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subnet with gateway out of range not allowed? [closed]

asked 2016-09-16 00:31:21 -0500

trying to address a routed subnet into openstack:

neutron subnet-create --name subnet_999 --disable-dhcp --allocation-pool=start=,end= --gateway= external_999

This route is in the physical router as such, why can i not use this as a subnet gateway?

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Closed for the following reason the question is answered, right answer was accepted by bcollins
close date 2016-09-18 20:32:59.179620

2 answers

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answered 2016-09-18 20:32:18 -0500

added 33 interface to physical router and recreated network like so: neutron subnet-create --name subnet_999 --disable-dhcp --allocation-pool=start=,end= --gateway= external_999

works like i originally thought. Thanks to barry.davis for help in remembering fundamentals !!!

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answered 2016-09-18 07:42:04 -0500

Even though the route ( is in the physical router, the subnet gateway address must exist in the subnet address range for packets to be routed outside of the subnet.
You could change the subnet definition to include the gateway address (

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Got this address scope from my provider, extending it is not an option. If this and 2 other networks i have are (provider) having there own router and network; Do I still need to setup another router in openstack if i'm trying to use this network as a provider??

bcollins gravatar imagebcollins ( 2016-09-18 08:13:46 -0500 )edit

Yes, you will need a router to move packets between different subnets.

barry.davis gravatar imagebarry.davis ( 2016-09-18 17:35:48 -0500 )edit

i agree. but the router is physical. maybe i should try what you said and create a scope /24 or /25 or /26 that includes the ip addresses in that scope and tune what's useable with an allocation pool ?

bcollins gravatar imagebcollins ( 2016-09-18 20:00:12 -0500 )edit

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Asked: 2016-09-16 00:31:21 -0500

Seen: 146 times

Last updated: Sep 18 '16