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New Member

Which one is Open Standard and which one is Cisco based?

Dear Friend,

I have 6 Cisco Catalyst 2955 Switches. I want to rum Spanning-tree Protocol. When I saw the STP configuration I found Two types of STP commands:

1- MSTP based (i.e. spanning-tree mode mst configuration)

2- Rapid-pvst+ (i.e. spanning-tree mode rapid-pvst)

I want to ask you people that which one of the above TWO is Open Standard and which one is Cisco based.

Regards,

Shahid

7 REPLIES

Re: Which one is Open Standard and which one is Cisco based?

Hi

Both are ieee standards.

Thanks

Mahmood

New Member

Re: Which one is Open Standard and which one is Cisco based?

Yar I am confused b/c I want to use Open Standard Protocol which should support other Non-Cisco Switches????

waiting

Purple

Re: Which one is Open Standard and which one is Cisco based?

Shahid,

Rapid-PVST+ is Cisco Proprietary

MST (based on 802.1s) is an IEEE standard.

Paresh

Re: Which one is Open Standard and which one is Cisco based?

HI

Thanks Paresh i missed it.

Thanks

Mahmood

New Member

Re: Which one is Open Standard and which one is Cisco based?

I want to use such a Spanning-tree Protocol configuration which should also run on Non-Cisco Switches...so for Non-Cisco Switches support which one of the above I should use.

As I understand that If I use Rapid-pvst+ based commands on mix topology (Cisco + Non-cisco Switches) then it will not run.

While If I use MST based commands on mix topology (Cisco + Non-cisco Switches) then it will definitely run...or it will run only on Non-cisco switches???

waiting ...I think this will resolve my issue.

Regards,

Shahid Raza

Re: Which one is Open Standard and which one is Cisco based?

Hi shahid,

I think it will run on both cisco and non-cisco devices as it is a standard based protocol.So it will be compatiable with each-other.

Thanks

Mahmood

New Member

Re: Which one is Open Standard and which one is Cisco based?

Paresh is correct.

----

Spanning Tree can operate in a single instance across the entire bridged network, independantly of VLANs (Cisco calls this Common Spanning-Tree (CST)), or can be run within each VLAN (Cisco?s Per-VLAN Spanning-Tree (PVST)), or selected groups of VLANs (Multiple Spanning Tree Protocol (MSTP) (IEEE 802.1s))

- CST reduces the CPU load on the switches, as they only need maintain once Spanning-Tree instance. It assumes a common, consistent layer-2 topology for all VLANs. The original 802.1Q standard uses CST.

- PVST requires more switch resources, however allows an elementary load-balancing through forwarding some VLANs on one trunk link, and others on other trunks (this is not an automatic process and requires manual configuration of port priorities for the selected VLANs).

- MSTP is the natural combination of CST and PVST - it allows a STP instance per group of VLANs. One significant difference over PVST is that MSTP sends only one BPDU for all STP groups.

-- MSTP has a couple of gotchas around assigning VLANs to MSTP instances - see Understanding Multiple Spanning Tree Protocol (802.1s) Document ID: 24248 for the pitfalls

- Cisco?s PVST (ISL) and PVST+ (802.1Q) implementations are proprietary, MSTP is standard (802.1s, now in 802.1Q-2003)

----

Rgds,

Ben

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