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

Dave [Hawk-Systems] dave at hawk-systems.com
Mon Mar 31 09:24:38 EST 2003

>> >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.
>You are confusing your Layer2 and Layer3 functions throughout this.. as the
>devices are all in the same VLAN (L2) they are already all bridged.
>Your problem is your IP addresses (L3) are in different subnets, to traverse
>between subnets you must use a router (L3) which your SP is providing.

The confusion may also be stemming from this swtich being only L2 and the 3550
we have slated to replace it being capable of L3 (or so the documentation
reads).  Would things be different with the 3550 (L3) being able to
intelligently route the IP traffic between the two networks without involving
the SP router or requiring the installation of an additional router into the

>Have a good long think and read about L2 (ethernet, VLANs) and L3 (IP,
>it might help to clear things in your head,

Sleep too. :)  Thanks.

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