From: Church, Chuck (cchurch@netcogov.com)
Date: Tue Jan 17 2006 - 11:03:02 GMT-3
Throw a cheap hub between the switch and the modem, and run a sniffer on
there to determine how the cable modem is learning about the switch.
Chuck Church
Lead Design Engineer
CCIE #8776, MCNE, MCSE
Netco Government Services - Design & Implementation
1210 N. Parker Rd.
Greenville, SC 29609
Home office: 864-335-9473
Cell: 703-819-3495
cchurch@netcogov.com
PGP key: http://pgp.mit.edu:11371/pks/lookup?op=get&search=0x4371A48D
-----Original Message-----
From: Mike O [mailto:mikeeo@email.msn.com]
Sent: Monday, January 16, 2006 1:14 PM
To: Church, Chuck; Joseph Eleazar; ccielab@groupstudy.com
Subject: Re: OT-switch MAC addresses
Chuck,
I tried it and I seem to be still picking up the MAC of the switch port
FastEthernet0/24 is up, line protocol is up (connected)
Hardware is Fast Ethernet, address is 0012.005d.0a58 (bia
0012.005d.0a58)
MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
My cable modem lists that MAC as 1 of 3 allowed which blocks my one host
from pulling an address.
Any ideas? I tried "no mac-address 0012.005d.0a58 " with no luck.
----- Original Message -----
From: "Church, Chuck" <cchurch@netcogov.com>
To: "Mike O" <mikeeo@email.msn.com>; "Joseph Eleazar"
<joseph_eleazar@hotmail.com>; <ccielab@groupstudy.com>
Sent: Monday, January 16, 2006 11:04 AM
Subject: RE: OT-switch MAC addresses
You need to disable all traffic on the 2950 switchport that would have
it's own MAC address in the frame. So for the port facing the cable
modem, disable:
Spanning tree
Any trunk-negotiation frames
And channel-negotiation frames
CDP
Chuck Church
Lead Design Engineer
CCIE #8776, MCNE, MCSE
Netco Government Services - Design & Implementation
1210 N. Parker Rd.
Greenville, SC 29609
Home office: 864-335-9473
Cell: 703-819-3495
cchurch@netcogov.com
PGP key: http://pgp.mit.edu:11371/pks/lookup?op=get&search=0x4371A48D
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Mike O
Sent: Monday, January 16, 2006 9:39 AM
To: Joseph Eleazar; ccielab@groupstudy.com
Subject: Re: OT-switch MAC addresses
Joe,
As soon as I plug in the modem, it records the 2950's switchport MAC
address. If I use a cheapy linksys switch it doesn;t. Is there anyway to
disable the switchport MAC?
----- Original Message -----
From: "Joseph Eleazar" <joseph_eleazar@hotmail.com>
To: <mikeeo@email.msn.com>; <ccielab@groupstudy.com>
Sent: Sunday, January 15, 2006 11:35 PM
Subject: RE: OT-switch MAC addresses
> Mike,
>
> Assuming that all ports on the 2950 and 3550 are on the same vlan, use
> vlan 1 for simplicity, then:
>
> 1. Make sure that the interface vlan 1 on both switches are not set up
for
> dhcp.
> 2. Make sure that the trunk between the switches are passing vlan 1.
> 3. Make sure that the ethernet port on the 2620 that connects to the
> switch is configured for dhcp.
>
> With that setup and the cable modem connected to the 2950, the the
2620 on
> the 3550 should grab an IP address, that should leave 2 addresses for
2
> more devices that connect to either switch to grab a dhcp address from
the
> cable modem.
>
> Joe
>
>
>>From: "Mike O" <mikeeo@email.msn.com>
>>Reply-To: "Mike O" <mikeeo@email.msn.com>
>>To: <ccielab@groupstudy.com>
>>Subject: OT-switch MAC addresses
>>Date: Sun, 15 Jan 2006 13:20:51 -0500
>>
>>My ISP (Comcast) assigns IP addresses per MAC. And my cable modem
allows 3
>>MAC addresses to be registered. My problem is I want my 2620 in my lab
to
>>be assigned an address but when I plug the cable modem into my 2950 it
>>picks of the MAC of the switch port and doesn't let the 2620 register.
Is
>>there anyway to disable the mac address of the port?
>>
>>My 2620 is plugged into my 3550 which is trunked to the 2950 and VLAN
is
>>created to carry internet traffic to the cable modem, but like I said
it
>>picks up the switchport MAC instead.
>>
>>Thanks,
>>
>>Mike
>>
>>______________________________________________________________________
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