2008-07-24 00:04:00 dual network interface issue

Tinku Jose (INDIA)

Message: 59299

Hi,

We are facing an issue while enabling 2 network interfaces in uClinux. (we are using 2007R1)

The issues is as follows.

enable eth0 with IP 'a', MAC address is 'x'

enable eth1 with IP 'b', MAC address is 'y'

In this mode both 'a' and 'b' can be pinged from the PC and the arp tables show proper values

bring down eth0

clear the arp tables in the PC

ping 'b' from PC and it works

ping 'a' from PC, it also works!!!! (whereas it should not have, as eth0 is down)

if you check the arp tables it is observed that both 'a' and 'b' are mapped to same MAC address, that is of 'b' which is 'y'

if the same experiment is done with disabling eth1 instead of eth0,

the arp tables are having the MAC address of 'a' which is 'x' for both 'a' and 'b'

Have any issues similar to this observed? Please let me know if there are any know issues or is it any configuration problem and what are the solutions

currently the only option we are having is to set the ip address of the interface which is brought down to 0.0.0.0.

thanks in advance

best regards

tinku

QuoteReplyEditDelete

2008-07-24 00:17:32 Re: dual network interface issue

Mike Frysinger (UNITED STATES)

Message: 59300

this is expected default behavior. Linux will respond to any IPs it has on any interface. bringing down an interface does not unbind the associated IPs, it just means the interface will not be used. if you want to unbind an IP, then you need to do so explicitly.

QuoteReplyEditDelete

2008-07-24 01:52:26 Re: dual network interface issue

Tinku Jose (INDIA)

Message: 59302

Hi Mike,

But when a interface is brought down, is the IP address associated with that interface be reachable? As i mentioned,

when eth0 is down, still we are able to ping to the ipaddress associated to eth0

best regards

tinku

QuoteReplyEditDelete

2008-07-24 02:05:36 Re: dual network interface issue

Mike Frysinger (UNITED STATES)