03-14-2007 11:41 PM - edited 03-05-2019 02:55 PM
If I connect connect two equipment as below. The result is I can ping the 2924 ip from 3560.
Why ? Why 2924 fast ethernet port is vlan 1 but 3560 fast ethernet port is vlan 2. the connection is also success ?
2924
Int fa0/1
!
Int Vlan1
Ip address 10.10.10.1 255.255.255.0
!
Ip-default gateway 10.10.10.254
3560
Int fa0/1
Switchport mode access vlan 2
!
Vlan 2
Ip address 10.10.10.254 255.255.255.0
03-15-2007 12:07 AM
Hi Friend,
Thats a leakage in technology which you can term as VLAN Leakage. The reason WHY it is pinging is because you have access ports configured on both the switches which are connected to each other.
Now when frame comes to fa0/1 port on 2924 switch and because that port is not a trunk port but just an access port when frame moves out of that potr there is no tagging on that frame and its just a frame without any vlan information and once it reaches 3560 switch on fa0.1 and because it is configured also as an access port for vlan 2 it assigns PVID 2 for that frame and now that frame is a part of vlan 2 when it reaches 3560 backplane and is the reason your communication is working between switches.
If you configure the connection between the 2 switches as a trunk port it will not work.
HTH
Ankur
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03-15-2007 12:37 AM
Then how about if 3 pc is connected to a single switch with 3 switchport and assigned to vlan 1,2,3 respectively. Can they be pinging each other ?
03-15-2007 01:25 AM
HI
In that case u need to have a layer 3 device to communicate between diferent vlans.
Thanks
Mahmood
03-15-2007 01:43 AM
Hi Friend,
In this situation you need to have layer 3 device doing inter vlan routing because frames from one pc is not going out of switch.
But if you have 2 switches connected to each other via access port like vlan 1 on switch one connected to vlan 2 on switch 2 and pc on vlan 1 on switch 1 will be able to ping pc on vlan 2 on switch 2.
HTH
Ankur
*Pls rate all helpfull post
03-15-2007 02:26 AM
Hi Mahmood,
Thanks! I know what you mean. I just suprised that why switch can change the PVID from 1 to 2 when two switch is connected by access port
However, within a Single switch with different vlan assigned to each port (e.g. port 1 is vlan1, port 2 is vlan 2, port 3 is vlan 3.....)
then single switch has not the ability to change the PVID from 1 to 2 when port 1 want to communication with port 2
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