Re: SpeedStream 4100: "Bridged mode" vs "PPP on the computer" in AT&T Midwest http://www.dslreports.com/forum/r17050905 en Sat, 28 Nov 2009 19:37:04 EDT Sat, 28 Nov 2009 19:37:04 EDT Re: SpeedStream 4100: "Bridged mode" vs "PPP on the computer" http://www.dslreports.com/forum/remark,17141630 NormanS : The DMZ is a common NAT function, found on routers without firewalls, as well as router with firewalls.

When I think of firewall, I don't think of NAT, or port forwarding. I think of Access Control. Some routers have it. Many do not. The screen shot shows my Netgear FVS114 firewall. I have seen such on the D-Link D-704UP, the Netgear FR114P, and the SMC Barricade 7004BR with a certain firmware level, though that was only limited to eight entries each way (outbound and inbound). I have not seen it on earlier firmware versions on the SMC Barricade 7004BR, nor on the oldest hardware level of the Linksys BEFSR11, and related Linksys products.

I believe some call it an SPI filter. Unlike NAT port forwarding, which can only control local port access by the entire Internet, this SPI filter, firewall, or ACL (you pick the term which best fits) controls remote, and local access by IP address, or range of IP addresses.
--
Norman
~Oh Lord, why have you come
~To Konnyu, with the Lion and the Drum
Click for full size
Netgear FVS114 firewall.
]]> http://www.dslreports.com/forum/remark,17141630 Mon, 23 Oct 2006 18:12:34 EDT Re: SpeedStream 4100: "Bridged mode" vs "PPP on the computer" http://www.dslreports.com/forum/remark,17139658 d_l : Actually if you allow the modem to issue the 192.168.1.64 IP to your router, you are using the DMZ function of the 4100's internal router. From the CLI of the 4100:
xsh> show ipfw dmz
Firewall DMZ is enabled, DMZ Host IP = 192.168.1.64
]]> http://www.dslreports.com/forum/remark,17139658 Mon, 23 Oct 2006 13:01:36 EDT Re: SpeedStream 4100: "Bridged mode" vs "PPP on the computer" http://www.dslreports.com/forum/remark,17139587 NormanS :
said by d_l See Profile :

The underlying CLI of the 4100 has numerous firewall function settings. I haven't tested whether all of them are still functional or not. It is probably possible to go under the AT&T GUI firmware and change some firewall settings which would remain operative once the GUI locks out telnet access. :)
That is a bit of an obscure thing. Most AT&T users of the SBC issued SS4100 don't even know about the Telnet access, or CLI. I don't find it necessary to use the SS4100 beyond the limited mode that SBC issued; I have all the firewall I need on the router.
--
Norman
~Oh Lord, why have you come
~To Konnyu, with the Lion and the Drum]]> http://www.dslreports.com/forum/remark,17139587 Mon, 23 Oct 2006 12:51:48 EDT Re: SpeedStream 4100: "Bridged mode" vs "PPP on the computer" http://www.dslreports.com/forum/remark,17139555 d_l : The underlying CLI of the 4100 has numerous firewall function settings. I haven't tested whether all of them are still functional or not. It is probably possible to go under the AT&T GUI firmware and change some firewall settings which would remain operative once the GUI locks out telnet access. :)]]> http://www.dslreports.com/forum/remark,17139555 Mon, 23 Oct 2006 12:46:57 EDT Re: SpeedStream 4100: "Bridged mode" vs "PPP on the computer" http://www.dslreports.com/forum/remark,17139517 NormanS :
said by 59126125 See Profile :

