I have a customer where we are planning on using a 3925 to transport 3 VLANs across the WAN to the DR location. We are going to be using L2TPv3 in order to do this. When I configure the subinterface on the 3925 WITHOUT the xconnect, we have no issues. If I configure the xconnect, we start getting periodic unicast storms on the Nexus that last a couple minutes and then stop. The odd thing is that we don't even have the WAN interface turned up where this tunnel would be going out. Literally the only active connection is to the Nexus. The L2TPv3 tunnel isn't even up.
The config of the router is below as well as the port config on the Nexus. I can confirm that its a unicast storm because when I turn unicast storm control on on the port, I see suppressed packets in the interface storm-control counters. We also did a packet capture and see packets that should not be arriving to this router. Not only does the port with the router get flooded, but all the ports on the Nexus on that VLAN (obviously since its a unicast storm). Close to 100Mbps gets pushed out of the interfaces for the duration of the storm. As soon as I take the xconnect off during a storm, it stops.
Not sure why a non-working pseduowire would somehow make a unicast storm periodically occur.
Router Config
pseudowire-class dr_pwc
encapsulation l2tpv3
ip local interface GigabitEthernet0/1.999
ip pmtu
!
interface GigabitEthernet0/0
description Nexus
no ip address
no ip redirects
no ip proxy-arp
load-interval 30
duplex auto
speed auto
!
interface GigabitEthernet0/0.1
description Server VLAN
encapsulation dot1Q 1 native
xconnect 192.168.250.82 1 pw-class dr_pwc
!
interface GigabitEthernet0/0.253
desc iSCSI VLAN (10.254.253.0/24)
encap dot1q 253
xconnect 192.168.250.82 253 pw-class perry_pwc
shut
!
interface GigabitEthernet0/0.254
desc iSCSI VLAN (10.254.254.0/24)
encap dot1q 254
xconnect 192.168.250.82 254 pw-class perry_pwc
shut
!
interface GigabitEthernet0/0.802
description Nexus Routing - Global
encapsulation dot1Q 802
ip address 192.168.1.58 255.255.255.252
no ip redirects
no ip proxy-arp
!
interface GigabitEthernet0/0.852
description Nexus Routing - VIST VRF
encapsulation dot1Q 852
ip vrf forwarding vist_vrf
ip address 10.201.4.2 255.255.255.252
no ip redirects
no ip proxy-arp
!
interface GigabitEthernet0/1
description VPLS
bandwidth 200000
no ip address
no ip redirects
no ip proxy-arp
shutdown
duplex full
speed 1000
!
interface GigabitEthernet0/1.991
description Site #1
bandwidth 100000
encapsulation dot1Q 991
ip address 10.192.251.77 255.255.255.252
no ip redirects
no ip proxy-arp
!
interface GigabitEthernet0/1.999
description DR Site
bandwidth 200000
encapsulation dot1Q 999
ip address 192.168.250.81 255.255.255.252
no ip redirects
no ip proxy-arp
!
Nexus Config
interface Ethernet8/6
description 3925 router
switchport mode trunk
switchport trunk allowed vlan 1,253-254,802,852
