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Two links to different ISPs with Loadsharing

TWO LINKS TO DIFFERENT ISPs WITH LOADSHARING
 
• Announce /19 aggregate on each link
 
• Split /19 and announce as two /20s, one on each link basic inbound loadsharing
 
• When one link fails, the announcement of the /19 aggregate via the other ISP ensures 
  continued connectivity
 
 
• RouterA Configuration 
 
router bgp 100 
   network 221.10.0.0 mask 255.255.224.0 
   network 221.10.0.0 mask 255.255.240.0 
   neighbor 222.222.10.1 remote-as 200 
   neighbor 222.222.10.1 prefix-list firstblock out 
   neighbor 222.222.10.1 prefix-list default in 
 
ip prefix-list default permit 0.0.0.0/0 
 
ip prefix-list firstblock permit 221.10.0.0/20 
ip prefix-list firstblock permit 221.10.0.0/19 
 
 
• RouterB Configuration 
 
router bgp 100 
   network 221.10.0.0 mask 255.255.224.0 
   network 221.10.16.0 mask 255.255.240.0 
   neighbor 220.1.5.1 remote-as 300 
   neighbor 220.1.5.1 prefix-list secondblock out 
   neighbor 220.1.5.1 prefix-list default in 
 
 
ip prefix-list default permit 0.0.0.0/0 
 
ip prefix-list secondblock permit 221.10.16.0/20 
ip prefix-list secondblock permit 221.10.0.0/19
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