If you only need this between one specific set of clients, then you can do a work-around where you add a static ARP entry on each client with the CCR’s MAC address instead of the real MAC address of the “neighbor” 750G.
So in your example, in the left-side 750GL:
/ip arp add mac-address=MAC:OF:CCR interface=vlan5 address=192.168.5.19
and on the right-side 750GL:
/ip arp add mac-address=MAC:OF:CCR interface=vlan5 address=192.168.5.11
This will work, but is a bit sloppy because the CCR is going to be sending ICMP redirect messages like crazy. The 750GL routers won’t do anything different due to the ICMP redirects because they think they’re already talking directly to the “neighbor”
This is of course a sloppy work-around. A more scalable solution is to use a dedicated per-customer logical interface and to configure each customer interface with arp=proxy-arp and a /32 address assignment. This way, whenever a customer device sends an ARP for a neighboring customer device’s IP, it will receive the MAC address of the CCR and thus direct all packets to the CCR for forwarding. The CCR will see each customer as a different interface, so it won’t send ICMP redirects.
The way to configure the IP addresses on the CCR is as a /32 for each customer interface:
/ip address add interface=customerX address=192.168.5.1/32 network=192.168.5.X
Interface customerX would be a vlan interface on the physical interface that leads to the GPON concentrator. Each customer would therefore require their own dedicated VLAN tag.
The way to scale this beyond just ~4000 vlans would be to use q-in-q between the CCR and the GPON concentrator(s)
(i.e. use s-tag / c-tag configuration)
So on the CCR, you’d have:
ether1
-vlan10 (id=10) ← s-tag
-
- customerA (id=101) ← c-tag
-
- customerB (id=102) ← c-tag
-vlan20 (id=20) ← s-tag
-
- customerC (id=101) ← c-tag
Note that customer C uses inner vlan 101 just like customer A does, but a different outer VLAN.
Ideally, the GPON system lets you provision the ONTs with the s-tag/c-tag information so that the customer router behind the ONT doesn’t need any vlan configuration at all. You build the ONT profile and CCR interface with the correct tags, and you’re done. The S-tag would basically be unique for each OLT in your network, or for each shelf of OLTs.
I wish that ROS had a certain feature that Cisco has - namely DHCP relay that adds a /32 route to the interface based on replies from the DHCP server. This way, you wouldn’t need to actually configure the IP directly on the CCR - you would just configure DHCP relay and then when the server assigns an IP to a customer on any given interface, the CCR would just add the IP for the lifetime of the lease. This would further reduce administrative overhead.
