Solved: Re: Smooth conversion of a network to many subnets on the same range

rgdelank · ‎05-13-2023

I am planning the migration of a Network 172.16.0.0 Mask 255.255.0.0 to a VLSM VLANS so that I get the following topology:

A New range VLSM Subnet of 172.16.0.0/19 for the Actual range of IPs 172.16.0.0 to 172.16.31.254

Many Subnets of VLSM CIDR 22 beginning on 172.16.32.0 Mask 255.255.252.0

So 172.16.36.0, 172.16.40.0 etc.

Question: It is feasible to have the old network 172.16.0.0 Mask 255.255.0.0 mix with the new Subnets actives 172.16.32.0 Mask 255.255.252.0. at the same time for migration, routing between network and theirs selbst subnetworks ?

I am not sure if is possible to route between the network and the subnetworks of the same network....

Is there a conflict on configuration, organized I avoid having the same ip being defined two times so, as you can see the old range is up to 172.16.31.254 so no host ip is in conflict, but the range of the network is going to be overlapped with the new subnet mask.

PS.: I can not change the Mask of all Servers at the same time...

thanks in advance for a response

Roberto

rgdelank · ‎05-14-2023

As I understand, it is not possible because the Suppernet 172.16.0.0 could
not be mixed with the new Subnets configuration.
Is that right ?
I understood what you replayed ?

I sendit the Switch to you with a specific example.
*Is the restriction Network and Subnetworks on the same device not possible
?*

What is your recommendation, implementing a new device ?

Was the last Question...

many thanks in advance
truly Roberto

View solution in original post

Kasun Bandara · ‎05-13-2023

@rgdelank this is depend on your network topology.

is your all devices pointed to same gateway now? if so where is the gateway located? how you planning to sperate new subnetworks and where is the gateway address planned to configure. better if we can see some current diagram and expected new diagram.

Please rate this and mark as solution/answer, if this resolved your issue
Good luck
KB

rgdelank · ‎05-14-2023

I wonder if it is possible because of overlapping the Network
172.16.0..0/16 Mask 255.255.0.0 with many Subnets 172.16.32.0/16,
172.16.36.0/16 etc.
It is not depending on topology is more a question of Routing and Standards.

As an Example:

*N5860-48SC - 48-Port Ethernet L3 Switch*


12 Ports on VLAN ID 1000 ( Old Konfiguration ) No-Subnet, Network
172.16.0.0 /16
12 Ports on VLAN ID 2000 ( New Konfiguration ) Subnet
172.16.32.0/22
12 Ports on VLAN ID 3000 ( New Konfiguration ) Subnet
172.16.36.0/22
12 Ports on VLAN ID 4000 ( New Konfiguration ) Subnet
172.16.40.0/22
and so one ....

thanks for comments

Roberto

Kasun Bandara · ‎05-14-2023

@rgdelank topology is important because we dont know how your devices are connected. or your gateway IPs are configured in same device or different devices after changes.

1. if you have different devices configured to allocate new ip ranges, it can do via supernet routing.

2. if you are planning to use same device which is configured now, you cannot create different interfaces with subnets under super net in same device.

Please rate this and mark as solution/answer, if this resolved your issue
Good luck
KB

rgdelank · ‎05-14-2023

As I understand, it is not possible because the Suppernet 172.16.0.0 could
not be mixed with the new Subnets configuration.
Is that right ?
I understood what you replayed ?

I sendit the Switch to you with a specific example.
*Is the restriction Network and Subnetworks on the same device not possible
?*

What is your recommendation, implementing a new device ?

Was the last Question...

many thanks in advance
truly Roberto

Kasun Bandara · ‎05-14-2023

@rgdelank if you have only 1 x L3 device to do this, this is not possible. because L3 devices can configure with multiple interfaces (SVIs or physical) and IP ranges cannot overlap.

