what is the difference between rj45 and rj48?

[admin_2]

what is the difference between rj45 and rj48 connectors? Are they interchangeable?

[#2]

RJ-45 and RJ-48 are "interchangeable" in the sense that one kind of plug will fit into the other kind of jack.

However, that doesn't mean that it's a good idea to use straight RJ-45 (e.g., Cat5 UTP) cable for your RJ-48 (T1 line) application.

In particular, RJ-48 is supposed to have pins 3 and 6 grounded (shielding).

[ja1064]

so

1. to connect a CSU/DSU to a T1, i should always use shielded cable?

2. and i should specify an RJ 48?

[mathijs.versteeg]

Maybe this helps:

http://www.cisco.com/warp/public/534/cables.html

[dsalisbury]

RJ-48 is a SmartJack meaning the jack will automatically go into a loopback if the framing is disconnected from the Users CSU.

[thirdp1]

If I'm in a rush to run a cable connection between Cisco 2651 RJ48 port to RJ45 Patch Panel,I can use a UTP CAT5 cable with RJ45 connectors on both ends and it should work,correct?

Or if I have to build a cable(RJ48-RJ45) for E1(2651),what isthe pinout?

Thanks.

Dan

[michael-faust · Accepted solution]

There are many variations to the "RJ" standard. The RJ45S for example is used for programmed data equipment. It is wired to pins 4 & 5 and a programming resistor is placed across pins 7 & 8. The RJ48C is used for T1 service. It is wired to pins 1,2,4 & 5. Pins 7 & 8 are used for cable shield. An RJ48X is wired like an RJ48C but shorting bars are added. When nothinig is plugged into the jack the shorting bars loop back the line toward the far end (pin 1 shorts to pin 4 and pin 2 shorts to pin 5). An RJ48S is used for subrate data services such as 56K. It is wired to pins 1,2,7 and 8. There are others as well. When in doubt, look it up.

[mishra.rahul]

Check out the link

http://www.technicafe.net/2012/07/rj45-vs-rj48-comparison.html

Regards

Rahul Mishra

[Abhishek Ranjan]

Both RJ48 and RJ45 use the 8P8C modular plug and 2 pairs of the wires, one pair for transmitting and one pair for receiving data. The RJ45 that we are already very familiar with uses the pins 1,2,3, and 6 for receiving and transmitting data. With RJ48, there are a few configurations that can be used depending on the situation and how they are to be used. One configuration uses the pins 1,2,4, and 5 while another uses 1,2,7, and 8. Other wires are also used for extra shielding while the remaining wires are reserved in case some uses would arise in the future.

RJ45 is used mainly in local area networks where the distances between each network element is relatively short. It uses the more common UTP or Unshielded Twisted Pair that have categories 1 to 6, with cat5e being the most predominantly used.

RJ48 is used in T1 data lines where the wires can extend longer distances and are often exposed to the environment. To protect the integrity of the signal, RJ48 wirings use STP or Shielded Twisted Pair cables.

In short:

• RJ45 and RJ48 use the same connector
• RJ45 differs from RJ48 in the way they are wired
• RJ45 is predominantly used in LAN while RJ48 is more commonly seen on T1 lines
• RJ45 is connected with UTP cable while RJ48 uses STP

[tibij@cisco]

In simple terms:  RJ45/RJ48 has their own "pinout" used to wire the modular plugs.

                           RJ45/RJ48 uses 8 pins & 8 connectors - Yet not compatible. (why it matters)

The difference is:  RJ48 is designed for STP (Shielded Twisted Pair) Cable (thicker)

                              RJ45 is designed for UTP (Unshielded Twisted Pair) Cable (thinner)

Why it matters:

If you have STP cable trying to put it in a RJ45 connecter will be difficult as the shielding would have to be removed in order for the cable to fit in the connector.  However, doing this negates the shielding at a point where the signal would be the most vulnerable to interference. 

Conversely if you have UTP cable and try to put it in an RJ48 connector the cable itself will be loose causing strain on the connectors.  After plugging and unplug devices the strain on the pin connectors will cause one or more pins to intermittently fail.

In the end the only difference between is that one is designed for shield cable the other for unshielded cable.  Pinouts change over time but using the right connector for the right cable will preserve the signal integrity and modular plug usability.