Basic IP Routing - mikerm19/cisco GitHub Wiki

This config works, but there are problems. A lot of services like SMB and FTP on the ethernet side won't work for clients on the token ring side, presumably due to weird asymmetrical routing problems around multiple ports. As long as the far side internet router understands where 172.20.0.x is, and a rule for nat-ting that network is put in, you will get internet access on the token ring side. Ping will work, provided that the clients will respond to pings (e.g. pfsense/OPNsense won't respond by default since it won't have the token ring side in the firewall rules as a valid network).

Note: The default gateway of the ethernet clients must have a static route defined to the token ring's network. For example, the route would be: ip route 172.20.0.0 255.255.255.0 192.168.10.95 in this case. If the default gateway is the router that the token ring network is attached to, then you don't need the extra step.

CISCO router config:

!
interface FastEthernet1/0
 ip address 192.168.10.95 255.255.255.0
 duplex auto
 speed auto
!
interface TokenRing1/0
 ip address 172.20.0.1 255.255.255.0
 ring-speed 16
!
ip route 0.0.0.0 0.0.0.0 192.168.10.1
!

Token ring client's TCP/IP config:

IP Address:  172.20.0.99
Subnet Mask: 255.255.255.0
Gateway:     172.20.0.1
DNS Server:  192.168.10.2