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New Member

bad mask

Hi

on switch1.

port-chanel 1

Desc "to the core"

ip address 192.168.1.1 255.255.255.252

switch 2

Desc "to the core"

port-chanel 12

ip address 192.168.1.5 255.255.255.252

when i assign the second ip address on the 2 port-chanel i received bad mask.why?so what ip addresses can i assign to the 2 port-chanel toward the core(point-to-point)?

10xs

10 REPLIES

Re: bad mask

Hi there,

Seems a bit strange, try putting in the command "ip classless" - although it should have been funny about the first address if that was the caes...

Regards

LH

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New Member

Re: bad mask

Hi

on switch1.

port-chanel 1

Desc "to the core"

ip address 192.168.1.1 255.255.255.252

switch 2

port-chanel 12

Desc "to the core"

ip address 192.168.1.5 255.255.255.252

...............................

core

port-chanel 1

desc "switch1".

ip address 192.168.1.2 255.255.255.252

port-chanel 12

Desc "to switch2."

ip address 192.168.1.6 255.255.255.252

Look;on the switch 2 when i assign this IP: I RECEIVED bad MASK

10XS

Cisco Employee

Re: bad mask

What type of device is switch2 and what IOS version are you running on it?

Thx,

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México
Hall of Fame Super Silver

Re: bad mask

I think that Leigh is referring to the behavior where IOS would give the "bad mask" error if an address in subnet zero was assigned to an interface. But from the addresses given in the original post that should have been an issue on switch 1 not on switch 2.

And the command to fix it is the command ip subnet-zero not the command ip classless.

I wonder if there could possibly have been a keystroke error in entering the configuration. Would Ali do the configuration again and capture the terminal output and post it so that we can see exactly what was entered and the error message?

HTH

Rick

New Member

Re: bad mask

Because it seems that they are not on the same network...

Switch 1: 192.168.1.0/30

Switch 2: 192.168.1.4/30

Change Switch 2 IP as 192.168.1.2

Hope it helps

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Re: bad mask

Maybe it's just me but I did not get the second ip address that you are referring to. Here is my understanding:

switch1 po1 .1 ---192.168.1.0/30--- .2 "core"

switch2 po12 .5 ---192.168.1.4/30 --- .6 "core"

Waht exactly are you putting in on what "2" port channel toward the core? The above should be the only addressing scheme available given the mask and address base you've given.

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New Member

Re: bad mask

HI

the 2 Switches are 6509-SUP1

IOS:c6sup11-dsv-mz.121-20.E2

10XS

Purple

Re: bad mask

Have you tried configuring the 'ip subnet-zero' command on the switch where you are getting the error ?

Paresh

New Member

Re: bad mask

HI Paresh

From long Time;i'm not see ur reply.hope that u r fine.i'm realy happy when i saw u in the Meet the netpro.also ur picture.Paresh could u please tell me what is the effect of 'ip subnet-zero' and without 'ip subnet-zero'

10xs

Purple

Re: bad mask

Thanks for looking out for me, mate :-) I'm well but am caught up with a new role which means less time for NetPro, unfortunately.

Anyways, in the early days of subneting, the first subnet in every subnetted network was not used, so as to avoid confusion between that subnet and the major network from which the subnet was derived. For example, if you subnetted the network 10.0.0.0 using the mask 255.255.0.0, the subnet 10.0.0.0/16 would not have been legal. Instead, you would have had to start from 10.1.0.0/16. Nowadays, we don't have the restriction and in fact the 'ip subnet-zero' command is enabled by default.

Hope that helps...

Paresh

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