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Dwight Reifsnyder

Virtual LANS. Dwight Reifsnyder. “IEEE 802.1Q tagging (VLAN) is a useful method of managing VoIP traffic in your LAN. Avaya recommends that you establish a voice VLAN, set L2QVLAN to that VLAN and provide voice traffic with priority over other traffic.” IP Phones LAN Admin Guide, Feb 2007.

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Dwight Reifsnyder

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  1. Virtual LANS Dwight Reifsnyder

  2. “IEEE 802.1Q tagging (VLAN) is a useful method of managing VoIP traffic in your LAN. Avaya recommends that you establish a voice VLAN, set L2QVLAN to that VLAN and provide voice traffic with priority over other traffic.” IP Phones LAN Admin Guide, Feb 2007 What’s the Point? Why Bother?

  3. EYAWTK – Session Overview • Provide a basic understanding of VLANS • Discuss IP phone VLAN implementation • We might accidentally learn some other useful information if we are not careful

  4. Broadway Suites • Service Provider for downtown Boulder office buildings, including Executive Suites • Multiple, diverse businesses in one space • Fortune 500 services on a small company budget

  5. Broadway Suites

  6. What is a Virtual LAN? • A virtual LAN, commonly known as a VLAN, is a method of creating independent logical networks within a physical network. • Virtual LANs operate at Layer 2 (the data link layer) of the OSI model. Wikipedia

  7. OSI Model Squishy, not specific VLANs are in Layer 2 Background – The 7 layer burrito

  8. What Lives at Layer 2? • Software – Ethernet Protocol • End Points • Ethernet Hubs • Ethernet Switches

  9. L2 Hardware – Endpoints • Phones and PCs are multi layer devices • We will talk about them at layer 2 today

  10. L2 Hardware – Network Hub • Network Hubs – • broadcast traffic • not very efficient

  11. L2 Hardware – Network Switch • Network Switches – • Starts like a hub • Gradually directs traffic to specific ports instead of broadcast • How do they do that?

  12. Detour - L2 MAC Addresses • Like a VIN Number on a car • Unique to each and every network device 00-07-E9-55-64-4D • MAC addresses are used to identify the sender and recipient of an ethernet packet

  13. Network Switch • Stores MAC addresses and associated port numbers in a table • Makes network more efficient!

  14. Evolution - Managed Switches Have a user console that can show - • If a port is connected or not • Port speed (10MB, 100MB, 1000MB) • MAC address table • Calls out with alarms • Best solution for Administrators • Cost more $$$$$!

  15. Segregation – Sorry Dr. King.. • Sometimes we need to have departments separated – • HR, confidentiality • Marketing, high bandwidth usage • Operations • Each department needs its own LAN

  16. Segregation – The Old Way • Multiple Managed Network Switches • Costly • Complex

  17. Segregation – The New Idea • Multiple MAC Address Tables • One switch, divided into 'Virtual LANs‘ • Great idea, how would it work?

  18. Detour - RFCs (secret recipes) • Request for Comments • Internet Engineering Task Force (IETF) • Institute of Electrical and Electronics Engineers (IEEE)

  19. Some Common RFCs

  20. RFC 802.1q - VLANs • Defines how to segregate a single L2 network switch into multiple “virtual' LANs or networks with multiple MAC tables • One managed network $witch can now serve multiple departments without losing security or performance

  21. Layer 2 Switch with VLANs • Logical evolution from switching table • Port based VLAN identification – every port belongs to a VLAN • Separate broadcast domains VLAN 2 – Human Resources VLAN 3 – Marketing VLAN 1 – Operations

  22. VLANs Across Switches

  23. VLAN Tags – Don't Lose my Bag • DEN • CHI • NYC • ELM • SAT

  24. VLAN Tags – Ethernet Packets • Ethernet packet fields • Header • Payload • End • VLAN tagging information is added to the header, making it slightly longer

  25. VLAN Trunking Across Switches The ports which join the switches are defined as belonging to native VLAN and a secondary VLAN. The secondary VLAN sends ‘tagged’ packets so they can be segregated

  26. Read you loud and clear… • VLAN compliant devices can accept tagged or untagged packets • Packets without tags stay in the native VLAN (port based VLAN) • Packets with tags go into the VLAN defined by the tag (if that VLAN is allowed on that port)

  27. Eh? What was that? • Non VLAN compliant devices discard tagged packets – they have an invalid header length!

  28. What Devices Read Tags? • VLAN compliant switches • VLAN compliant IP phones • Microsoft Windows ? X

  29. Review - Who Sends Tags? Trunk between switches must send and receive tags Devices are all in Port Based VLANs – no tags

  30. 802.1q VLAN Port Parameters • Native VLAN (port based VLAN) • Secondary VLANs • Tagging

  31. IP Phone Deployment • Avaya suggests that phones should always be in their own VLAN • Increases security • Cuts down on broadcast traffic • Increases voice quality • Makes troubleshooting easier

  32. VLAN Deployment Options 2 VLANs, 2 Ports 2 VLANs, 1 Port!

  33. IP Phones have a Network Switch! 2 VLANs, 1 Port! The phone contains a VLAN compliant 3 port network switch!!

  34. Detour – Phones & DHCP & VLANs • DHCP is an ethernet broadcast request used by devices to get an IP number • Broadcast packets do not cross VLANs • Each VLAN needs its own DHCP Server

  35. Detour – Phones & DHCP & VLANs • On bootup, the phone sends a DHCP request in the native VLAN (port VLAN) • The phone is notified if there is a specific voice VLAN • The phone sends a new DHCP request with the correct VLAN tag

  36. Review – Who Sends Tags? The blue VLAN is a secondary VLAN for both network switch ports The green VLAN is the native VLAN for both network switch ports

  37. 1942 Broadway LEGEND SM Fiber (LX) MM Fiber (50 micron SX) 1919 14th (Vectra Bank) 1300 Walnut 1877 Broadway 1800 Broadway 1801 13th 1301 Canyon Broadway Suites, 100+ VLANs

  38. Do You Understand VLANs? • You don't really understand something unless you can explain it to your grandmother... Albert Einstein

  39. Final Reminders • Please remember to turn in session evaluations • The session number is: 706

  40. Thank You Thank You

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