cable modem and NAT

[YeOldeStonecat]

From the reading that I did to answer you earlier, it sounds like PPPoE is actually PPPoA with another added layer of encapsulation. I saw it described basically as PPPoEoA (if that makes any sense). My concern there is that Untangle disassembles packets, processes them and reassembles them. They plan on PPPoE or standard ethernet, but not PPPoA. Untangle doesn't provide that third option, so there would likely be difficulties in the disassembly and/or reassembly..

I believe PPPoA runs an MTU of 1500, similar to cable or bridged DSL, versus PPPoE DSL which is 1492. The thing I recall reading about PPPoA DSL setups is it still requires a username and password "login"..similar to PPPoE.

[kirkcaine]

I believe PPPoA runs an MTU of 1500, similar to cable or bridged DSL, versus PPPoE DSL which is 1492. The thing I recall reading about PPPoA DSL setups is it still requires a username and password "login"..similar to PPPoE.

Thanks...I suppose there's no harm in trying. I'll do as suggested and keep it at 1500 with username and password credentials...I've also saved an older post regarding this so I'll refer to that if needed.

Re. Spam filter - this works best in Router mode or equally as efficient in Bridge mode?

I have a client that wants to trial UT to stop/slow down spam in Outlook before considering Professional package. His current setup is:

Adsl modem/router (PPPoA) - switch - lan - SBS2k3 (DHCP/DNS/Exchange)

Preferred setup:
Adsl modem (bridged) - UT (router) - switch - lan - SBS (DHCP/DNS/Exchange)

[mrunkel]

Ok, lots of questions.

PPPoA is PPP over ATM.

Here's the best solution (for PPPoA and PPPoE setups):

Set the modem to do the PPPoA logins, but not perform NAT. It's possible with most business class DSL modems. (By the way, I hate you telcos for the whole PPPoE and PPPoA abomination)

Then put the untangle in router mode, have your SBS server do DNS/DHCP.

If that's not possible, have the DSL modem do the NATing, put the Untangle in bridge mode in front of it and have the SBS server continue to do DNS/DHCP.

All the filtering functions of the Untangle work the same whether it's in bridging or routing mode.

I hope that helps.

[YeOldeStonecat]

That would be my preferred....but since I doubt you'll get Untangle to work with PPPoA, I don't think you have a choice but to leave the ISP supplied gateway appliance as it..and just stick Untangle into the mix as a transparent bridge.

Over here what some of the ISPs do (which I like) for their business accounts...they'll provide an all in one combo cable modem/router or DSL modem/router (gateway appliance). Such as an SMC for cable, or Netopia for DSL. They'll usually have 4x LAN ports like a regular home grade router.

They also give you a block of 5x static IP addresses.
By default the ISP supplied modem/gateway will put a static IP address, first or last in your block. Plug a PC with IP set to obtain auto into the back of the unit...boot up, it will get a private IP address like 192.168.xxx.xxx or 10.1.10.xxx. And hit up whatismyip.com and there's one of your static IP addresses. But you can use the next IP in your block as your actual static IP assigned to your own router. You just assign the WAN interface of your own router with that static IP, the subnet they gave you, and the default gateway they gave you (which is usually the public IP address that the modem/gateways gets in the whatismyip example above). Uplink your routers WAN port in one of the LAN ports of the ISP supplied gateway, and you're online.

[YeOldeStonecat]

MRunkles example of leaving the modem to do the PPPoE, but passing the WAN IP and NAT to your own device...is actually a better option if your hardware supports it. I've seen one brand of DSL gateway allow that kind of setup. (although PPPoE, not A)

[sky-knight]

PPPoA is used by Qwest to fuel their DSL networks out here in the southwest. I was recently informed they have finally decided to correct this moronic situation and switch to the far more accepted PPPoE standard.

Just to let you know... the issues aren't all across the pond.

[donhwyo]

Since you mentioned qwest I have been using qwest with the pppoa settings set in untangles pppoe for well over a year. Maybe 2.

FYI
Don