Subject: (usr-tc) RIPv2 CPU Issue

From: "G. Douglas Davidson" <[email-masked]>
Date: Thu, 09 Nov 2000 17:44:52 +0000

I've been using RIPv2 to allow our Cisco to route to our TCs, but I just
noticed recently that RIP is a CPU hog on the Cisco.  It is consuming around 60
percent of the CPU.  Is there anything that can be done to decrease the amount
of RIP updates that the TCs send?  Is OSPF less of a pig?  Should I segement
things so that I proxy arp the regular dialups and only RIP a subnet for the
people I need to route a subnet to?

Any thoughts appreciated.

-- 
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G Douglas Davidson                      | CityNet, Inc.
[email-masked]                    | Pittsburgh, PA
voice: 412.481.5406                     | fax: 412.431.1315

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From: Jeff Mcadams <[email-masked]>
Date: Thu, 09 Nov 2000 18:36:09 +0000

Also sprach G. Douglas Davidson
>I've been using RIPv2 to allow our Cisco to route to our TCs, but I
>just noticed recently that RIP is a CPU hog on the Cisco.  It is
>consuming around 60 percent of the CPU.  Is there anything that can be
>done to decrease the amount of RIP updates that the TCs send?  Is OSPF
>less of a pig?  Should I segement things so that I proxy arp the
>regular dialups and only RIP a subnet for the people I need to route a
>subnet to?

>Any thoughts appreciated.

passive-interface on the cisco is your friend!

If you passive-interface all of your RIP interfaces on the cisco, then
the cisco knows it doesn't have to keep track of many of the timers on
each route that it has to keep track of if its not set for
passive-interface.  Each route has a timer associated with it so the
router knows when it needs to rebroadcast the route back out again...by
eliminating these timers with the passive-interface command, I dropped
the cpu load on my 7507 from ~50% to ~15%

The only thing you loose by putting passive-interface on everything on
the cisco is the ability for the cisco to inform the Arcs about routes
it has...but since the usual mode of deployment is for the Arcs to be
default routed to the cisco...you really don't loose much of any
functionality.
-- 
Jeff McAdams                            Email: [email-masked]
Head Network Administrator              Voice: (502) 966-3848
IgLou Internet Services                        (800) 436-4456

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From: Marius Kirschner <[email-masked]>
Date: Fri, 10 Nov 2000 03:02:16 +0000

I have an odd problem with my TC Hub (at least I think it's the TC's
problem).  Starting this afternoon suddenly all my ISDN customers can't
connect while modems work just fine connecting to the same unit.  One
customer says he can connect to another ISP using his ISDN line but not to
us (but he can connect via a modem).

I'm a little clueless as where to look for the culprit, moreso since we
haven't touched the unit in months.  Any ideas what, where I should check?
Oh, it's an older unit, pre-DSP....about 3 years old.  Thanks,

---Marius

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From: [email-masked]
Date: Fri, 10 Nov 2000 04:18:13 +0000

> Oh, it's an older unit, pre-DSP....about 3 years old.  Thanks,

There used to be a problem with the piggy back board for ISDN having a memory 
leak and running out of memory then ceasing to function. (Several years ago).
The symptoms are just as you described.

I think we put a terminal on the console of the arc and saw "out of memory" 
messages that gave the clue. 

Solution at that time was two fold. You could re-boot either the arc or nmc 
and it would reset the memory and be good for a while. (In our case it was a 
couple of months). Later on we had some information about switching the isdn 
detection/hardware to a different card and that solved the problem 
completely. I think we switched it to the dsp card instead of the arc card.

Its been a while. 

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From: Jeff Mcadams <[email-masked]>
Date: Fri, 10 Nov 2000 04:28:43 +0000

Also sprach Marius Kirschner
>customer says he can connect to another ISP using his ISDN line but not
>to us (but he can connect via a modem).

>haven't touched the unit in months.  Any ideas what, where I should
>check?  Oh, it's an older unit, pre-DSP....about 3 years old.  Thanks,

Can the customer connect if they set their ISDN equipment to use 56kbps
channels rather than 64kbps?  It could be that a telco has a circuit
somewhere in there that is using robbed-bit signalling or something like
that which is preventing 64kbps clear channel calls from going through
correctly.
-- 
Jeff McAdams                            Email: [email-masked]
Head Network Administrator              Voice: (502) 966-3848
IgLou Internet Services                        (800) 436-4456

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From: Marius Kirschner <[email-masked]>
Date: Fri, 10 Nov 2000 16:58:01 +0000

When I telnet into our TC and do a "show all" is displays the following for
the ISDN ports:

I0   idle   0.0.0.0    Login/ IDLE     0    0    0
I1   idle   0.0.0.0    Login/ IDLE     0    0    0
I2   idle   0.0.0.0    Login/ IDLE     0    0    0
I3   idle   0.0.0.0    Login/ IDLE     0    0    0
I4   idle   0.0.0.0    Login/ IDLE     0    0    0

Can somebody please verify that this is what it should display when nobody
is using the ports?  Thanks,

---Marius

> -----Original Message-----
> From: [email-masked]
> [mailto:[email-masked]]On Behalf Of Jeff Mcadams
> Sent: Thursday, November 09, 2000 9:28 PM
> To: [email-masked]
> Subject: Re: (usr-tc) Odd problem
>
>

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