to add a couple of cents worth of observations here, one can have an undetermined number of secondary addresses on an interface. I used to use secondaries indiscriminantly when trying to emulate huge networks on a three router pod. this was before I discovered the joys of loopbacks. We have had a couple of discussions here lately about gotchas when using secondary addressing.
IP subinterfaces in the Cisco world are limited to routers and IOS versions that support ISL/802.1q trunking, for inter VLAN routing. Not too lonmg ago Cisco supported this only on 100 mbs ful duplex interfaces. Recently, however, cisco expanded support to the 2610 router and the 10 mbs port on that device. One can do IPX subinterfaces on a 25xx router. Each subinterface must have a different IPX encapsulation type. subinterfaces take up IDB's. Although recent IOS versions have greatly increased the number of IDB's supported, it is possible that you could run into that particular limitation. I do not know if secondary addressing uses any of these kinds of resources. when working with secondary addresses, one must be aware of split horizon. Again, we have had some discussion here about isues with various routing protocols and routing. I have not done any testing of subinterface / split horizon issues becasue, as stated earlier, IP subinterfaces are not supported AFAIK on the 25xx routers that are the mainstay of my test lab. HTH Chuck ""Steven A. Ridder"" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > In a secondary interface, you can have 1 interface with 2 addresses/subnets. > A subinterface is different in that you create multiple interfaces, as > opposed to the 1 in the secondary interface. You do all the addressing by > creating sepreate logical interfaces. These subinterfaces look like > seperate physical interfaces to the routing protocol. > > > > > ""John Mairs"" wrote in message > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > Thank you sir! I appreciate your time on this. one > > side though if it's ok, what is the difference between > > secondary interfaces and sub-interfaces? > > > > John > > > > > > --- Darren Crawford wrote: > > > You will have to use secondary addressing. > > > > > > interface ethernet 0 > > > ip address 10.1.1.1 255.255.255.0 > > > ip address 10.1.2.1 255.255.255.0 secondary > > > > > > HTH > > > > > > Darren > > > > > > At 03:10 PM 12/27/2001 -0500, John Mairs wrote: > > > >Hi, > > > > > > > >I have a 2501 (one ethernet interface) and I wanted > > > to > > > >route over that interface by setting up two > > > >sub-interfaces. I can't assign an address because > > > it > > > >replies with > > > > > > > >"configuring IP routing on a LLAN subinterface is > > > only > > > >allowed if that subinterface is already configured > > > as > > > >part of an IEEE 802.10 or ISL vLAN." > > > > > > > >what will I need to do (specifically if you can) to > > > >route over a single E0 interface? > > > > > > > >thanks > > > > > > > >__________________________________________________ > > > >Do You Yahoo!? > > > >Send your FREE holiday greetings online! > > > >http://greetings.yahoo.com > > > [EMAIL PROTECTED] > > > > > > > > > x$:0`0:$x,,,,x$:0`0:$x,,,,x$:0`0:$x,,,,x$: > > > > > > Lucent Technologies > > > NetworkCare Professional Services > > > http//www.lucent.com/netcare/ > > > Darren S. Crawford - CCNP, CCDP, CCIE TBA > > > > > > Northwest Region - Sacramento Office > > > Voicemail (916) 859-5200 x310 > > > Pager (800) 467-1467 > > > mailto:[EMAIL PROTECTED] > > > > > > x$:0`0:$x,,,,x$:0`0:$x,,,,x$:0`0:$x,,,,x$: > > > > > > "You always have time for things you put first" - > > > Tucker Resources > > > > > > > > > > > > ===== > > John L. Mairs > > > > __________________________________________________ > > Do You Yahoo!? > > Send your FREE holiday greetings online! > > http://greetings.yahoo.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=30242&t=30225 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
