What are the shielding structures of network cables?

What are the shielding structures of network cables?
Wire Shielding Structure (ISO/IEC 11801 international standard naming, essential for foreign trade)

Format: A/B
A = Overall Outer Shielding; B = Individual Shielding for Each Pair of Lines
U = Unshielded; F = Foil; S = Screen
4 Main Shielding Structures
U/UTP (UTP) Unshielded
Outer layer: None; Line pairs: None
No metal shielding layer at all
Advantages: Cheap, simple wiring, no need for grounding
Disadvantages: Poor anti-interference, not suitable for strong electromagnetic environments
Applications: Ordinary office, home use; Large quantities of Cat5e/Cat6 shipments
F/UTP (FTP) Total Aluminum Foil Shielding
Outer layer: Aluminum foil on the outside of all 4 pairs of lines; Line pairs: No shielding for each pair
Includes a drain wire for grounding
Blocks external interference, no isolation between internal line pairs
Advantages: High cost performance, most commonly used in Cat6A European and American engineering
Note: Aluminum foil is prone to damage, cannot be forcefully pulled during construction
U/FTP (STP) Pair-by-Pair Aluminum Foil Shielding

Outer layer: No overall shielding; Line pairs: 4 pairs, each pair wrapped separately with aluminum foil
Isolates the crosstalk between line pairs, significantly improving the performance of 10 Gigabit Cat6A
Disadvantages: Generally poor protection against external electromagnetic interference; Construction is cumbersome
S/FTP (SFTP) Double Shielding  Main product for high-end foreign trade
Outer layer: Copper woven screen S; Line pairs: Each pair of lines independently wrapped with aluminum foil F
Dual shielding: Woven screen for low-frequency interference, pair-by-pair aluminum foil to suppress crosstalk between line pairs
Must be grounded! Poor grounding can make the effect worse
Applications: Cat6A high-end projects, Cat7, Cat8 mandatory use; Industrial, data center with strong interference environment
Rare: S/UTP
Outer layer copper woven screen, no shielding for internal line pairs. Rare in the market, almost never used in foreign trade.
Quick Comparison Table
Table
Model Outer Shielding Pair Shielding Features Export Scenarios
U/UTP (UTP) No No Unshielded, lowest cost Ordinary household and office use
F/UTP (FTP) Aluminum foil overall shielding No Resistant to external interference, highCat6A popular in Europe and America
U/FTP No Each pair of aluminum foil Reduces internal crosstalk 10 Gigabit projects
S/FTP (SFTP) Copper braided net Each pair of aluminum foil Double shielding, strongest anti-interference High-end Cat6A, Cat7, Cat8, industrial environment
Key points for export practical operation
F/UTP vs S/FTP are the most confusing
F/UTP： Only one layer of aluminum foil on the outside， no copper braided net
S/FTP： Copper braided net + each pair of wires with aluminum foil， higher cost
Shielded cables must have drain wire for drainage. European customers will specifically check this.
The ends of shielded cables must be grounded. Poor grounding makes the shielding useless， even causing greater interference.
Cat7/Cat8 standards mandate S/FTP double shielding.