Public IP globally reach via other ISP

[NOC_Infonet]

Hi Team,

I have above mention the scenario. My query is customer end provide 2 ISPs wan links, In case ISP-1 wan link is down. Now the ISP-1 public IP reach globally via ISP-2.  Its possible or not, If possible means kindly explain the concept briefly.     

[MHM Cisco World]

You get defualt route from both ISP or many subnet ?

[NOC_Infonet]

Yes sir.

[MHM Cisco World]

Two ISP and one router learn defualt route via bgp

Use weight to prefer one path "ISP1" than "ISP2"

Command needs 

Router bgp xx

Neighbor <isp1 ip> route-map MHM in 

!

Route-map MHM permit 10

Set weight 40000

Note:- bgp prefer highest weightpath

[Kanan Huseynli]

Hi,

if ISP subnets are publicly routable IP addresses (i.e public IPs), then you can reach one ISP subnet through another ISP in case of failure, it is normal internet design.

Of course, you should have default route (static or via BGP) towards ISPs or you should get partial / full routing table (this option requires more resources on customer side, so used when only real need exists).

[Joseph W. Doherty]

Do you have your own AS with a public IP address block?  Or, is your public IP address(es) provided by your ISPs?  If the latter, do you have a (different) public IP address from each ISP?