.cisco.com 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.

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

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