routing and ARP questions

[unixjingleman]

Hi there
I'm still trying to set up my network. The devices that concern me at this stage in the set-up that i want are:

---|LAN|---|switch|---|OpenBSD|---|switch|------|ADSL/router|

So OpenBSD will hopefully be a firewall/rouer for the internal LAN.
Here is the output of netstat -rn on OpenBSD:
I

nternet:
Destination        Gateway            Flags   Refs      Use   Mtu  Prio Iface
default            192.168.1.254      UGS        0        0     -     8 xl0  
127/8              127.0.0.1          UGRS       0        0 33200     8 lo0  
127.0.0.1          127.0.0.1          UH         2        0 33200     4 lo0  
192.168.1/24       link#1             UC         1        0     -     4 xl0  
192.168.1.66       127.0.0.1          UGHS       0        0 33200     8 lo0  
192.168.1.254      00:24:17:f7:d5:88  UHLc       1       41     -     4 xl0  
192.168.2/24       link#2             UC         1        0     -     4 xl1  
192.168.2.77       34:15:9e:2e:0b:ac  UHLc       0       23     -     4 xl1  
224/4

xl0 is the external interface.xl1 is the internal interface. I have routing turned on in /etc/sysctl.conf.
What i'm trying to establish is whether the border router/ADSL box(which is a home router) Won't allow anything from interfaces that are on different subnets to it's internal interface, or whether i just haven't configured routing properly on OpenBSD.
A tcpdump sniff of the OpenBSD boxes external interface, while i'm trying to ping the border router from the LAN just revealed that OpenBSD's external interface was sending the icmp echo packets out. The only other thing mentioned in this sniffing session was that the ADSL/border router did an ARP request for the host on the LAN that pinged it. No reply was received. I can ping either the external or internal interface on the OpenBSD box from hosts on the LAN. I just need to establish whether it's the ADSL box/border router that is refusing to deal with packets that have source I.Ps that are not on the same subnet as it's internal interface/dhcp range or whether there is anything i can do on OpenBSD to improve the situation?.
btw when i did:

#route add 192.168.2.77 192.168.2.12

the situation was the same. I couldn't ping the border router from the LAN.
Thank you for your time and any replies.