03-25-2009 06:08 AM - edited 03-04-2019 04:05 AM
I currently have a Cisco 1700 with the configuration below.
I would like to divide one of the subnets on FA0 : ip address 216.17.190.1 255.255.254.0.
What do I need to do to divide that into two equal subnets.
hostname stdshersteambocomdfrtra
!
aaa new-model
aaa authentication login default local
enable secret 5 $1$YMlo$30YilvB4w29dKa8Zivhbm1
!
username Sh3rstsp password 7 10691D4C544643524D
username admin privilege 15 password 7 07062F584B1B4F564240
memory-size iomem 25
ip subnet-zero
!
ip audit notify log
ip audit po max-events 100
!
!
!
!
interface FastEthernet0
description **** to IP3 outside ****
ip address 204.10.250.57 255.255.255.252 secondary
ip address 216.17.190.1 255.255.254.0
no ip redirects
no ip unreachables
speed 100
full-duplex
!
interface Serial0
no ip address
encapsulation frame-relay IETF
frame-relay lmi-type ansi
!
interface Serial0.1 point-to-point
description **** to SpringSips.com - Ckt#24/HCGX/805484 ****
ip address 204.10.250.30 255.255.255.252
frame-relay interface-dlci 104
!
ip classless
ip route 0.0.0.0 0.0.0.0 204.10.250.29
ip route 66.151.160.0 255.255.254.0 204.10.250.58
ip http server
!
!
03-25-2009 06:56 AM
The problem that I immediately see is that your mask wouldn't match up to the providers mask any longer, and you might lose connection.
Theoretically, you could change your private primary address to a 24 bit mask (255.255.255.0) and then your next network would be:
216.17.191.0/24
So you would set up 216.17.191.1 as a secondary address.
HTH,
John
03-25-2009 07:01 AM
So could I remove the current:
ip address 216.17.190.1 255.255.254.0
and replace it with:
ip address 216.17.190.1 255.255.255.0
ip address 216.17.191.1 255.255.255.0
Now I would have two fully functional Class C subnets?
03-25-2009 07:04 AM
"Now I would have two fully functional Class C subnets?"
Yes, but I'd warn you that you might lose connection to your provider. Theoretically it should work, but it might not.
HTH,
John
03-25-2009 07:12 AM
What would I want to do to make sure I would not lose connectivity?
03-25-2009 07:16 AM
I would call the provider and ask them to split them up for you. Then schedule downtime to make the change.
Since I don't see your topology, I'm assuming that the interface you want to change does connect to an ISP. If so, then I would call them and tell them the change that you want to make.
Are you local to the router, or are you remote? If you want to try to make the change without calling the ISP, then you can telnet into the Serial interface, and make your changes on the interface that you want to change. I would get a ping going to the address that's on the interface you want to change, and I'd ping both .1s from both "new" subnets to make sure they were routing correctly through your providers network after the change.
HTH,
John
03-25-2009 07:21 AM
Thanks!
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