asked on

Cisco 2900

so I am a total hack on cisco IOS and need to change a fringe router ISP to different IP/SNM/GTW. Below are my givens and my assumed commands. please let me know if I am correct:
GIVENS:
Network:       108.188.yx.128
Gateway:       108.188.yx.129
Useable:       108.188.yx.130 thru 108.188.yx.158
Broadcast:       108.188.yx.159
Size:       /27
Subnet:       255.255.255.224

#END GIVENS

enable
config t

interface gigabitethernet 0/0
! THE FOLLOWING IS MY BIG ASSUMPTION Doesn't work - get Bad Mask (where do I get this value?)
ip address 108.188.yx.128 255.255.255.224
no shutdown

interface gigabitethernet 0/1
ip address 108.188.yx.130 255.255.255.224
no shutdown
exit

#default route
ip route 0.0.0.0 0.0.0.0 108.188.yx.129

ctrl-z
exit

then I need to write to running/ or boot config correct?

thanks

asavener

A subnet mask of 255.25.255.224 gives you 32 addresses per subnet. The bottom and top addresses are unusable. That's why you're getting an error. x.x.x.128 is not a valid interface address when your subnet is 255.255.255.224.

Also, you'll get an error with trying to put two interfaces in the same subnet. Pick one interface (g0/1 looks like from your example).

ASKER CERTIFIED SOLUTION

bill30

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bill30

And then for your last question, yes you need to do a "copy run start" to make sure the commands are persistent through a reboot.

Benjamin Van Ditmars

can you give us youre complete running config. because what does youre router do. is it only nat from external to internal. or is it working as gateway / shaper for youre connection.

what we normaly see. is a small network on the outside interface /30 and a bigger subnet on the local internet side.

if you share youre config we can help you much better