3com 530 Manuel D’Utilisation

 

 

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The list below outlines some of the reasons why you 

 

might choose to configure the 

 

OfficeConnect Remote

 

 

 

as a bridge or a router. Read through the rest of this 

 

appendix for more explanation and to help decide 

 

which of the above conditions apply to your network.

■

 

A bridge is simpler to configure but a router can 

 

provide more security on a busy network and filter 

 

unwanted data transmissions more effectively.

■

 

If your network consists of only one or two links 

 

between different sites and your network is not 

 

heavily loaded, in most circumstances you can 

 

configure your OfficeConnect Remote units as 

 

bridges.

■

 

If your network structure is complicated and consists 

 

of a mixture of leased line and ISDN links, or if it uses 

 

several different protocols, you may obtain better 

 

performance from the OfficeConnect Remote units if 

 

you configure them as routers.

■

 

If you are connecting to a routed corporate network 

 

that is already running IP and/or IPX protocols or if you 

 

are using the 

 

OfficeConnect Remote

 

 to connect to the 

 

Internet you must configure the unit as a router.

 

 

When a bridge is first powered on, it does not know 

 

the number or the locations of stations that are 

 

connected to the LAN. To minimize the amount of 

 

data passed over the bridge it must 

 

 the 

 

whereabouts (address) of stations to ensure that it 

 

passes only the data that is intended to be passed 

 

over the bridge. 

 

Like the envelope of a letter, the header of each 

 

frame of data transmitted on the network has a From 

 

(source) address and To (destination) address. This 

 

ensures that data reaches its destination on the LAN 

 

and that the receiving station can reply. The bridge 

 

reads every frame of data received at the LAN port 

 

and extracts the source address of the frame. From 

 

this information it builds an address table of stations 

 

it knows to be on the LAN.

 

To decide if data should be passed over the bridge, 

 

the bridge examines the destination address of the 

 

frame. If the address is already in its address table, 

 

the bridge knows the destination is on the LAN and 

 

therefore rejects or 

 

 the frame.

 

If the destination address is not in the address table, 

 

the bridge transmits the data across the bridge. It 

 

does this even if the destination device is on the 

Rc.bk : RCAPPA.FRM  Page 2  Thursday, July 10, 1997  9:53 AM