2500 series router ethernet transceiver?

briangl

My 2500 series router has a DB-15 AUI port for Ethernet. I have found DB-15 to RJ-45 adapters and I have also seen Eternet transceivers.

I just looked on Cisco's site and it looks like I need the tranceiver. What does the transceiver do?

I was going to try just the DB-15 to RJ-45 adapter ( cheaper ). Would that not work? Would it damage something?

forbesl

Adapter ain't gonna work. You need a transceiver. Get one from ebay, they're pretty cheap.

Webmaster

www.techexams.net/techlabs/ccna/lab_hardware.shtml

briangl

Thanks for the info, I will have to look at the CCNA labs some when I can find time.

I still don't understand why the transceiver is needed. Doesn't the router itself do the ethernet processing?

Webmaster

The reason I posted the link to that TechLab is because it covers the hardware setup including the transceivers. I see it doesn't really answer the 'why' though...

I still don't understand why the transceiver is needed. Doesn't the router itself do the ethernet processing

Because your 2500 is equiped with an AUI connecter, from the time when Ethernet was not UTP but 10Base5 and 10Base2. It uses a different type of cabling (see my Network+ TechNotes for details). In short, it converts between the old original Ethernet format and UTP.

Check the bottom section of these TechNotes about Transceivers (Media Converters):
www.techexams.net/technotes/networkplus/networkcomponents.shtml

I guess I should add that section to that TechLab...

briangl

I went to my Cisco textbook.

10Base2, 10Base5 and 10BaseT all use the same timing parameters, frame format and transmission process. 10Base2 and 10Base5 use 50 ohm cable and 0V to -1V. 10BaseT uses 100 ohm cable. This is the only difference I see. I couldn't find any good information on voltage of 10BaseT, even with a quick google.

I will assume that the transceiver has to do with impedance matching and possibly voltage conversion.

briangl

Actually that dosen't make sense either. I just looked at Cisco's installation documentation and it shows using an Ethernet tranceiver connecting to 10Base2 with a BNC connector.

I will just have to take it on faith that it is needed, without understaning why. I hate that.

georgemc

Try this link:

http://en.wikipedia.org/wiki/Attachment_Unit_Interface

Remember that Ethernet is capable of supporting many different media formats, UTP or 10BaseT being only one of them. The MAU or transciever you use is dependant upon the physical medium of you network, UTP, thinnet, thicknet, MM Fiber, SM fiber, etc. (And no, I've never installed thicknet, although I've seen it operational, vampire taps and all.)

Georgemc

redgoblin

From memory 10Base5 aka 'Thicknet' used a coax cable which went into the AUI port of older routers. 10Base2 aka 'Thinnet' also used a (thinner) coax cable which went into the BNC connector.

The transceiver simply converts from an AUI connection to RJ45 for those who still use the legacy 2500 routers (you won't find these on the 2600's). Also if I remember correctly, Transceiver is short for 'Transmitter Receiver' so presumably there is some circuitry on the Transceiver that decodes and encodes the signal from one format to the other.