specific subnetwork not exiting MX 2nd ISP when internet flow preference is configured

[Shyam1]

We have Two MX 105 in HA , 2 ISPs with 1st ISP - with /29 and 2nd ISP - with /30.

When i configure specific subnetwork to exit 2nd ISP in internet flow preference , it does not work.

Kindly help me with this issue. I have a switch in between ISP router and Firewall too.After Firewall - switches are in standalone.

[alemabrahao]

To use the second ISP, you need at least one /29 because each MX requires an IP address.

[Shyam1]

I am trying to exit the traffic from a subnetwork when there is no HA failure , when there is no ISP failure.

Could you please explain me why I require that /29 on 2nd ISP

[alemabrahao]

First question, is the second ISP only connected to the active MX ?

If so, okay. But consider that in case one of the MXes fails, wouldn't it be better to have a link on each MX ?

The /29 is necessary because the /30 only provides two usable IPs, in this case the gateway and its MX. Since each MX needs an IP (ideally), you need at least one /29.

[Shyam1]

Hi ,

2nd ISP is connected to 1st MX. We tried reaching 2nd ISP for increase in subnet size but no luck. So deployed HA with /29 ISP1.

Any ways we can achieve this 

[alemabrahao]

Is it possible to test this link direct on your device or another one? Just to be sure that's working as expected.