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interface flapping in Cat3560 and routers

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bluejays

bluejays

Technical User
Dec 25, 2004
12
0
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CA
Hi, there, I have a interface flapping issue in my network. 2 Cat3560 is connected through 2 trunk port configured with port-channel. When I shutdown one of port in Vlan100, other 2 ports in the same vlan will flap going up and down and OSPF will lose the neighbor. One thing I notice that is when I shutdown the switch port, on the other side of router, the L1-L2 is still up/up. I think it should be up/down. I have a keepalive setting on the router interface to 1800. Any body can give me some hints here to troubleshoot?
Here is the switch configs.
Building configuration...

Current configuration : 4453 bytes
!
version 12.2
no service pad
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname RCHdmzSW01
!
logging buffered 8192 debugging
!
ip subnet-zero
ip routing
!
no ip domain-lookup
!
spanning-tree mode pvst
no spanning-tree optimize bpdu transmission
spanning-tree extend system-id
!
!
!
!
!
interface Port-channel1
switchport trunk encapsulation dot1q
switchport trunk native vlan 999
switchport trunk allowed vlan 100,200,300,400,600,700
switchport mode trunk
!
interface GigabitEthernet0/1
switchport access vlan 600
speed 100
duplex full
!
interface GigabitEthernet0/2
switchport access vlan 100
speed 100
duplex full
!
interface GigabitEthernet0/3
switchport access vlan 600
speed 100
duplex full
!
interface GigabitEthernet0/4
switchport access vlan 700
speed 100
duplex full
!
interface GigabitEthernet0/5
switchport access vlan 700
speed 100
duplex full
!
interface GigabitEthernet0/6
switchport access vlan 100
speed 100
duplex full
!
interface GigabitEthernet0/7
switchport access vlan 100
speed 100
duplex full
!
interface GigabitEthernet0/8
switchport access vlan 100
!
interface GigabitEthernet0/9
switchport access vlan 100
speed 100
duplex full
!
interface GigabitEthernet0/10
switchport access vlan 100
speed 100
duplex full
!
interface GigabitEthernet0/11
switchport access vlan 100
speed 100
duplex full
!
interface GigabitEthernet0/12
switchport access vlan 100
speed 100
duplex full
!
interface GigabitEthernet0/13
switchport access vlan 100
speed 100
duplex full
!
interface GigabitEthernet0/14
switchport access vlan 100
speed 100
duplex full
!
interface GigabitEthernet0/15
switchport access vlan 100
speed 100
duplex full
!
interface GigabitEthernet0/16
switchport access vlan 100
speed 100
duplex full
!
interface GigabitEthernet0/17
speed 100
duplex full
!
interface GigabitEthernet0/18
!
interface GigabitEthernet0/19
!
interface GigabitEthernet0/20
!
interface GigabitEthernet0/21
!
interface GigabitEthernet0/22
!
interface GigabitEthernet0/23
!
interface GigabitEthernet0/24
!
interface GigabitEthernet0/25
!
interface GigabitEthernet0/26
!
interface GigabitEthernet0/27
switchport access vlan 400
!
interface GigabitEthernet0/28
switchport access vlan 400
!
interface GigabitEthernet0/29
switchport access vlan 400
!
interface GigabitEthernet0/30
switchport access vlan 200
!
interface GigabitEthernet0/31
switchport access vlan 200
!
interface GigabitEthernet0/32
switchport access vlan 200
!
interface GigabitEthernet0/33
switchport access vlan 200
!
interface GigabitEthernet0/34
switchport access vlan 200
!
interface GigabitEthernet0/35
switchport access vlan 200
!
interface GigabitEthernet0/36
switchport access vlan 200
!
interface GigabitEthernet0/37
switchport access vlan 200
!
interface GigabitEthernet0/38
switchport access vlan 200
!
interface GigabitEthernet0/39
switchport access vlan 200
!
interface GigabitEthernet0/40
switchport access vlan 200
!
interface GigabitEthernet0/41
switchport access vlan 200
!
interface GigabitEthernet0/42
switchport access vlan 200
!
interface GigabitEthernet0/43
switchport access vlan 200
!
interface GigabitEthernet0/44
switchport access vlan 200
!
interface GigabitEthernet0/45
switchport access vlan 500
speed 100
duplex full
!
interface GigabitEthernet0/46
switchport access vlan 500
speed 100
duplex full
!
interface GigabitEthernet0/47
switchport trunk encapsulation dot1q
switchport trunk native vlan 999
switchport trunk allowed vlan 100,200,300,400,600,700
switchport mode trunk
channel-group 1 mode on
!
interface GigabitEthernet0/48
switchport trunk encapsulation dot1q
switchport trunk native vlan 999
switchport trunk allowed vlan 100,200,300,400,600,700
switchport mode trunk
channel-group 1 mode on
!
interface GigabitEthernet0/49
!
interface GigabitEthernet0/50
!
interface GigabitEthernet0/51
!
interface GigabitEthernet0/52
!
interface Vlan1
no ip address
shutdown
!
interface Vlan100
ip address 192.168.40.11 255.255.252.0
no ip redirects
no ip proxy-arp
standby 1 ip 192.168.40.1
standby 1 priority 110
standby 1 preempt
standby 1 track Vlan600 20
!
interface Vlan200
no ip address
!
interface Vlan600
ip address 192.168.35.1 255.255.255.0
!
router ospf 7
log-adjacency-changes
network 192.168.0.0 0.0.255.255 area 0
!
ip classless
ip http server
!
!
!
control-plane
!
!
line con 0
line vty 5 15
!
end

When I shutdown interface gig 0/2, interface gig0/3 and gig0/4 will go down as well and come back online after a while.

Thanks for your help.
 
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The topology is like the following.

V100 (192.168.43.0)
-----------------------------
| |
| |
| |
|----------| Trunk |----------
| SW1 |---------------| SW2 |
----------- ----------
| | | V600 | | | V700
| | | | | |
| | |-------R1----------- | |
| |-----------R2------------- |
|---------------R3---------------
 
Upvote 0 Downvote
What did you suspect? I will confirm the IOS version tomorrow. However, I am leaning toward the Port-channel command. Since it has etherchannel configured and set the mode to "ON", it might cause the spanning-tree loop as per Cisco's Document if the etherchannel is misconfigured.
I saw the spanning-tree on VLAN 600 will do the spanning-tree calculation 2 times when I shut some port belongs to VLAN 600.
I also noticed that some VLAN assignment to the port is not correct, will double-check tomorrow.

Thanks.
 
Upvote 0 Downvote
mode on" only means that you don't use PAgP/LACP for channel negotiation. Make sure both sides are set to "mode on".

And in older IOS image for Catalyst switches, it has bugs in STP/RSTP/MSTP so it'll be good to make sure that all Catalyst switches are running the most up-to-date IOS version (this may not necessarily be the same case for routers).
 
Upvote 0 Downvote
The IOS is 12.2(20)SE4. c3560-i5-mz.122-20.SE4.bin
BOOT IOS is 12.2(25r)SE.

It is not the latest, but it should be close enough. Any thought?
 
Upvote 0 Downvote
Cisco IOS Date Retired
12.2(20)SE4 12-MAY-2005

I can only find 12.2.25-SEB2 which is the most updated release as of today and which doesn't have any "Software Advisory Notice"....yet.

I suggest you should try upgrading your IOS to the most current version and try again. At least this is what you can do at this moment.
 
Upvote 0 Downvote
It is a bug in the IOS, Thanks. I got the TAC confirmed from Cisco
 
Upvote 0 Downvote
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