Jens, MY 3550-EMI certainly can have layer 3 interfaces. All you need to do is to enter the command "no switchport" on the interface. Check out this link:
http://www.cisco.com/univercd/cc/td/doc/product/lan/c3550/12112cea/3550cr/cl i2.htm#xtocid104 I quote: switchport Use the switchport interface configuration command with no keywords to put an interface that is in Layer 3 mode into Layer 2 mode for Layer 2 configuration. Use the no form of this command to put an interface in Layer 3 mode. switchport no switchport Use the no switchport command (without parameters) to set the interface to the routed-interface status and to erase all Layer 2 configurations. You must use this command before assigning an IP address to a routed port. -Bob Sinclair CCIE #10427, MCSE Senior Network Engineer Networking For Future, Inc. www.nffinc.com ----- Original Message ----- From: "Jens Neelsen" To: Sent: Monday, February 17, 2003 3:28 PM Subject: Re: Does MLS (Layer 3 switching) require VLANs? YES [7:63147] > 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. > > The VLANs are the (virtual) interfaces to the routing engine > (=layer3 switch). > > 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. > > 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] Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=63189&t=63147 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
