I have a flat layer 2 network composed by Routerboards (mainly 532A running 2.9.50).
RB.201 ----- RB.202 ----- RB.203 ----- RB.204 ----- RB.205 _____ RB.206 ----- CL1
----- wireless connection
_____ cable ethernet connection
All Routerboard have address like 10.21.0.x/16 (e.g. RB.201 = 10.21.0.201).
RB.201 to RB.204 are double radio routerboards.
CL1 is a client PC and has:
IP 10.21.7.7
subnet mask 255.255.0.0
default gateway 10.21.0.206
On RB.206 there is only a static route 0.0.0.0/0 to 10.21.0.4
10.21.0.4 is a Cisco router directly wired to RB.205 and RB.206 through a L2 switch.
Now, what's the problem?
All is working. From CL1 I can go outside, tracepath is fine (all the packets are shown as going out through the Cisco...) but if I enable the connection tracking on external RB (e.g. RB.201 or RB.202) or if I use TORCH tool, I can see the packets with destination 10.21.7.7 (from public addresses to 10.21.7.7).
How can it be possible? Is it unicast isn't it?
How can external Routerboards know about 10.21.7.7?
Actually, if I query these routerboards ARP TABLE I don't see 10.21.7.7. listed. I do see it in the ARP table of RB.206 (and this is normal to me).
Please give me some hints, I'm so confused...
