Network Cabling & SFPs Cheat Sheet

🔌 Ethernet Cable Distance Limits (Copper)

Speed	Cable Type	Max Distance	Notes
10 Mbps	Cat3/Cat5	100 m	Legacy
100 Mbps	Cat5/Cat5e	100 m	Fast Ethernet
1 Gbps	Cat5e/Cat6	100 m	Standard gigabit
2.5 Gbps	Cat5e/Cat6	~100 m	Used for APs
5 Gbps	Cat6	~100 m	Degrades beyond 55m (Cat5e)
10 Gbps	Cat6A	100 m	Cat6 = 55m only
25/40/100 Gbps	Cat8	30 m	Data center only

Fiber Optic Distance Limits by SFP Type

Multimode Fiber (MMF)

SFP Type	Speed	Fiber	Max Distance	Wavelength	Connector
SX	1 Gbps	OM1–OM4	275–550 m	850 nm	LC
SR	10 Gbps	OM3/OM4	300–400 m	850 nm	LC
SR4	40 Gbps	OM3/OM4	100–150 m	850 nm	MPO/MTP

Singlemode Fiber (SMF)

SFP Type	Speed	Max Distance	Wavelength	Connector	Notes
LX	1 Gbps	10 km	1310 nm	LC	Basic SMF
LR	10 Gbps	10 km	1310 nm	LC	Standard long reach
ER	10 Gbps	40 km	1550 nm	LC	High power optics
ZR	10 Gbps	80 km	1550 nm	LC	Needs compensation
25G-LR	25 Gbps	10 km	1310 nm	LC	Modern SMF
100G-LR4	100 Gbps	10 km	4× 1310 nm	LC	DWDM tech

SFP Types Summary

Type	Form Factor	Speed	Use Case
SFP	SFP	1 Gbps	Legacy/access
SFP+	SFP	10 Gbps	Backbone
SFP28	SFP	25 Gbps	Modern core
QSFP+	QSFP	40 Gbps	Spine/leaf
QSFP28	QSFP	100 Gbps	Datacenter

Singlemode vs Multimode Fiber

Feature	Singlemode	Multimode
Core Size	8–10 µm	50–62.5 µm
Wavelength	1310/1550 nm	850/1300 nm
Distance	Up to 80+ km	< 500 m
Cost (Fiber)	Higher	Lower
Cost (SFP)	Higher	Lower
Use Case	WAN, backbone	Campus, LAN

📦 DAC & AOC

Type	Use	Max Distance	Notes
DAC	Rack to rack	1–7 m	Passive/Active, cost-effective
AOC	Rack/link	Up to 100 m	Active, flexible

✅ Deployment Tips

• Use OM3/OM4 for short fiber runs (up to 10G)
• Use SMF for >500m or inter-building links
• Always match SFP to fiber type
• Check switch/SFP compatibility (vendor restrictions)
• Use MPO cables for 40/100G