From: Laidlaw, Patrick A. (Patrick.Laidlaw@wwt.com)
Date: Fri Dec 14 2007 - 17:55:33 ART
Which IOS version are you usering for the 3725? Could you send the
binary name?
Patrick Laidlaw
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
George Goglidze
Sent: Friday, December 14, 2007 11:21 AM
To: Cisco certification
Subject: Re: SPT flapping
Hi all,
If someone is interested, I've solved it.
By just changing the router version and IOS on dynamips.
before I had 3640 now I have 3725 with 16ESW module.
With the same config, I have no errors.
Thanks,
On Dec 12, 2007 5:38 PM, George Goglidze <goglidze@gmail.com> wrote:
> Hello group,
>
> I'm trying to resolve this problem for couple hours already, and
> cannot find anything that could help.
>
> let me describe my lab first:
>
> I've got two 3550's which I've connected to my PC.
> on ubuntu with br interfaces I bridge physical interface and tap
> interface.
>
> now in dynamips I create another 2 switches(NM-16ESW), and I connect
> switches all together.
> (dynamips)SW1 F0/1 -> (dynamips) SW2 f0/1 <<<---trunk
> (dynamips)SW1 F0/3 -> (REAL) SW3 f0/3 <<<---trunk
> (dynamips)SW1 F0/15 -> (REAL) SW4 f0/21 <<<---trunk
>
> (dynamips)SW2 F0/1 -> (dynamips) SW1 f0/1 <<<---trunk
> (dynamips)SW2 F0/3 -> (REAL) SW4 f0/3 <<<---trunk
> (dynamips)SW2 F0/15 -> (REAL) SW3 f0/21 <<<---trunk
>
> (REAL)SW3 F0/3 -> (dynamips) SW1 F0/3
> (REAL)SW3 (f0/11,f0/12,f0/13) Po1 -> (REAL) SW4 (f0/11,f0/12,f0/13)
> Po1
> (REAL)SW3 F0/21 -> (dynamips) SW2 F0/15
>
> (REAL)SW4 F0/3 -> (dynamips) SW2 F0/3
> (REAL)SW4 (f0/11,f0/12,f0/13) Po1 -> (REAL) SW3 (f0/11,f0/12,f0/13)
> Po1
> (REAL)SW4 F0/21 -> (dynamips) SW1 F0/15
>
> ---------------------------------
>
> Ok, I hope the physical config is clear.
>
> I've got many NIC's in computer and each of them bridged to particular
> TAP interface which is linked to dynamips appropriate routers.
>
> now the configs:
>
> SW1:
>
> spanning-tree vlan 10 priority 4096
> spanning-tree vlan 20 priority 4096
> spanning-tree vlan 30 priority 4096
> spanning-tree vlan 40 priority 4096
> spanning-tree vlan 55 priority 4096
> spanning-tree vlan 60 priority 4096
> spanning-tree vlan 100 priority 4096
> !
> interface FastEthernet1/0
> switchport mode trunk
> !
> interface FastEthernet1/3
> switchport mode trunk
> !
> interface FastEthernet1/15
> switchport mode trunk
> !
>
>
> SW2:
>
> !
> interface FastEthernet1/0
> switchport mode trunk
> !
> interface FastEthernet1/3
> switchport mode trunk
> !
> interface FastEthernet1/15
> switchport mode trunk
> !
>
>
> SW3:
>
> spanning-tree mode pvst
> spanning-tree extend system-id
> spanning-tree vlan 1 priority 4096
> !
> !
> interface Port-channel1
> switchport trunk encapsulation dot1q
> switchport mode trunk
> !
> interface FastEthernet0/3
> switchport trunk encapsulation dot1q
> switchport mode trunk
> !
> interface FastEthernet0/11
> switchport trunk encapsulation dot1q
> switchport mode trunk
> channel-group 1 mode desirable
> !
> interface FastEthernet0/12
> switchport trunk encapsulation dot1q
> switchport mode trunk
> channel-group 1 mode desirable
> !
> interface FastEthernet0/13
> switchport trunk encapsulation dot1q
> switchport mode trunk
> channel-group 1 mode desirable
> !
> interface FastEthernet0/21
> switchport trunk encapsulation dot1q
> switchport mode trunk
> !
>
>
> ----------------
>
> SW4:
>
>
> spanning-tree mode pvst
> spanning-tree extend system-id
> spanning-tree vlan 70 priority 4096
> !
> interface Port-channel1
> switchport trunk encapsulation dot1q
> switchport mode trunk
> !
> interface FastEthernet0/3
> switchport trunk encapsulation dot1q
> switchport mode trunk
> !
> interface FastEthernet0/11
> switchport trunk encapsulation dot1q
> switchport mode trunk
> channel-group 1 mode desirable
> !
> interface FastEthernet0/12
> switchport trunk encapsulation dot1q
> switchport mode trunk
> channel-group 1 mode desirable
> !
> interface FastEthernet0/13
> switchport trunk encapsulation dot1q
> switchport mode trunk
> channel-group 1 mode desirable
> !
> interface FastEthernet0/21
> switchport trunk encapsulation dot1q
> switchport mode trunk
> !
