Description

On an EX network which has converged with VSTP (as spanning tree topology), a change in the name of the VLAN participating in spanning tree causes an issue with STP convergence. The device undergoing the change tends to skip STP ,and hence the reason for the issue. This problem is explained in detail in the following section.

Affected Junos OS releases include: 11.4R1, 11.4R2, 11.4R3,11.4R7.5 and 12.1R1



Symptoms

SW1 ge-0/0/0 ========TRUNK==========ge-0/0/0 SW2


  • SW1 and SW2 are configured for VSTP for all the vlan 10.
  • SW2 is the root-bridge for vlan10 with a priority of 0k.
  • Link between the two switches is configured as trunk.
  • On both switches the VLAN name is configured as “V10”.
  • On SW1 the VLAN name is changed from  “V10” to “TEST” as soon as the VLAN name is changed from “V10” to “TEST”.
  • STP broke between the switches for vlan 10.
  • In this case both the switches were acting as a root bridge for vlan 10.
  • On SW1 the BPDU is being missed from SW2.
  • If there are redundant links between the two switches, interface on SW1 and SW2 will be in forwarding state
  • This behavior implies to renaming of the VLAN.
  • Verified same with both the replace pattern and rename vlan command.
  • On both cases, we see the same behavior where renaming of the VLAN causes STP to break.

SW1 = > 

root@SW1# run show spanning-tree bridge
STP bridge parameters
Context ID : 0
Enabled protocol : RSTP
Root ID : 32768.5c:5e:ab:65:6a:81
Hello time : 2 seconds
Maximum age : 20 seconds
Forward delay : 15 seconds
Message age : 0
Number of topology changes : 1
Time since last topology change : 447 seconds
Local parameters
Bridge ID : 32768.5c:5e:ab:65:6a:81
Extended system ID : 0
Internal instance ID : 0

STP bridge parameters
Context ID : 1
Enabled protocol : RSTP

STP bridge parameters for VLAN 10
Root ID : 10.00:21:59:cb:b5:41 === SW2 is the root bridge for vlan10
Root cost : 20000
Root port : ge-0/0/0.0
Hello time : 2 seconds
Maximum age : 20 seconds
Forward delay : 15 seconds
Message age : 1
Number of topology changes : 1
Time since last topology change : 2 seconds
Topology change initiator : ge-0/0/0.0
Topology change last recvd. from : 00:21:59:cb:b5:43
Local parameters
Bridge ID : 32778.5c:5e:ab:65:6a:81
Extended system ID : 1
Internal instance ID : 0


root@SW1# show interfaces ge-0/0/0
unit 0 {
family ethernet-switching {
port-mode trunk;
vlan {
members 10;
}
}
}

{master:0}[edit]
root@SW1# show vlans
V10 {
vlan-id 10;
}

The STP breaks because of the “MST Index” change on the switch where the VLAN name was changed.


root@SW1# run start shell

root@SW1:RE:0% vlaninfo -a
Index Name Inst Tag Flags HW-Token L3-ifl MST Index
1 mgmt 1 0 0x20c8 65535 0 0
4 default 0 0 0x100 2 0 0
5 V10 0 10 0x1000100 1 0 1 ======= MST Index number for vlan “V10” is 1
6 Internal 0 0 0x20 0 0 0


root@SW1# rename vlans V10 to TEST ===Vlan name change from “V10” to “TEST”

root@SW1# commit
configuration check succeeds
commit complete

root@SW1# run start shell

root@SW1:RE:0% vlaninfo -a
Index Name Inst Tag Flags HW-Token L3-ifl MST Index

1 mgmt 1 0 0x20c8 65535 0 0
4 default 0 0 0x100 2 0 0
6 Internal 0 0 0x20 0 0 0
7 TEST 0 10 0x1000100 3 0 0 ======= MST Index number for vlan “TEST” is change to 0

root@SW1# run show spanning-tree bridge
STP bridge parameters
Context ID : 0
Enabled protocol : RSTP
Root ID : 32768.5c:5e:ab:65:6a:81
Hello time : 2 seconds
Maximum age : 20 seconds
Forward delay : 15 seconds
Message age : 0
Number of topology changes : 1
Time since last topology change : 550 seconds
Local parameters
Bridge ID : 32768.5c:5e:ab:65:6a:81
Extended system ID : 0
Internal instance ID : 0

