N9K – Migrate B2B vPC
1. Initial State
The dotted line are links not patched. A pair of routers connect all the SS and SD. The VLAN gateway is currently at SS003/004. B2B vPC is between SS000A03 and SS003/004.
2. Set Link between SS & SD as Independent Trunk Ports
It is a square among the SDs and SSs.
STP blocks Eth1/2 on SS004 only as the downstream switches uses vPC to avoid STP blocked ports.
SS004# show spanning-tree vlan 10
VLAN0010
Spanning tree enabled protocol rstp
Root ID Priority 10
Address 0023.04ee.be28
Cost 8
Port 4107 (port-channel12)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 10 (priority 0 sys-id-ext 10)
Address 0023.04ee.be32
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Interface Role Sts Cost Prio.Nbr Type
—————- —- — ——— ——– ——————————–
Po12 Root FWD 4 128.4107 (vPC peer-link) Network P2p
Po100 Desg FWD 1 128.4195 (vPC) P2p
Eth1/2 Altn BLK 4 128.2 P2p
3. A03 Move 2 Uplinks to SD
Move the crosslinks from SS to SD. VPC 100 and 101 are both up now. The VLAN gateway is still at SS003/004. H1 ping is still working.
4. Move the Remaining 2 Uplinks to SD
There are 4 packet drops from H1 when moving the remaining 2 uplinks to SD.
64 bytes from 1.1.1.1: icmp_seq=399 ttl=252 time=124.435 ms
Request 400 timed out
Request 401 timed out
Request 402 timed out
Request 403 timed out
64 bytes from 1.1.1.1: icmp_seq=404 ttl=252 time=37.029 ms
5. Move VLAN GW to SD
- Shut GW on SS004. No impact.
- Unshut GW on SD002. It becomes HSRP standby. No impact.
- Shut GW on SS003. SD002 becomes HSRP active. 1 Packet drop on H1.
- Unshut GW on SD001. After the preempt timer times out, it becomes HSRP active. 1 Packet drop on H1.
6. Final State
