Which is the best DDoS protection solution for a big ISP for monitoring and mitigating?

I would say if it’s an ISP that will build a scrubbing center, Netscout/Arbor is a good solution. In all other solutions, Imperva is a great choice.

Arbor would be the best bid, apart from Arbor, Palo Alto and Fortinet have good solutions. As this is an ISP, I would prefer Arbor.

What type of DDoS protection are you looking for? There are many types of attacks, which vary from volumetric (L3/L4), protocol attacks, and application-layer attacks.

There are also in-band solutions, out-of-band solutions, and hybrid solutions.

I would be happy to discuss in more detail, but I can't suggest a specific vendor/solution without knowing more about the specific customer needs.

I would recommend A10 Networks due that it delivers high performance in a small form factor to reduce OPEX with significantly lower power usage, rack space, and cooling requirements compared to other vendors.

I am a gold partner for A10 Networks. Should you have any queries please do not hesitate to contact me on d.theron@tracenetops.net.

I would say how impressed I am with "PROPHAZE" and their unrivaled DDoS protection solution. I have always been concerned about the potentially devastating effects of DDoS attacks on my online operations. Since implementing Prophaze, my worries have been put to rest.

Cloudflare. We are moving from Akamai prolexic to Cloudflare. Cloudflare anycast network outperforms Akamai static GRE tunnels. We have decreased site load times on Mobile 3G from 8 to 1,6 seconds by moving to Cloudflare and don't have to care about tuning our own WAF and DDOS protection.

My recommendation is Imperva.

I believe you should look at F5 DDOS solution. Check the URL below
https://www.f5.com/solutions/application-security/ddos-protection##