Lukas Beeler's IT Blog

Since about one and a half year, we’ve been using cablecom hispeed business for internet access.

Shortly after installing the line back in 2008, we’ve ran into an issue where cablecom hispeed business blocks GRE packets. After almost three days and speaking with a variety of technicians, they were finally able to resolve the issue.

Now, we’ve run into another, much more grave problem. Since about 15:45, a variety of hosts on the Internet aren’t reachable and of course several other hosts can’t reach us.

Of course this isn’t a clear-cut “my DSL modem has no link” issue – so cablecom currently isn’t even trying to fix the problem. I’ve been on the phone twice, never get any callbacks and don’t get any updates on the state of the problem resolution.

Fact is, some hosts can reach our OWA 2010 and some can’t. Nasty thing is, Swisscom’s GPRS/UMTS IP addresses can’t – this means no push-email for all 35 of our employees. Since we’re working for a rather important project (ERP and POS implementation) this weekend, this is a big issue for us.

It also looks interesting in a tcpdump – some packets just get lost – and from other hosts it works without any issues.

The 77. addresses are cablecom hispeed business, the 217. are my cablecom residential connection. In the first part, we see a TCP connection to port 80. In the second part, we see a ping -t. As you can see, there are a lot of dropped packets.

23:12:12.629457 IP 217.162.252.98.18417 > 77.59.216.227.80: S 4006182815:4006182815(0) win 8192 <mss 1460,nop,wscale 2,nop,nop,sackOK>
23:12:12.629479 IP 77.59.216.227.80 > 217.162.252.98.18417: S 1280362581:1280362581(0) ack 4006182816 win 5840 <mss 1460,nop,nop,sackOK,nop,wscale 6>
23:12:15.826736 IP 77.59.216.227.80 > 217.162.252.98.18417: S 1280362581:1280362581(0) ack 4006182816 win 5840 <mss 1460,nop,nop,sackOK,nop,wscale 6>
23:12:22.026734 IP 77.59.216.227.80 > 217.162.252.98.18417: S 1280362581:1280362581(0) ack 4006182816 win 5840 <mss 1460,nop,nop,sackOK,nop,wscale 6>
23:12:34.026733 IP 77.59.216.227.80 > 217.162.252.98.18417: S 1280362581:1280362581(0) ack 4006182816 win 5840 <mss 1460,nop,nop,sackOK,nop,wscale 6>

08:51:49.642995 IP 217.162.252.98 > 77.59.216.227: icmp 40: echo request seq 65
08:51:49.643024 IP 77.59.216.227 > 217.162.252.98: icmp 40: echo reply seq 65
08:52:00.641330 IP 217.162.252.98 > 77.59.216.227: icmp 40: echo request seq 68
08:52:00.641345 IP 77.59.216.227 > 217.162.252.98: icmp 40: echo reply seq 68
08:53:16.641813 IP 217.162.252.98 > 77.59.216.227: icmp 40: echo request seq 84
08:53:16.641829 IP 77.59.216.227 > 217.162.252.98: icmp 40: echo reply seq 84

Cablecom gets 180 CHF per month for 24/7 support. The case has now been open for 7 hours, with no resolution in sight. There’s no escalation path and there are no workarounds – we don’t have redundant connections.

Interestingly, one of our customers who also uses cablecom hispeed business had a similar issue, that lasted for roughly three weeks – one of their IP addresses wasn’t reachable externally, from one minute to the other. Unfortunately for us, all of our public IP addresses are affected by this issue, so we don’t have an easy workaround.

Of course, for some part we’re also to blame. Luckily i’m not one of the higher ups who gambled with non-redundant internet connections and lost.

Have you made negative experiences with cablecom hispeed business? Positive ones? Was support able to fix your issues quickly?

Update: I’ve called cablecom again on Saturday at 09:00. Apparently, these sort of issues are supported on a best-effort base from 9 to 5, and not covered by our 24/7 support contract. We will have to wait until monday – they will not look at this issue further during the weekend.

Update: Monday morning, 11:00. Problem is still unsolved.

--- hor-fw-01.acommit.ch ping statistics ---
20 packets transmitted, 3 received, 85% packet loss, time 19012ms
rtt min/avg/max/mdev = 20.490/21.360/22.585/0.891 ms

Update: Monday morning, 11:36. Problem is now solved. According to the Tech i talked to, the he fixed the issue in 5 minutes. He could’ve done that on Friday, but apparently noone at cablecom felt like doing so. The issue was that cablecom configured our new line for the planned office move and configured load sharing between the new line for the new office and the old line. Since the new line didn’t physically exist yet, half of the packets were dropped.

Thanks to the Tech who fixed the issue, no thanks to cablecom in general for wasting an entire weekend on what could’ve been a five minute fix on Friday evening.