3com 530 Manuel D’Utilisation

 

 

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If your network topology is star shaped, a 

 

combination of ISDN and bridging is usually the 

 

most efficient and successful option. Routing is a 

 

better solution if your network topology is a complex 

 

mix of both leased line and ISDN circuits, running at 

 

64 Kbps to 2 Mbps.

 

 

Bridges are programmed to automatically forward 

 

data packets by default while routers filter data 

 

packets by default. These attributes have an impact 

 

on the overall flow of data across the network. Much 

 

has been made of 

 

 in connection 

 

with bridged networks, where the broadcast signals 

 

from bridges propagate to fill all of the wide area 

 

bandwidth, and bring the network down. Broadcast 

 

storms cannot be attributed to installation of 

 

bridges or routers, but by poor protocol 

 

implementation and network design. However the 

 

deployment of routers can effectively 

 

 one 

 

logical network from another.

 

 

Bridged networks use Spanning Tree Protocol (STP) 

 

to provide network resilience, by retaining redundant 

 

links on stand-by, in case the primary link fails. This 

 

means that you are not making maximum use of 

 

available resources. 

 

Routing protocols make each node aware of the 

 

primary and alternate routes available, ensuring that 

 

resources (particularly WAN links) are not wasted.

 

Routers have been designed to provide the optimum 

 

route through the network from the workstation 

 

through to the destination resource with which the 

 

user wishes to communicate. In a very large network 

 

there could be multiple paths available, and these 

 

could change as dedicated links go in or out of 

 

service. These changes in network topology are 

 

handled by routing protocols. However, when using 

 

the ISDN the source network can dial direct to the 

 

destination network, and establish a point-to-point 

 

bridged or routed connection. Generally, when 

 

using this type of ISDN dial-up link, routing does not 

 

provide much extra benefit.

Rc.bk : RCAPPA.FRM  Page 6  Thursday, July 10, 1997  9:53 AM