I am extreme beginner on firewalls and network. I have a question, which will sound very naive. My brother company has around 500 employees in the same branch where he works. They have two firewalls in HA and then switches and then their servers. They run many web applications in their servers and a large amount of data is uploaded to the internal storages from internal endpoints.
They have multiple 16G and 25G network cards in their server, storage, switches and firewalls and they have 3 ILL line 2x500 Mbps and 1x350 Mbps.
My question is why do they need 25G interfaces in the firewalls? For servers, storage and swithes I can understand, since a lot of data is moved internally. But internal data can be routed through switches and their fastest ILL is 500Mbps. Since internal data dosen't need firewall to move around, so whats the use for 25G interfaces? Even most companies I have seen with fast ILL is 1Gbps, so shouldn't 1Gbps interface on firewall is enough, since data that come and goes through internet cannot be more than their ILL spped ? In general whats the use of firewall interfaces with higher gigabit speed than the ILL ?