Which type of encoding is used on 8-Gbps links as compared to 10-Gbps links?

Line encoding schemes are used to ensure clock recovery and DC balance on high-speed serial links. 8-Gbps Fibre Channel links use 8b/10b encoding, where 8 bits of data are encoded into a 10-bit symbol for transmission. This scheme has a 20% overhead. In contrast, most 10-Gbps links, such as 10 Gigabit Ethernet, use the more efficient 64b/66b encoding. This scheme encodes 64 bits of data into a 66-bit block, resulting in a much lower overhead of approximately 3%. This efficiency allows for higher data throughput at a given line rate.

A. This option incorrectly reverses the encoding schemes used for 8-Gbps and 10-Gbps links.
C. This is incorrect because 10-Gbps links predominantly use 64b/66b encoding, not 8b/10b.
D. This is incorrect because 8-Gbps Fibre Channel links use 8b/10b encoding, not 64b/66b.

1. Cisco, "Cisco MDS 9000 Family NX-OS Fundamentals Configuration Guide, Release 5.2," Document ID: OL-24129-01. In the "Fibre Channel Basics" chapter, section "Fibre Channel Speeds," it is stated that 1-, 2-, 4-, and 8-Gbps speeds use 8B/10B encoding.

2. IEEE Computer Society, "IEEE Standard for Ethernet," IEEE Std 802.3-2018, Section 3, Clause 49, "Physical Coding Sublayer (PCS) for 64B/66B, type 10GBASE-R." This official standard specifies the use of 64b/66b encoding for 10GBASE-R PHYs, which are the most common form of 10-Gbps Ethernet.

3. Cisco, "Cisco Nexus 5000 Series and Cisco Nexus 2000 Series Configuration Guide," Document ID: c07289923. In discussions of interface characteristics, the guide implicitly follows the industry standards where 8G FC ports use 8b/10b and 10G Ethernet ports use 64b/66b encoding.