RE: CDP

Just because there is a question, doesn't mean there is a correct answer (or
that I know it). J

From the information provided, the question needs us to define a 5 minute
hold time which cannot be done as the hold time fits into an 8-bit value
(which measures seconds). The CDP hold time is sent between neighbors in the
TTL field (a 1 byte field) of a CDP packet. This value specifies how long
the information should be stored for. It can never be set above 255 (4min
15sec) based on the current frame format, unless Cisco have invented some
kind of CDP Hold Time TTL multiplier command I don't know about, that
multiplies the value in the field when the packet is recieved.

http://www.cisco.com/univercd/cc/td/doc/product/lan/trsrb/frames.htm#xtocid1
2

Cheers,

Jared Scrivener CCIE3 #16983 (R&S, Security, SP), CISSP

Sr. Technical Instructor - IPexpert, Inc.

Telephone: +1.810.326.1444

Fax: +1.810.454.0130

Mailto: <mailto:jscrivener_at_ipexpert.com> jscrivener_at_ipexpert.com

From: Tharak Abraham [mailto:tharakabraham_at_gmail.com]
Sent: Friday, 17 April 2009 10:25 AM
To: Jared Scrivener
Cc: Ryan West; Ram Shummoogum; ccie.weaver_at_gmail.com; ccielab_at_groupstudy.com
Subject: Re: CDP

Jared,

Am re-writing the Qs Paul asked in here couple of days back.

(Q) : All neighbour devices of SW4 must hold cdp information 5 minutes. (
neighboring device of SW4 are SW1 / SW2 / R1 / R2 )

Ryan is pointing that as the max parameter which can be configured is 255
sec implies that the hold time is 4 mins and 15 secs !

So how do we go about this Qs ?

On Fri, Apr 17, 2009 at 3:58 PM, Jared Scrivener <jscrivener_at_ipexpert.com>
wrote:

Consensus? The command will accept a maximum parameter of 255 so 4min 15sec
is the maximum configurable value.

Cheers,

Jared Scrivener CCIE3 #16983 (R&S, Security, SP), CISSP
Sr. Technical Instructor - IPexpert, Inc.
Telephone: +1.810.326.1444
Fax: +1.810.454.0130
Mailto: jscrivener_at_ipexpert.com

-----Original Message-----
From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of Ryan
West
Sent: Friday, 17 April 2009 9:27 AM
To: Ram Shummoogum; ccie.weaver_at_gmail.com
Cc: ccielab_at_groupstudy.com

Subject: RE: CDP

Is that the consensus then? 4 mins and 15 seconds is the max?

-ryan

-----Original Message-----
From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of Ram
Shummoogum
Sent: Friday, April 17, 2009 9:23 AM
To: ccie.weaver_at_gmail.com
Cc: ccielab_at_groupstudy.com
Subject: Re: CDP

Here u go

SWLAB001#sh cdp nei
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
                 S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone

Device ID Local Intrfce Holdtme Capability Platform Port
ID

2960 Fas 8/1 253 S I WS-C2960-2Fas
0/24

the holdtime is configured to 255 on the 2960

RAM

Darby Weaver <ccie.weaver_at_gmail.com>
Sent by: nobody_at_groupstudy.com
04/16/2009 10:30 PM
Please respond to
Darby Weaver <ccie.weaver_at_gmail.com>

To
Ryan West <rwest_at_zyedge.com>
cc
Tharak Abraham <tharakabraham_at_gmail.com>, Cisco Fanatic
<ebay_products_at_hotmail.com>, "ccie.paul_at_gmail.com" <ccie.paul_at_gmail.com>,
"ccielab_at_groupstudy.com" <ccielab_at_groupstudy.com>
Subject
Re: CDP

Has anyone put in one a switch or router and just labbed it up?

