Re: [Bridge] STP bug, loop not detetcted

[Francesco Dolcini <fdolcini@sysnetsistemi.it>]

Stephen Hemminger wrote:
> Spanning Tree absolutely has to follow the standard. What ever the standard
> says, that is what it should do. No special cases, no changes. Get the standard
> for free from IEEE (get 802) and read it.
I do not agree, I absolutely think that linux STP must be 100% 
compatible with IEEE standard, but if we can improve it, adding 
additional functions without breaking 100% compatibility, why not do it?

> That said, we really need to get the STP updated to RSTP. There are currently
> four options:
> 
> 1) Existing userlevel RSTP daemon based on rstplib.  
> 2) New RSTP code (from EMC) as daemon
> 3) Update of old STP kernel code to RSTP, this was done on ancient 2.4
>    for embedded system
> 4) Port EMC RSTP code to kernel
>

> There doesn't appear to be lots of advantages to user space RSTP long term
> and the conversion process would be more painful.
I think that having user space STP can make easier to have different 
implementation of STP algorithms available:
- plain old 802.1D legacy slow STP
- 802.1D-2004 RSTP
- 802.1Q-2005 MSTP
- Cisco proprietary PVSTP
- Cisco proprietary PVRSTP

Or we just need "one protocol to rule them all"?

What I think that is really missing at the moment, apart from RSTP, is a 
vlan aware forwarding engine in the bridge code.

> EMC code is slightly uglier (sorry) but has advantage of being recently
> interop tested.
The original rstplib is outdated, it implement the old 802.1w standard. 
We have a working implementation updated to the latest standard (802.1D 
2004) of rstplib, if it can be usefull we can think about releasing it.

Francesco