Best of the ISP-Lists

Shotgun DSL

Members of the ISP-DSL list discuss using two DSL lines to create a single connection at twice the speed. One respondent claims it "Smokes along better than a T1 and is cheaper, too!" It is, however, complex.

[July 6, 2000]

On the ISP-DSL list in May, EI indulged his curiosity about a technical question:

"This may be an easy question to answer but is it possible to do a shotgun DSL setup, using two phone lines or DSL connections piped to a merged connection and allowing users to have dual-DSL bandwidth?"

A number of respondents offered ideas for making such a setup work:

[AM wrote] "A Linux/FreeBSD machine with 3 NIC's (1 for each DSL connection plus 1 for the LAN) could easily load balance this. You could even do 2 different types of DSL at 2 different speeds and do bandwidth throttling between the 2 ports, if the UNIX machine was the default gateway. If the ISP is bridging the ports with routable IPs, it won't work unless you set up the load balancer with NAT; dedicate one IP to the load balancer. You can do the same thing if the ISP does routed PPP, or route a subnet for the LAN to the load balancer which will act as the router."

[Jay suggested] "Why not use directional ADSL?"

Another respondent opined that this could be a tricky, though workable, proposition:

[TR wrote] "If you are talking about bonding, that would require a DSLAM with that ability and therefore is unlikely. On the other hand, you can put a router on each end, set up a small private network for each line and set up two static routes to the networks on the same subnet. Make the metrics for the routes equal. Most routers will be intelligent enough to load balance between the two lines or have a command to enable it."

LF offered this advice:

"Check up on the Netopia 7000 series. You can bond two channels for 3 Mbps."

[Ed. Note: According to the Netopia site (http://www.netopia.com/equipment/routers/r7100/index.html), the R7100 SDLS Router enables "always-on" connectivity and SDLS bonding for speeds up to 3 Mbps using two SDSL lines.]

One respondent enthusiastically shared his experience with a shotgun solution:

[DS wrote] "I have two GTE Platinums (1.5 Mbps downstream on each and 700 Kbps up stream on each) on separate LINUX routers terminating on the far end on 2 different routers on different circuits. Great fail over this way too. Both go to same hub and all NT machines on the inside use RIP to see which one is available. Smokes along better than a T1 and is cheaper, too!"

 —End