[lug] Re: switch

[rm at mamma.varadinet.de]

On Tue, Jun 12, 2001 at 10:01:28AM -0400, Hugh Brown wrote:
> I powered it off and powered it back on again and all seems to be working again.  Can any one clue me
> in on what makes a switch go brain dead?

Because it _has_ a brain :-) 
Even though i can't come up with a convincing explanation ... Some switches are
'intelligent' and remember things like IP-MAC tables etc. If you use DHCP and 
give the same box (i.e. the same NIC) different IPs every time it boots the switch
might get confused and send the packets to the wrong NIC (i.e. on the wrong cable)
thanks to cached ARP entries.

> Also, why don't things work when I plug the cable from the internal nic on the firewall to the uplink
> port (it works if I choose a different port)?

You _do_ use a "twisted" cable if you connect to the uplink port, do you?
Twisted cables are the equivalent of nullmodem cables. You need them if you want
to plug a normal NIC into an uplink port (or if you want to connect to NICs without
using a hub/switch).

just my 2 cnts.
> 
> I am relatively clueless when it comes to networking.  What are some good resources to help me know
> what is going on with these things?

same with me,

  Ralf