02-23-2020 10:11 AM
hi everyone, i wanna ask about how trunk forwarding works between multiple switch (i've been doubting my understanding about the concept).
So for an example, i have 2 PC (PC A and PC B) connected to a L2 switch (f0/1 for A and f0/2 for B). port f0/1 is assigned as access port for VLAN 10, while f0/2 for VLAN 20. This switch (we can called it as Switch1) is also connected to another switch (called Switch2) using a trunk port using port f0/3 (on Switch1) and f0/1(on Switch2).
on Switch 2, The Switch is also connected to a Router (called Router1) that provide interVLAN routing and act as DHCP server service (using sub interface).
And now, comes the problem. On my understanding, when either PC A or B is sending a DCHP Discover (to any available DHCP server, in this case Router1), it will received by the switch1 at the port which i already signed as an access port earlier (f0/1 & f0/2) then it will be tagged as part of VLAN 10 or 20 when it's enter trunk port (to differ it from others). after that, when the frame arrives at the trunk port of Switch2, the tag on the frame will be removed, and that frame will be forwarded to any access port with the same VLAN ID as the tag on the frame when it enters OR it will be forwarded again to another trunk port if any (which in this case there is a trunk port heading to Router1). From this part i understand how the DHCP server will respond.
My Question is, is my understanding about the concept are correct ? or is there any other factor ?
because when im testing some simple lab on packet tracer. (which i'm going to attach below).
On the 1st lab, one of the PC receives the IP from DHCP server but the other are not, infact the Switch2 dropped the frame saying that it doesn't have the VLAN indicated on the 802.1q frame tag.
Meanwhile on the 2nd lab, both PC are not receiving the IP from DHCP server. because the Switch2 dropped the frame from both PC.
Solved! Go to Solution.
02-23-2020 11:06 AM
Can't read your files but your understanding is correct in how it should work.
Have you made sure vlans 10 and 20 exist in the vlan databases of both switches ?
Jon
02-23-2020 11:06 AM
Can't read your files but your understanding is correct in how it should work.
Have you made sure vlans 10 and 20 exist in the vlan databases of both switches ?
Jon
02-23-2020 11:17 AM
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