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sblair
Asked: 2009-10-20 03:20:07 +0800 CST

Should the 3Com NJ225 switch implement the spanning tree protocol?

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We recently purchased some 3Com IntelliJack NJ225 switches:

alt text
(source: 3com.com)

The specification states that they support IEEE 802.1D, and a mandatory part of this standard is support for the rapid spanning tree protocol. However, we quickly realised that we could not safely create loops when connecting these devices together (using the four "front" ports). After several support calls, 3Com confirmed that they did not implement the RSTP.

I think it's fair to say that we're not using these switches for their intended purpose. But, did 3Com incorrectly claim support for IEEE 802.1D? Or is there a technical reason why these switches are exempt from implementing the RSTP?

switch

2 Answers

  1. Best Answer

    3com are correct in the information you've provided. They specify support for STP (802.1D), but not RSTP (802.1W). RSTP is an extension of the STP spec which provides faster convergence.

    They should still perform bridge loop prevention though. Just not as promptly as RSTP would. If they aren't functioning at all, then re-open the case.

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  2. Dumb question, but you have checked that STP is enabled? These are managed switches.

    I actually only enable STP on end-user VLAN's, I've just had 2-3x more failures of STP then failures STP could have saved me from.

    My preference is actually MSTP, but vendor interoperability is a bit bad.

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