Cisco Cisco 1800 2800 3800 Series 4-Port EtherSwitch High-Speed WIC Information Guide
Q&A
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interface.
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Use access list, NAT, or GRE to restrict local LAN traffic from traversing the WAN link.
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The card works for a few minutes and then it looks like the network requests a
disconnect and drops the PPP session. I have verified that the proper phone number
(MDN) and MSID are programmed.
Typically it happens if some IP addresses illegal for cellular networks are sent to the cellular
interface. Please use the access list to restrict IP addresses and NAT.
Typically it happens if some IP addresses illegal for cellular networks are sent to the cellular
interface. Please use the access list to restrict IP addresses and NAT.
An installed card is having a problem with the interface recycling itself and in some
instances losing the IP address, even without going down. It also takes a long time
(minutes) to obtain a new IP address. We have a -72-dbm signal strength. What could be
wrong?
Make sure you are using NAT or GRE for LAN traffic that goes over the 3G network.
Make sure you are using NAT or GRE for LAN traffic that goes over the 3G network.
Is it a requirement to have another IP interface up along with the cellular interface? Ping
is failing in my setup. For example, do I need to add IP on Fast Ethernet? If no IP
address is associated to any physical interface, ip route 0.0.0.0 0.0.0.0 cellular 0/0/0
does not work. It will not route traffic to the cellular interface. Is this the correct
behavior?
When no IP address is configured on any interface, the ping is not initiated because there is no
source IP address to put in to the ICMP packets for ping. You can try Telnet or any other
protocol to set up the call. To avoid this situation, you can configure a loopback interface with
some private IP address. You do not have to configure Gigabit Ethernet, but in general the
router has one LAN interface and one WAN interface in a normal scenario and customers will
not have this problem.
When no IP address is configured on any interface, the ping is not initiated because there is no
source IP address to put in to the ICMP packets for ping. You can try Telnet or any other
protocol to set up the call. To avoid this situation, you can configure a loopback interface with
some private IP address. You do not have to configure Gigabit Ethernet, but in general the
router has one LAN interface and one WAN interface in a normal scenario and customers will
not have this problem.
My customer initially had an IP Security (IPsec) tunnel to the host, but it kept dropping.
The customer then configured a GRE tunnel to see if that kept the tunnel up. It did keep
the tunnel up, but every 5 minutes the interface resets. What could be causing this
problem?
Typically it happens because you send illegal IP addresses for the cellular network such as
10.x.x.x, and the firewall disconnects the call. To debug it, restrict the access list only to the IP
addresses range that the network can use, and also use NAT.
Typically it happens because you send illegal IP addresses for the cellular network such as
10.x.x.x, and the firewall disconnects the call. To debug it, restrict the access list only to the IP
addresses range that the network can use, and also use NAT.
I understand the configuration is correct, but I don't understand why NAT is required if
the customer's network is behind the tunnel. Isn't the LAN hidden behind the IPsec
tunnel? Why would the tunnel be terminated by the network for an illegal address? I
thought the network bit bucketed anything not originated from the assigned static IP
address.
Even though the LAN traffic is hidden behind the tunnel, the cellular interface advertises some
information that service providers do not recognize. Therefore, the service provider sends out
a TERMREQ message and Cisco IOS Software acknowledges it and brings the interface
down. At the same time, there is interesting traffic that keeps coming in and the Cisco IOS
Software then tries to call out the cellular again-explaining why the interface comes up until the
next TERMREQ is received.
Even though the LAN traffic is hidden behind the tunnel, the cellular interface advertises some
information that service providers do not recognize. Therefore, the service provider sends out
a TERMREQ message and Cisco IOS Software acknowledges it and brings the interface
down. At the same time, there is interesting traffic that keeps coming in and the Cisco IOS
Software then tries to call out the cellular again-explaining why the interface comes up until the
next TERMREQ is received.