Cisco 3800 AP: Max Cat5e Distance for 5 Gbps?
An 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?
Community Votes
50% of anonymous learners picked answer B. Votes are pick records left by other test-takers — they are not the verified answer.
Community Insight
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.
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.
Community Discussion (3 comments)
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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
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.