Kevin Dorrell, CCIE #20765

16 Feb 2008

NMC Lab 7.16 – Address Administration

Filed under: NAT — dorreke @ 22:02

I cannot get the NAT requirement working at all, even with the same config as in the SHOWiT. R4 or R6 may well be doing the translation of the source from 172.16.110.1 to 172.16.104.10 for the outgoing packet, and in reverse for the echo response, but then where does R4 send the response? It has no route to 172.16.110.1 does it?

CAT1#ping 
Protocol [ip]: 
Target IP address: 172.16.101.1 
Repeat count [5]: 
Datagram size [100]: 
Timeout in seconds [2]: 
Extended commands [n]: y 
Source address or interface: 172.16.110.1 
Type of service [0]: 
Set DF bit in IP header? [no]: 
Validate reply data? [no]: 
Data pattern [0xABCD]: 
Loose, Strict, Record, Timestamp, Verbose[none]: 
Sweep range of sizes [n]:  

Type escape sequence to abort. 
Sending 5, 100-byte ICMP Echos to 172.16.101.1, timeout is 2 seconds: 
..... 
Success rate is 0 percent (0/5) 
CAT1#

If we have debug ip icmp on R1 during this operation, this is what we see:

R1# 
*Jan 6 02:30:56.168: ICMP: echo reply sent, src 172.16.101.1, dst 172.16.104.10 
*Jan 6 02:30:56.196: ICMP: dst (172.16.101.1) host unreachable rcv from 172.16.234.4 
R1# 
*Jan 6 02:30:58.163: ICMP: echo reply sent, src 172.16.101.1, dst 172.16.104.10 
*Jan 6 02:30:58.195: ICMP: dst (172.16.101.1) host unreachable rcv from 172.16.234.4 
R1# 
*Jan 6 02:31:00.451: ICMP: echo reply sent, src 172.16.101.1, dst 172.16.104.10 
*Jan 6 02:31:00.483: ICMP: dst (172.16.101.1) host unreachable rcv from 172.16.234.4 
R1# 
*Jan 6 02:31:02.165: ICMP: echo reply sent, src 172.16.101.1, dst 172.16.104.10 
*Jan 6 02:31:02.193: ICMP: dst (172.16.101.1) host unreachable rcv from 172.16.234.4 
R1# 
*Jan 6 02:31:04.165: ICMP: echo reply sent, src 172.16.101.1, dst 172.16.104.10 
*Jan 6 02:31:04.193: ICMP: dst (172.16.101.1) host unreachable rcv from 172.16.234.4 
R1#

Futhermore, I seem to have a problem with my R6.  As soon as I try to enter an NAT commands on it, it just dies.  Definitively.  No response from the console, and all its adjacencies start timing out.  I suspect an IOS bug.  I wonder what is doing it.  NAT with  HSRP in standby?  NAT on a subinterface?  All three together?  Who knows.

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