dear All,
i have come accross this following network scenario and got kind of stuck.
The Service Provider is connecting two remote sites of its customer with customer's head office.
Requirement of the customer is to provide them Trunk Links to all the remote sites as well as at the head office so that they can carry their own VLAN information. Basically they have only switched network.
Customer's internal setup is as follows:
VLAN: 1 - PC/Printers etc.
VLAN: 97 - MGT IP of Switches
VLAN: 99 - IP Phone [this is configured as voice VLAN]
VLAN: 100 - for Cisco Call Manager
All of customer's switches are either catalyst 3560 or 3750. at head office there is one switch acting as a core switch [catalyst 3750 / 3 stacked switches] to provide all the trunk links over Fiber Optic links as well as acting as Access Gateway. also all these switches are in VTP TRANSPARENT Mode and all the above mentioned VLANs are manually created in each switch prior to deployment. all the switches are using VLAN 97 as their MGT access but native vlan is 1 as default.
it is also been confirmed that there is no physical loop in between the switches at head office end or any of the remote sites of customer. as for connecting with SP network customer has to use two switch ports [cofigured as trunk] for connecting two of their remote sites.
at the SP end switches are catalyst 3550 and routers used are 7206VXR-NPE-G1.
for each remote sites SP has configured a QinQ tunnel with a unique VLAN ID and carried that tunnel through MPLS L2 circuits to the remote site where the switch ports are also configured as QinQ tunnel ports with corresponding VLAN ids. these remote ports are then connected with customers LAN switches [trunk ports].
all trunk port settings of Customer switches are as follows:
int g0/XXX
switchport trunk encapsulation dot1q
switchport mode trunk
switchport trunk allowed vlan all
Configuration details for SP end Routers/Switches are as follows:
please note that vlan 641 and 648 has been removed from spanning-tree at respective SP sites using:
"no spanning-tree vlan 641/no spanning-tree vlan 648"
native vlan tagging is not enabled in any switches of SP or Customer.
Switches at SP Site:
SP Head Office end configuration:
-------------------------------------------------
interface FastEthernet0/30
description To-Location-1
switchport access vlan 641
switchport mode dot1q-tunnel
l2protocol-tunnel cdp
l2protocol-tunnel stp
l2protocol-tunnel vtp
no cdp enable
spanning-tree bpdufilter enable
end
interface FastEthernet0/31
description To-Location-2
switchport access vlan 648
switchport mode dot1q-tunnel
l2protocol-tunnel cdp
l2protocol-tunnel stp
l2protocol-tunnel vtp
no cdp enable
spanning-tree bpdufilter enable
end
SP Remote end configuration - Location 1:
-------------------------------------------------------------
interface FastEthernet0/10
description To-Location-1-LAN
switchport access vlan 641
switchport mode dot1q-tunnel
l2protocol-tunnel cdp
l2protocol-tunnel stp
l2protocol-tunnel vtp
no cdp enable
spanning-tree bpdufilter enable
end
SP Remote end configuration - Location 2:
-------------------------------------------------------------
interface FastEthernet0/8
description To-Location-2-LAN
switchport access vlan 648
switchport mode dot1q-tunnel
l2protocol-tunnel cdp
l2protocol-tunnel stp
l2protocol-tunnel vtp
no cdp enable
spanning-tree bpdufilter enable
end
Routers at SP Sites:
SP Head Office:
-----------------------
interface FastEthernet1/0.641
description Location-1
encapsulation dot1Q 641
no snmp trap link-status
no cdp enable
mpls l2transport route X.X.127.231 641
end
interface FastEthernet1/0.648
description Location-2
encapsulation dot1Q 648
no snmp trap link-status
no cdp enable
mpls l2transport route X.X.250.221 648
end
SP Remote Site: Location - 1
------------------------------------------
interface FastEthernet0/0.641
description Location-1
encapsulation dot1Q 641
no snmp trap link-status
no cdp enable
mpls l2transport route X.X.127.204 641
end
SP Remote Site: Location - 2
------------------------------------------
interface FastEthernet2/0.648
description Location-2
encapsulation dot1Q 648
no snmp trap link-status
no cdp enable
mpls l2transport route X.X.127.204 648
end
With these configurations customer is facing the following issues:
1. if any one site is connected with head office then all services are running smoothly. IP phone calls are established, LAN Pcs are being able to browse properly. switches are accessible.
2. if both sites are connected then the following issues are raised:
- no calls can be established using IP Phones but rings can be heard. if the call is received then there is no voice.
- icmp is available in random manner. i mean not all the equiments which are available via icmp if one link is connected can be reached if both the links are alive.
- PCs can not reach Internet. and sometimes they have problem reaching gateway as well.
- most of the times DHCP doesn't work.
all these are resolved instantly when either one of the locations are shutdown.
Dynamic MAC Address Table in SP switches shows that MAC is propagating accross the provider network from each remote sites to head office and the way back.
however i have noticed a problem in the MAC flow. during the time when both the links were alive.
MAC address of Remote Switch at Location 1: xxxx.xxxx.d0e1
this MAC was found at Port Fa0/31 of SP Head Office end Switch instead of Fa0/30 [ show mac address-table dynamic | include d0e1 ] and this switch was not accessible from HO.
Till now I have come accross all these and could not resolve.
Please suggest what need to be done to overcome the situation when no network service is working if both the remote locations are connected. Also please feel free to knock for any further queries ....
Looking forward for suggestions as well as Thank You in Advance.
Tahmeed
