Aggregate in bgp

HI Expert,
                One Q, I'm doing one lab of bgp in this lab there is one
task ( Advertise 155.1.0.0 with ,mask 255.255.0.0 to external ebgp router)
now he did this thing through aggregate-address

R6 which is connected with BB1 .R1 in bgp 100 and BB1 in bgp 54
So on R6 configuration for advertise 155.1.0.0 255.255.0.0 to BB1

R6

neighbor 54.1.1.254 remote-as 54
aggregate-address 155.1.0.0 mask 255.255.0.0

So my Q is why he use this aggregate to advertise subnet .Y he didn't use
network command ( network 155.1.0.0 mask 255.255.0.0 ) .

If this Q is silly so plz forgive me but I really want to know y he did'nt
do through this why.

Thanks.

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Received on Tue May 12 2009 - 16:51:20 ART