Router User Manual

4 NAT troubleshooting
Nortel Secure Router 8000 Series
Troubleshooting - VAS
4-10 Nortel Networks Inc. Issue 01.01 (30 March 2009)
Step 6 Run the display ip routing-table command to check whether a static route to the address pool
is configured on Ethernet 4/0/0. It is required that the next hop of the static route be interface
Null0 and the mask of the Null0 route have the same length as that of the address pool.
However, it is found that the lengths of the masks are different.
----End
Troubleshooting procedure
Do as follows on Router B:
Step 1 Run:
system-view
The system view is displayed.
Step 2 Run:
ip route-static ip-address { mask | mask-length } null0 [ gateway address| preference
preference ]
A static route to the address pool is configured.
----End
After the configuration, you can find that Router A can successfully ping Router C.
Summary
When the NAT address pool and the IP address used to configure the NAT interface are not in
the same network segment, you need to configure a static route to the address pool on the
interface connected to the public network.
The next hop is Null0. The length of the mask in the route must be the same as that of the
address pool.
4.4 FAQs
z
Q: In NAPT Mode, Why the NAT Traffic Cannot Be Sent by the Tester?
A: NAT in NAPT mode supports the NAT translation for only TCP, UDP, and ICMP
packets. Other types of IP packets are directly discarded. So, when NAT in NAPT mode
is adopted, the tester directly discards data packets that are not TCP, UDP, or ICMP
packets.
z
Q: Why the User in the Internal Network Cannot Access the Internal Server Through the
Public Address?
A: You need to configure a route to the public address of the internal server on the router;
the outbound interface of the route is the interface on which the NAT server is
configured., there must be routes on the internal server to the public address.
z
Q: When the Public Address of the NAT Server Is the Same as That of Interfaces,
Internal Users Cannot Access the Internal Server. How to Solve This Problem?