RSTP problem

Unanswered Question
Jan 28th, 2009
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Hello all!



I've run into a big STP problem that I need advice on how to deal with.



See attached PDF for a network drawing of the current network.


I've got one core that I have configured to be the STP root on 3 VLANS


The rest are pretty much access-switches (Cat2960G) that I connect with Etherchannels.


The issue that I'm having is that one switch (of a total of 9) are not getting the STP information correctly.


The malfunctioning switch wants to become STP root on two of the three VLANS. They get the correct STP priority of the network management VLAN (200) but not on the other two VLANS (119,125).


See the stp-error word document for STP outputs.



When debugging STP events I see in the edge-switch that it gets STP for VLANS that doesnt even exists on the network.


Jan 28 14:29:11.845: STP SW: PROC RX: 0100.0ccc.cccd<-001e.1430.9e15 type/len 0032no de

Jan 28 14:29:11.845: encap SNAP linktype sstp vlan 109 len 64 on v109 Po3

Jan 28 14:29:11.854: AA AA 03 00000C 010B SSTP

Jan 28 14:29:11.854: CFG P:0000 V:02 T:02 F:3C R:607D 001f.ca34.3880 00000005

Jan 28 14:29:11.854: B:807D 001e.1430.9e00 80.48 A:0200 M:1400 H:0200 F:0F00

Jan 28 14:29:11.854: T:0000 L:0002 D:007D

Jan 28 14:29:11.854: STP SW: DROP BPDU: received sstp(118) BPDU on interface Po3 vlan 109: vlan 109 does not exist

Jan 28 14:29:12.835: STP SW: RX ISR: 0100.0ccc.cccd<-001e.1430.9e15 type/len 0032

Jan 28 14:29:12.835: encap SNAP linktype sstp vlan 103 len 64 on v103 Po3

Jan 28 14:29:12.835: AA AA 03 00000C 010B SSTP

Jan 28 14:29:12.835: CFG P:0000 V:02 T:02 F:3C R:6077 001f.ca34.3880 00000005

Jan 28 14:29:12.835: B:8077 001e.1430.9e00 80.48 A:0200 M:1400 H:0200 F:0F00

Jan 28 14:29:12.835: T:0000 L:0002 D:0077

Jan 28 14:29:12.835: STP SW: PROC RX: 0100.0ccc.cccd<-001e.1430.9e15 type/len 0032

Jan 28 14:29:12.835: encap SNAP linktype sstp vlan 103 len 64 on v103 Po3

Jan 28 14:29:12.835: AA AA 03 00000C 010B SSTP

Jan 28 14:29:12.835: CFG P:0000 V:02 T:02 F:3C R:6077 001f.ca34.3880 00000005

Jan 28 14:29:12.835: B:8077 001e.1430.9e00 80.48 A:0200 M:1400 H:0200 F:0F00

Jan 28 14:29:12.835: T:0000 L:0002 D:0077

Jan 28 14:29:12.835: STP SW: DROP BPDU: received sstp(118) BPDU on interface Po3 vlan 103: vlan 103 does not exist


Only have VLAN 119,125 and 200 on the entire network.


No other switch that I debug gets that message when I check them.


Anyone got a hint of what I may have done wrong?


Thank you



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glen.grant Wed, 01/28/2009 - 09:08
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I would say the trunk etherchannel is not working correctly. I would also go thru each of the switches and do a show vlan and see if those show up anywhwere. It appears they are defined in at least one of the switches somewhere. Try pulling off spanning guard root on SW4 and see if that does anything.

azore2007 Thu, 01/29/2009 - 02:44
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Hi Glen


I've disabled the etherchannels and configured a new interface as a new trunk.


Still getting the same problems.



Regarding the "unknown vlans" is abit strange, since no other switch gets those packets.. I've debugged "spanning-tree all" on all switches attached to SW04 and they just report the configured vlans (119,125,200) and nothing else.


Gonna grab a brand new switch and try tomorrow... its just very strange.

Francois Tallet Thu, 01/29/2009 - 11:04
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SSTP BPDUs can be flooded by non-cisco switches, or by Cisco switches with STP disabled.

Do you have any non-Cisco switch on your network?

Did you disable STP for some vlans? Be particularly careful about access vlans. Your suspect BPDUs might have been generated by a device connected to an access port in a vlan with STP disabled.

Regards,

Francois

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