Jimmy,
I do not have the title you note in your post but a few things to
consider when identifying and trying to configure the root device within
your network.
A MDF or Distribution switch as you mentioned depending on the network
design will more than likely provide both L2 connectivity to the IDF and L3
connectivity to the network core. Try and think of the operation within the
MDF switch as totally separate
processes in which the switch speaks only L2 to the IDF, but then L3 to the
network core. In this regard the MDF switch will be a part of STP
calculations when designating a root device within the network. The fact
that you see designated ports on the MDF switch is because it is the root,
which suggest that it wining the STP election.
A couple things to look at would be the election process of root bridges
which goes as follows;
1. Lowest Root BID
2. Lowest path cost to Root Bridge
3. Lowest Sender BID
4. Lowest Port ID
Can you confirm that The mdf switch(switch D) isn't winning the election
through some other means(i.e a lower priority, use the "set spanning-tree
root" command). Also, this would depend on the switches and at what point
they were both powered onto the network. What exactly do you mean by
smaller MAC address? Do you care to post the MAC address of the mdf switch
and switch C.
HTH
Nigel
----- Original Message -----
From: "Jimmy"
To:
Sent: Tuesday, October 22, 2002 2:37 AM
Subject: STP and Switching ! [7:56061]
> Hi,
> I am confused by the CCNP exam certification guide (Cisco Press). It
> mentioned that a switch in the Distribution layer would make a better Root
> Bridge choice than one in Access layer. I thought for distribution switch
is
> of layer 3 so STP is not necessary for it unless it is a flat switched
> network. (Pg 178 of the book) In the Figure 5.8 (Pg 176), i couldn't
> understand how come Catalyst D is the DP for Catalyst E and F. I told
> Catalyst C has priority than D since the MAC address is smaller. Is there
> any mistake. Can anyone please advise.
>
> Where can i find the errata for the ciscopress book? I have went to
> ciscopress.com but couldn't find any. Can anyone give me the URL?
>
> Cheers!
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