[nsp] adding another class C network switched by 3524XL

Dave [Hawk-Systems] dave at hawk-systems.com
Mon Mar 31 08:39:53 EST 2003

>> Since the datacenter we host our equipment in applies the gateway IP
>> for our current block to their end, we just route to it via eth0...  I
>> am assuming that to serve the second class C we just have the
>> datacenter advertise the YYY.YYY.YYY.4 address on the same interface on
>> their end along with the XXX.XXX.XXX.1 address, and we just have each
>> server use the appropriate gateway address, and the switch will route
>> everything out the eth0 port once it leans that both gateway IP
>> addresses are there?
>Your switch does not route.  It is only forwarding Ethernet frames.
>You need to change its default gateway only if you renumber out of
>your XXX.XXX.XXX.0/24 netblock.  As long as your service provider
>properly configures YYY.YYY.YYY.4/24 on the same interface (as a
>secondary IP address, for example) no further configuration is needed
>on your part.

Assumed such, jut didn't want to be caught unaware of anything at 1am  :)

>Be aware, however, that communication between machines on the same
>Ethernet but on different IP subnets will travel via your service
>provider's router, thus causing a possible bottleneck at the 100 Mbps
>port towards their equipment.

I am (at this point in time) not critically concerned about clogging up that
link.  However, could we bridge the two networks in the switch to avoid this?
Since machines from both IP addresses connect directly to the switch I would
suppose we would set up VLANs or something then provide a bridge between the two
VLANs...  a little beyond my Cisco expertise though.

Thanks for the comments received to date.


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