Does it still do firewall functions?
I am not aware that the SS4100 has firewall functions. I certainly can't find any. But what do I know? I am just used to having a device with firewall functions; my Netgear FVS 114.
--
Norman
~Oh Lord, why have you come
~To Konnyu, with the Lion and the Drum]]> http://www.dslreports.com/forum/remark,17139517 Mon, 23 Oct 2006 12:40:40 EDT Re: SpeedStream 4100: "Bridged mode" vs "PPP on the computer" http://www.dslreports.com/forum/remark,17062987 59126125 : Kick ass, I love it when it all clicks. Maybe I'll get the hang of this networking stuff after all. :D]]> http://www.dslreports.com/forum/remark,17062987 Tue, 10 Oct 2006 19:19:30 EDT Re: SpeedStream 4100: "Bridged mode" vs "PPP on the computer" http://www.dslreports.com/forum/remark,17061756 nwrickert :
So, all in all, the 4100 is never classified as a router until it actually does the login?
That's correct (at least for the SBC version of the 4100).]]> http://www.dslreports.com/forum/remark,17061756 Tue, 10 Oct 2006 16:05:00 EDT Re: SpeedStream 4100: "Bridged mode" vs "PPP on the computer" http://www.dslreports.com/forum/remark,17061498 59126125 : Oh yeah, forgot about that situation. Which brings up more questions. It apparently wouldn't be doing NAT or have a WAN IP in that situation either. So I'm assuming it would technically be a smart bridge. Does it still do firewall functions? So, all in all, the 4100 is never classified as a router until it actually does the login?
--
There is a reason the wires are twisted together, it's called a pair. It defeats the whole purpose of twisted pair cabling by using the solid orange and solid green to wire the jack.]]> http://www.dslreports.com/forum/remark,17061498 Tue, 10 Oct 2006 15:27:01 EDT Re: SpeedStream 4100: "Bridged mode" vs "PPP on the computer" http://www.dslreports.com/forum/remark,17061166 d_l : If you set the modem to be PPP on the modem, leave the UserID/PW blank, and let the router or computer initiate the PPPoE connection, you pretty much end up with your Mode 2 with some slight differences, e.g. the modem is continually broadcasting to the computer/router.]]> http://www.dslreports.com/forum/remark,17061166 Tue, 10 Oct 2006 14:37:55 EDT Re: SpeedStream 4100: "Bridged mode" vs "PPP on the computer" http://www.dslreports.com/forum/remark,17061013 59126125 : I like pictures since it is easier to remember that way. So I made a diagram of my now corrected understanding of the three PPP settings on the 4100 modem. I'm sure that other people have been confused about this also, so here is the diagram. Again, I would appreciate any corrections and another thank you for the information from nwrickert See Profile and wayjac See Profile.
--
There is a reason the wires are twisted together, it's called a pair. It defeats the whole purpose of twisted pair cabling by using the solid orange and solid green to wire the jack.
Click for full size
]]> http://www.dslreports.com/forum/remark,17061013 Tue, 10 Oct 2006 14:13:49 EDT Re: SpeedStream 4100: "Bridged mode" vs "PPP on the computer" http://www.dslreports.com/forum/remark,17057536 59126125 : Thanks for the info, quite the confusing concept, but at least it makes some sense now. I think it's time for a scotch... :D]]> http://www.dslreports.com/forum/remark,17057536 Mon, 09 Oct 2006 22:20:11 EDT Re: SpeedStream 4100: "Bridged mode" vs "PPP on the computer" http://www.dslreports.com/forum/remark,17057444 nwrickert : Correct.]]> http://www.dslreports.com/forum/remark,17057444 Mon, 09 Oct 2006 22:04:14 EDT Re: SpeedStream 4100: "Bridged mode" vs "PPP on the computer" http://www.dslreports.com/forum/remark,17057292 59126125 : Ah, I think it is getting clearer now. So basically, whatever device does the authentication gets assigned the IP from the Redback. So, when the 4100 is set to "PPP on the computer", the modem has to "bridge" straight to a LAN IP for the connection to work to the MAC address. Yet, it keeps a LAN IP so it can be accessed via regular ethernet. Do I finally have it right?
--
There is a reason the wires are twisted together, it's called a pair. It defeats the whole purpose of twisted pair cabling by using the solid orange and solid green to wire the jack.]]> http://www.dslreports.com/forum/remark,17057292 Mon, 09 Oct 2006 21:31:47 EDT Re: SpeedStream 4100: "Bridged mode" vs "PPP on the computer" http://www.dslreports.com/forum/remark,17056563 nwrickert : In mode 2 (from your list), the 4100 is not an IP device on the WAN. It has no WAN IP, and it does not know what the public IP should be. It merely accepts ethernet frames from the redback, and bridges them to the local ethernet. It likewise picks up ethernet frames on the local ethernet, and bridges those to the redback.

