CCNP - Distribution Layer Switching

Author

Distribution Layer Switching

2000-10-12, 2:19 am

This may be a really stupid question, but hey, what the hell....

I am looking at a diagram of a switch block with multiple multilayer switches connecting to a core. I understand why there are redundant links from the distribution layer switches to the core devices, but why does it show fast ethernet links also going between the 2 distribution layer devices as well? Because it seems to me that even if 1 of the MLS's were to go down, the other would be able to provide routing due to the redundant links from the access layer switches. Are these fast ethernet links for HSRP?

Thanks

2000-10-13, 2:33 pm

Maybe I should have also stated that it was in the exam cram book.

Thanks Again

2000-10-16, 1:25 am

Could really use your help on this one Yankee

Thanks

2000-10-16, 11:16 am

Hey Doc,

What page is the diagram on? I might be able to help if I could look at the same picture your question is based on.

Reamer

2000-10-16, 12:57 pm

No the HSRP is only at the Core layer
at distributed layer you have to use the STP
at redundent links !!!

right ???

2000-10-17, 2:57 am

But what if your core comprises of layer 2 high end switches? You couldn't have HSRP with that scenario (HSRP is implemented with routers or a layer 3 device). By the way, the diagram I am looking at is on page 37 in the BCMSN from Cisco Press. If you notice, there is a fast ethernet link between the two distribution switches in each switch block......

Maybe I'm just missing the boat on this one.

I appreciate your help!

[This message has been edited by DrWatsonJr (edited 10-16-2000).]

2000-10-17, 5:48 am

Hey Doc,
Take a look at page 30-31 starting with the "Dual Core" topic.HSRP will be running in the distribution layer switches and STP is not needed because the core switches are not connected.

2000-10-17, 11:52 am

So then the answer to my question is.....
The reason for the fast etherchannel at the distribution layer is for HSRP?

There surely must be another reason.....

Thanks to all that have replied...

[This message has been edited by DrWatsonJr (edited 10-17-2000).]

2000-10-18, 11:45 am

You have the FastEtherchannel between the switches primarily for VLAN trunking and STP redundancy, the core should only be used for switching between seperate switch blocks not distribution layer switches in the same switch block.

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