Cisco 3800 AP: Max Cat5e Distance for 5 Gbps?
Short answer
C Cisco 3800 APs achieve 5 Gbps over Cat5e cabling at a maximum distance of 70 meters.
Question
Key Takeaways
This question tests the maximum cable length for 5 Gbps Multigigabit Ethernet on Cat5e; the common trap is choosing the lower bound of the supported range or applying the generic 100 m Ethernet limit.
Cisco Aironet 3800 Series APs with Multigigabit Ethernet can achieve 5 Gbps over existing Cat5e cabling only up to a specific maximum distance. This page confirms the correct limit is 70 meters, based on Cisco's 2800/3800 deployment guide.
Common mistake: Many candidates choose 40 m because they recall a 30–70 m range but select a mid-range value, or choose 90 m by assuming all Cat5e runs support 100 m; Cisco's table specifies 70 m as the maximum for 5 Gbps on Cat5e.
Expert Analysis
Why the Answer Is Correct
The Cisco Aironet 2800/3800 Series deployment guide includes a Multigigabit cable-distance table. For 5 Gbps over Category 5e cabling, the supported cable length is 30–70 m, so the maximum distance is 70 m. This aligns with the 802.3bz (NBASE-T) implementation on the 3800's mGig port, which is more conservative than the generic 100 m limit used at lower speeds. Therefore option C (70 m) is the correct maximum distance to achieve 5 Gbps.Why the Other Options Are Wrong
Option A (30 m) is the minimum of the supported range, not the maximum. Option B (40 m) is a mid-range value that may appear in lab notes but is not the documented upper limit. Option D (90 m) exceeds the 70 m Cat5e limit for 5 Gbps; while 2.5 Gbps can reach 100 m, 5 Gbps cannot on Cat5e. Choosing 90 m confuses the 100 m limit for 2.5 Gbps or Cat6 with the specific Cat5e 5 Gbps rating.Community Comment Notes
As AlmightKas noted, the Cisco deployment guide PDF states "the cable length should be between 30-70m," which confirms 70 m as the upper bound. Another commenter argued for 100 m based on generic Cat5e Ethernet standards, but that ignores Cisco's specific 5 Gbps rating. A third comment guessed 30–50 m, which is not the maximum. The community vote split between 40 m and 90 m reflects these misconceptions.Official Reference
This link opens the official vendor documentation in a new tab.
Exam Strategy
Memorize the Multigigabit cable-distance table for the 3800 AP: 5 Gbps on Cat5e = 70 m, 2.5 Gbps = 100 m, and 10 Gbps on Cat6 = 55 m. When a question asks for maximum distance at a specific speed and cable type, avoid generic Ethernet 100 m assumptions.
Frequently Asked Questions
Why is 90 m wrong for 5 Gbps on Cat5e?
Cisco rates 5 Gbps over Cat5e at a maximum of 70 m; 90 m exceeds that. The 100 m limit applies to 2.5 Gbps or to Cat6.
Does 802.3bz guarantee 5 Gbps at 100 m on Cat5e?
The IEEE standard allows 5GBASE-T over Cat5e up to 100 m in ideal conditions, but Cisco's 3800 deployment guide specifies 70 m for guaranteed 5 Gbps.
Community Votes
50% of anonymous learners picked answer B. Votes are pick records left by other test-takers — they are not the verified answer.
Discussion 3 contributions
Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors, not of islever. The comments shown first are the most substantive of the thread — ranked by depth, community endorsement and relevance; expand the list below to read the rest.
From public community threads 3
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AlmightKas 👍 3On the third page in the table at the bottom, it says the cable length should be between 30-70m. https://www.cisco.com/c/en/us/td/docs/wireless/controller/technotes/8-3/b_cisco_aironet_series_2800_3800_access_point_deployment_guide/b_cisco_aironet_series_2800_3800_access_point_deployment_guide_chapter_0101.pdf
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grivanoj 👍 1 Answered BAn engineer has deployed Cisco Aironet 3800 Series APs with switches that support 802.11bz on existing CAT-5e cabling. Which value is the maximum distance supported to achieve up to 5 Gb speed? When deploying Cisco Aironet 3800 Series APs with switches that support 802.11bz on existing CAT-5e cabling, the maximum distance supported to achieve up to 5 Gb speed is 30-50 meters
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55f2ace 👍 1 Answered DIEEE 802.3bz (mGig or N-BASET) can be used on CAT5e cabling up to 100 meters long. This standard allows for speeds of 2.5 Gbps and 5 Gbps on existing twisted-pair copper cabling According to Ethernet standards, the maximum length of a Cat5e cable run is 100 meters (or 328 feet). It is possible to go further by using a POE repeater.
Reader comments & corrections
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