On Thu, Apr 16, 2009 at 4:09 PM, Ryan West <rwest_at_zyedge.com> wrote:

> Tharak,
>
> Everything I have found still point to 4 minutes and 15 seconds as the
> maximum. If anyone has different information, please let me know.
>
> -ryan
>
> From: Tharak Abraham [mailto:tharakabraham_at_gmail.com]
> Sent: Thursday, April 16, 2009 4:02 PM
> To: Ryan West
> Cc: Cisco Fanatic; ccie.paul_at_gmail.com; ccielab_at_groupstudy.com
> Subject: Re: CDP
>
> Ryan / Paul ,
>
> Any luck with this one?
> How to configure CDP hold time as 5 mins?
>
> cant afford to miss on easy ones...
>
> Tharak.
>
> On Tue, Apr 14, 2009 at 7:41 PM, Ryan West
> <rwest_at_zyedge.com<mailto:rwest_at_zyedge.com>> wrote:
>
> Looks like that's correct. Although, I don't know how you could get to
5
> mins, it seems the max is 255. I just set a cdp hold time of 255 on
SW1,
> SW2
> adjusts its holdtime to that value. SW1 does not adjust its holdtime
> towards
> SW2.
>
>
>
> Rack1SW2#show cdp nei | i Holdtme|0/15
>
> Device ID Local Intrfce Holdtme Capability Platform Port
ID
>
> Rack1SW1 Fas 0/15 215 S I WS-C3560- Fas
> 0/15
>
>
>
> Rack1SW1#show cdp nei | i Holdtme|0/15
>
> Device ID Local Intrfce Holdtme Capability Platform Port
ID
>
> Rack1SW2 Fas 0/15 155 S I WS-C3560- Fas
> 0/15
>
>
>
> Rack1SW1(config)#cdp holdtime ?
>
> <10-255> Length of time (in sec) that receiver must keep this packet
>
>
>
> This group is great BTW, I like having to verify answers, even if I'm
wrong
> :)
>
>
>
> -ryan
>
>
>
> From: Cisco Fanatic
> [mailto:ebay_products_at_hotmail.com<mailto:ebay_products_at_hotmail.com>]
> Sent: Tuesday, April 14, 2009 1:33 PM
> To: tharakabraham_at_gmail.com<mailto:tharakabraham_at_gmail.com>; Ryan West
> Cc: ccie.paul_at_gmail.com<mailto:ccie.paul_at_gmail.com>;
> ccielab_at_groupstudy.com<mailto:ccielab_at_groupstudy.com>
> Subject: RE: CDP
>
>
>
> If you configure "cdp holdtime" on SW4.
>
> Then a receiving device (R1, R2, SW1, SW2, etc) should hold the
information
> sent by your device for x amount of seconds before discarding it.
>
> Take a look at the command usage.
>
> -Yuri
>
> > Date: Tue, 14 Apr 2009 16:58:16 +0200
> > Subject: Re: CDP
> > From: tharakabraham_at_gmail.com<mailto:tharakabraham_at_gmail.com>
> > To: rwest_at_zyedge.com<mailto:rwest_at_zyedge.com>
> > CC: ccie.paul_at_gmail.com<mailto:ccie.paul_at_gmail.com>;
> ccielab_at_groupstudy.com<mailto:ccielab_at_groupstudy.com>
> >
> > Paul,
> > As Ryan said change the hold-time, but is it all the neighbors of SW4
or
> is
> > it that SW4 should hold of the neighbor devices.??
> > Both are different, so please double check the question.
> >
> >
> > BR,
> > Tharak.
> >
> >
> >
> >
> >
> > On Tue, Apr 14, 2009 at 4:05 PM, Ryan West
> <rwest_at_zyedge.com<mailto:rwest_at_zyedge.com>> wrote:
> >
> > > Paul,
> > >
> > > I would say all devices need their hold time changed.
> > >
> > > -ryan
> > >
> > > -----Original Message-----
> > > From: nobody_at_groupstudy.com<mailto:nobody_at_groupstudy.com>
> [mailto:nobody_at_groupstudy.com<mailto:nobody_at_groupstudy.com>] On Behalf
Of
> > > Paul Adams
> > > Sent: Tuesday, April 14, 2009 9:58 AM
> > > To: Cisco certification
> > > Subject: CDP
> > >
> > > Hi GS,
> > >
> > > (Q) : All neighbour devices of SW4 must hold cdp information 5
minutes.
> (
> > > neighboring device of SW4 are SW1 / SW2 / R1 / R2 )
> > >
> > >
> > > I didnt understood the requirement for the above question, I know
the
> > > default CDP holdtime is 180
> > >
> > >
> > > using the help ? i get only command cdp hold-time, but do I need to
use
> on
> > > all neighboring device of SW4 or just on SW4
> > >
> > >
> > > Blogs and organic groups at http://www.ccie.net <http://www.ccie.net/>
<http://www.ccie.net/
>
> > >
> > >
Received on Fri Apr 17 2009 - 10:53:45 ART