In addition, it assigns itself an IP address of 192.168.0.1 on the local ethernet, and can exchange IP packets with other systems on the local ethernet. It does not exchange IP packets with WAN hosts - it only bridges ethernet frames but does not look inside those frames. It does give out a DHCP address of 192.168.1.64 to one client on the local ethernet. This would normally be used only for getting the modem statistics.

A local host on the ethernet can do the authentication. But then that same local host has to use the assigned WAN address, and has to extract IP packets from the PPPoE transmissions that it receives. It can't just authenticate - it has to do all of the PPPoE. If that local host wants to act as a router, it can. But then it needs a second ethernet interface.

Mode 3 (bridged mode) differs in that it does not do DHCP. I think (but I'm not sure) that it will still accept packets to IP=192.168.0.1 for requesting statistics. But the computer that wants to see the statistics would need to be manually configured with IP=192.168.1.64, netmask=255.255.0.0.

-------

Let me describe my WAP (Wireless Access Point). The WAP is, in effect, a bridge between the WiFi LAN and the wired LAN. It acts on ethernet frames, and transfers them between the wired LAN and the wireless LAN. It does not do any routing, so both wired and wirless LANs have to share the same range of IP addresses. The WAP happens to also have an IP address. It is a smart bridge, and uses its own IP address so that you can configure it. But, except when you are configuring the WAP (or getting info on settings from the WAP), it is acting only as a bridge.

The 4100 in "PPP on computer" mode is likewise a smart bridge. It is mostly doing bridging, but it has its own IP address on the LAN so that it can be configured and so that you can get info from it. It happens to also give out a DHCP address to make that configuration a little easier to do.]]> http://www.dslreports.com/forum/remark,17056563 Mon, 09 Oct 2006 19:33:26 EDT Re: SpeedStream 4100: "Bridged mode" vs "PPP on the computer" http://www.dslreports.com/forum/remark,17056539 wayjac : The PPPoE client reguardless of where it is gets the wan IP info

PPP on the modem and PPP on the computer have a lot in common, the modem's lan DHCP server is active, with the correct configuration another device can do the PPPoE.

In Bridged mode the modem's lan DHCP server is disabled.

I agree fully with statement 1 and 3 statement 2 should read just like statement 3 with a few "buts"
--
God bless our troops]]> http://www.dslreports.com/forum/remark,17056539 Mon, 09 Oct 2006 19:27:41 EDT Re: SpeedStream 4100: "Bridged mode" vs "PPP on the computer" http://www.dslreports.com/forum/remark,17056181 59126125 : Ok, still confused. Here is my understanding on how the three different configurations for the 4100 work and would appreciate any corrections.

1. PPP on the modem - modem authenticates, is first IP device in contact with the WAN network and is assigned the WAN IP from the AT&T Redback router. 4100 hands out private IP to first device behind it. 4100 acting as a router.

2. PPP on the computer - any device behind the 4100 can do the authentication, yet the 4100 is still the first IP device in contact with the WAN and still gets assigned the WAN IP from the AT&T Redback router. 4100 hands out private IP to first device behind it. 4100 acting as a router.

3. Bridged Mode - 4100 ceases to exist as far as IP goes and merely translates protocols and forwards packets. The router is now assigned the WAN IP from the AT&T Redback router since it is the first IP device in contact with the WAN. The router is now on the same network as the Redback Router. 4100 acting as a bridge.
--
There is a reason the wires are twisted together, it's called a pair. It defeats the whole purpose of twisted pair cabling by using the solid orange and solid green to wire the jack.]]> http://www.dslreports.com/forum/remark,17056181 Mon, 09 Oct 2006 18:25:33 EDT Re: SpeedStream 4100: "Bridged mode" vs "PPP on the computer" http://www.dslreports.com/forum/remark,17055974 nwrickert : If the 4100 is fully bridged, it is talking ethernet, not TCP/IP. It doesn't have a WAN IP address. The WAN IP address is assigned over PPPoE, so is assigned to the system that actually does the PPPoE.]]> http://www.dslreports.com/forum/remark,17055974 Mon, 09 Oct 2006 17:46:55 EDT Re: SpeedStream 4100: "Bridged mode" vs "PPP on the computer" http://www.dslreports.com/forum/remark,17055954 59126125 : My understanding is when the 4100 is fully bridged the router is then assigned a WAN IP (69.xxx.xxx.xxx), but if the 4100 is configured to "PPP on the computer" it still hands out a LAN IP (192.xxx.xxx.xxx) to the router.
--
There is a reason the wires are twisted together, it's called a pair. It defeats the whole purpose of twisted pair cabling by using the solid orange and solid green to wire the jack.]]> http://www.dslreports.com/forum/remark,17055954 Mon, 09 Oct 2006 17:43:30 EDT Re: SpeedStream 4100: "Bridged mode" vs "PPP on the computer" http://www.dslreports.com/forum/remark,17055942 nwrickert : Let's remember that the 4100 has several modes of operation. In some of those modes, it is acting as a router.

