Choice between Routed Access Network and switching Network L2

[Rowlands Price]

Hello Support,

I have a LAN with a Distribution switch 9300 and Access switch 9200. 

9200 series support L3 routing, my question is about implementing L2 network with Trunk or implementing routed access Network with OSPF. which is the best architecture is this situation and why?

L2 switching or L3 routing?

[Enes Simnica · Accepted solution]

gDay to u @Rowlands Price, Both designs work, but it depends on ur goals my G, so;;

• L2 (Trunking), simpler and fine for small networks. The 9300 handles all inter-VLAN routing, and access switches just pass VLANs up. Downside: larger broadcast domains and slower convergence if loops or STP events occur.

• L3 (Routed Access with OSPF) - better for scalability and fault isolation. Each access switch routes directly to the distribution layer (no VLANs extended), giving faster convergence and easier troubleshooting.

Which means that if u have multiple access switches or expect the network to grow, go with L3 routed access + OSPF. If it’s a small, simple LAN, L2 trunks are still perfectly fine..........

and check these G:

https://www.cisco.com/c/en/us/td/docs/solutions/CVD/Campus/cisco-campus-lan-wlan-design-guide.html

https://www.ciscolive.com/c/dam/r/ciscolive/global-event/docs/2025/pdf/BRKENS-1500.pdf

hope it helps and PEACE!

-Enes

[Rowlands Price]

Thanks Enes, indeed it's a small network with one distribution (9300) and 9 access switches (9200).

what about the speed? which is more speed between L2 (Trunking) and L3 (rouring)?

[Enes Simnica]

Speed-wise, there’s no real performance difference between L2 trunking and L3 routing on modern Catalyst switches like the 9200/9300, cause both forward traffic in hardware (ASIC), so line-rate is the same. The main difference is design, not speed:

• L2 = simpler, but relies on STP and can have bigger broadcast domains.

• L3 = cleaner fault isolation and faster recovery if a link/switch fails.

So for ur setup (1 distro + 9 access), you can safely stay L2 if things are stable, u won’t gain speed by moving to L3...

happy to help G, and GOOD LUCK MY FRIEND!

-Enes

[Rowlands Price]

Many Thanks Enes, i will go with L2, more simpler.

for reducing broadcast domains, will configure 2 vlans per switch (one vlan for data, one for voice)