S9300 switches and S3300 switches MSTP domain inconsistencies lead to abnormal port status at one site of East Aafrica

Publication Date:  2013-04-01 Views:  466 Downloads:  0
Issue Description
S3300 switch version: V1R5C01
S9300 switch version: V1R6C01
Network diagram: and fault description: the access switch S3300 dual-homed to two S9300 switch, while the STP configuration on switches didn't achieve the goals as it's desired, the spanning tree port was in wrong state. . Access Switch S3300 spanning tree port state is shown as follows
[BOLE-AS-S3300-GF-1-GigabitEthernet0/0/1] dis stp instance 1 bri
MSTID                                         Port Role        STP State            Protection
   1 GigabitEthernet0/0/1           ALTE           DISCARDING         NONE
   1 GigabitEthernet0/0/2           MAST          FORWARDING       NONE
Alarm Information
None
Handling Process
According to the results of the above analysis, it is necessary to make switch configuration changes;
Method One: three switches do the same configuration changes, make sure the Regionname, revision level, VLAN mapping are all the same on 3 switches.  The modificaton results of the S3300 switch is as follows:
stp region-configuration
region-name Bole-RG1
revision-level 10
instance 1 vlan 101
instance 2 vlan 102
instance 3 vlan 103
instance 4 vlan 104
instance 5 vlan 1 to 100 105 to 4094
active region-configuration

The MSTP spanning tree state come back to normal after the S3300 switch configuration modified accordingly:
[BOLE-AS-S3300-GF-1-GigabitEthernet0/0/2] dis stp instance 1
------- [MSTI 1 Global Info] -------
MSTI Bridge ID: 32768.4c1f-cc79-788c
MSTI RegRoot / IRPC: 0.4c1f-ccfd-bbc8 / 20000
MSTI RootPortId: 128.79
Master Bridge: 32768.4c1f-cc5c-14d2
Cost to Master: 20000
TC received: 37
TC count per hello: 0
Time since last TC: 0 days 0h: 3m: 47s
Number of TC: 31
Last TC occurred: GigabitEthernet0/0/1
---- [Port79 (GigabitEthernet0/0/1)] [FORWARDING] ----
Port Role: Root Port
Port Priority: 128
Port Cost (Dot1T): Config = auto / Active = 20000
Designated Bridge / Port: 0.4c1f-ccfd-bbc8 / 128.50
Port Times: RemHops 20
TC or TCN send: 4
TC or TCN received: 8
---- [Port80 (GigabitEthernet0/0/2)] [DISCARDING] ----
Port Role: Alternate Port
Port Priority: 128
Port Cost (Dot1T): Config = auto / Active = 20000
Designated Bridge / Port: 4096.4c1f-cc5c-14d2 / 128.50
Port Times: RemHops 19
TC or TCN send: 4
TC or TCN received: 9
Based on the information shown above, the access switch has correctly identified the MSTP BPDU packets from the core switch, and participate in the MSTP domain shortest path calculation, and then rightly blocks the port.

Method Two: Configure stp config-digest-snoop  at S3300 switch dua-homedl uplink interfacee , configuration is as follows:
interface GigabitEthernet0/0/2
description TO BOLE-DS-S9303-2
port link-type trunk
port trunk pvid vlan 101
port trunk allow-pass vlan 10 101 2000
stp config-digest-snoop
ntdp enable
ndp enable
Because the VLAN Mapping information is not passed in BPDU packets, but instead in digest information, the stp config-digest-snoop can correctly identify the MSTP BPDU packets from the core switch, and thus participate in the MSTP domain shortest overhead path calculation.

Effect configured as follows:
[BOLE-AS-S3300-GF-1-GigabitEthernet0/0/2] dis stp instance 1 bri
MSTID                                         Port Role        STP State            Protection
   1 GigabitEthernet0/0/1           ALTE           DISCARDING         NONE
   1 GigabitEthernet0/0/2           MAST          FORWARDING       NONE