>
>
> ----------------------------------------------------------------------
> ---------------------------------
>
>
> now the problem:
>
> on sw4 I've got
> debug spanning-tree events
>
> and the output is:
>
>
> 02:35:58: STP: VLAN0040 new root port Po1, cost 28
> 02:35:58: STP: VLAN0040 Po1 -> listening SW4#
> 02:36:02: STP: VLAN0040 new root port Fa0/21, cost 19
> 02:36:02: STP: VLAN0040 Po1 -> blocking SW4#
> 02:36:15: STP: VLAN0055 new root port Po1, cost 28
> 02:36:15: STP: VLAN0055 Po1 -> listening SW4#
> 02:36:18: STP: VLAN0055 new root port Fa0/21, cost 19
> 02:36:18: STP: VLAN0055 Po1 -> blocking SW4#
> 02:36:22: STP: VLAN0020 new root port Po1, cost 28
> 02:36:22: STP: VLAN0020 Po1 -> listening SW4#
> 02:36:23: STP: VLAN0040 new root port Po1, cost 28
> 02:36:23: STP: VLAN0040 Po1 -> listening SW4#
> 02:36:25: STP: VLAN0020 new root port Fa0/21, cost 19
> 02:36:25: STP: VLAN0020 Po1 -> blocking
> 02:36:25: STP: VLAN0040 new root port Fa0/21, cost 19
> 02:36:25: STP: VLAN0040 Po1 -> blocking SW4#
> 02:36:45: STP: VLAN0100 Po1 -> listening
> 02:36:46: STP: VLAN0100 new root port Fa0/3, cost 38
> 02:36:46: STP: VLAN0100 Fa0/3 -> listening SW4#
> 02:36:46: STP: VLAN0100 new root port Po1, cost 28
> 02:36:46: STP: VLAN0100 Fa0/3 -> blocking
> 02:36:46: STP: VLAN0100 new root port Fa0/21, cost 19
> 02:36:46: STP: VLAN0100 Po1 -> blocking SW4#
> 02:37:04: STP: VLAN0020 new root port Po1, cost 28
> 02:37:04: STP: VLAN0020 Po1 -> listening SW4#
> 02:37:09: STP: VLAN0020 new root port Fa0/21, cost 19
> 02:37:09: STP: VLAN0020 Po1 -> blocking SW4#
> 02:37:29: STP: VLAN0020 new root port Po1, cost 28
> 02:37:29: STP: VLAN0020 Po1 -> listening
>
>
>
> on sw3 the same:
>
> 02:30:56: STP: VLAN0100 Fa0/21 -> blocking
> 02:31:02: STP: VLAN0030 we are the spanning tree root
> 02:31:02: STP: VLAN0030 heard root 4096-cc01.1abe.0003 on Fa0/3
> 02:31:02: supersedes 32798-0013.7ff5.f280
> 02:31:02: STP: VLAN0030 new root is 4096, cc01.1abe.0003 on port
> Fa0/3, cost 19
> 02:31:02: STP: VLAN0030 sent Topology Change Notice on Fa0/3
> 02:31:02: STP: VLAN0030 Fa0/21 -> blocking
> 02:31:11: STP: VLAN0055 new root port Fa0/21, cost 38
> 02:31:11: STP: VLAN0055 Fa0/21 -> listening
> 02:31:13: STP: VLAN0055 new root port Fa0/3, cost 19
> 02:31:13: STP: VLAN0055 Fa0/21 -> blocking
> 02:31:20: STP: VLAN0030 Fa0/21 -> listening
> 02:31:26: STP: VLAN0030 Fa0/21 -> blocking
> 02:31:27: STP: VLAN0020 new root port Fa0/21, cost 38
> 02:31:27: STP: VLAN0020 Fa0/21 -> listening
> 02:31:29: STP: VLAN0020 new root port Fa0/3, cost 19
> 02:31:29: STP: VLAN0020 Fa0/21 -> blocking
> 02:31:31: STP: VLAN0100 new root port Fa0/21, cost 38
> 02:31:31: STP: VLAN0100 Fa0/21 -> listening
> 02:31:32: STP: VLAN0100 new root port Fa0/3, cost 19
> 02:31:32: STP: VLAN0100 Fa0/21 -> blocking
> 02:32:09: STP: VLAN0055 new root port Fa0/21, cost 38
> 02:32:09: STP: VLAN0055 Fa0/21 -> listening
> 02:32:09: STP: VLAN0055 new root port Fa0/3, cost 19
> 02:32:09: STP: VLAN0055 Fa0/21 -> blocking
> 02:33:01: STP: VLAN0100 new root port Fa0/21, cost 38
> 02:33:01: STP: VLAN0100 Fa0/21 -> listening
> 02:33:01: STP: VLAN0100 new root port Fa0/3, cost 19
> 02:33:01: STP: VLAN0100 Fa0/21 -> blocking
>
>
> ----------------------------------------------------------------
>
>
> I think for some reason real switches stop receiving BPDU's but why
> could that be?
> has anyone experienced that kind of behavior?
>
> P.S. by the way the brctl is configured without STP it just forwards
> all traffic.
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