From: Andrew (arousch@xxxxxxxx)
Date: Thu Sep 28 2000 - 11:58:19 GMT-3
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
>
This archive was generated by hypermail 2.1.4 : Thu Jun 13 2002 - 08:25:08 GMT-3