We were, in particular, discussing the "PPP on computer" mode. There, it is simply taking the ethernet frames it receives encapsulated in the ATM data, and placing them on the local ethernet. It is not examining the content of those frames at all. It is not seeing the IP address encoded in the PPPoE data that is encapsulated in the ethernet frames.

Quite separately from its action as above, it also gives out a single DHCP address purely for communication on the LAN.

For LAN communication, it will receive ethernet frames addressed to the 4100 MAC address. For PPPoE communication it will handle frames addressed to the ISP equipment at the other side of the bridge (which tunnels through the ATM network). There is no difficulty distinguishing between these two classes of frames.]]> http://www.dslreports.com/forum/remark,17055942 Mon, 09 Oct 2006 17:41:19 EDT Re: SpeedStream 4100: "Bridged mode" vs "PPP on the computer" http://www.dslreports.com/forum/remark,17055887 docinthebox : I thought the 4100 is forwarding packets from the WAN side (69.xxx.xxx.xxx) to the WAN port of the router which is still 69.xxx.xxx.xxx. It is the router that's connecting 69.xxx.xxx.xxx with 192.xxx.xxx.xxx]]> http://www.dslreports.com/forum/remark,17055887 Mon, 09 Oct 2006 17:30:28 EDT Re: SpeedStream 4100: "Bridged mode" vs "PPP on the computer" http://www.dslreports.com/forum/remark,17055831 59126125 :
said by nwrickert See Profile :