Effects after the modification are as follows:
[BOLE-AS-S3300-GF-1-GigabitEthernet0/0/2] dis stp instance 1
------- [MSTI 1 Global Info] -------
MSTI Bridge ID: 32768.4c1f-cc79-788c
MSTI RegRoot / IRPC: 0.4c1f-ccfd-bbc8 / 20000
MSTI RootPortId: 128.8
Master Bridge: 32768.4c1f-cc5c-14d2
Cost to Master: 20000
TC received: 72
TC count per hello: 0
Time since last TC: 0 days 0h: 0m: 10s
Number of TC: 8
Last TC occurred: GigabitEthernet0/0/1
---- [Port8 (GigabitEthernet0/0/1)] [FORWARDING] ----
Port Role: Root Port
Port Priority: 128
Port Cost (Dot1T): Config = auto / Active = 20000
Designated Bridge / Port: 0.4c1f-ccfd-bbc8 / 128.50
Port Times: RemHops 20
TC or TCN send: 5
TC or TCN received: 3
---- [Port9 (GigabitEthernet0/0/2)] [DISCARDING] ----
Port Role: Alternate Port
Port Priority: 128
Port Cost (Dot1T): Config = auto / Active = 20000
Designated Bridge / Port: 4096.4c1f-cc5c-14d2 / 128.50
Port Times: RemHops 19
TC or TCN send: 3
TC or TCN received: 9
Based on the information shown above, the access switch has correctly identified the MSTP BPDU packets from the core switch, and participate in the MSTP domain shortest path calculation, and then rightly blocks the port.
Root Cause
Root cause analysis

The analysis procedure is as follows:
1) collection spanning tree status, port state information. The results are as follows:
BOLE-AS-S3300-GF-1-GigabitEthernet0/0/1] dis stp instance 1 bri
MSTID                                         Port Role        STP State            Protection
   1 GigabitEthernet0/0/1           ALTE           DISCARDING         NONE
   1 GigabitEthernet0/0/2           MAST          FORWARDING       NONE
[BOLE-AS-S3300-GF-1-GigabitEthernet0/0/1] dis stp instance 1
------- [MSTI 1 Global Info] -------
MSTI Bridge ID: 32768.4c1f-cc79-788c
MSTI RegRoot / IRPC: 32768.4c1f-cc79-788c / 0
MSTI RootPortId: 0.0
Master Bridge: 32768.4c1f-cc79-788c
Cost to Master: 0
TC received: 72
TC count per hello: 0
Time since last TC: 0 days 0h: 0m: 47s
Number of TC: 9
Last TC occurred: GigabitEthernet0/0/2
---- [Port8 (GigabitEthernet0/0/1)] [DISCARDING] ----
Port Role: Alternate Port
Port Priority: 128
Port Cost (Dot1T): Config = auto / Active = 20000
Designated Bridge / Port: 32768.4c1f-cc79-788c / 128.8
Port Times: RemHops 20
TC or TCN send: 5
TC or TCN received: 3
---- [Port9 (GigabitEthernet0/0/2)] [FORWARDING] ----
Port Role: Master Port
Port Priority: 128
Port Cost (Dot1T): Config = auto / Active = 20000
Designated Bridge / Port: 32768.4c1f-cc79-788c / 128.9
Port Times: RemHops 20
TC or TCN send: 5
TC or TCN received: 9
The above results show that the access switch is not properly identifying MSTP BPDU packets from the core switches, resulting in the failure to participation of shortest cost path calculation  in MSTP domain. Thus, it's suspected to be  MSTP spanning tree problem.

2) Get the switch configuration, Spanning Tree configuration details are as follows:
S33 switch:
#
stp region-configuration
  region-name Bole-RG1
  revision-level 10
  instance 1 vlan 101
  active region-configuration

S93-1 switch:
#
stp instance 1 root primary
stp instance 2 root primary
stp instance 3 root secondary
stp instance 4 root secondary
stp enable
#
stp region-configuration
region-name Bole-RG1
revision-level 10
instance 1 vlan 101
instance 2 vlan 102
instance 3 vlan 103
instance 4 vlan 104
active region-configuration

S93-2 switch:
#
stp instance 0 priority 8192
stp instance 3 priority 0
stp instance 1 root secondary
stp instance 2 root secondary
stp instance 4 root primary
stp enable
#
stp region-configuration
region-name Bole-RG1
revision-level 10
instance 1 vlan 101
instance 2 vlan 102
instance 3 vlan 103
instance 4 vlan 104
active region-configuration
The contrast can be seen from the above configuration between the three interconnect switches-S3300  with  two S9300 switches. Region name, revision level are all the same, but the VLAN mapping is inconsistent, making the switches not in the same  MSTP domain, port state exception.
Suggestions
Recommendations and summary

Properly configured switch Spanning Tree parameters needed in the implementation of the project, to ensure that the port state's normal.

END