STP bridge parameters
Context ID : 1
Enabled protocol : RSTP

STP bridge parameters for VLAN 10
Root ID : 32778.5c:5e:ab:65:6a:81
Hello time : 2 seconds
Maximum age : 20 seconds
Forward delay : 15 seconds
Message age : 0
Number of topology changes : 1
Time since last topology change : 105 seconds
Topology change initiator : ge-0/0/0.0
Topology change last recvd. from : 00:21:59:cb:b5:43
Local parameters
Bridge ID : 32778.5c:5e:ab:65:6a:81
Extended system ID : 1
Internal instance ID : 0


root@SW1> show chassis mac-addresses
FPC 0 MAC address information:
Public base address 5c:5e:ab:65:6a:80
Public count 128

root@SW1> monitor traffic interface ge-0/0/0 layer2-headers extensive <===== On monitoring the interface, it can be seen that SW1 is sending with BPDU with port cost of 0, and the local switching is ignoring the BPDU received from the root bridge SW2


Address resolution is ON. Use <no-resolve> to avoid any reverse lookup delay.

Address resolution timeout is 4s.
Listening on ge-0/0/0, capture size 1514 bytes


07:11:30.176229 bpf_flags 0x81, In
Juniper PCAP Flags [Ext, In], PCAP Extension(s) total length 16
Device Media Type Extension TLV #3, length 1, value: Ethernet (1)
Logical Interface Encapsulation Extension TLV #6, length 1, value: Ethernet (14)
Device Interface Index Extension TLV #1, length 2, value: 45568
Logical Interface Index Extension TLV #4, length 4, value: 72
-----original packet-----
00:21:59:cb:b5:43 > 01:00:0c:cc:cc:cd, ethertype 802.1Q (0x8100), length 68: vlan 10, p 7, LLC, dsap SNAP (0xaa) Individual, ssap SNAP (0xaa) Command, ctrl 0x03: STP 802.1w, Rapid STP, Flags [Proposal], bridge-id 000a.00:21:59:cb:b5:41.8201, length 47
message-age 0.00s, max-age 20.00s, hello-time 2.00s, forwarding-delay 15.00s
root-id 000a.00:21:59:cb:b5:41, root-pathcost 0, port-role Designated
07:11:31.062893 bpf_flags 0x80, Out
Juniper PCAP Flags [Ext], PCAP Extension(s) total length 16
Device Media Type Extension TLV #3, length 1, value: Ethernet (1)
Logical Interface Encapsulation Extension TLV #6, length 1, value: Ethernet (14)
Device Interface Index Extension TLV #1, length 2, value: 45568
Logical Interface Index Extension TLV #4, length 4, value: 72
-----original packet-----
5c:5e:ab:65:6a:83 > 01:00:0c:cc:cc:cd, ethertype 802.1Q (0x8100), length 68: vlan 10, p 7, LLC, dsap SNAP (0xaa) Individual, ssap SNAP (0xaa) Command, ctrl 0x03: STP 802.1w, Rapid STP, Flags [Learn, Forward, Agreement], bridge-id 800a.5c:5e:ab:65:6a:81.8201, length 47
message-age 0.00s, max-age 20.00s, hello-time 2.00s, forwarding-delay 15.00s
root-id 800a.5c:5e:ab:65:6a:81, root-pathcost 0, port-role Designated
07:11:32.175301 bpf_flags 0x81, In
Juniper PCAP Flags [Ext, In], PCAP Extension(s) total length 16
Device Media Type Extension TLV #3, length 1, value: Ethernet (1)
Logical Interface Encapsulation Extension TLV #6, length 1, value: Ethernet (14)
Device Interface Index Extension TLV #1, length 2, value: 45568
Logical Interface Index Extension TLV #4, length 4, value: 72
