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Disabling STP - interaction with OSPF & HSRP

I recently returned from a large client where I performed a hands-off network analysis (due to security policy I was not allowed to sniff the network).

The customer stated that they disabled STP throughout their campus environments and used a combination of OSPF and HSRP instead.

I've never heard of such an approach before and do not fully understand how it is possible to deal with potential layer 2 looping issues with multiple layer 3 & 7 protocols (OSPF and HSRP).

The typical network layout consists of dual redundant 6509's at the distribution layer (MDF), with dual MSFC's, connected to 6513 closet (IDF) switches also with dual MSFC's. IDF/MDF connectivity is via Fast-etherchannel gigabit fiber links - separate links to each MDF 6509 switch.

The infrastructure engineer stated that STP was not being used due to the overhead and bpdu storms it caused.

Is such a design commonplace or even workable? If so what are it's risks, advantages?

I'm drawing a blank as to how OSPF and HSRP provide a solution in lieu of STP, especially across swwtches with multiple redundant paths.

Thank you in advance for you help.

2 REPLIES
Gold

Re: Disabling STP - interaction with OSPF & HSRP

They are probably just not using bridging to sort out the redundant paths--they are making all links seperate layer three subnets, and routing between them. They are probably using hsrp to provide redundancy for their hosts, rather than multiple connections through multiple bridges, and counting on spanning tree to find the alternate path.

Russ.W

Re: Disabling STP - interaction with OSPF & HSRP

Yes,

I remember there are some examples in CCNP - Switching Training CD.

But it's absolutely necessary to avoid L2 loops manually.

Regards,

Milan

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