[lug] Comcast users (OT)

James Yonan jim at yonan.net
Fri Jun 27 10:54:59 MDT 2003

I've been fairly satisfied with Comcast/AT&T so far (I'm located in east
Boulder and my IP address still reverse maps to .attbi).  One improvement I've
noticed recently is that comcast is now peering to other networks in Denver. 
It used to be if you pinged a local boulder address (such as www.coop.net),
that packet would go all the way to California and back and the latency would
be 60 or 70ms.  Now the same ping can be 15ms or less (if traffic is light).

I have occasionally noticed failures between 12am and 6am that last up to 30
minutes.  I have one linux box running dhcpcd that is directly connected to
the cable modem.  dhcpcd seems to run fine and is able to negotiate the IP
address changes which generally seem to occur about once every two months. 
There have been about 2 or 3 instances this year where dhcpcd wouldn't
renegotate the lease, not during an IP address change sequence, and often
after a server reboot.  I think that one potential cause was that comcast/att
was sending bootpc packets with a source address in the 10.x.x.x netblock
which my firewall was blocking.  Power cycling the modem usually fixes the

My biggest gripe so far (which is not really Comcast's fault) is that my IP
address is increasingly associated with blocks of IP addresses which send
spam.  Therefore my SMTP server often cannot send email.  As a result of this,
I am going to have to find an SMTP relay somewhere on a "clean" netblock (I
tried using comcast's own relay, but it wouldn't relay traffic coming from my


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