Is 200m too long..experience some intermittent issues?

Answered Question
May 31st, 2008

In one of my setups, I have about 200m length of Cat5e from the phone directly to a cisco 3560. The phone is having intermittent issues. Sometimes the quality of the call is bad, and the call usually gets dropped a few times.

I'm being told that even though 100m is the max length of Cat5e, that 200m is fine?

Would you do this? What can I do to improve call quality?

I have this problem too.
0 votes
Correct Answer by rob.huffman about 8 years 6 months ago

Hi Dustin,

The standard 100m ethernet rules (90m drop + 10m patch/cross connect) still apply here and this 200m length is almost surely causing these issues. If you try to test a 200m cable run with a "Fluke" type test meter you will see many problems. This length can only run an Analog/FXS circuit :(

Check out Page 29;

The maximum lengths of horizontal distribution cables are shown in the

following table.

Table 4.1: Cable lengths

Horizontal Cables . . . ***Must Be No More Than . . .

From the horizontal 90 m (295 ft.) long.

cross-connect to the

outlet/connector

Used for patch cords and 6 m (20 ft.) long

cross-connect jumpers in

the horizontal cross-connect

These limits apply to all types of horizontal cable.

System designers should plan for a combined cable

length of 10 m (33 ft.) for patch cords and for equipment connections in the

work area and telecommunications closet. This length is in addition to the

90 m (295 ft.) of cable allowed between the horizontal cross-connect and the

telecommunications outlet/connector.

http://www.iescomputers.com/bicsi/chap04.pdf

If the cables fall outside this standard and fail the testing you won't be good to go.

Hope this helps!

Rob

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Correct Answer
rob.huffman Sun, 06/01/2008 - 01:35

Hi Dustin,

The standard 100m ethernet rules (90m drop + 10m patch/cross connect) still apply here and this 200m length is almost surely causing these issues. If you try to test a 200m cable run with a "Fluke" type test meter you will see many problems. This length can only run an Analog/FXS circuit :(

Check out Page 29;

The maximum lengths of horizontal distribution cables are shown in the

following table.

Table 4.1: Cable lengths

Horizontal Cables . . . ***Must Be No More Than . . .

From the horizontal 90 m (295 ft.) long.

cross-connect to the

outlet/connector

Used for patch cords and 6 m (20 ft.) long

cross-connect jumpers in

the horizontal cross-connect

These limits apply to all types of horizontal cable.

System designers should plan for a combined cable

length of 10 m (33 ft.) for patch cords and for equipment connections in the

work area and telecommunications closet. This length is in addition to the

90 m (295 ft.) of cable allowed between the horizontal cross-connect and the

telecommunications outlet/connector.

http://www.iescomputers.com/bicsi/chap04.pdf

If the cables fall outside this standard and fail the testing you won't be good to go.

Hope this helps!

Rob

DMobley1022 Sun, 06/01/2008 - 05:31

Is there any type of equipment cisco has that will amplify this signal, would putting another switch in between help?

Thanks that is a lot of help. I'm sure that is what the issue is, and then when you also add that we are running the internet over the same, and the internet we have is usually about 1.5 down and 512 up, it probably just adds to the problem. Its an office with 8 other phones as well, but this one phone just happens to be about 200-210m away.

It was just a few people said since the phone is connected directly to that switch that the distance shouldn't matter too much, however this phone is the only one out of the 8 that has had any problems.

rob.huffman Sun, 06/01/2008 - 07:34

Hi Dustin,

I like your thinking here! Your only real alternative is to setup a "mid-point" switch of some sort. The 90m rule is always the guideline we have to work within.

Take care,

Rob

DMobley1022 Sun, 06/01/2008 - 11:00

We just tested the phones with a Fluke Meter and the wiring is A OK! The phones will power up, but just display Ethernet disconected. The distance is about 210m. So I'm thinking my problem is with distance. I will call our cisco rep and see about getting a mid-point switch.

My question though in that regards is this. The only place to install that switch is at about 200m point. Do you think that would still cause the phones to work intermittently, or should I try somehow to get the switch closer to 100m mark?

rob.huffman Sun, 06/01/2008 - 11:13

Hi Dustin,

As long as the new switch (mid-point) is within 90m of the IP Phone you should be good to go :)

Hope this helps!

Rob

Sushil Kumar Katre Mon, 06/02/2008 - 01:08

Hi Dustin,

Are you saying this -

Existing Switch --- 200mts --- new switch -- IP Phone?

If the connectivity between the switches is Copper then again the 90 mts rule applies.

The option that you have is to have a fiber connectivity between the swiches and then a copper connectivity between new switch & IP Phone.

Or else instead of inventing on a new switch why don't you look for some media converter which can convert fiber connection to copper.

Switch --Fiber--Converter--IP Phone

If you us ea MultMode Fiber and 1000Base-SX standard you can span up to 550mts which is more than suficient in your case.

Or else if you have wireless APs you can achieve the same.

Switch--Ethernet--AP--wireless-AP--ethernet--IP Phone.

-> Sushil

DMobley1022 Mon, 06/02/2008 - 07:52

That is the route we are going to go: Switch--Ethernet--AP--Wireless--AP--Ethernet--IP Phone.

However in the meantime, do you think if we configured the port to do 10mb half duplex, do you think that would work?

Sushil Kumar Katre Mon, 06/02/2008 - 08:14

By AO I meant Wireless Bridge. I was actually refering to Cisco's AP which can be configured as point to point bridges [root or non root with clients].

DMobley1022 Tue, 06/03/2008 - 14:19

We were able to get a temp solution to work.

We configured the ports that these phones were plugged into to : Half Duplex 10mpbs and now the phones are working.

rob.huffman Tue, 06/03/2008 - 15:06

Hi Dustin,

Thanks for posting back with your resolution :) +5 points for this kind follow-up!

Take care,

Rob

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