For our access layers we primarily use Linksys/Cisco SRW2048 managed switches. They run around $800 bucks and aside from being very reliable, have the features we need (Link Aggregation, VLAN, GB, miniGBIC). We had an issue last week where an unknown staff member (I have an idea who), created a loop along our access layer, causing our core switches (Procurve 2848 series) to block the uplink port dropping a good portion of the network. Thus, I decided to disable all inactive switch ports to prevent random IT staff from plugging stuff in.
While doing this I came across a switch that had not been configured for IP management, so I needed to console in to configure it. After trying 10 different serial cables and 100 different terminal settings, I found out that the Linksys console cable (normally included with new switches) appears to be a straight-through cable of sorts:
1 <-> 1
2 <-> 2
3 <-> 3
4 <-> 4
5 <-> 5
6 <-> 6
7 <-> 7
8 <-> 8
So I called Linksys sales, which informed me they do not sell said cable and could not send me another for free. After hanging up I contemplated a way of building my own version and looking to see what parts I had, found 2 RJ45 to DB9 adapters. Cutting off a 5′ chunk of Cat5 and wiring it straight through, I made my own pin to pin serial cable for the Linksys SRW2048.
If anyone is interested, the terminal settings are as followed:
Bits per second: 38400
Data bits: 8
Parity: None
Stop Bits: 1
Flow Control: None
Hello,
Do you happen to have the pin mapping specifications for Linksys SRW2048? I would like to know which pin is which. I need it for my Perle remote serial console, as I have to make a DB9F-RJ45M cable.
Thanks in advance!
As I said in the post, they are mapped straight across.
WOW – how about this one?
I was trying to use the cable (included with SRW2048) to connect to linux console. I was sure it was null modem cable.
I did countless troubleshooting etc and I was sure I went nuts. Thanks to your blog I was able to isolate the problem. Thanks!
I have in my bag cables for APC UPSes, Cisco (RJ45/DB9), Common like HP,embedded (RJ45/DB9), Kantech and Null (RJ45/DB9).
Those bastards…
I just did this – instead of wiring a cable. I just took my USB/Serial adapter and put a F/F gender changer on the end. The adapter had enough slack that I could connect it directly to the console port.
THANK YOU! I thought I was losing my mind..
Thanks mate! Pulling my hair out trying to get access to the Linksys switch!
All 9 pins must be connected ?
Omg thank you for this post. Tried so many different serial cables / PCs / laptops / settings and I honestly though the port was busted.
Followed ur instruction on the 1-1 mapping and connected 2 x rj45 – db9 cables together and it works fine now !! 😀
I made this cable from an old HP female to female cable wired as the author indicated at it worked. Now I just have to figure out how to get past the userid and password prompt.
Was searching online how to access the SRW2048 after I was having troubles. This had exactly all the information I needed. Thanks for sharing! You made my job a lot less frustrating.
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