Dears, i have an isr4431, and I'm configuring a BDI interface to ensure redundancy in case a leg went down.
below the config i used in the router:
spanning-tree mode rapid-pvst
!
inter BDI100
ip address 192.168.1.254 255.255.255.0
!
interface GigabitEthernet0/0/0
no ip address
negotiation auto
service instance 100 ethernet
encapsulation dot1q 100
rewrite ingress tag pop 1 symmetric
bridge-domain 100
!
interface GigabitEthernet0/0/1
no ip address
negotiation auto
service instance 100 ethernet
encapsulation dot1q 100
rewrite ingress tag pop 1 symmetric
bridge-domain 100
switch configuration was:
interface GigabitEthernet1/1/1
description 4431 Leg1
switchport trunk allowed vlan 100
switchport mode trunk
spanning-tree guard loop
!
interface GigabitEthernet2/1/1
description 4431 Leg2
switchport trunk allowed vlan 100
switchport mode trunk
spanning-tree guard loop
spanning tree from router side on this vlan is:
4431#sh spanning-tree vlan 100
G1:VLAN0100
Spanning tree enabled protocol rstp
Root ID Priority 100
Address 0008.e3ff.fc28
Cost 4
Port 8 (GigabitEthernet0/0/0)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32770 (priority 32768 sys-id-ext 2)
Address 0027.e37a.20a2
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 0
Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Gi0/0/0 Root FWD 4 128.8 P2p Peer(STP)
Gi0/0/1 Altn BLK 4 128.9 P2p Peer(STP)
now, when i disconnect/reconnect the Gi0/0/1 nothing happens to the traffic.
when i disconnect the Gi0/0/0 one ping is dropped only, and after reconnecting it, spanning tree works on making the Gi0/0/0 a root interface, i receive a couple of HOSTFLAPPING errors on the switch then all return to normal, and around 8 pings are lost.
is this normal! are there any way prevent this error when the root link is reconnected, should i be concerned of future HOSTFLAPPING, especially that I'm going to make this router a spoke for a DMVPN.
thanks in advance.
