SOURCECODEBD.NET

Live Experience

Two links to different ISPs with More Controled Loadsharing

TWO LINKS TO DIFFERENT ISPs WITH MORE CONTROLLED LOADSHARING
 
• Announce /19 aggregate on each link On first link, announce /19 as normal
  On second link, announce /19 with longer AS PATH, and announce one /20 subprefix
  controls loadsharing between upstreams and the Internet
 
• Vary the subprefix size and AS PATH length until “perfect” loadsharing achieved
 
• Still require redundancy!
 
 
• RouterA Configuration 
 
router bgp 100 
    network 221.10.0.0 mask 255.255.224.0 
    neighbor 222.222.10.1 remote-as 200 
    neighbor 222.222.10.1 prefix-list default in 
    neighbor 222.222.10.1 prefix-list aggregate out 
 
ip prefix-list aggregate 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 default in 
     neighbor 220.1.5.1 prefix-list subblocks out 
     neighbor 220.1.5.1 route-map routerD out 
 
route-map routerD permit 10 
     match ip address prefix-list aggregate 
     set as-path prepend 100 100 
 
route-map routerD permit 20 
 
ip prefix-list subblocks permit 221.10.0.0/19 le 20 
ip prefix-list aggregate permit 221.10.0.0/19 
You are here: Home / BGP / TWO LINKS TO DIFFERENT ISPS WITH MORE CONTROLLED LOADSHARING