12-01-2011 03:09 AM - edited 03-07-2019 03:41 AM
Dear Experts,
We are facing issue related to STP.
Find the Topology Diagram:
I am getting MAC FLAP error on Cisco 4510 switch. The effect on network is intermittent Pkt drops in the network. When I checked the specific Ip address I am getting the same with two different
XXXX # show ip arp 172.24.101.115
Protocol Address Age (min) Hardware Addr Type Interface
Internet 10.10.101.115 0 000c.2903.1625 ARPA Vlan101
XXXX # show mac add add 000c.2903.162
No entries present.
XXXX# show mac add add 000c.2903.1625
Unicast Entries
vlan mac address type protocols port
-------+---------------+--------+---------------------+--------------------
101 000c.2903.1625 dynamic ip GigabitEthernet7/20
102 000c.2903.1625 dynamic ip GigabitEthernet7/22
When I have check the STP paramerters :
STP config on Cisco 4510 CORE switch :
spanning-tree mode pvst
spanning-tree loopguard default
spanning-tree extend system-id
spanning-tree vlan 100,101,102 priority 0
XXXX# sh spanning-tree
VLAN000100
Spanning tree enabled protocol ieee
Root ID Priority 100
Address 0023.04c1.b580
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 2 (priority 0 sys-id-ext 100)
Address 0023.04c1.b580
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300
VLAN000101
Spanning tree enabled protocol ieee
Root ID Priority 101
Address 0023.04c1.b580
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 3 (priority 0 sys-id-ext 101)
Address 0023.04c1.b580
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300
VLAN0102
Spanning tree enabled protocol ieee
Root ID Priority 101 Address 0023.04c1.b580
Cost 20020
Port 406 (GigabitEthernet7/22)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 102 (priority 0 sys-id-ext 102)
Address 0023.04c1.b580
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300
Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Gi7/22 Root FWD 4 128.406 P2p
Vlan is created on CORE switch and assign priority 0 than CORE switch should be the Root. but instead Root port is becoming the port where server is connected. Server at last connected to CORE switch via HP switch via other Vlan to CORE switch and creating a loop as shown in Diag.
SH OUTPUT of 10.10.102.3 switch :
sh spanning-tree interface gi0/5 detail
Port 5 (GigabitEthernet0/5) of VLAN0102 is root forwarding
Port path cost 4, Port priority 128, Port Identifier 128.5.
Designated root has priority 3, address 0023.04c1.b580
Designated bridge has priority 65534, address 0817.f41a.8d00
Designated port id is 128.23, designated path cost 20012
Timers: message age 5, forward delay 0, hold 0
Number of transitions to forwarding state: 3
Link type is point-to-point by default
Loop guard is enabled by default on the port
BPDU: sent 212, received 3510823
Port 48 (GigabitEthernet0/48) of VLAN0102 is designated forwarding
Port path cost 4, Port priority 128, Port Identifier 128.48.
Designated root has priority 3, address 0023.04c1.b580
Designated bridge has priority 32870, address 0022.0d5d.3d80
Designated port id is 128.48, designated path cost 20016
Timers: message age 0, forward delay 0, hold 0
Number of transitions to forwarding state: 1
Link type is point-to-point by default
Loop guard is enabled by default on the port
BPDU: sent 370806, received 1
sh spanning-tree interface gi0/5 rootcost
VLAN0102 20012
sh spanning-tree interface gi0/48 rootcost
VLAN0102 20016
sh spanning-tree interface gi0/9 rootcost
VLAN0102 20016
sh spanning-tree interface gi0/8 rootcost
VLAN0102 20016
Can you help to identify the exact issue? The Priority of Vlan 102 is changed and Root port has been changed due to that. The Bridge ID is the same as CORE switch.
Please help.
Regards,
12-01-2011 03:38 AM
Hi Dipesh,
Vlan is created on CORE switch and assign priority 0 than CORE switch should be the Root. but instead Root port is becoming the port where server is connected. Server at last connected to CORE switch via HP switch via other Vlan to CORE switch and creating a loop as shown in Diag.
