how to make linux bridge's 802.1q STP packet across cisco switch?

May 19, 2005 1 Replies

I'm testing linux redhat fedora 3 bridge STP function. don't enable stp on cisco switch. I found linux send BPDU packet with 802.1Q tag, and then cisco 3550 switch block the packet. then, if linux had two cable connected to cisco switch's same vlan(one is using 802.1q trunk), althrough I have STP enabled on linux, linux will let all two ports working as forwarding state, then it will cause broadcast storm. the problem may be based on two points: one is Linux shouldn't add



802.1q tag for its BPDU packet although it's using 802.1q trunk, another one is that cisco should not block the BPDU packet, it should broadcast it after untagging it. which one is the real problem?

linux use 01:80:c2:00:00:00 as destination mac address for its BPDU packets, maybe cisco doesn't recognize this packet in its non-native vlan. (according cisco's pvst+ knowledge, it only recognize this mac address in its native vlan, in its non-native vlan, it use



01:00:0c:cc:cc:cd as BPDU's mac address.) how can i workaround this problem?

Thanks.


Hans Yin



Sounds to me you have a native-vlan mismatch. Try to either change the linux or cisco switch to properly tag the vlans. If you're not able to change the native-vlan on the linux machine, configure the cisco to use an unused vlan as native vlan

Erik

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