How can a device be handing out a private IP and yet not be doing NAT?
It is only doing NAT if it is also mapping that private IP to a different (usually public) IP. If it is merely giving out a private IP for communication on the LAN, and is handling the DSL traffic purely as an ethernet bridge would, then it is not acting as a router and is not doing NAT.
Well, that's what has me confused the most. Wouldn't the 4100 still be acting as a router since it is connecting two different networks? For an example of why I believe it would still be doing NAT, lets say the WAN side is assigned an IP of 69.xxx.xxx.xxx while the LAN side is 192.xxx.xxx.xxx, wouldn't there have to be a translation from address to address / network to network and some type of routing table used? I always thought that a bridge could only forward packets to devices assigned on the same network / IP range.
--
There is a reason the wires are twisted together, it's called a pair. It defeats the whole purpose of twisted pair cabling by using the solid orange and solid green to wire the jack.]]> http://www.dslreports.com/forum/remark,17055831 Mon, 09 Oct 2006 17:21:09 EDT Re: SpeedStream 4100: "Bridged mode" vs "PPP on the computer" http://www.dslreports.com/forum/remark,17054399 nwrickert :
How can a device be handing out a private IP and yet not be doing NAT?
It is only doing NAT if it is also mapping that private IP to a different (usually public) IP. If it is merely giving out a private IP for communication on the LAN, and is handling the DSL traffic purely as an ethernet bridge would, then it is not acting as a router and is not doing NAT.
Also, my understanding is that a true bridge only translates different protocols, like ATM to Ethernet, without doing NAT.
Right. But an ethernet can sustain multiple traffic. There is no reason that you could not use LAN tcp-ip communication on the local ethernet at the same time that the bridged ethernet packets are being transferred between the local ethernet and the remote ATM network.]]> http://www.dslreports.com/forum/remark,17054399 Mon, 09 Oct 2006 13:26:57 EDT Re: SpeedStream 4100: "Bridged mode" vs "PPP on the computer" http://www.dslreports.com/forum/remark,17053435 59126125 : Ok, now that has me confused. How can a device be handing out a private IP and yet not be doing NAT? If that's the case, that would mean the 4100 is always a bridge since it only hands out one private IP? My understanding is that if a device is doing NAT, it is a router, even if it is a very simple one and only hands out one private IP. Also, my understanding is that a true bridge only translates different protocols, like ATM to Ethernet, without doing NAT. The PPP login's sole purpose is authenticating the user on the network so a WAN IP gets assigned to the circuit to access the Internet. If this is incorrect, someone please let me know.
--
There is a reason the wires are twisted together, it's called a pair. It defeats the whole purpose of twisted pair cabling by using the solid orange and solid green to wire the jack.]]> http://www.dslreports.com/forum/remark,17053435 Mon, 09 Oct 2006 10:33:12 EDT Re: SpeedStream 4100: "Bridged mode" vs "PPP on the computer" http://www.dslreports.com/forum/remark,17052905 docinthebox : Thanks for all your help!]]> http://www.dslreports.com/forum/remark,17052905 Mon, 09 Oct 2006 08:19:06 EDT Re: SpeedStream 4100: "Bridged mode" vs "PPP on the computer" http://www.dslreports.com/forum/remark,17051912 nwrickert : In my quick browse through that documentation, I didn't find the "PPPoE on the computer" option. So maybe that's an option only for the SBC version. The SBC version of the 4100 is not doing NAT when set for PPPoE on the computer.]]> http://www.dslreports.com/forum/remark,17051912 Mon, 09 Oct 2006 00:06:47 EDT Re: SpeedStream 4100: "Bridged mode" vs "PPP on the computer" http://www.dslreports.com/forum/remark,17051222 59126125 : Sorry about that, I should have included that in my post. Though it still describes the functionality of the modem.]]> http://www.dslreports.com/forum/remark,17051222 Sun, 08 Oct 2006 22:09:23 EDT Re: SpeedStream 4100: "Bridged mode" vs "PPP on the computer" http://www.dslreports.com/forum/remark,17051198 nwrickert :
Well, according to this »kb.efficient.com/article.asp?art···82&p=351
Note that your link is the documentation for the full retail version of the 4100, not for the SBC version with its more restrictive firmware.]]> http://www.dslreports.com/forum/remark,17051198 Sun, 08 Oct 2006 22:04:22 EDT Re: SpeedStream 4100: "Bridged mode" vs "PPP on the computer" http://www.dslreports.com/forum/remark,17051169 nwrickert : Right, no speed difference. Unless you are trying to get statistics, you should not notice any difference.

As far as I know, the "PPP on computer" is the recommended setting if you are using a separate router and want that router to handle the PPPoE.]]> http://www.dslreports.com/forum/remark,17051169 Sun, 08 Oct 2006 21:58:41 EDT Re: SpeedStream 4100: "Bridged mode" vs "PPP on the computer" http://www.dslreports.com/forum/remark,17051164 59126125 : Well, according to this »kb.efficient.com/article.asp?art···82&p=351

The Router supports two fundamental modes of operation with respect to connectivity between the Local Area Network (LAN) and the Wide Area Network (WAN): bridge/routing mode and bridge mode.
The default mode of operation is bridge/routing mode. With bridge/routing mode, the Router provides typical routing functionality between the WAN side and the LAN side. However, all LAN-side interfaces are "bridged."
The second mode of operation provides only "bridging" functionality. This applies to both WAN-to-LAN connectivity as well as to all LAN-side interfaces. Point-to-Point (PPP) connections are not available under the bridge mode of operation.
Important! If you switch to Bridge mode, you will lose access to the Web management interface and can only return to Router mode by resetting the Router to factory defaults.


