Student - Understanding HSRP , STP and general topology.

[MartinClay]

Hi everyone. I'm starting out on my Cisco journey and I'm having a little trouble understanding a particular topology.  Please see the image attached, this is my current arrangement.

As you can see, STP has shut down the link between PS47 and PR02, my secondary router. I understand why this is the case. However, I want to ask the experts about the general topology of this network. 

My intention is to use HSRP and connect the remaining dead end legs to the secondary router.

So before I get into the detail of configuration , my questions are :-

Is this an acceptable arrangement, bearing in mind I do have some fiber install limitations ?

If not, what are the pitfalls ?  

Should I expect STP to shut down loop circuits whilst using HSRP ?

Will HSRP operate properly whilst loop connections are in place ?

I was kind of expecting HSRP to take care of the loops and not see them shut down by STP. Am I miss understanding this ?

Thanks for reading.. :-)

EDIT:- Screen grab also attached as file. All switches are CISCO 2960X , Routers are 3850XS. All displayed links are currently fiber connections at layer 2.

[Reza Sharifi]

Hi,

Can you post the drawing as an attachment? It is very hard to see the devices, links, description, names, etc..

HTH

[MartinClay]

Yep sure. Original post edited.

[Deepak Kumar]

Hi,

What is the mode of a link from PS47 to  RP02 and from PS39 to RP02? Is it an L3 or L2 link?

Regards,

Deepak Kumar

[MartinClay]

Hi Deepak, all links are currently L2. I have been researching this. Am I correct to say that STP does not operate at L3 and therefore will not block loop connections ?

[Deepak Kumar]

Hi,

Spoiler

 Am I correct to say that STP does not operate at L3 and therefore will not block loop connections ?

Yes, it is correct.

[Jon Marshall]

No it is not correct. 

It is STP that creates a L2 loop free topology, nothing to do with HSRP and even if we were talking about L3 loops (which I don't think we are) HSRP has nothing to do with that either. 

Jon

[Deepak Kumar]

Hi,

You mentioned that mentioned links are working on L2 mode then it is not advised to turn off the STP because It will expose the Layer 2 loop. 

Regards,

Deepak Kumar

[MartinClay]

Yes I understsand that. Is it acceptable to have blocked links when using HSRP ? 

Or is there a better solution ?

[Jon Marshall]

Yes it is perfectly acceptable and in a lot of implementations using HSRP with access layer switch dual connected to L3 switches you usually block an uplink per vlan. 

As long as you have a L2 path per vlan between your HSRP devices you are fine. 

Jon

[Deepak Kumar]

Hi,

Yes, But you have to implement L3 link between at both ends. 

Regards,

Deepak Kumar