Troubleshooting guide

If the ping test fails (a ping success rate of 0 percent), you see output similar to the output shown below. In
this case, continue with the troubleshooting steps that follow.
Router#ping 192.168.1.1
Type escape sequence to abort.
Sending 5, 100−byte ICMP Echos to 192.168.1.1, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
Router#
Is the bridge port in a forwarding state?
For your Cisco DSL Router to forward packets to your ISP, your bridged interface must be in a forwarding
state. If your bridged interface is in a blocking state, there is a loop in your network that you have to remove
before you are able to pass traffic. The most common cause of a loop in a ADSL network is having two
bridged ADSL circuits to the same ISP.
Router#show spanning−tree
Bridge group 1 is executing the ieee compatible Spanning Tree protocol
Bridge Identifier has priority 32768, address 0000.0c5d.3694
Configured hello time 2, max age 20, forward delay 15
We are the root of the spanning tree
Topology change flag not set, detected flag not set
Number of topology changes 7 last change occurred 00:03:45 ago from ATM0.1
Times: hold 1, topology change 35, notification 2
hello 2, max age 20, forward delay 15
Timers: hello 0, topology change 0, notification 0, aging 300
Port 3 (ATM0) of Bridge group 1 is forwarding
Port path cost 1562, Port priority 128, Port Identifier 128.3.
Designated root has priority 32768, address 0000.0c5d.3694
Designated bridge has priority 32768, address 0000.0c5d.3694
Designated port id is 128.3, designated path cost 0
Timers: message age 0, forward delay 0, hold 0
Number of transitions to forwarding state: 4
BPDU: sent 49843, received 0
Router#
Is there an entry in the bridge table?
When you are sure that your bridged interface is forwarding, you need to determine if you have the Layer 2
media access control (MAC) address of your ISP's gateway router. Use the show bridge command to check
for the Layer 2 address. This command lists all the Layer 2 entries for a specific bridge group.
Router#show bridge
Total of 300 station blocks, 299 free
Codes: P − permanent, S − self
Bridge Group 1:
Address Action Interface Age RX count TX count
0010.7bb9.bd1a forward ATM0 0 10 9
Router#
Cisco DSL Router Configuration and Troubleshooting Guide