Rapid STP queston

Deathmage

hey guys so I'm doing Rapid Spanning tree last night and I'm curious if rapid spanning tree is really this simple...

here is the packet tracer lab:



So on switch 1 I do the following:

config t#
config# spanning-tree mode rapid
config# spanning-tree vlan 10 root primary
config# spanning-tree vlan 20 root primary

bear in mind the links are etherchannel's.

Could I setup S3 as:

config t#
config# spanning-tree mode rapid
config# spanning-tree vlan 30 root primary - ?

Would this keep all of the links as RP's and leave the network in a loop state or just block ports on a per vlan basis?

volfkhat

Deathmage wrote: »

Would this keep all of the links as RP's and leave the network in a loop state or just block ports on a per vlan basis?

Obviously this is above my current level... but i'll ask anyway:
1) WHat does RP stand for?


2) Also, when i look at your picture,
I see S2 as the Root Bridge.

So... this image doesnt make sense to me unless it is before you issued the S1 commands.
?

3) What the heck is --> "spanning-tree mode rapid" <enter>

Is there a distinction between the Modes: "rapid" and "rapid-pvst"
?

3) "bear in mind the links are etherchannel's."

If the links are Etherchannels... then i would except All the Ports (on S1 S2 & S3) to be Green.

But i see several AMber/orange ports in your pic.

So... i'm mixed up!
:]

shortstop20

Since it's Rapid PVST, there will be a separate instance of STP for each VLAN. There will not be loops.

Based on the informaton you have given us, S3's Port Channel facing S1 would be a root port for VLAN 10 and 20. For VLAN 30, that link between S2 and S1 would be blocked on one side, using the STP election rules.

Edit: Corrected.

volfkhat

shortstop20 wrote: »

For VLAN 30, that link between S3 and S1 would be blocked on one side, using the STP election rules.

How did you arrive at that conclusion?

If S3 is going to be the Root Bridge for Vlan 30.....
then wouldn't the BLOCK occur between S2 & S1 (etherchannel)?

Just ask'in :]

shortstop20

volfkhat wrote: »

How did you arrive at that conclusion?

If S3 is going to be the Root Bridge for Vlan 30.....
then wouldn't the BLOCK occur between S2 & S1 (etherchannel)?

Just ask'in :]

Sorry yes, the block would be between S2 and S1 for VLAN 30.

theodoxa

volfkhat wrote: »

1) WHat does RP stand for?

Root Port -- There is one root port on each switch other than the root bridge. This port is the best path back to the root bridge as determined by Spanning Tree.

3) What the heck is --> "spanning-tree mode rapid" <enter>

Rapid STP (IEEE 802.1W). It is basically an improved version of IEEE 802.1D Spanning Tree. In fact, the IEEE 802.1D standard replaced classic STP with Rapid STP in 2004, which is why RSTP is also known as IEEE 802.1D-2004. Traditional STP is 802.1D-1998.

Is there a distinction between the Modes: "rapid" and "rapid-pvst"

No. On Cisco IOS, if you type enough characters in the command that there is only one possible command you could have meant, it will take it.

spanning-tree mode rapid-pvst
spanning-tree mode rapid
span mode rapid

will all work.

If the links are Etherchannels... then i would except All the Ports (on S1 S2 & S3) to be Green.

If the etherchannel is configured correctly and all ports have been added, all of them would be forwarding for a given VLAN. Of course, the etherchannel might be blocking for a different VLAN. I wouldn't rely too heavily on the lights in Packet Tracer. [EDIT] That said, I went back to the original post and I don't see any mention of Etherchannels. They links may not be in a Port Channel, in which case STP would be blocking one of them.

Deathmage

Thank you everyone for your feedback, I figured I was doing it correctly I just wanted clarification. As always the explanations on here are better than the books and vidoes I read/watch for these certifications. Koodos to everyone.

My home-lab has pretty much everything in the CCNa encompassed in it.

theodoxa wrote: »

I went back to the original post and I don't see any mention of Etherchannels. They links may not be in a Port Channel, in which case STP would be blocking one of them.

Quite the contrary my good man, read in the middle.

volfkhat

Hmmmm

so..... if i enter this command on a 2960:

config# spanning-tree mode rapid

Which IEEE version of spanning tree is activated?
802.1D or 802.1w
?

And if i enter:

config# spanning-tree mode pvst

Which IEEE version of spanning tree is activated?

And,
Which IEEE version of spanning tree is running by default?
(assuming a cisco 2960, for instance)

Thanks :]

james43026

volfkhat wrote: »

Hmmmm

so..... if i enter this command on a 2960:


Which IEEE version of spanning tree is activated?
802.1D or 802.1w
?

And if i enter:

Which IEEE version of spanning tree is activated?

And,
Which IEEE version of spanning tree is running by default?
(assuming a cisco 2960, for instance)

Thanks :]

There are three options for STP in the Cisco world, PVST+ and Rapid PVST+, both are Cisco proprietary, and do not have an IEEE specification because of this. And then you have MST, which I believe is a Cisco proprietary blend as well.

config# spanning-tree mode rapid

Will turn on Rapid PVST+

config# spanning-tree mode pvst

This will turn on PVST+

PVST+ is the default for Cisco all switches that I have dealt with. Including the 2960, I have two at home and just fired them up to test this.

theodoxa

Deathmage wrote: »

Quite the contrary my good man, read in the middle.

Yep...right there in between the lines of config. I just missed it.

volfkhat

Thanks james!!

Clearly I was having a brain-overload when i didn't remember the difference between IEEE and 'propriety'.
lol

So many details to learn/understand in order to Fully wrap my mind around How everything works together.


But rest assured, i'm slowly getting there.

And when i do eventually get my CCNA.... it will because all you guys help; for taking the time to answer my (rather Obvious) questions :]

james43026

We are all constantly learning in the IT world. And it can be a lot easier to understand something when you talk to other people who may have knowledge on the subject. I'm happy I could help. Good luck with your CCNA, my biggest piece of advice when it comes to the exam, is watch your time. I finished with just 10-15 minutes left, those sim questions can really suck you in.