Solr replicating at 5 mb/sec

[Cool Techi]

Hi,
I am running solr replication between two machine which are connected by a 1 gb 
network speed. The best speed I am getting for replication is 5mb/sec, how can 
this be increased.
The replication keeps failing and this is the first time replication of an 
index over 300Gb in size. We are using solr verson 4.1 on master and solr 4.3 
on slave.
Regards,Ayush