-----original packet-----
00:21:59:cb:b5:43 > 01:00:0c:cc:cc:cd, ethertype 802.1Q (0x8100), length 68: vlan 10, p 7, LLC, dsap SNAP (0xaa) Individual, ssap SNAP (0xaa) Command, ctrl 0x03: STP 802.1w, Rapid STP, Flags [Proposal], bridge-id 000a.00:21:59:cb:b5:41.8201, length 47
message-age 0.00s, max-age 20.00s, hello-time 2.00s, forwarding-delay 15.00s
root-id 000a.00:21:59:cb:b5:41, root-pathcost 0, port-role Designated
07:11:32.930798 bpf_flags 0x80, Out
Juniper PCAP Flags [Ext], PCAP Extension(s) total length 16
Device Media Type Extension TLV #3, length 1, value: Ethernet (1)
Logical Interface Encapsulation Extension TLV #6, length 1, value: Ethernet (14)
Device Interface Index Extension TLV #1, length 2, value: 45568
Logical Interface Index Extension TLV #4, length 4, value: 72
-----original packet-----
5c:5e:ab:65:6a:83 > 01:00:0c:cc:cc:cd, ethertype 802.1Q (0x8100), length 68: vlan 10, p 7, LLC, dsap SNAP (0xaa) Individual, ssap SNAP (0xaa) Command, ctrl 0x03: STP 802.1w, Rapid STP, Flags [Learn, Forward, Agreement], bridge-id 800a.5c:5e:ab:65:6a:81.8201, length 47
message-age 0.00s, max-age 20.00s, hello-time 2.00s, forwarding-delay 15.00s
root-id 800a.5c:5e:ab:65:6a:81, root-pathcost 0, port-role Designated
07:11:34.175910 bpf_flags 0x81, In
Juniper PCAP Flags [Ext, In], PCAP Extension(s) total length 16
Device Media Type Extension TLV #3, length 1, value: Ethernet (1)
Logical Interface Encapsulation Extension TLV #6, length 1, value: Ethernet (14)
Device Interface Index Extension TLV #1, length 2, value: 45568
Logical Interface Index Extension TLV #4, length 4, value: 72
-----original packet-----
00:21:59:cb:b5:43 > 01:00:0c:cc:cc:cd, ethertype 802.1Q (0x8100), length 68: vlan 10, p 7, LLC, dsap SNAP (0xaa) Individual, ssap SNAP (0xaa) Command, ctrl 0x03: STP 802.1w, Rapid STP, Flags [Proposal], bridge-id 000a.00:21:59:cb:b5:41.8201, length 47
message-age 0.00s, max-age 20.00s, hello-time 2.00s, forwarding-delay 15.00s
root-id 000a.00:21:59:cb:b5:41, root-pathcost 0, port-role Designated
07:11:34.856855 bpf_flags 0x80, Out
Juniper PCAP Flags [Ext], PCAP Extension(s) total length 16
Device Media Type Extension TLV #3, length 1, value: Ethernet (1)
Logical Interface Encapsulation Extension TLV #6, length 1, value: Ethernet (14)
Device Interface Index Extension TLV #1, length 2, value: 45568
Logical Interface Index Extension TLV #4, length 4, value: 72
-----original packet-----
5c:5e:ab:65:6a:83 > 01:00:0c:cc:cc:cd, ethertype 802.1Q (0x8100), length 68: vlan 10, p 7, LLC, dsap SNAP (0xaa) Individual, ssap SNAP (0xaa) Command, ctrl 0x03: STP 802.1w, Rapid STP, Flags [Learn, Forward, Agreement], bridge-id 800a.5c:5e:ab:65:6a:81.8201, length 47
message-age 0.00s, max-age 20.00s, hello-time 2.00s, forwarding-delay 15.00s
root-id 800a.5c:5e:ab:65:6a:81, root-pathcost 0, port-role Designated
^C
6 packets received by filter
0 packets dropped by kernel

Solution


This has been addressed through an internal report and has been fixed from Junos OS 12.3R3 and later.

