cisco1811: mac addresses from vlan interfaces problem

Hi!

The router model has two WAN ethernet interfaces - fe0, fe1 and 8 (fe2-fe9) ports as emended switching module. (All of them has own MAC addresses).

I'd like to use some of switching ports as an individual ports. I can't set IP addresses for them directly (they're L2 interfaces), so I create vlans for them:

interface FastEthernet2 switchport access vlan 2 end

interface Vlan2 ip address 192.168.1.5 255.255.255.0 end

etc.

A problem is: all vlan interfaces has the same MAC address. They take it from fe0 interface. And I can't change the MACs for unknown reasons: conf t int vlan2 mac-address 0007.eb84.fc43 % "mac-address" not valid on this interface

The problem with switches where I plug the interfaces in. It does not work because of MAC address duplicates.

Is there a work around for this?

-- Sem.

Reply to
Sergey Matveychuk
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What version of IOS is been used ?

Post output of show version

Did you try:

int fa2 no switchport exit

Reply to
Merv

Cisco IOS Software, C181X Software (C181X-ADVIPSERVICESK9-M), Version

12.4(6)T3, RELEASE SOFTWARE (fc2) Technical Support:
formatting link
(c) 1986-2006 by Cisco Systems, Inc. Compiled Fri 21-Jul-06 15:17 by kellythw

ROM: System Bootstrap, Version 12.3(8r)YH8, RELEASE SOFTWARE (fc2)

c1811-turaevo uptime is 4 days, 2 hours, 5 minutes System returned to ROM by power-on System image file is "flash:c181x-advipservicesk9-mz.124-6.T3.bin"

--------------- I'm not sure how no switchport helps? I try to change MAC on vlan interface. Well, anyway I tried 'no switchport' but it did not help. Just disconnect fa2 from vlan2.

-- Sem.

Reply to
Sergey Matveychuk

Perhaps can be acccomplished using HSRP

interface Vlan99 ip address 99.99.99.98 255.255.255.0 standby ip 99.99.99.99 standby 99 mac-address aaaa.aaaa.aaaa end

Reply to
Merv

So it does!

#sh int vlan1 | inc rotocol|bia Vlan1 is up, line protocol is up Hardware is EtherSVI, address is 0019.2f48.xx60 (bia 0019.2f48.xx60) #sh int gi 0/0 | inc rotocol|bia GigabitEthernet0/0 is up, line protocol is up Hardware is BCM1125 Internal MAC, address is 0019.2f48.xx60 (bia

0019.2f48.xx60)

Thing is, this does not usually matter, it is normal for example for Sun workstations to use the same mac on all interfaces, there are millions out there.

Since a Cisco router will not normally let you put the same IP subnet on more than one interface the two interfaces never "see" each other.

You can also do this:-

interface FastEthernet1/5 description no switchport ip address xxx.xxx.98.65 255.255.255.224

In this config the ports get their own individual macs.

FastEthernet1/4 is up, line protocol is up Hardware is Fast Ethernet, address is 0018.1926.xxbe (bia

0018.1926.xxbe) FastEthernet1/5 is up, line protocol is up Hardware is Fast Ethernet, address is 0018.1926.xxbf (bia 0018.1926.xxbf)

This is a NM-16ESW in a 3845.

Why do you think that this is something to worry about?

Reply to
Bod43

Great! Thanks! It works.

-- Sem.

Reply to
Sergey Matveychuk

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