Traffic Flow | STP topology behavior in vPC Design

[zekebashi]

Hello,

Refer to the diagram attached.

I'm trying to find out the path that frames/packets take from an ESXi host to the default gateway: 10.1.120.1 if link2 was used?

The show spanning-tree root on 5K_a shows that the root is the core switch (VSS) which is what is expected

The show spanning-tree root on 5K_b shows that the root is the vPC peer switch 5K_a.

There are a few vPC options that aren't enabled on neither vPC peer Primary nor vPC peer Secondary

Peer Switch --- Not enabled
Peer Gateway --- Not enabled
STP Root Primary/STP Root Secodary = Not enabled

VSS consists of two C6509s. BID 24764 for all VLANs
vPC Domain consists of two NX5Ks BID 32768 for all VLANs
vPC nx5k_a and nx5k_b uplinked to VSS via a port-channel/vPC (Po1/vPC1)
vPC nx5K_a and nx5K_b interconnected via a Peer-link port-channel (Po10)
ESXi host is attached to two vPC peer switches (configured in a vPC domain) with individual ports/orphan ports

On nx5k_a (Opertional Primary): the output of the "show spanning-tree root" command displays

Root Hello Max Fwd
Vlan                Root ID                            Cost    Time    Age    Dly    Root Port
---------------- -------------------- ------- ----- --- --- ----------------
VLAN0001     24577 0000.0000.0001     1        2         20     15      port-channel1
VLAN080       24656 0000.0000.0001     1        2         20      15      port-channel1
VLAN088       24664 0000.0000.0001    1         2         20     15      port-channel1
VLAN0120     24696 0000.0000.0001    1         2         20     15      port-channel1
VLAN0122     24698 0000.0000.0001    1         2         20     15      port-channel1
VLAN0124     24700 0000.0000.0001    1         2         20     15      port-channel1
VLAN0126     24702 0000.0000.0001    1         2         20     15      port-channel1
VLAN0128     24704 0000.0000.0001   1         2         20     15      port-channel1
VLAN0140     24716 0000.0000.0001   1         2         20     15      port-channel1
VLAN0141     24717 0000.0000.0001   1        2         20      15      port-channel1
VLAN0150     24726 0000.0000.0001   1        2         20      15      port-channel1
VLAN0300     24876 0000.0000.0001   1        2         20      15      port-channel1
VLAN0320     24896 0000.0000.0001   1       2          20      15      port-channel1
VLAN0321     24879 0000.0000.0001   1       2          20      15      port-channel1
VLAN0400     24976 0000.0000.0001   1       2          20      15      port-channel1
VLAN0401     24977 0000.0000.0001   1       2          20     15       port-channel1

On nx5k_b (Operational Secodary) : the output of the "show spanning-tree root" command display

Root Hello Max Fwd
Vlan                Root ID                            Cost    Time    Age    Dly    Root Port
---------------- -------------------- ------- ----- --- --- ----------------
VLAN0001     24577 0000.0000.0001     1        2         20     15      port-channel10
VLAN080       24656 0000.0000.0001     1        2         20      15      port-channel10
VLAN088       24664 0000.0000.0001    1         2         20     15      port-channel10
VLAN0120     24696 0000.0000.0001    1         2         20     15      port-channel10
VLAN0122     24698 0000.0000.0001    1         2         20     15      port-channel10
VLAN0124     24700 0000.0000.0001    1         2         20     15      port-channel10
VLAN0126     24702 0000.0000.0001    1         2         20     15      port-channel10
VLAN0128     24704 0000.0000.0001   1         2         20     15      port-channel10
VLAN0140     24716 0000.0000.0001   1         2         20     15      port-channel10
VLAN0141     24717 0000.0000.0001   1        2         20      15      port-channel10
VLAN0150     24726 0000.0000.0001   1        2         20      15      port-channel10
VLAN0300     24876 0000.0000.0001   1        2         20      15      port-channel10
VLAN0320     24896 0000.0000.0001   1       2          20      15      port-channel10
VLAN0321     24879 0000.0000.0001   1       2          20      15      port-channel10
VLAN0400     24976 0000.0000.0001   1       2          20      15      port-channel10
VLAN0401     24977 0000.0000.0001   1       2          20     15       port-channel10

[MHM Cisco World]

No attachment 

[zekebashi]

just re-attached it.

[balaji.bandi]

what is the end device? Windows Server how is the configuration on the Server.

If this is orphan ports, based on the Server side config it will decide which port to use to send traffic. again this based on the information provided here.

please post the connected (where the end servers)  port configuration information? is this trunk with an access port or many VLAN passing here?

when you want to be orphan port here, is the server not support LACP and vPC should solve many issues. (you have the best technology you need to take advantage of that) - until you have any reason to deploy this please explain.

[zekebashi]

I just revised the diagram.

The device attached to both vPC peers is an ESXi host

Each link is configured as Trunk port with several VLANs allowed on the trunk

No LACP used. This was decided by the system/vmware team (orphan ports)

[balaji.bandi]

Ok, i have a closed look at the diagram here - upper side (north is VSS). and the only vPC on 5K here.

1. your HSRP where active will be decided here to reach the path in best way in Layer 2 based on root port of spanning tree

if the network relies on STP then the process same for the election path method of old school of STP.

can you post both the nexus spanning-tree output?

[zekebashi]

Apologies. I revised the diagram, again!

Since we are using VSS, there no HSRP. The default GW for VLAN120 is 10.1.120.1.

Here's the output from the spanning-tree vlan 120 command from both 5Ks:

5K_a#
sh spanning-tree vl 120

VLAN0120
Spanning tree enabled protocol rstp
Root ID Priority 24696
Address 0000.0000.0001
Cost 1
Port 4096 (port-channel1)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32888 (priority 32768 sys-id-ext 120)
Address 0000.0000.0003
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Interface  Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Po1 Root FWD 1 128.4096 (vPC) P2p
Po10 Desg FWD 1 128.4105 (vPC peer-link) P2p
Po80 Desg FWD 1 128.4209 (vPC) Edge P2p
Po88 Desg FWD 1 128.4211 (vPC) Edge P2p
Po120 Desg FWD 1 128.4212 (vPC) Edge P2p
Po122 Desg FWD 1 128.4214 (vPC) Edge P2p
Po124 Desg FWD 1 128.4215 (vPC) Edge P2p

===============================================================================

5K_b#

VLAN0120
Spanning tree enabled protocol rstp
Root ID Priority 24696
Address 0000.0000.0001
Cost 2
Port 4105 (port-channel10)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32888 (priority 32768 sys-id-ext 120)
Address 0000.0000.0004
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Po1 Root FWD 1 128.4096 (vPC) P2p
Po10 Root FWD 1 128.4105 (vPC peer-link) P2p
Po80 Desg FWD 1 128.4209 (vPC) Edge P2p
Po188 Desg FWD 1 128.4211 (vPC) Edge P2p
Po120 Desg FWD 1 128.4212 (vPC) Edge P2p
Po122 Desg FWD 1 128.4214 (vPC) Edge P2p
Po124 Desg FWD 1 128.4215 (vPC) Edge P2p