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a0rtega
Asked: 2010-02-11 10:54:30 +0800 CST

Bad mask /XX for address X.X.X.X in Router Cisco (Packet Tracer), VLSM

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Im trying to do a practice in packet tracer. Im configuring a 1841 Router (but the problem happens in all routers).

When I try to set an IP address with a mask different of the by defect mask for this Class of address (using VLSM), the router said me that the mask is incorrect (Bad mask) and don't change anything.

I will implement a classless routing protocol (RIPv2).

Here the line of commands:

Router>
Router>enable
Router#config termin
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)#int Ser0/0/0
Router(config-if)#ip address 172.16.199.228 255.255.255.252
Bad mask /30 for address 172.16.199.228                 <--- HERE
Router(config-if)#

How can I set an IP address with a no by defect mask?

Thanks you! :)

cisco netmask mask

1 Answers

  1. Best Answer

    172.16.199.228 is the network address. You need to use 172.16.199.229 or .230

    Output of ipcalc:

    Address:   172.16.199.228       10101100.00010000.11000111.111001 00
Netmask:   255.255.255.252 = 30 11111111.11111111.11111111.111111 00
Wildcard:  0.0.0.3              00000000.00000000.00000000.000000 11
=>
Network:   172.16.199.228/30    10101100.00010000.11000111.111001 00
HostMin:   172.16.199.229       10101100.00010000.11000111.111001 01
HostMax:   172.16.199.230       10101100.00010000.11000111.111001 10
Broadcast: 172.16.199.231       10101100.00010000.11000111.111001 11
Hosts/Net: 2                     Class B, Private Internet
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