Vlan Access - List confusion
Posted on 2007-11-27
Two Pc's in two 2 Vlans
PC A - 10.20.20.39 /23 in Vlan A (Vlan A details - ip address10.20.20.1 255.255.254.0)
PC B - 192.168.50.50 /24 in Vlan B ( Vlan B details - ip address 192.168.50.1 255.255.255.0)
This access list applied on interface on Vlan B
ip access-list extended Test_Network_Vlan
deny ip any 10.20.20.0 0.0.1.255
permit ip any any
using Ping to test
Applying the access-list with the IN command
Traffic gets from PC A to B but not from B back to A and ping fails - as expected
If I ping the other way then traffic simply won't get from B to A in the first place so there is no reply - as expexted.
Applying the access-list with the OUT command
All traffic gets through wherever I ping from.
When pinging frob B to A Packets still have source B dest A and have to cross this access list and
I can't see how they get through.
Same applies the other way, I can see why A's ping request packets get through but the replies source PC-B to PC-A should fail but they don't they just sail through
I must be missing something obvious - can anyone help