How a 2950 can learn a default gateway when none is configured

[mbartsch]

Hello
i had the following topology

internet----trunk----CAT6509----trunk(vlan99)-----2950

the 2950 had only configured the ip address, and the default gateway for the 2950 network is the catalyst, the funny/strange part , is that the 2950 knows it's default route. the question is, how it knows? 2950 had now routing protocols, but when i do a traceroute it goes to the 6509 and then the rest of then net.

any ideas on why this happend?

TIA!

 

[andf1]

You say you have configured the 6509 as the default gateway on the 2950. So, the 6509 is the default route for the 2950. The 6509 knows how to send the packet to the Internet that is why your packets to the Internet got a response.

andf1

 

[mbartsch]

andf1, i express myself wrong, what i mean is:

the 2950 has no ip default-gateway configured, but anyway it know how to send the trafic to what should be it's default gateway, the 6509. so, those the 6509 send the default route to the 2950 somehow , and i need to disable it. so i need that the 2950 didn't go to the internet, or the rest of the network

 

[ADB100]

Proxy Arp

 

[ADB100]

To make sure the 2950 can't get outside the local subnet I would just create a default route to null:

ip route 0.0.0.0 0.0.0.0 null 0

Is this what you really want though? I would just create an ACL an apply it as an access-class to the VTY lines, i.e.

!
access-list 10 permit 10.1.1.0 0.0.0.255 (local subnet)
line vty 0 4
access-class 10 in
!

That way you restrict who can telnet to the switch based on source ip address, this can also be applied to SNMP access.

Andy