[nycbug-talk] Can RTSP and dumb switches coexist?

Alex Pilosov alex at pilosoft.com
Thu Oct 18 02:10:09 EDT 2007

On Thu, 18 Oct 2007, Jonathan Stewart wrote:

> As the subject asks based on what I have read so far (including chunks
> off the IEEE spec) it appears that RTSP can coexist with dumb switches
> as long as the dumb switches themselves don't form loops.  Can someone
> confirm or refute this for me please.
a) I suppose you mean RSTP (rapid spanning tree protocol). RTSP is voip 

b) dumb switches *must* comply with 802.1d (the STP protocol) anyway.  
RSTP is backward compatible (theoretically), and it should (theoretically) 
work fine, with loops or without.

c) the above being said, I encourage my competitors to rely on any
incarnation of STP to detect loops.

d) if above is too dense, explanation:
1) You *really* do not want loops in your l2 network. doubly so if you are 
mixing STP protocols.

2) Unless you understand *exactly* how all variations of STP work, and how 
they interact with each other, you *will* shoot yourself in the foot.

3) When STP breaks, it breaks in a very strange, and unstable ways, and
takes down your network completely.  Troubleshooting it, when your network 
is down, is not for weak-minded. 

4) Just don't do it (tm). This is what happens when STP breaks: 

5) Use layer 3 if you need redundancy (and loops).

The above being said, we (pilosoft) use STP/RSTP/PVST+/etc...But, the 
thought about touching my configs makes hair raise on top of my head. 
It'll be shortly ripped out and replaced with proper l3 stuff.


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