802.1s (MSTP) on ProCurve 4100gl Series

[Luigi_30]

On the 4100gl series switches I'm only able to configure the STP and the RSTP Spanning-Tree protocol, but not the MSTP. Someone known a valid reason for this ? Seems not supported even with a fw upgrade. On the 5300xl, the 2800.. etc the MSTP is supported, but not on the 4100gl... In a fully-meshed with multiple VLAN's LAN how can I configure the Spanning-tree ?

Thanks in advance for any ideas..

Luigi

[Kell van Daal]

Hi Luigi,

MST is indeed not supported on the 4100gl series.
If you say that your network is fully meshed, do you mean you used the mesh protocol, or do you just mean that every switch is connected to every other switch?

If you use the mesh protocol, why would you want MST? All the redundancy is taken care for by the mesh, and MST isn't needed to ensure a loopfree network. The only thing you could consider spanningtree for, is for loops users could create by plugging in rogue equipment like hubs and use two links for it, or users connecting both ends of a cable in the same switch.
But for those cases STP or RSTP should be sufficient.

If you mean with meshing only the connections and not the protocol, you could just use RSTP (or mesh still ;)). It doesn't matter if you have more than one VLAN. You only should be carefull with planning links that carry multiple VLAN's so that you won't have a link blocked that carries a VLAN that isn't present on the active links.
Normally MST is used for "loadbalancing" with spanningtree. With MST you can make sure traffic from a VLAN uses another route than traffic from another VLAN. This can enable you to make a network where no link is blocked for all VLAN's, which is allways the case with STP/RSTP (if there are redundant links present offcourse).

If you allready use MST on other switches, you can mix RSTP (or STP) with MST. MST is designed to be backward compatible with other versions of STP. In short: A MST region appears as a single bridge to adjacent single instance spanning trees (STP/RSTP).

If you can provide a topology of your network, I could give you a more specific advice if needed.

[Luigi_30]

Hi Kell,

Thanks for your faster answer.
I mean that every switch is physically connected to other switches without the use of the mesh protocol.
I have two ProCurve 2824 switches running MST and two 4100gl running RSTP (a 4104gl and a 4108gl) for inter-VLAN routing (Basic IP routing).

In this scenario, without the MST on all the switches, I will plan to carry all the VLAN's to all the links via tagging. I'm pleased with the backward compliance MST/RSTP.

For L3 redundancy I would also configure a protocol (eg. VRRP/SRP or XRRP), but I'm afraid that (like MST) they are not supported... Do you think I will need an external router connected via an 802.1Q link ?

Thanks again and best regards

Luigi

[Kell van Daal]

Hi Luigi,

If the drawing is your complete setup, you should just set all switches to RSTP.
You won't get any advantage with MST if only the two 2800 switches have it running.

It's true the 2800 and the 4100 switches indeed do not have support for XRRP or something alike. If you really need it, you would need at least two extra routers for it.
Be aware that all inter-vlan traffic will pass at least one of those routers, meaning they could become a bottleneck in your network, unless you are willing to pay a lot for them.
Maybe swapping the 4100 switches for 5300 switches is a possibility? Then you have MST and XRRP. That should be better for performance if implemented well (no links blocked for all VLAN's, no external router that could be a bottleneck).

[Luigi_30]

Hi Kell,

thanks again for your valuable support. I'm looking around amongst the installed Cisco routers one (two, if possible, working with HSRP) having 802.1q support to do L3 routing. I cannot plan in a short time a switch swapping...

Could be a good idea leaving MST on the two 2824 to avoid switch reboots (this is the server side) in case of future migration to 5300xl models.

I think we can close the thread. Many thanks, Kell.-

Best regard

Luigi