06-22-2023 08:04 AM - last edited on 07-04-2023 05:13 AM by Translator
Maybe dumb question, but at some point in time, a previous network engineer defined a machine network as 10.100.1.0 255.255.0.0 when it should have been 255.255.255.0. It was in place for several years and there are several hundred PLC devices now configured that way. My other remote sites have PLC subnets of 10.100.5.0 255.255.255.0, 10.100.6.0 255.255.255.0 and so on. In my core, can I do broad
IP route
statement with smaller
ip route
statement subnets under it or above it?
ip route 10.100.5.0 255.255.255.0 172.16.1.14
ip route 10.100.6.0 255.255.255.0 172.16.1.14
ip route 10.100.7.0 255.255.255.0 172.16.1.14
ip route 10.100.0.0 255.255.0.0 172.16.12.25
Solved! Go to Solution.
06-22-2023 08:07 AM
If it mater of static route'
Then config order not important to router
The router will select longest path in rib'
So always .5/24 .6/24 .7/24 longest than .0/16
06-25-2023 06:42 PM - edited 06-26-2023 01:09 AM
06-22-2023 08:07 AM
If it mater of static route'
Then config order not important to router
The router will select longest path in rib'
So always .5/24 .6/24 .7/24 longest than .0/16
06-22-2023 08:31 AM
I should also include that 10.100.0.0 255.255.0.0 is a subnet at a local plant and the others 10.100.5.0, 10.100.6. and etc are routed to the firewall and are remote.
So you think this should work?
06-22-2023 08:41 AM - last edited on 07-04-2023 05:26 AM by Translator
For static route it work but
You will face many issue with conflict IP in site and
HQ
For example pc in
HQ
have
ip 10.100.7.1
Which is same IP of host in other site .7/24
So overlapping happened sure.
There some solution like use
NAT
https://www.cisco.com/c/en/us/support/docs/ip/network-address-translation-nat/13774-3.html
06-22-2023 08:45 AM - last edited on 07-04-2023 05:17 AM by Translator
At the
HQ
plant site, they only use 10.100.1.0 - 10.100.4.254 so even though they technically could assign a
10.100.7.1 IP,
there is no DHCP, they wouldn't assign that IP statically at the
HQ.
I've wanted to change it, but there are literally 700 or so devices that they would need to manually change on the plant production side
06-22-2023 08:52 AM - last edited on 07-04-2023 05:21 AM by Translator
That good if
HQ
use from .0 ip to .4
But pc in
HQ
get ip from DHCP with
10.100.x.x/16
Now this pc need to connect to 10.100.5.100
The pc not send this traffic to GW' the pc with subnet and subnet mask receive from dhcp assume that 10.100.5.100 in same subnet and send
arp ask IP-MAC'
here the connection is failed.
So using
NAT
or change site SuperNer (instead of 10.100 let be 10.101) is better.
06-22-2023 08:55 AM
there is no dhcp on the 10.100.xxx.xxx subnets. Anything on these subnets for the local and remote locations has to be manually assigned. These specific networks are also blocked from any internet access
06-22-2023 09:05 AM
I clear some points yoh will face' I will run also lab and update you other issue appear with this subnet overlapping.
In my lab I will use only static route.
MHM
06-25-2023 06:42 PM - edited 06-26-2023 01:09 AM
I run lab test static router there is no issue.
06-25-2023 11:56 PM
Hello
those static routes look okay - the longer static statements /24 point to a different next hop then the shorter /16 which is applicable meaning any packet not matching any of the /24 routes will be routed via the /16 route
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