ryanm
10-09-2011, 07:22 PM
I have just completed chapter 10 and reviewing what I have learned by running the show commands my own environment. I was wondering if someone could shed some light on something I have discovered.
I have a core switch with around 30 VLAN. This holds the root bridge for 29 of my VLANS. If I look at spanning tree I see that for one of my VLANS it is actually not the root bridge.
Core:
VLAN0030
Spanning tree enabled protocol ieee
Root ID Priority 32768
Address 0007.affb.9ce1
Cost 23
Port 913 (GigabitEthernet8/17)
Hello Time 1 sec Max Age 16 sec Forward Delay 13 sec
Bridge ID Priority 32768
Address 001a.303b.dc1e
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300
Switch connected to GI8/17
VLAN0030
Spanning tree enabled protocol ieee
Root ID Priority 32768
Address 0007.affb.9ce1
Cost 19
Port 48 (FastEthernet1/0/44)
Hello Time 1 sec Max Age 16 sec Forward Delay 13 sec
Bridge ID Priority 32798 (priority 32768 sys-id-ext 30)
Address 0026.51e7.c080
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300 sec
Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Gi1/0/1 Desg FWD 4 128.1 P2p
Fa1/0/10 Desg FWD 19 128.12 P2p Edge
Fa1/0/34 Desg FWD 19 128.38 P2p Edge
Fa1/0/40 Desg FWD 19 128.44 P2p Edge
Fa1/0/44 Root FWD 19 128.48 P2p
Fa1/0/45 Desg FWD 19 128.49 P2p Edge
so what I thing I am seeing here is that even though GI8/17 and GI1/0/1 are connected at a cost of 4, for some reason it is using fa1/0/44 as the root. if I look at CDP information and port information this is simply just an access port with no connection back to the Core.
could someone explain what I am seeing here. Thanks!
I have a core switch with around 30 VLAN. This holds the root bridge for 29 of my VLANS. If I look at spanning tree I see that for one of my VLANS it is actually not the root bridge.
Core:
VLAN0030
Spanning tree enabled protocol ieee
Root ID Priority 32768
Address 0007.affb.9ce1
Cost 23
Port 913 (GigabitEthernet8/17)
Hello Time 1 sec Max Age 16 sec Forward Delay 13 sec
Bridge ID Priority 32768
Address 001a.303b.dc1e
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300
Switch connected to GI8/17
VLAN0030
Spanning tree enabled protocol ieee
Root ID Priority 32768
Address 0007.affb.9ce1
Cost 19
Port 48 (FastEthernet1/0/44)
Hello Time 1 sec Max Age 16 sec Forward Delay 13 sec
Bridge ID Priority 32798 (priority 32768 sys-id-ext 30)
Address 0026.51e7.c080
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300 sec
Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Gi1/0/1 Desg FWD 4 128.1 P2p
Fa1/0/10 Desg FWD 19 128.12 P2p Edge
Fa1/0/34 Desg FWD 19 128.38 P2p Edge
Fa1/0/40 Desg FWD 19 128.44 P2p Edge
Fa1/0/44 Root FWD 19 128.48 P2p
Fa1/0/45 Desg FWD 19 128.49 P2p Edge
so what I thing I am seeing here is that even though GI8/17 and GI1/0/1 are connected at a cost of 4, for some reason it is using fa1/0/44 as the root. if I look at CDP information and port information this is simply just an access port with no connection back to the Core.
could someone explain what I am seeing here. Thanks!