Cisco 1841, Bridge T1 WAN to hosts with public IPs?

Question

We currently have a Samsung router given to us by Covad. It is configured like this:

              PPPoFR T1 WAN (samsung router)
              x.x.x.49/29(public address)
             gateway
                 |
                 |
__________________________________________________________________
|                                                              |
|                                                              |
ethernet port(samsung router)              ethernet port(samsung router)
|                                                              |
|                                                              |
separate firewall/NAT                                separate firewall/NAT
x.x.x.50/29(public address)                       x.x.x.51/29(public address)
|                                                              |
server LAN                                             VOIP LAN

So the Samsung router is routing the T1 WAN to the two firewalls, each firewall has its own public address in the same network as the gateway.

I desperately need to replicate this with a Cisco 1841 so I can get QOS going for the VOIP side. I have looked at IRB, but that mentions VLANs which seemed confusing when all of the hosts that will connect to the router have public IPs.

So how do I configure fe0/0 and fe0/1 to let their connected hosts with public IPs (x.x.x.50 and x.x.x.51) get to serial0/0/0(T1 WAN x.x.x.49)?

Thanks.

Answer 1

In the Samsung (ibg1000???), the two ethernet ports form a switch:

interface ethernet 0/0
  no keepalive
    switchport
    bridge-group 1
    switchport mode access
  qos
    exit qos
  no flowcontrol
  exit ethernet
interface ethernet 0/1
  no keepalive
    switchport
    bridge-group 1
    switchport mode access
  qos
    exit qos
  no flowcontrol
  exit ethernet

In the 1841, the two ethernet ports are independent routed interfaces. You can simulate a switch by bridging the two ethernet ports, but I would not recommend it. Buy an external switch.

Answer 2

I think your best bet would be to put the Cisco router inside the firewall. You can mark the traffic on your switch(es), and queue it on the Cisco router interface to the firewall.

While it is a good idea to separate the VoIP traffic from the regular data traffic, you can do that with VLANs or with separate interfaces into the Cisco router. It doesn't matter if the traffic merges before or after the firewall since the queuing will will happen as it leaves the router, and that can happen before the firewall, too.

Your QoS policies will not be honored on the Internet, so all you can do is queuing on the exit interface.