[j-nsp] Multihoming Using Juniper SRX 240

[Pavel Lunin]

- Load balancing all traffic between 2 ISP connections, not sure if its
> possible or not?
>
> - Send/Receive traffic of some subnets through one ISP and for others
> through other ISP to maximum utilize both ISP links
>


First thing I must say, in 100% of cases (I am assuming it's an enterprise
application because of the SRX beeng used as an ASBR) these two tasks
aren't really worth it for outgoing traffic. If you wish to balance
outgoing traffic, per-flow ECMP is enough almost everywhere. All those
"this subnet goes here and that subnet goes there" and consequent FBF's and
PBR's do nothing but increase unnecessary complexity and lengthen
troubleshooting time.

I bet your incoming traffic is at least 10 times greater than outcoming
(well, I might be wrong with <5% probability). What you might really need
is balancing incoming traffic. It means you should play with what you
advertise to influence how the world forwards traffic to you, not what you
forward to the world. Having a single /24 prefix you still have tools to do
so. Prepends and TE communities (if your ISPs support them) allow to
achieve quite a lot.

Also, check the "JUNOS Enterprise routing" book, it's all there.