Please rate this and mark as solution/answer, if this resolved your issue
Good luck
KB

paul driver · ‎05-14-2023

Hello

@rgdelank wrote:

Question: It is feasible to have the old network 172.16.0.0 Mask 255.255.0.0 mix with the new Subnets actives 172.16.32.0 Mask 255.255.252.0. at the same time for migration, routing between network and theirs selbst subnetworks ?I

No is isn't, as the CIR'd networks will belong to the classful /16 network.

@rgdelank wrote:
I wonder if it is possible because of overlapping the Network
172.16.0..0/16 Mask 255.255.0.0 with many Subnets 172.16.32.0/16,
172.16.36.0/16 etc.
It is not depending on topology is more a question of Routing and Standards.

As an Example:

*N5860-48SC - 48-Port Ethernet L3 Switch*



12 Ports on VLAN ID 1000 ( Old Konfiguration ) No-Subnet, Network
172.16.0.0 /16
12 Ports on VLAN ID 2000 ( New Konfiguration ) Subnet
172.16.32.0/22
12 Ports on VLAN ID 3000 ( New Konfiguration ) Subnet
172.16.36.0/22
12 Ports on VLAN ID 4000 ( New Konfiguration ) Subnet
172.16.40.0/22

and so one ....

In the above wont work either as again the the /22 are overlapping with the /16,

What would work is dividing the /16 into two /17 networks
172.16.0.0/17
172.16.128.0/17
Then use the first /17 ip range to accommodate your /19 and /22 ranges

172.16.0.0/19
172.16.32.0/22
172.16.36.0/22
172.16.40.0/22
172.16.44.0/22
172.16.48.0/22
etc...
172.16.124.0/22

Please rate and mark as an accepted solution if you have found any of the information provided useful.
This then could assist others on these forums to find a valuable answer and broadens the community’s global network.

Kind Regards
Paul

rgdelank · ‎05-14-2023

I already devided the /16 into a /19 and /22 but is not feasible because of overlapping, in your proposition of /17 and /19 is the same case because I can not reconfigure 1000s of Servers at the same time, I wanted to have a grace time to disappear the 172.16.0.0 and have only subnets ...

Thank you.

paul driver · ‎05-14-2023

Hello
Apologies but I believe you have misunderstood - what i was alluding to was how to divide the /16 classfull address correctly so to allow the usage of a /19 and /22- I had already stated you couldn’t use them if your currently actively using the /16.

In any case glad to see you have been provided with an answer you were seeking

Please rate and mark as an accepted solution if you have found any of the information provided useful.
This then could assist others on these forums to find a valuable answer and broadens the community’s global network.

Kind Regards
Paul

rgdelank · ‎05-14-2023

Yes Thank you,

It is a good improvement to have in CISCO IOT a kind of translation for all
Classfull Masks into Subnetting for the case of a Smooth migration.
So as NAT can translate an IP to another, IOT could change incoming
traffic of a full qualified network to a Subnet automatically so you can
reconfigure the Hosts one by one and not at a time.
As to say:
ip address 172.16.0.0 255.255.0.0 incoming traffic interpreted as
255.255.224.0

So that can be an improvement for the future supporting migrations from
Networks to small Subnetworks.

kind regards
Roberto

rgdelank · ‎05-14-2023

I wonder if it is possible because of overlapping the Network 172.16.0..0/16 Mask 255.255.0.0 with many Subnets 172.16.32.0/16, 172.16.36.0/16 etc.

It is not depending on topology is more a question of Routing and Standards.

As an Example:

N5860-48SC - 48-Port Ethernet L3 Switch

VLSM on TCP/IP Subnets and VLAN ( Mitigating Broadcast domains...) a VLAN is a Subnet.

12 Ports on VLAN ID 1000 ( Old Konfiguration ) No-Subnet, Network 172.16.0.0 /16

12 Ports on VLAN ID 2000 ( New Konfiguration )            Subnet  172.16.32.0/22

12 Ports on VLAN ID 3000 ( New Konfiguration )            Subnet  172.16.36.0/22

12 Ports on VLAN ID 4000 ( New Konfiguration )            Subnet  172.16.40.0/22

and so one ....

thanks for comments

Roberto