3Com 3C840 Network Router User Manual


 
5-8
C
HAPTER
5: C
ONFIGURING
B
RIDGING
IPX routing is enabled if an IPX network is present over the Ethernet
interface (see “Configuring IPX for the LAN”
in Chapter 9). Bridging is
enabled by adding a bridge network over the Ethernet interface (see
“Configuring Bridging for the LAN”
). Routing and bridging are enabled
for each destination in its remote site profile.
When configured for simultaneous bridging and routing, packets
received from the LAN are first passed through the router for any
configured protocols. If the packet can not be routed, it is passed to the
bridge depending on the setting of the Bridge Firewall function. The
bridge firewall has three modes, which are configured on the Advanced
Bridging Options screen.
The three modes are:
1. Discard Routed Protocols (Discard):
This is the default mode. If a protocol is configured for routing, and a
packet for that protocol type is received from the LAN that is not
addressed to the MAC address of the OfficeConnect Remote 840, it is
discarded. Additionally, broadcasts (including ARPs) for the protocol
are not passed to the bridge.
2. Forward Unicast Packets Only (Unicast):
If a protocol is configured for routing, and a packet for that protocol
type is received from the LAN that is not addressed to the MAC
address of the OfficeConnect Remote 840, it is bridged. Additionally,
ARP broadcasts for IP addresses other than that of the OfficeConnect
Remote 840 are also bridged. Other broadcasts for the configured
protocol are not bridged.
3. Forward Broadcast/Unicast Packets (All):
Unicast packets for a configured protocol received from the LAN that
are not addressed to the MAC address of the OfficeConnect Remote
840 are bridged. Received broadcasts (e.g., DHCP) are bridged.
Packets received from the WAN do not pass through the Bridge Firewall.
Instead, packets received from the WAN are delivered to the router or
they are delivered to the router or bridging function based on their
encapsulation and on the state of the MAC-Encapsulated Routing
parameter in the remote site profile.
840ug.book Page 8 Friday, July 7, 2000 2:23 PM