SH OUTPUT of 10.10.102.3 switch :
sh spanning-tree interface gi0/5 detail
Port 5 (GigabitEthernet0/5) of VLAN0102 is root forwarding
Port path cost 4, Port priority 128, Port Identifier 128.5.
Designated root has priority 3, address 0023.04c1.b580
Designated bridge has priority 65534, address 0817.f41a.8d00
Designated port id is 128.23, designated path cost 20012
Timers: message age 5, forward delay 0, hold 0
Number of transitions to forwarding state: 3
Link type is point-to-point by default
Loop guard is enabled by default on the port
BPDU: sent 212, received 3510823
Port 48 (GigabitEthernet0/48) of VLAN0102 is designated forwarding
Port path cost 4, Port priority 128, Port Identifier 128.48.
Designated root has priority 3, address 0023.04c1.b580
Designated bridge has priority 32870, address 0022.0d5d.3d80
Designated port id is 128.48, designated path cost 20016
Timers: message age 0, forward delay 0, hold 0
Number of transitions to forwarding state: 1
Link type is point-to-point by default
Loop guard is enabled by default on the port
BPDU: sent 370806, received 1
The port facing the root bridge will be a root port as you might be aware so I am not surprised at that and the other port is designated forwardign which is the expected behaviour.
You seem to running some VM stuff on the blades. The mac flaps occurs when you are running the VM's in a active/active state or trying to perform load balancing. I would suggest you to check that bit first. STP should work fine unless you tweak it and twist.
HTH
Kishore
12-01-2011 10:53 PM
Dear Kishore,
Than why the Root port is not teh port connected to CORE switch?
Regards,
12-02-2011 12:49 AM
The port of the core switch must be all, or also for vlan you have configured a low priority in designated state.
I see the 3 switches connected to the core, so no redundant link exist, but on hpc7000 the link is trunk? The hp procurve is without stp enabled? can crete loop between the switch of blade?
12-02-2011 03:13 AM
The root port is the port on the switch that is connected to the Root switch. The ports on the Root switch will NOT be root ports. They will be in FWD mode.
Hope this helps otherwise let me know if you want more information
Kishore
12-02-2011 05:03 AM
From looking at your diagram, all vlans that call the 4510 the root switch, will have all ports in DP mode. Remember all ports on the root switch will need to be in designated, because the root switch is the one who sends out BPDU, unless we are talking about RSTP/RPVST in which all switches can do both. The other switches in STP/PVST+ will receive the BPDUs from the root switch and relay them down stream. The switch at the bottom can form a switching loop, since it has multiple paths to the root switch for the specified vlans. According to the config, One of the ports will be a Root Port, and the others will be in blocking.
So I dont see anything out of the orrdinary with PVST.
As for the VM/Blade servers, I don't have any experience with dealing with those, but I do know that if you are load balancing or perform aggregation/etherchannel that it can cause mac flaps but I believe that is normal in that situation, but don't quote me on that.
12-02-2011 11:22 PM
How can I made Vlan 102 Priority 102 instead of 101? As per configuration it should 102 but somehow it was changed to 101 why I can't understand. Can anybody tell me?
VLAN0102
Spanning tree enabled protocol ieee
Root ID Priority 101 Address 0023.04c1.b580
Cost 20020
Port 406 (GigabitEthernet7/22)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 102 (priority 0 sys-id-ext 102)
Address 0023.04c1.b580
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300
Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Gi7/22 Root FWD 4 128.406 P2p
Regards,
12-03-2011 03:18 AM
If you give vlan 102 a priority of 0 it should be 102 if you have 'spanning-tree extend system-id' configured.
That should make your priority = 0 + 102 = 102.
If you can following the root ports for vlan 102 back to the root switch and give us the BID and priority of that
root switch.
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