[c-nsp] interfaces flapping QinQ and/or spanning tree

[Bruno Filipe]

Hi there,...

Something Weird is happening to me...the setup is very simple (there's nothing fancy) but for some reason I do have my switch ports flapping all the time and due to the fact the spanning tree is busy converging whenever that happens causing lot of problems...

Have you guys ever faced a problem similar to this?? What's the way around?

Cisco error message document says misconfiguration...I suspect that there's something to do with QinQ...any idea?

#[PRIMO]
Problem Description: Switch interfaces flapping between them

Syslog OUTPUT
Sep  1 11:37:37 cat1.lda2.ao.isp.net 2045: Sep  1 11:37:17.823 GMT+1:
%SW_MATM-4-MACFLAP_NOTIF: Host 0023.3314.0420 in vlan 291 is flapping
between port Fa0/9 and port Fa0/1
Sep  1 11:37:37 cat1.lda2.isp.net 2046: Sep  1 11:37:17.932 GMT+1:
%SW_MATM-4-MACFLAP_NOTIF: Host 0013.8fb8.cb9d in vlan 292 is flapping
between port Fa0/9 and port Fa0/11


#[SECUNDO]
Partial Network Diagram
                              +-+                                                            802.1Q Trunk
                              | |                                       +-----------+ to Another Base Station
           __  WiMAX (802.16) | |--||                             POP#3 |WS-C3550-24|--------> 
          /  \----------------| |  ||                                   +-----------+ Fa0/3
          \__/                | |  ||                                        /Fa0/7
            |                 +-+  ||                                       /
            |                      ||                                      /-->MicroWave link
+--------+  |                      ||                                     /                    802.1Q Trunk
|Customer|--+                      ||  +-----------+                     /Fa0/9    ___________to Another Base Station
| Router |                         ||--| BreezeMAX | 802.1Q Trunk + ----/-------+ /
+--------+                         ||  |   Base    |--------------|WS-C3560-24TS|/ POP#2
                                       |  Station  |         Fa0/4+--/--\-------+
                                       +-----------+          Fa0/1 /    \Fa0/10
                                                                   /      \
                                                Microwave link <--/        \-->Microwave link  
                                                      to         /          \
                                              Another POP(POP#4)             \Fa1/0/1
                                                                            +-\-----------+    802.1Q Trunk     +----+
                                                                      POP#6 |WS-C3750-24TS|---------------------| PE | 
                                                                            +-------------+ Fa1/0/22      Ge0/0 +----+ 

#[TERTIO]
Interface Configs (relevant):
POP#2
interface FastEthernet0/4
 description Link to BreezeMAX Base Station
 switchport trunk encapsulation dot1q
 switchport trunk allowed vlan 2,291,800-849
 switchport mode trunk
 switchport nonegotiate
 spanning-tree portfast
 spanning-tree bpdufilter enable
 spanning-tree bpduguard enable
 spanning-tree guard none

interface FastEthernet0/1
 description Backhaul Microwave link to POP#4
 switchport trunk encapsulation dot1q
 switchport trunk native vlan 2
 switchport mode trunk
 no cdp enable
 spanning-tree mst 0-1 cost 100000

interface FastEthernet0/9
 description Backhaul Microwave link to POP#3
 switchport trunk encapsulation dot1q
 switchport trunk native vlan 2
 switchport trunk allowed vlan 2-4094
 switchport mode trunk
 no cdp enable

interface FastEthernet0/10
 description Backhaul Microwave link to POP#6
 switchport trunk encapsulation dot1q
 switchport trunk native vlan 2
 switchport mode trunk

POP#6
interface FastEthernet1/0/1
 description Backhaul Microwave link to POP#2
 switchport trunk encapsulation dot1q
 switchport mode trunk
 switchport nonegotiate
 bandwidth 100000
 load-interval 30
 spanning-tree mst 0-1 cost 100000

interface FastEthernet1/0/22
 description 802.1Q Trunk to PE Router
 switchport trunk encapsulation dot1q
 switchport mode trunk
 switchport nonegotiate
 no cdp enable
 spanning-tree portfast
 spanning-tree bpdufilter enable

PE Router:
interface GigabitEthernet0/0.2910025
 description Connection to Customer XYZ
 encapsulation dot1Q 291 second-dot1q 25
 ip address 192.168.158.241 255.255.255.252
 ip verify unicast source reachable-via rx
 no ip redirects
 no ip unreachables
 no ip proxy-arp
 no cdp enable
 service-policy output reg384

CE Router:
interface FastEthernet0/0
 description Connection to ISP XYZ
 ip address 192.168.158.242 255.255.255.252
::
ip route 0.0.0.0 0.0.0.0 192.168.158.242


Base Station QinQ configuration
ID                                  : 1
Metro Tag                           : 291
Data VLAN Range                     : [20...799]
--------------------------------------------------
ID                                  : 2
Metro Tag                           : 291
Data VLAN Range                     : [830...4094]
--------------------------------------------------


/bruno filipe