From: David Goldsmith (dgoldsmi@xxxxxxxxx)
Date: Thu Sep 28 2000 - 12:30:55 GMT-3
Andrew,
That's not really correct, see link already included. IDB's are still mostly a
t
300 but this really depends on platform... This is in the link already sent.
Dave G.
Router Limit
1000
300
2600
300
3600
800
4x00
300
5200
300
5300
700
5800
3000
7200
3000
RSP
1000
Andrew wrote:
> Ok. These are explaination that I pretty much already understand
> ;) Thanks anyway. As far as IDB limits go it used to be ~230 in pre 12.0
> and older hardware but it's around ~1024 at this point with some images
> pushing it to 3000.
>
> -Thanks
> -Andrew
>
> At 02:30 PM 9/27/00 -0700, Sreeram P Bandakavi wrote:
> >Some theory on IDB hope this helps..
> >
> >**********
> >You are limited by the total number IDBs allowed on the router which is
> >approximately
> >260 due to overhead. However, each physical interface and subinterface in
> >the router
> >also uses an IDB, so you need to subtract these from the 260. This number is
> >just
> >theoretical. The actual number also depends on how much memory you have and
> >how much
> >data you are going to transmit on each subinterface.
> >
> >For example, if your serial port was running at T1 speed (1536KB) and all of
> >the remotes were 64KB circuits, you probably shouldn't go much above 24
> >subinterfaces, because if all sites tried sending at once, the T1 couldn't
> >handle all of the data.
> >http://www.cisco.com/warp/customer/105/39.html#odr_point this link gives
> >you some theoretical figures.
> >
> >***********
> >
> >
> >Memory consumption for Frame Relay resources occurs in four areas:
> >
> > 1.Each data-link connection identifier (DLCI): 216 bytes
> >
> > 2.Each map statement: 96 bytes (or dynamically built map)
> >
> > 3.Each IDB (hardware interface + encap Frame Relay): 5040 + 8346 = 13,386
> >bytes
> >
> > 4.Each IDB (software subinterface): 2260 bytes
> >
> >For example, a Cisco 2501 using two Frame Relay interfaces, each with four
> >subinterfaces, with a total of eight DLCIs, and
> >associated maps needs the following:
> >
> > 2-interface hardware IDB x 13,386 = 26,772
> >
> > 8-subinterface IDB x 2260 = 18,080 subinterfaces
> >
> > 8 DLCIs x 216 = 1728 DLCIs
> >
> > 8 map statements x 96 = 768 map statements or dynamics
> >
> >The total is equal to 47,348 bytes of RAM used.
> >
> >Note: The values used here are based on Cisco IOS Release 11.1 software.
> >Values for other releases may vary.
> >
> >Sreeram
> >
> >
> > -----Original Message-----
> >From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> >Scott Morris
> >Sent: Wednesday, September 27, 2000 9:43 AM
> >To: 'Andrew'; ccielab@groupstudy.com
> >Subject: RE: IDB
> >
> >It's like a memory matrix. In older models (2500's or so), there used to be
> >a hardware enforced limit of 300, as far as I know. In newer models, it is
> >solely based on the processor capabilities and the amount of memory
> >available. Obviously, the spiffier models with lots of memory will be able
> >to support more virtual interfaces than older models will.
> >
> >IDB interfaces include any physical or virtual interfaces... So tunnels,
> >dialers, virtual-profiles, sub-interfaces, etc., etc., etc...
> >
> >You can use "show idb" to give you an idea of what's up with your current
> >system. That's a hidden command still as far as I know.
> >
> >Scott
> >
> >-----Original Message-----
> >From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
> >Andrew
> >Sent: Wednesday, September 27, 2000 11:45 AM
> >To: ccielab@groupstudy.com
> >Subject: IDB
> >
> >
> >Does anyone have a good description, explaination, or verbose documentation
> >on interface descriptor blocks? I know WHAT they are but I have never been
> >able to find a really good document on them, where they live, what makes
> >them the limiting factor in sub-interfaces, etc.
> >
> >-Thanks
> >-A
> >
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