I have this problem with my ISP which they cannot resolve yet.
I have a fiber connection from my 3750G to their 6509 switch.
They report that they see my mac-addresses but I dont see them.
If I check spanning-tree detial i see that I sent about 12000 bpdus on this port but received none.
Seems like some type of communication problem, BUT CDP works.
If I run show cdp neighbors, I see their switch and they see mine.
The switches are both on the same network and I cannot ping them nor can they ping me.
The ports on both sides show Up Up.
GigabitEthernet1/0/27 is up, line protocol is up (connected)
Hardware is Gigabit Ethernet, address is 0019.e71e.be9b (bia 0019.e71e.be9b)
MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive not set
Full-duplex, 1000Mb/s, link type is auto, media type is 1000BaseZX SFP
input flow-control is off, output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:00, output 00:00:01, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
I tried swapping the fiber cables and changes sfp modules along with switching to a different sfp port.
Anyone have any suggestions?