2 subnets 1 switch no VLAN

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Hi All,

One simple question, can I use 2 subnets on 1 switch without VLAN setup.
What is the Pros and Cons?
Thanks.


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Re: 2 subnets 1 switch no VLAN
wubing wrote:

  >One simple question, can I use 2 subnets on 1 switch without VLAN setup.
  >What is the Pros and Cons?

Yes, you can. It will work and the main difference is that broadcast of
either network will be visible in the other one.

Regards

    fw

Re: 2 subnets 1 switch no VLAN
PRO - You can still have two IP address ranges functioning on a switch
without VLANs if your switch cannot use VLANs.
PRO - The IP hosts in one subnet cannot directly unicast to the IP hosts in
the other subnet.
PRO - Your router for these subnets can use the "ip address W.X.Y.Z W.X.Y.Z
secondary" command to provide a default gateway IP addres for each
additional subnet on the same interface.  That's right, you can have
multiple secondary IP addresses.

CON - This is not why subnets were invented.  These two subnets are supposed
to be on different LAN segments.
CON - The broadcasts from either subnet will be present in the same
broadcast domain.  Multicasts, if present, will be the same.
CON - Your router interface throughput will be more heavily loaded.  Hosts
must send data into the router interface for it to be sent right back out to
a host in the same LAN segment.  This would still be the case if the router
had a VLAN trunk to the switch, but at least more capabilities would be
available.

If the destination IP address is within the sending hosts IP address range,
the data is sent with the destination IP address in the IP packet and the
destination MAC address in the ethernet frame.

If the destination IP address is not within the sending hosts IP address
range, the data is sent with the destination IP address in the IP packet and
the default gateway router MAC address in the ethernet frame.
The router would then receive the frame, discard the frame to examine the IP
packet inside, see the destination IP as some other IP address (as opposed
to someone telnetting directly to the router for administration), re-wrap
the IP packet with an ethernet frame destined to the next hop router, and
forward the frame.
This repeats until the last router connected to the destination host subnet
sends the IP packet wrapped in an ethernet frame with the destination hosts
MAC address on the frame and the destination host receives it.

     ===========
     Scott Perry
     ===========
Indianapolis, Indiana
________________________________________

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Re: 2 subnets 1 switch no VLAN
Scott Perry wrote:
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What about two routers, two subnets and one switch?

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Re: 2 subnets 1 switch no VLAN
Frank Winkler wrote:
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Thanks. But 2 subnets will not talk to each other, only broadcast. Is
this will slow down the switch?

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Re: 2 subnets 1 switch no VLAN
Huh.

And here I thought switches that can't support VLAN only worked at layer two
and could only switch by MAC address.



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