BGP Multihoming - ISP 2 interface IP not reachable from outside

[mhrznamn]

We have BGP peering with two ISP's  (ISP A and ISP B). Both the ISP's are connected on a same border Router on different interface. Both  ISP are directly connected and connected routes can be seen in routing table.

We are receiving  default-routes from both the ISP's. We have advertised our IP prefix to both the ISP's (103.XX.XX.XX/24) subscribed from APNIC . We have configured route-map and called in  bgp neighbor to make ISP A as primary.

interface gig 0/0/0

des. ISP A

ip address xxx.xxx.xxx

interface gig 0/0/1

des. ISP B

ip address xxx.xxx.xxx

route-map ISPB-in permit 10
set local-preference 80

route-map ISPB-out permit 10
set as-path prepend 132407 132407 132407 132407

Above route map has been called to bgp neighbor with ISP B

Now, the problem we are facing is we are not able to ping IP of interface gig 0/0/1 from internet, where IP of ISP B has been configured  . 

Howerver the ping is reachable from outside  if the  interface gig 0/0/0 ( ISP A) is shutdown. 

[chrihussey]

That is because when you ping the ISP2 interface, the response is routing out the link to ISP1. Chances are you and/or ISP1 has filters in place and only will accept packets with your advertised address space as source.

You could check with ISP 1 to see if they could allow it.

Other than that I don't know of a way for the ISP 2 interface to respond to pings from the Internet out that same interface without making things overly complicated. Other may have ideas though.

Hope this helps a bit.