1/28 Just switched to Comcast from SBC and generally happy with it. But
can someone please explain to me why they are constantly pumping
ARP traffic through the network? It seems harmless, but I'm curious
as I didn't see it with DSL. It's a little disconcerting to see
constant traffic on your router, even if ARPs are harmless from
a bandwidth perspective, and it makes the WAN send/receive light
basically useless. Is there a cable modem I can get that won't
forward these stupid things? From reading around the net, all I see
are vague references to the fact that Comcast's network configuration
is such that all of their customers on a particular link will see
all customers ARP traffic.
\_ Further searching turns up this from 8 Dec 2005:
"I'm a relatively new comcast customer, and also a network
engineer. I'm not sure how they have their routers configured,
but I get upwards of 10-20 arp requests per second during the day,
and from 6:00 to midnight I get so many that packets start getting
dropped. I recieve the arps from at least 5 different source IPs
that appear to be routers (they all have ips that end in .1, but on
different /24 networks. This leads me to believe that they are
using multiple virtual IPS on the same interface of a single
router, or that they have something bridging data between parallel
networks (which should not be happening). Regardless, I'm trying to
get some resolution. I can't imagine what would create a requirement
for this level of arp traffic; it has to be a misconfiguration
somewhere."
\_ Good luck trying to explain this problem to their technical
support staff! -another comcast user
\_ would you recommend SBC DSL or Comcast cable? Is DSL really
that much cheaper?
\_ My brother is getting 2 mbps down off his Dslextreme line for
$20/month on a yearly subscription. I'm getting 2 mbps (yes,
I know Comcast advertises more, but that's my roughly measured)
from Comcast for $50/month on month-to-month (Comcast doesn't do
annual). I'd switch to DSL in a heartbeat if it were available
at my house. The only thing nice about my Comcast feed is the
pseudo-static IP (infinite dhcp lease, keyed off my mac address
and their equipment, and neither changes all that often).
\_ For what it's worth, I'm getting 6 mbps downstream from
Comcast pretty consistently. Oddly, using a Belkin router/
firewall in between the cable modem and my network cuts
it to about 5 mbps. The Belkin's WAN activity light was how
I originally found all the frickin' ARP traffic. Is it
possible the overheard of blocking the ARPs is slowing the
(admittedly very cheap) Belkin down? --ARP traffic guy
\_ My segment get continuous arps but not *that* kind of
traffic. I get 1 or 2 per second at most. Sometimes it
fades off a bit to 1 every 3-5 seconds. How many are
you getting?
\_ It fluctuates, but I'm seeing roughly 5 to 10 a second.
From what I've read, Comcast does configure it's
customers into very large LANs, and that you'll
tend to see more of the ARPs when some of the people
on your LAN are infected with something like Code Red.
\_ I'm over 20,000 feet from the nearest DSL POP so cable is my
only choice. The pseudo-static IP changes about once every
15 months which isn't too horrible and the service itself has
been quite reliable overall. It is pricey but when dialup is
your only other choice....
\_ Ha! I'm only 13k feet from the nearest CO. Of course,
according to SBC, I have steel pairs running to my house
instead of copper, and DSL will never happen till they
rip up the sidewalk to swap to copper. |
http://csua.com/feed/