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Estimado compañero, en mi opinión si es posible usarlo, checa este artículo 
Que es parte de la curricula de cisco systems: 
 
 
1.1  VLSM  
  
  1.1.2  A waste of space  
  
   
   
In the past, it has been recommended that the first and last subnet not be 
used. Use of the first subnet, known as subnet zero, for host addressing was 
discouraged because of the confusion that can occur when a network and a 
subnet have the same addresses. The same was true with the use of the last 
subnet, known as the all-ones subnet. It has always been true that these 
subnets could be used. However, it was not a recommended practice. As 
networking technologies have evolved, and IP address depletion has become of 
real concern, it has become acceptable practice to use the first and last 
subnets in a subnetted network in conjunction with VLSM.  
 
In this network, the network management team has decided to borrow three 
bits from the host portion of the Class C address that has been selected for 
this addressing scheme.  
 
If management decides to use subnet zero, it has eight useable subnets. Each 
may support 30 hosts. If the management decides to use the no ip subnet-zero 
command, it has seven usable subnets with 30 hosts in each subnet. From 
Cisco IOS version 12.0, remember that Cisco routers use subnet zero by 
default. Therefore Sydney, Brisbane, Perth, and Melbourne remote offices may 
each have 30 hosts.  The team realizes that it has to address the three 
point-to-point WAN links between Sydney, Brisbane, Perth, and Melbourne. If 
the team uses the three remaining subnets for the WAN links, it will have 
used all of the available addresses and have no room for growth. The team 
will also have wasted the 28 host addresses from each subnet to simply 
address three point-to-point networks. Using this addressing scheme one 
third of the potential address space will have been wasted. 
 
Such an addressing scheme is fine for a small LAN. However, this addressing 
scheme is extremely wasteful if using point-to-point connections.  
  
 
  
 
 
-----Mensaje original----- 
De: carlos _ _ _ @ [mailto:carlossegurag@hotmail.com]  
Enviado el: jueves, 10 de junio de 2004 12:09 
Para: consultas@usuarios.saulo.net 
Asunto: Re: [SauloNet] Primera y última Subred. 
 
Creo que no se refería al uso de la parte de host, sino al uso de la parte  
de subred, es decir, si tenemos por ejemplo: 
10.0.0.0/16 
 
las subredes que se usan son: 
10.1.0.0 
10.2.0.0 
10.3.0.0 
... 
pero no se usan ni la 10.0.0.0 ni la 10.255.0.0 
 
la verdad es que yo tengo la misma duda, porque sé que se aconseja eso y yo  
nunca las uso, pero la razón no la sé. 
 
En cuanto a la parte de host, es lógica, porque una referencia a la red y  
otra a la parte de broadcast 
 
Vilius 
 
_________________________________________________________________ 
MSN. Más Útil Cada Día  http://www.msn.es/intmap/ 
 
 
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