We have two Comcast Business Internet circuits. We've had long-term performance issues. Comcast upgraded our routers to 3.0 versions, and installed an upgrade of an RG11 cable to reduce signal loss and bring the cable into spec. Performance at times is great, up to 30 MB/sec download and 3.5 MB/sec upload speeds.
We still see download speeds drop from 20+ MB/sec to 1-10 MB/sec when one of the users is uploading a large file. Comcast is investigating at the supervisor level, but I thought I'd ask here and find out if anyone else has seen this issue.
Three Comcast technicians, one of them tier two, and another an installer I talked to today, told me that Comcast Business Internet traffic on routers with fixed IP addresses is treated differently than residential internet traffic which is on routers with dynamic IP addresses. Business/fixed IP address traffic isn't "bundled" with residential traffic at the upstream node and has a higher priority. Business/fixed circuits get their own virtual connections.
First time I ever heard of this. The tier 2 guy I talked to on Friday was very specific about this, and I asked him several times to clarify.
I asked another tech this afternoon if fixed IP addresses for our Comcast routers would improve performance, specifically the upload/download issue. He didn't know.
The other question is if there's a performance improvement, do the individual computers behind the Comcast router need Comcast IP addresses, or is NAT'ing them OK?
Thanks for your help with this.
Solved! Go to Solution.
Hello Tom and welcome to Comcast Business Forum and thank you for your post!
To answer your questions. When uploading large files that exceed the upload bandwidth, the gateway will utilize part of the download bandwidth in order to complete the upload. This should not be a problem unless the upload exceeds the rated service level. In regards to a “fixed” IP address or a dynamic IP address, traffic are treated equally and do not receive a higher priority.
We always recommend keeping the network simple but giving your business needs we know at times this may not be the case. Comcast’s IP-Gateway will continue to lease LAN dhcp address as before introducing the fixed (static) IP address for your network.
Hope this helps
Thanks for responding.
We have a premium circuit. The spec is 22Mbps/5Mbps.
I uploaded a 54 MB file to a Web site and got a 2Mbps upload speed, which is well under the 5Mbps spec.
I ran the Comcast speed test on the uploading computer and got 2.25 Mbps down and 1.58 Mbpsec up, showing that there was additional upload bandwidth available.
Another computer ran the Comcast speed test while the upload was going on, and got a download speed of .5 Mbsec. Sometimes non-uploading computers get 1-5 Mbpsec download speeds.
This doesn't seem right. It wasn't a perfect test as other computers are on the network attached to the Comcast router, but I will be running more formal tests to elimate those variables.
Is there any throttling going on that could explain these results?
I believe you are working with my colleague via PM, to address this issue.
Please continue do so.
Regarding "throttling" of connection, Comcast do not throttle connectives.
I think I may have found the source of the problem - the two affected users were connected to the SMC SMCD3G cable modem via a shared Ethernet switch, as there was only Ethernet circuit to their office.
I did simultaneous upload/download testing with two computers connected to two different ports of the SMCD3G. The problem didn't occur.
I ran another Ethernet cable for the second computer, so both users would have their own direct connection to the SMCD3G. No problem reports today. PowerBoost speeds of up to 35 Mbps on a 22Mbps/5Mbps circuit.
The SMCD3G user guide on page 15 states “Using an Ethernet LAN cable, you can connect the Gateway to a desktop computer, notebook, hub, or switch. Your Gateway supports auto-MDI/MDIX, so you can use either a standard straight-through or crossover Ethernet cable.”
This statement implies that it's OK to connect computers to the modem via a switch or hub, but this may not be the case. I emailed SMC support to see what they have to say, but haven't heard back yet.
Hopefully this wil resolve the issue.
Thank you for the information.
I hope your issue has been resolve with this change.
Move post to: Domain Names/Static IP