Real world networka are so different! Simple question

[Patryczek803]

Hi everyone! I've finally landed my first job as a network engineer in a small company. I can't understand one thing regarding the uplink. While I was preparing for CCNA the main connection to the internet was via the firewall. In almost every network I have here the Internet goes directly to the switch and then to the firewall. I totally don't understand this design concept. Could somebody explain it to me in depth? I am very curious. When I asked my colleague he said:"This is how the network was built in the past... but why? 

Thanks in advance,

Patryk

[Joseph W. Doherty · Accepted solution]

A possible reason, to support public/Internet accessible servers logically outside the interior network (i.e. might be totally outside or on a DMZ protected by the FW).

BTW, in the "real world", you often find networks far from what "the book" suggests. Sometimes that might be due to some special need (often a monetary limitation), sometimes due to "network engineers" not knowing best practices, sometimes due to "old" designs from earlier "best practices" never updated, etc.

[pieterh]

check more details of your topology.

It could simply be that the FW is not physically between the ISP and your network,  but logically

just like the "router on a stick" it can be a "firewall on a stick"

e.g. the ISP is connected to the switch, this connection is forwarded by a vlan to a subinterface on the FW as  outside link

same for inside vlan(s)

[Patryczek803]

Thank you for your response. I think I get it now. Everyday something new comes up. Sorry for the delay in responding. 

KR,

Patryk