RE: Possible BUG?

From: Brian Dennis (bdennis@internetworkexpert.com)
Date: Tue Jun 13 2006 - 02:02:11 ART


It's not a bug. You can have the same IP address (subnet) applied to
multiple WAN interfaces but not to multiple LAN interface (assuming IP
routing is enabled). Also I'm not sure of the exact number of times it
can be applied but it appears to be hardware dependant. See below:

2620:

Router(config)#
Router(config)#int s0/0
Router(config-if)#en fram
Router(config-if)#int s0/0.1 p
Router(config-subif)#int s0/0.1 p
Router(config-subif)# ip add 1.1.1.1 255.255.255.0
Router(config-subif)#
Router(config-subif)#int s0/0.2 p
Router(config-subif)# ip add 1.1.1.1 255.255.255.0
Router(config-subif)#
Router(config-subif)#int s0/0.3 p
Router(config-subif)# ip add 1.1.1.1 255.255.255.0
Router(config-subif)#
Router(config-subif)#int s0/0.4 p
Router(config-subif)# ip add 1.1.1.1 255.255.255.0
Router(config-subif)#
Router(config-subif)#int s0/0.5 p
Router(config-subif)# ip add 1.1.1.1 255.255.255.0
Router(config-subif)#
Router(config-subif)#int s0/0.6 p
Router(config-subif)# ip add 1.1.1.1 255.255.255.0
Router(config-subif)#
Router(config-subif)#int s0/0.7 p
Router(config-subif)# ip add 1.1.1.1 255.255.255.0
% Too many interfaces on subnet 1.1.1.0
Router(config-subif)#
Router(config-subif)#int s0/0.8 p
Router(config-subif)# ip add 1.1.1.1 255.255.255.0
% Too many interfaces on subnet 1.1.1.0
Router(config-subif)#

3640:

Router(config)#
Router(config)#int s0/0
Router(config-if)#en fram
Router(config-if)#int s0/0.1 p
Router(config-subif)# ip add 1.1.1.1 255.255.255.0
Router(config-subif)#
Router(config-subif)#int s0/0.2 p
Router(config-subif)# ip add 1.1.1.1 255.255.255.0
Router(config-subif)#
Router(config-subif)#int s0/0.3 p
Router(config-subif)# ip add 1.1.1.1 255.255.255.0
Router(config-subif)#
Router(config-subif)#int s0/0.4 p
Router(config-subif)# ip add 1.1.1.1 255.255.255.0
Router(config-subif)#
Router(config-subif)#int s0/0.5 p
Router(config-subif)# ip add 1.1.1.1 255.255.255.0
Router(config-subif)#
Router(config-subif)#int s0/0.6 p
Router(config-subif)# ip add 1.1.1.1 255.255.255.0
Router(config-subif)#
Router(config-subif)#int s0/0.7 p
Router(config-subif)# ip add 1.1.1.1 255.255.255.0
Router(config-subif)#
Router(config-subif)#int s0/0.8 p
Router(config-subif)# ip add 1.1.1.1 255.255.255.0
Router(config-subif)#
Router(config-subif)#int s0/0.9 p
Router(config-subif)# ip add 1.1.1.1 255.255.255.0
Router(config-subif)#
Router(config-subif)#int s0/0.10 p
Router(config-subif)# ip add 1.1.1.1 255.255.255.0
Router(config-subif)#
Router(config-subif)#int s0/0.11 p
Router(config-subif)# ip add 1.1.1.1 255.255.255.0
Router(config-subif)#
Router(config-subif)#int s0/0.12 p
Router(config-subif)# ip add 1.1.1.1 255.255.255.0
Router(config-subif)#
Router(config-subif)#int s0/0.13 p
Router(config-subif)# ip add 1.1.1.1 255.255.255.0
Router(config-subif)#
Router(config-subif)#int s0/0.14 p
Router(config-subif)# ip add 1.1.1.1 255.255.255.0
Router(config-subif)#
Router(config-subif)#int s0/0.15 p
Router(config-subif)# ip add 1.1.1.1 255.255.255.0
Router(config-subif)#
Router(config-subif)#int s0/0.16 p
Router(config-subif)# ip add 1.1.1.1 255.255.255.0
Router(config-subif)#
Router(config-subif)#int s0/0.17 p
Router(config-subif)# ip add 1.1.1.1 255.255.255.0
% Too many interfaces on subnet 1.1.1.0
Router(config-subif)#
Router(config-subif)#int s0/0.18 p
Router(config-subif)# ip add 1.1.1.1 255.255.255.0
% Too many interfaces on subnet 1.1.1.0
Router(config-subif)#

HTH,

Brian Dennis, CCIE #2210 (R&S/ISP-Dial/Security)
bdennis@internetworkexpert.com
 
Internetwork Expert, Inc.
http://www.InternetworkExpert.com
Toll Free: 877-224-8987
Direct: 775-745-6404 (Outside the US and Canada)
 

-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Victor Cappuccio
Sent: Monday, June 12, 2006 9:44 PM
To: ccielab@groupstudy.com
Subject: Possible BUG?

Hi Guys, could this be a Bug?

Look at the IP Addresses at the Interfaces S0/0 and S0/1

 

Thanks

Victor.

 

Rack1R5#show ip int brief | ex un

Interface IP-Address OK? Method Status
Protocol

Ethernet0/0 152.1.125.5 YES manual up
up

Serial0/0 152.1.45.5 YES manual up
up

Serial0/1 152.1.45.5 YES manual up
up

Ethernet1/0 152.1.5.5 YES manual up
up

Loopback0 150.1.5.5 YES manual up
up

 

Rack1R5#show run

*Mar 1 07:22:27.241: %SYS-5-CONFIG_I: Configured from console by
console

Rack1R5#show run int s0/0

Building configuration...

 

Current configuration : 179 bytes

!

interface Serial0/0

 ip address 152.1.45.5 255.255.255.0

 encapsulation frame-relay

 no fair-queue

 frame-relay map ip 152.1.45.4 504 broadcast

 no frame-relay inverse-arp

end

 

Rack1R5#show run int s0/1

Building configuration...

 

Current configuration : 116 bytes

!

interface Serial0/1

 ip address 152.1.45.5 255.255.255.0

 encapsulation ppp

 clock rate 64000

 no cdp enable

end

 

Rack1R5#



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