Router - DLINK 320B

Currently shipping hardware version

At the time of writing, December 2017, the currently shipping hardware version of the DLink DSL-320B is the DSL-320B-Z1. Confusingly, in the past DLink has described several completely different modems as “DSL‑320B”. The following sections describe the DSL‑320B‑Z1 hardware.

Default settings

Default/Factory Settings
Username:	admin
Password:	admin
IP:	192.168.1.1

Notes

• AAISP ships these devices for use as straight ethernet modems. Although they are capable of working as (buggy) routers, AA pre-configures them to work in bridge mode only, that is, in simple PPPoE modem-only mode, not operating as routers.
• If you reset them to factory settings using the pin-in-hole technique, then with their factory defaults they will not work at all as straight PPPoE ethernet modems. Their configuration must be altered before use. Ask AA support for help with this or see post-factory reset configuration instructions below.
• No per-user or per-line login or password configuration is required. ISP account or line login and password info is configured in your router, the DLink modem doesn’t need these values.
• They do support 1500 byte MTU (unlike the Router - ZyXEL_P660R-D1). (Your router will also have to support 1500+8=1508 byte MTU too though for this to be effective.)
• Their web interface is quite insecure and in ‘router’ mode they have various critical security bugs, which is why we do strongly suggest that customers never use them configured in 'router' mode. They are sold by AAISP as bridge-only. Older modems, the now obsolete pre-Z (-D1) model, were shipped with their reset button covered to protect it and prevent them from being reset!
• It is vital that you not expose the LAN-side ethernet interface to users on the LAN unless all possible users and devices on the LAN are trusted because of various critical security bugs in this respect. Because of such bugs, setting passwords on the modem’s admin web UI etc is not enough. If your router happens to prevent LAN-internal users from accessing the modem then so much the better, otherwise your main router’s facilities / internal firewalling and access controls should be explored.
• Chipset: The currently shipping DSL-320B-Z1 units (at the time of writing, December 2017), and those shipped from approx 2015 onwards, use an old but capable MediaTek/TrendChip chipset. The older -D1 routers were Broadcom-based.
• Incorrect manufacturer’s defaults: The default settings shown in the router’s web admin user interface show defaults that are questionable. These settings should be fixed - see following section.

Initial setup using the web admin interface

The manufacturer’s default settings shown in the router’s web admin user interface show defaults that are very much sub-optimal. It is important to enable the ‘bitswap’ option for best reliability and performance in most cases. (See also this discussion of bitswap.) This default seems so odd that perhaps this is just a bug in the DLink software, and the bitswap feature really defaults to ‘enabled’. (Needs a volunteer to do reliability testing to compare the two cases.)

These settings need to be configured as follows:

‘ADVANCED’ (top horizontal navigation bar) > Advanced ADSL (lhs vertical navigation list)

• ANNEX A/I/J/L/M
• Bitswap - enable (very importent)
• SRA - enable (for future-proofing, but currently has no effect as SRA is not supported by eg BT currently)

Performance tip for long lines: If you have an extremely long phone line (>60 dB downstream attenuation) and you can use ADSL2+, it is worthwhile experimenting with setting the DSL mode/standard option to ‘ADSL 2’ (only) in the above list of options, that is, taking ADSL2+ out of the list of allowed standards, as opposed to allowing the modem to use ADSL2+, to see if this restriction gives a performance improvement. It will be a long process to get a meaningful comparison with take many restarts and many tests to confirm any possible performance difference between allowing and disallowing ADSL2+. If in any doubt enable ADSL2+ ie ADSL1/ADSL2/ADSL2+ ‘auto’ mode where the modem will use ADSL2+ (which can support much higher best-case speeds than ADSL2) if the exchange DSLAM or MSAN supports ADSL2+ too.

After each reset to factory settings

After any reset to factory settings you will need to make the following change using the web admin user interface in order to get the device to work properly as a straight modem. (Factory default http://192.168.1.1, your own ip address set to something suitable in that same /24 subnet, username=admin, password=admin.)

‘SETUP’ (top horizontal navigation bar) > Bridge Mode

• 1483 Bridged IP LLC. Important note: The leaner PPPoEoEoA + RFC2684’s [obsoletes RFC1483] “Bridged+VC-MUX” header option does not seem to work with BT Wholesale and the modem failed to establish a link for some reason when this tested

Following this you will then also need to make the configuration changes described in the previous section.

Resetting to factory settings

To reset the modem to factory settings, locate the reset button hole on the rear panel of the unit. With the modem powered on, use a paperclip to hold the button down for 10 seconds. Release the button and the modem will go through its reboot process. Wait about 30 seconds to access the modem. The default IPv4 address for the modem’s http admin user interface on the LAN is 192.168.1.1/24. Your own IPv4 address will need to be in the same subnet and different from that of the modem, ie set to something in the range 192.168.1.2 - .254. You can then log in to the web admin interface using a web browser at http://192.168.1.1, username=admin, password=admin.

Images

DLink DSL-320B-Z1 modem

The currently shipping (as of December 2017) DLink DSL-320B-Z1 modem, rear view

Rear view of obsolete ‑D1 modem

(The image below is of the older generation of routers.)

Rear view of obsolete pre-Z1 modem, showing blanked-off reset button