f13rce / spanningtreepracticer Goto Github PK

Hi,

Current OS3 student here. Thanks for this program!

While using this program I noticed that:

Results in the following topology:

According to the Wikipedia page, which based it on ref 12 (802.1d 1998) the transmitting (and thus received) port ID is used. The program seems to use the port ID on which the BPDU was received.

For example:
Bridge 67 blocks local port 47 and uses local port 17 as it's root port. This while port 47 received a BPDU containing bridge 14's port ID 39 which is lower/better then the BPDU local port 17 received from bridge 14 which contained 84.

Similar behaviour is seen at 77 which chooses local port 20 as root port while local port 22 received a BPDU with port ID 51 from bridge 14, thus making it better then port ID 84 that bridge 77 received on local port 20.

Expected behaviour would be for bridge 67 to use local port 47 as it's root port because it received the lower port ID from bridge 14. Similarly bridge 77 should use port 22 as it's root port and block port 20.

I can provide a GNS3 topology that shows the expected behaviour if necessary.