Network saturation

[Karl Chappell]

We have 3 managed hp J2524's - We have 2 backbone cables in 3 locations and want to plug both in independently into our main managed switch. - If we were to plug in both backbone cables should this cause a data sending loop within the network? If so, is there any way around it? (24 port). Ta

[Ron Kinner]

Don't know about 2524's but they seem to be very like Cisco switches which I do know. On a Cisco you have a process called the Spanning Tree Protocol (802.1d). If this is on then when a new connection is sensed it goes through several stages where it listens to the Bridge Protocol Data Units being sent by the other switches then sends a few of its own before finally deciding that allowing the connection to work would not cause a loop. If it finds that this is a loop then it blocks the port until such time as it discovers that the redundant link has failed then it unblocks the port.

Just checked and Spanning Tree is available on a 2524 but is off by default. See 9-109 in the config guide.

ftp://ftp.hp.com/pub/networking/software/59692354.pdf

There is also a process called EtherChannel which allows you to use both links in parallel. (Called FEC Fast EtherChannel on a 2524. See 6-27 in the above referenced config guide.)

So before you go plugging in the extra backbone cables verify that STP is running or that you have configured the links as Etherechannels or you will cause a loop.

Ron

[Ron Kinner]

Just realized the title of your post was network saturation so you should look closely at Fast EtherChannel.

Ron

[Karl Chappell]

Ron

I'll give it a shot over the next couple of days and let you know the result. Thanks in advance.