comments inline. --- Jens Neelsen wrote: > Hi, > > a layer3 switch (e.g.3550-EMI) does not have layer3 > interfaces. > All interfaces (Fastethernet and GigabitEthernet) > are layer2 > interfaces. They can not have IP addresses.
On the 3550, you can have IP addresses on the actual interface if you do a 'no switchport' command thus making it not a switch port. > The VLANs are the (virtual) interfaces to the > routing engine (=layer3 switch). You can group ports together in the same VLAN by making them in the same access VLAN with the switchport command. Then you can optionally create a SVI for the VLANs you want to route on this switch. It's akin to a BVI on the routers. I don't know why they call it a SVI - just more acronyms. A switch is a multiport bridge. And same for "fallback-bridging" which is regular "bridge" commands that have been used on routers for a long time. > Layer2 interfaces are grouped into different VLANs > and the > Layer3 switch (=Router) enables the communications > between these VLANs. > > A Router has to have different IP subnets on each > interface. > Because the VLANs are the interfaces to the router, > you need > different subnets on each VLAN. See above. > With secondary IP adresses you can have more than > one IP subnet > on a VLAN. But as with router interfaces the subnets > of the > VLANs cannot overlap. > > A 5000 switch with RSM works in the same way. This > is covered in > the Cisco BCMSN training course. > > With kind regards > Jens Neelsen > > --- Stephen Hoover wrote: > > > > Say for instance I have 2 hosts on the same > layer 3 > > switch, but the > > > two > > > hosts are on 2 different IP subnets (No VLANs > are defined). > > > > > > That's not possible! if you are talking about 2 > IP subnet, > > than: > > > ------------------------- > > > actually it is by doing secondaries, but i would > highly > > recommend doing > > > vlans if possible. keep it clean and simple. > > > > > > > > > Vicki, > > > > You mention the use of secondary IP's. On a L3 > switch (a > > switch with the > > router engine in it) is it not possible to define > Ethernet sub > > interfaces > > instead of using secondary IPs - without VLANs > defined? > > > > > > I'm sorry to be so thick, I'm just not getting > it. If a L3 > > switch (with > > a routing module/engine in it) is essentially a > wire speed > > router, then the > > VLAN just seems like an additional identifier on > top of the L3 > > address - and > > doesn't really serve any purpose. In my previous > example, 2 > > hosts on the > > same L3 switch, but on 2 different IP subnets - > wouldn't a > > defined Ethernet > > subinterface be each clients respective gateway, > and thus > > normal L3 routing > > would occur, just at switch speeds???? > > > > > > Thanks again! > > > > Stephen Hoover > > Dallas, Texas > [EMAIL PROTECTED] __________________________________________________ Do you Yahoo!? Yahoo! Shopping - Send Flowers for Valentine's Day http://shopping.yahoo.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=63197&t=63147 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
