A recently deployed server is experiencing significant connection issues after being plugged into the network switch. An administrator was asked to…

The server is experiencing connection issues due to a physical media mismatch. The server's "50-micron optic" and the switch's "short-range optic" are both designed for use with Multimode Fiber (MMF). However, they are connected using a single-mode fiber (SMF) cable. SMF has a core diameter of approximately 9 microns, while the MMF optics are designed for a 50-micron core. This significant difference in core size causes severe signal loss (insertion loss) and prevents a reliable link from being established. Replacing the incorrect SMF cable with a compatible MMF cable, such as an OM4 patch cable, will resolve the physical incompatibility and restore proper network connectivity.

A. The switch's "short-range optic" is already the correct type for MMF, so replacing it with another MMF optic would not fix the underlying cable mismatch.
B. The Network Interface Card (NIC) is not the problem; the issue lies with the mismatched cable and transceivers (optics). Replacing the entire NIC is unnecessary.
C. The server's "50-micron optic" is a type of short-range MMF optic. Replacing it with another short-range optic would be redundant and not solve the cable issue.

1. IEEE Std 802.3-2018

IEEE Standard for Ethernet

Section 4

Clause 52.5. This standard defines the 10GBASE-SR physical layer type. Table 52-12

"10GBASE-S transmit characteristics

" and Table 52-14

"10GBASE-S receive characteristics

" specify operation over MMF

with supported link lengths for different MMF types (including 50/125 µm fiber like OM4). This confirms that short-range (SR) optics require MMF.

2. MIT Information Systems and Technology (IS&T)

"Fiber Optic Cable

" Knowledge Base. In the section "Single-mode vs. Multi-mode

" it states

"Single-mode and multi-mode cables are not compatible; if you are extending or repairing a fiber cable

you will need to use the same type of cable." It also specifies the core diameters: 9µm for single-mode and 50µm or 62.5µm for multi-mode

highlighting the physical incompatibility central to the question.

3. Cisco

"Cisco 10GBASE SFP+ Modules Data Sheet

" Document ID: 115463

Table 1. This official vendor documentation lists the Cisco 10GBASE-SR SFP+ Module (SFP-10G-SR) and specifies its required cable type as "MMF." It details the maximum cable distance over different MMF grades (e.g.

400m over OM4

which has a 50µm core)

confirming that short-range 10Gb optics are designed exclusively for multimode fiber.