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At IU, is my Ethernet switch compatible with the campus network?

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Introduction

Ethernet hubs, repeaters, and switches are a cost-effective way to provide network connectivity to multiple devices via a single data jack. However, improperly implemented switches can result in network problems for an entire building or even, in some rare cases, an entire campus. To prevent network problems, end-user Ethernet switches on the Indiana University network must meet the basic requirements published by UITS.

For the purposes of this document, an end-user switch is any Ethernet switch, hub, or repeater connected to a UITS data jack.

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Requirements for end-user switches

UITS has established the following set of requirements for end-user switches. For a list of end-user switches that have been found to meet these requirements, see At IU, what switches are recommended for use on the campus network?

  1. End-user switches must support one of the following:

    • A functional IEEE standard spanning tree implementation (802.1d, 802.1w, or 802.1s)
    • Flooding of all IEEE standard spanning tree BPDU frames to all ports on the switch

  2. End-user switches must not implement Cisco's proprietary PVST spanning tree protocols.

  3. End-user switches must not implement IGMP snooping.

  4. End-user switches must not allow the user to alter the configuration or behavior of the switch in any way; only unmanaged switches are allowed.

  5. End-user switches must support the same functionality on all ports. No dedicated uplink ports are allowed.

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Testing end-user switches

Use the following set of testing procedures to confirm that switches comply with the UITS end-user switch requirements:

Testing for spanning tree compatibility

  1. Power on the switch and connect a single PC to the switch. Do not connect the switch to the data jack, other switches, or other PCs.

  2. Start a packet capture on the PC and look for spanning tree packets. Run the packet capture for at least 30 seconds.

    • IEEE spanning tree packets are sent to the MAC address 01:80:c2:00:00:00.
    • Cisco spanning tree packets are sent to the MAC address 01:00:0c:cc:cc:cd.

  3. If you detect IEEE spanning tree packets, the switch runs spanning tree and passes the test. If you detect Cisco spanning tree packets, the switch fails the test. If you do not detect any kind of spanning tree packets, proceed to step 4.

  4. Connect the PC directly to a data jack and repeat the packet capture from step 2. If you do not detect IEEE spanning tree packets, you cannot use this data jack for testing an end-user switch. If you do detect IEEE spanning tree packets, continue to step 5.

  5. Connect the PC to the end-user switch, and then connect the switch to the data jack. Repeat the test from step 2. If you detect IEEE spanning tree packets, the switch floods spanning tree packets and passes the test. If you do not detect spanning tree packets, this switch fails the test and cannot be used.

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Testing for IGMP snooping compatibility

For this test, you will need an application to test multicast streams, such as VLC media player. VLC player is a free application for Windows, Mac OS X, and Linux operating systems, and is available for download at the Videolan web site. To open a multicast stream with VLC player:

  1. Click File, and then click Open Network Stream... (Windows) or Open Network... (Mac OS X).

  2. In the Open (Windows) or Open Source (Mac OS X) window, select UDP/RTP Multicast.

  3. Enter the address and port of the multicast stream in the appropriate fields, and then click OK to open the stream. There may be a slight delay before the stream begins to play.

To test for IGMP snooping compatibility:

  1. Connect a PC to the data jack you plan to use for testing. Run a multicast application on the PC. Open a multicast stream, and verify that it works. Note the multicast group address of the stream.

    Note: From the IU network, you can use a sample multicast stream for this test; this sample stream address is 233.41.184.1 on port 3900 (udp://@233.41.184.1:3900).

  2. Connect the PC to the switch being tested, connect the switch to the data jack tested in step 1, and connect a second PC with packet-sniffing software installed to the switch.

  3. Restart the multicast stream tested in step 1, and verify it is working.

  4. Start a packet capture on the second PC, and run for at least 15 seconds.

  5. Check the packet capture for UDP packets with a destination of the multicast group address noted in step 1. There should be a lot of them! If you do not detect multicast packets, the switch implements IGMP snooping and therefore fails the test. If you do detect these multicast packets, the switch passes.

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This is document awlq in domain all.
Last modified on October 17, 2013.

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