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Emulated LANs

Emulated LANs. With a few VLAN concepts added for spice. Problems. Emulating a broadcast media LAN on a point-to-point WAN ARP? Multicast High Bandwidth Requirements. Typical Usage. Layers. Higher-layer. Higher-layer. protocols. protocols. (IP, ARP,. .). (IP, ARP,. .).

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Emulated LANs

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  1. Emulated LANs With a few VLAN concepts added for spice

  2. Problems • Emulating a broadcast media LAN on a point-to-point WAN • ARP? • Multicast • High Bandwidth Requirements

  3. Typical Usage

  4. Layers Higher-layer Higher-layer protocols protocols (IP, ARP, . . .) (IP, ARP, . . .) Ethernet-like interface Signalling Signalling + LANE + LANE AAL5 AAL5 ATM ATM ATM PHY PHY PHY PHY Host Switch Host

  5. Setup • Lan Emulation Client (LEC) contacts the Lan Emulation Configuration Server (LECS) to find out the ATM addresses of the Lan Emulation Server (LES) and Broadcast and Unknown Server (BUS) for the emulated LAN • The LEC then registers with the LES and BUS • The LES and BUS create virtual circuits to the LEC

  6. Forwarding • H1 LANE layer receives a packet for H2 • Since H2 is not in our cache, we send query to LES for H2 ATM address • Since the query and VC setup may take seconds, we start sending data through the BUS • We may wait until we receive several packets before setting up a separate virtual circuit • The LES replies with the ATM address of H2 • H1 sets up a direct VC to H2 and adds an entry in the cache for H2

  7. Other issues • You can set up many ELANs with a separate LES and BUS for each ELAN • A single ATM entity can be part of more than one ELAN

  8. Multiple ELANs Broadcast Domain 1 Broadcast Domain 2 H1 H2 H3 H2 cannot see H3

  9. What About VLANs? • VLANs create virtual broadcast domains out of whatever physical networks that are available • Most Ethernet switches will allow for VLANs to be created from a subset of the ports on the switch. • Machines that are not in this subset can not access the VLAN machines • The VLAN can extend across the internet

  10. Big Picture H4 H5 Ethernet links ATM links H3 H6 E2 E1 Ethernet switch H7 H12 H9 Ethernet links H13 H10 E4 E3 Ethernet switch H11 ATM switch ATM-attached host

  11. IEEE 802 Model • Physical (PHY) • Medium access control (MAC) • Logical Link Control (LLC) • Higher level services (HLS)

  12. 802.1 MAC Bridge Design Space • MAC Layer defines interface to a Port • Relay/Forwarding defines behavior of received packet as sent to other ports • Broadcast behavior • Unicast behavior • Multicast behavior • Trunking behavior

  13. 802.1 MAC Bridge Model End Node End Node LLC LLC Bridge Relay MAC MAC MAC MAC PHY PHY PHY PHY

  14. End Node End Node End Node End Node End Node End Node End Node End Node End Node LLC LLC LLC LLC LLC LLC LLC LLC LLC MAC MAC MAC MAC MAC MAC MAC MAC MAC Switch Relay Relay PHY PHY PHY PHY PHY PHY PHY PHY PHY MAC MAC MAC MAC MAC PHY PHY PHY PHY PHY 802.1 LAN Switch = MAC Bridge End Node LLC End Node LLC MAC MAC PHY PHY

  15. MAC MAC MAC MAC Signaling +Lane Signaling +Lane Signaling +Lane Signaling +Lane AAL5 AAL5 AAL5 AAL5 ATM ATM ATM ATM PHY PHY PHY PHY 802.1 MAC Bridge Model +ATM ELAN End Node End Node Bridge Relay ATM Switch ATM Switch

  16. MAC MAC Signaling +Lane Signaling +Lane AAL5 AAL5 ATM ATM PHY PHY 802.1 MAC Bridge Model +ATM ELAN End Node End Node Bridge LLC Relay MAC MAC PHY PHY ATM Switch

  17. Router Components

  18. Architecture LES Mac Mac Mac Mac Ethernet BUS Relay ATM Switch Mac LEC ATM Plug and Play

  19. Architecture Mac Mac Mac Mac Ethernet LEC Relay LES PVC BUS ATM Switch Mac ATM

  20. Architecture POS Mac Mac Mac Mac Ethernet Relay Relay Ether Switch Mac POS

  21. VPN Mac Mac Mac Ethernet Relay Mac VPN Translate IP address to TCP connection Send to TCP connection

  22. Dst=96.55.77.88 Dst= 128.187.23.44 Src= 128.187.23.44 Src= 96.55.77.88 Payload Payload Dst=96.55.77.67 Src= 96.55.77.88 Dst=96.55.77.88 Payload Src= 96.55.77.67 Payload Dst=128.187.23.44 Dst=96.55.77.1 Src= 128.187.23.44 Src= 96.55.77.1 TCP Header TCP Header Dst=96.55.77.88 Dst=96.55.77.67 Src= 96.55.77.67 Src= 96.55.77.88 Payload Payload VPN 128.187.23.44 96.55.77.88 Host1 Host2 Set up TCP connection, get local address=96.55.77.67 This looks like a P-P link 96.55.77.1 VPN Server

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