As a workaround, restart the ethernet-switching process on the device or delete and reconfigure all VLANs.


root@SW1# run restart ethernet-switching <====== Workaround is to restart the “Ethernet Switching table”
Ethernet Switching Process started, pid 3531

root@SW1# run show spanning-tree bridge
STP bridge parameters
Context ID : 0
Enabled protocol : RSTP
Root ID : 32768.5c:5e:ab:65:6a:81
Hello time : 2 seconds
Maximum age : 20 seconds
Forward delay : 15 seconds
Message age : 0
Number of topology changes : 0
Local parameters
Bridge ID : 32768.5c:5e:ab:65:6a:81
Extended system ID : 0
Internal instance ID : 0

STP bridge parameters
Context ID : 1
Enabled protocol : RSTP

STP bridge parameters for VLAN 10
Root ID : 10.00:21:59:cb:b5:41 ===After restarting the Ethernet switching renamed vlan started converging with SW2
Root cost : 20000
Root port : ge-0/0/0.0
Hello time : 2 seconds
Maximum age : 20 seconds
Forward delay : 15 seconds
Message age : 1
Number of topology changes : 1
Time since last topology change : 0 seconds
Topology change initiator : ge-0/0/0.0
Topology change last recvd. from : 00:21:59:cb:b5:43
Local parameters
Bridge ID : 32778.5c:5e:ab:65:6a:81
Extended system ID : 1
Internal instance ID : 0

root@Kalsi-LAb-2201# run start shell

root@Kalsi-LAb-2201:RE:0% vlaninfo -a
Index Name Inst Tag Flags HW-Token L3-ifl MST Index
1 mgmt 1 0 0x20c8 65535 0 0
2 TEST 0 10 0x1000100 1 0 1 ======= MST Index number for vlan “TEST” is 1
3 Internal 0 0 0x20 0 0 0
4 default 0 0 0x100 2 0 0

root@SW1> monitor traffic interface ge-0/0/0 layer2-headers extensive
Address resolution is ON. Use <no-resolve> to avoid any reverse lookup delay.
Address resolution timeout is 4s.
Listening on ge-0/0/0, capture size 1514 bytes

07:15:07.601462 bpf_flags 0x81, In
Juniper PCAP Flags [Ext, In], PCAP Extension(s) total length 16
Device Media Type Extension TLV #3, length 1, value: Ethernet (1)
Logical Interface Encapsulation Extension TLV #6, length 1, value: Ethernet (14)
Device Interface Index Extension TLV #1, length 2, value: 45568
Logical Interface Index Extension TLV #4, length 4, value: 72
-----original packet-----
00:21:59:cb:b5:43 > 01:00:0c:cc:cc:cd, ethertype 802.1Q (0x8100), length 68: vlan 10, p 7, LLC, dsap SNAP (0xaa) Individual, ssap SNAP (0xaa) Command, ctrl 0x03: STP 802.1w, Rapid STP, Flags [Learn, Forward], bridge-id 000a.00:21:59:cb:b5:41.8201, length 47
message-age 0.00s, max-age 20.00s, hello-time 2.00s, forwarding-delay 15.00s
root-id 000a.00:21:59:cb:b5:41, root-pathcost 0, port-role Designated
07:15:09.583318 bpf_flags 0x81, In
Juniper PCAP Flags [Ext, In], PCAP Extension(s) total length 16
Device Media Type Extension TLV #3, length 1, value: Ethernet (1)
Logical Interface Encapsulation Extension TLV #6, length 1, value: Ethernet (14)
Device Interface Index Extension TLV #1, length 2, value: 45568
Logical Interface Index Extension TLV #4, length 4, value: 72
-----original packet-----
00:21:59:cb:b5:43 > 01:00:0c:cc:cc:cd, ethertype 802.1Q (0x8100), length 68: vlan 10, p 7, LLC, dsap SNAP (0xaa) Individual, ssap SNAP (0xaa) Command, ctrl 0x03: STP 802.1w, Rapid STP, Flags [Learn, Forward], bridge-id 000a.00:21:59:cb:b5:41.8201, length 47
message-age 0.00s, max-age 20.00s, hello-time 2.00s, forwarding-delay 15.00s
root-id 000a.00:21:59:cb:b5:41, root-pathcost 0, port-role Designated