In situations with multiple named IP pools, it is required the option `next` to be sure that if IP addresses ended in one pool, then they would begin to be allocated from the next named pool
Proposed option `next-pool`
```
set service ipoe-server client-ip-pool name first-pool subnet 192.0.2.0/25
set service ipoe-server client-ip-pool name first-pool gateway-address 192.0.2.1
set service ipoe-server client-ip-pool name first-pool next-pool second-pool
set service ipoe-server client-ip-pool name second-pool subnet 203.0.113.0/25
set service ipoe-server client-ip-pool name second-pool gateway-address 203.0.113.1
set service ipoe-server client-ip-pool name third-pool gateway-address '198.51.100.1'
set service ipoe-server client-ip-pool name third-pool subnet '198.51.100.0/24'
```
Expected configuration (ordering is important)
```
[ipoe]
ip-pool=first-pool
gw-ip-address=192.0.2.1/25
gw-ip-address=203.0.113.1/25
gw-ip-address=198.51.100.1/24
[ip-pool]
198.51.100.1/24,name=third-pool
203.0.113.0/25,name=second-pool,next=third-pool
192.0.2.0/25,name=first-pool,next=second-pool
gw-ip-address=192.0.2.1/25
gw-ip-address=203.0.113.1/25
gw-ip-address=198.51.100.1/24
```