So my understanding is that the 4100 is technically acting as a router regardless of what is doing the login since it is still doing NAT, until it is put in bridge mode, at which point it is a true bridge and not a router.
--
There is a reason the wires are twisted together, it's called a pair. It defeats the whole purpose of twisted pair cabling by using the solid orange and solid green to wire the jack.]]> http://www.dslreports.com/forum/remark,17051164 Sun, 08 Oct 2006 21:58:10 EDT Re: SpeedStream 4100: "Bridged mode" vs "PPP on the computer" http://www.dslreports.com/forum/remark,17051150 docinthebox : So there shouldn't be any speed difference between the Bridge Mode and the "PPP on computer" mode, right?]]> http://www.dslreports.com/forum/remark,17051150 Sun, 08 Oct 2006 21:55:40 EDT Re: SpeedStream 4100: "Bridged mode" vs "PPP on the computer" http://www.dslreports.com/forum/remark,17051112 nwrickert : Basically it is a dumb bridge in "bridge mode", and a smart bridge in "PPP on computer" mode. The main difference is that it is easier to get to the modem statistics page in "PPP on computer" mode.]]> http://www.dslreports.com/forum/remark,17051112 Sun, 08 Oct 2006 21:50:05 EDT Re: SpeedStream 4100: "Bridged mode" vs "PPP on the computer" http://www.dslreports.com/forum/remark,17050924 docinthebox : So then what's the difference between the "PPP on the computer" mode and the "Bridged mode"? In the Bridged mode, I suppose all the packets just pass through the modem from the WAN to the router and vice versa, right? Is this also the case in the "PPP on the computer" mode?]]> http://www.dslreports.com/forum/remark,17050924 Sun, 08 Oct 2006 21:15:26 EDT Re: SpeedStream 4100: "Bridged mode" vs "PPP on the computer" http://www.dslreports.com/forum/remark,17050905 d_l : Your guess was correct. With "PPP on the computer", the modem will give out its only DHCP address. I use it this way all the time and the modem is definitely acting as a bridged modem this way.]]> http://www.dslreports.com/forum/remark,17050905 Sun, 08 Oct 2006 21:11:42 EDT Re: SpeedStream 4100: "Bridged mode" vs "PPP on the computer" http://www.dslreports.com/forum/remark,17050841 nwrickert : If you set the modem for PPP on the computer, it is basically set as a bridge.

I'm not sure, but possibly with "PPP on the computer" it might still give out a DHCP address of 192.168.1.64, if requested, and that could be used to direct connect to the modem for reading the statistics. Note that I am really guessing here - I haven't actually tested that.

If modem is set to "PPP on computer", and is connected to a router that does PPPoE, then you are using the modem as a bridge.]]> http://www.dslreports.com/forum/remark,17050841 Sun, 08 Oct 2006 21:00:52 EDT Re: SpeedStream 4100: "Bridged mode" vs "PPP on the computer" http://www.dslreports.com/forum/remark,17050623 59126125 : As a router, since it would still be doing NAT until it is fully bridged.]]> http://www.dslreports.com/forum/remark,17050623 Sun, 08 Oct 2006 20:20:43 EDT Re: SpeedStream 4100: "Bridged mode" vs "PPP on the computer" http://www.dslreports.com/forum/remark,17050596 docinthebox : So if I set the 4100 to "PPP on the computer" under "PPP location" in the 4100 menu, and have my router do the authentication, would the 4100 be acting as a router or as a bridge in this case?]]> http://www.dslreports.com/forum/remark,17050596 Sun, 08 Oct 2006 20:16:03 EDT Re: SpeedStream 4100: "Bridged mode" vs "PPP on the computer" http://www.dslreports.com/forum/remark,17050583 59126125 : With PPP on the computer you could actually have the 4100 work in either mode, as a router or as a bridge. You just need something to do the authentication, whether it is the computer, a router, or the modem. However, it's advisable to only have one device do the login.
--
There is a reason the wires are twisted together, it's called a pair. It defeats the whole purpose of twisted pair cabling by using the solid orange and solid green to wire the jack.]]> http://www.dslreports.com/forum/remark,17050583 Sun, 08 Oct 2006 20:12:50 EDT SpeedStream 4100: "Bridged mode" vs "PPP on the computer" http://www.dslreports.com/forum/remark,17049953 docinthebox : I've read past threads on this issue but I'm still not clear. What's the difference between the two? I know if you set "PPP on the modem", then the modem acts as a router, with firewall, NAT and everything. If you set "Bridged mode", then the modem acts as a dumb modem, and your DSL router (WRT54G for example) does the PPPoE authentication, firewall etc. But what about "PPP on the computer"? If you set this mode, is the modem acting as a router or as a bridge?]]> http://www.dslreports.com/forum/remark,17049953 Sun, 08 Oct 2006 18:08:52 EDT