Spanning Tree question for the Gurus PART TWO
mikeybinec
Member Posts: 484 ■■■□□□□□□□
in CCNA & CCENT
Alright Gurus, this has to do with an earlier post I made this week:
http://www.techexams.net/forums/ccna-ccent/113213-spanning-tree-question-gurus.html
I figured out what was going wrong but I still need a question or two answered on RSTP. Right off
the bat, the issue with my first issue was a VTP ISSUE!!! I'll explain. Here is tonight's topology:
This time, I used real equipment to figure out why I have two switches claiming to be the root bridge for VLAN 1O.The Packet
Tracer representation in the bottom left corner is how the real equipment is wired . Note carefully, that the far left
switch is a 2950.. For new people into networking, this switch is low rent BUT it has a lower bridge priority due to it's mac address so it will always win the election in deciding who get's to be the root bridge.
so I add vlan 10 to the far left switch--
Then I add vlan 10 to the far right switch and as you can see (just like the the far left switch) it also claims to be the root
It doesn't matter if I do a sp vlan 10 pri root or sp vlan 10 priortiy 4096, there will always be two root switches in this topology. The clue was when I added the hosts and installed the switchport mode access vlan 10 on the respective switches. The vlan information was not being transmitted to all the switches. For example, I could ping accross with the hosts added, but when I put in the switchport mode access and switchport access vlan 10, the hosts couldn't talk to each other. I thought this was a Packet tracer issue. BUT!!!! As soon as I did a VTP DOMAIN name , the far left switch became the sole root of VLANs 1 and 10 and the hosts could talk to each other..
Theodoxa was correct--the bpdu info was not transmitting to all the switches
If anybody wants to see my switch config, just go to "my cisco lab' under my name
Now, my question for the Gurus: Theory tells us newbies that RSTP has a port/link state called backup (especially when you have two or more links to the root bridge.
My question is how I can show/determine that with a sh sp command? Or do I guess?
THANK YOU!!! (I'm testing for ICND2 on the 26th so I appreciate the info)
http://www.techexams.net/forums/ccna-ccent/113213-spanning-tree-question-gurus.html
I figured out what was going wrong but I still need a question or two answered on RSTP. Right off
the bat, the issue with my first issue was a VTP ISSUE!!! I'll explain. Here is tonight's topology:
This time, I used real equipment to figure out why I have two switches claiming to be the root bridge for VLAN 1O.The Packet
Tracer representation in the bottom left corner is how the real equipment is wired . Note carefully, that the far left
switch is a 2950.. For new people into networking, this switch is low rent BUT it has a lower bridge priority due to it's mac address so it will always win the election in deciding who get's to be the root bridge.
so I add vlan 10 to the far left switch--
Then I add vlan 10 to the far right switch and as you can see (just like the the far left switch) it also claims to be the root
It doesn't matter if I do a sp vlan 10 pri root or sp vlan 10 priortiy 4096, there will always be two root switches in this topology. The clue was when I added the hosts and installed the switchport mode access vlan 10 on the respective switches. The vlan information was not being transmitted to all the switches. For example, I could ping accross with the hosts added, but when I put in the switchport mode access and switchport access vlan 10, the hosts couldn't talk to each other. I thought this was a Packet tracer issue. BUT!!!! As soon as I did a VTP DOMAIN name , the far left switch became the sole root of VLANs 1 and 10 and the hosts could talk to each other..
Theodoxa was correct--the bpdu info was not transmitting to all the switches
If anybody wants to see my switch config, just go to "my cisco lab' under my name
Now, my question for the Gurus: Theory tells us newbies that RSTP has a port/link state called backup (especially when you have two or more links to the root bridge.
My question is how I can show/determine that with a sh sp command? Or do I guess?
THANK YOU!!! (I'm testing for ICND2 on the 26th so I appreciate the info)
Cisco NetAcad Cuyamaca College
A.S. LAN Management 2010 Grossmont College
B.S. I.T. Management 2013 National University
A.S. LAN Management 2010 Grossmont College
B.S. I.T. Management 2013 National University
Comments
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Alceo
Member Posts: 80 ■■□□□□□□□□
show spanning-tree clearly state that a port is in backup mode:
Interface Role Sts Cost Prio.Nbr Type
---- ---
Fa0/1 Desg FWD 19 128.1 Shr
Fa0/2 Desg FWD 19 128.2 Shr
Fa0/3 Back BLK 19 128.3 Shr