dear experts
a customer of mine has a legacy environment with 4 x Cisco 9500 (IOS XE
17.09.03) connected in a square mode with 2 links (2 per each connection)
and each couple of links is considered a single virtual port (port-channel).
Loops are managed with PVSTP.
Two x C9500 are in DC1 while the other two x 9500 are in DC2.
9500-1 == 9500-3
|| ||
9500-2 == 9500-4
The issue is: when there is a provider flapping, ie one out of the two link
connecting C9500 in the two DC is flapping, we see one port flaps,
port-channel remains UP but PVSTP reconverge and there is a communication
failure.
The question: since the PO remains up, why we see this behaviour ?
are BDPU sent just over one link (ie the higher interfac e) ?
how can we solve this issue keeping this scenario ?
moving to RSTP could solve ?
Thanks in advance
Cheers
James
here some logs:
May 6 11:48:35.590: %LINEPROTO-5-UPDOWN: Line protocol on Interface
TwentyFiveGigE1/0/48, changed state to down
May 6 11:48:36.593: %LINK-3-UPDOWN: Interface TwentyFiveGigE1/0/48,
changed state to down
May 6 11:48:40.343: %LINK-3-UPDOWN: Interface TwentyFiveGigE1/0/48,
changed state to up
May 6 11:48:44.171: %LINEPROTO-5-UPDOWN: Line protocol on Interface
TwentyFiveGigE1/0/48, changed state to up
#sh etherchannel summary
------+-------------+-----------+-----------------------------------------------
1 Po1(SU) LACP Twe1/0/1(P) Twe1/0/2(P)
12 Po12(SU) LACP Twe1/0/47(P) Twe1/0/48(P)
Port-channel: Po12 (Primary Aggregator)
------------
Age of the Port-channel = 187d:15h:09m:01s
Logical slot/port = 9/12 Number of ports = 2
HotStandBy port = null
Port state = Port-channel Ag-Inuse
Protocol = LACP
Port security = Disabled
Fast-switchover = disabled
Fast-switchover Dampening = disabled
Ports in the Port-channel:
Index Load Port EC state No of bits
------+------+------+------------------+-----------
0 00 Twe1/0/47 Active 0
0 00 Twe1/0/48 Active 0
Time since last port bundled: 0d:01h:50m:00s Twe1/0/48
Time since last port Un-bundled: 0d:01h:50m:09s Twe1/0/48
# sh spanning-tree interface port-channel 12 state
VLAN0015 blocking
VLAN0016 forwarding
# sh spanning-tree vlan 15 detail
VLAN0015 is executing the rstp compatible Spanning Tree protocol
Bridge Identifier has priority 20480, sysid 15, address 8c84.4236.5fe0
Configured hello time 2, max age 20, forward delay 15, transmit
hold-count 6
Current root has priority 8207, address 444c.a830.ff71
Root port is 2089 (Port-channel1), cost of root path is 2000
Topology change flag not set, detected flag not set
Number of topology changes 73 last change occurred 01:52:13 ago
from Port-channel1
Times: hold 1, topology change 35, notification 2
hello 2, max age 20, forward delay 15
Timers: hello 0, topology change 0, notification 0, aging 300
Port 2089 (Port-channel1) of VLAN0015 is root forwarding
Port path cost 1000, Port priority 128, Port Identifier 128.2089.
Designated root has priority 8207, address 444c.a830.ff71
Designated bridge has priority 16399, address cc79.d760.73e0
Designated port id is 128.2089, designated path cost 1000
Timers: message age 15, forward delay 0, hold 0
Number of transitions to forwarding state: 18
Link type is point-to-point by default
BPDU: sent 289, received 4527220
Port 2100 (Port-channel12) of VLAN0015 is alternate blocking
Port path cost 1000, Port priority 128, Port Identifier 128.2100.
Designated root has priority 8207, address 444c.a830.ff71
Designated bridge has priority 12303, address 444c.a830.fc01
Designated port id is 128.107, designated path cost 1999
Timers: message age 15, forward delay 0, hold 0
Number of transitions to forwarding state: 20
Link type is point-to-point by default
BPDU: sent 340, received 4525304
_______________________________________________
cisco-nsp mailing list cisco-nsp@puck.nether.net
https://puck.nether.net/mailman/listinfo/cisco-nsp
archive at http://puck.nether.net/pipermail/cisco-nsp/
