Re: Slow browsing with cable modem

From: Clifford Kite (kite_at_see.signature.id)
Date: 04/24/04 

Date: Sat, 24 Apr 2004 15:58:01 -0500

P Gentry <rdgentry1@cablelynx.com> wrote:
> Clifford Kite <kite@see.signature.id> wrote in message
> news:<buod6c.q1l.ln@corncob.localhost.tld>...
>> P Gentry <rdgentry1@cablelynx.com> wrote:
>> > "Stephen Zilliox" <szilliox@charter.net> wrote in message
>> > news:<108hvmqm1lerqbf@corp.supernews.com>...
>>
>> >> lease {
>> >> interface "eth0";
>> >> fixed-address 68.113.7.247;
>> > See, 68.113.7.247 _is_ the IP for your Linux interface. This is quite
>> > common on dual boot machines because Win and Linux use different
>> > client-ids when requesting a lease. J.M. is newly familiar with Win
>> > vs. Linux client-ids re: Verizon ;-)
>>
>> >> option subnet-mask 255.255.254.0;
>> >> option time-offset -21600;
>> >> option routers 68.113.6.1;
>> > This is your GW when using Linux. Should be able to ping this almost
>> > as fast as localhost. It _must_ be on the same subnet as you.
>>
>> It seems to me that his IP address, 68.113.7.247, is on the same CIDR
>> subnet, 68.113.6.0/31, as the router's IP address, 68.113.6.1 .
>>
>> If I'm wrong then please don't hesitate correct me and explain why.

> You are almost correct, and I was too loose with my late day typing
> freenzy.

> My, erh, comments related to the IPs in the first post where there
> were inconsistent IP address/subnet numbers. The last post does
> indeed reveal what seems to be a consistent set of IPs. It was also
> meant to warn OP against changing the DHCP settings manually in an
> attempt to fix it by trial-n-stumble. I should have been clearer.

> I _think_ the first post inconsistencies were typos mostly, but can't
> be sure without confirmation from OP.

There were indeed many strange things, some of which I am unable to
see as being typos.

> BTW, OP's net uses a /23 prefix -- there is no such beast as a /31.
> /30 is the smallest posssible as one IP for net, one IP for broadcast,
> and two IP's for hosts (one at each end) is the smallest you can go.
> /31 provides only 2 IPs and 2 are always reserved -- one for net
> segment and one for broadcast, leaving no IPs for hosts.

Okay, that would be true in regard to 68.113.6.0/31 if it applied only to
the last quad, i.e., with a netmask of 255.255.255.0 . The netmask above
is shown to be 255.255.254.0, so I'm not sure that's correct in this case.

In exploring the effect of the netmask 255.255.254.0 here I came up with
these results for my eth0 interface:

ifconfig eth0 192.168.1.1/23 broadcast 255.255.255.255 up
ifconfig eth0
eth0 Link encap:Ethernet HWaddr 00:20:AF:1B:5C:48
          inet addr:192.168.1.1 Bcast:255.255.255.255 Mask:255.255.254.0
          UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          Interrupt:10 Base address:0x280

route add 192.168.0.247 eth0
route add default gw 192.168.1.1 eth0
route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.0.247 0.0.0.0 255.255.255.255 UH 0 0 0 eth0
192.168.0.0 0.0.0.0 255.255.254.0 U 0 0 0 eth0
127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 lo
0.0.0.0 192.168.1.1 0.0.0.0 UG 0 0 0 eth0

OTOH, I found this when trying to add a default route that wasn't covered
by the netmask 255.255.254.0 this was the result:

route del default gw 192.168.1.1 eth0
route add default gw 192.168.2.1 eth0
SIOCADDRT: Network is unreachable

> I'm always preaching the need for exactness and clarity when dealing
> with network configuration problems, so it's only fair to be rightly
> called to task. I hope I've cleared it up. Sharp eyes make for
> quicker fixes.

Thanks.. 

-- 
Clifford Kite                Email: "echo xvgr_yvahk-ccc@ri1.arg|rot13"
PPP-Q&A links, downloads:                      http://ckite.no-ip.net/
/* The wealth of a nation is created by the productive labor of its
 * citizens. */

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