4500

Unanswered Question

I am replacing a failing 4500 switche with a newer 4500. This should have been easy but the old switch is using CATOS and the new one has IOS installed. I am slowly recreating the config but have come across something I am not sure about. I have the following line set port channel 2/1-4 183 in the old config. As far as I can see this is aggregating interfaces 2/1-4 is this correct? What does the 183 mean is it just an identifier?


In the router part of the config I have interface Port-channel1.2 and this has an IP address and 802.1q set if I do SH VLAN I can see that this is vlan 2. Can I just use interface vlan 2 and assign it an IP address in IOS?


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Jon Marshall Sun, 07/22/2007 - 08:14
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Hi Tim


Set port channel 2/1-4 183 is indeed aggregating ports 2/1-4 into an etherchannel. The 183 is the admin group which is an identifier between 1 and 1024 and is an optional value.


With IOS you would just create a vlan 2 interface and assign it the IP address as you say. Obviuosly make sure the vlan exists at layer 2.


HTH


Jon



Pavel Bykov Mon, 07/23/2007 - 00:00
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IOS equivalent of those commands are (assuming the port is trunk):


interface range Fa (or Gi) 2/1 - 4

switchport

channel-group 1 mode on

no shutdown


interface po 1

switchport

switchport trunk encapsulation dot1q

switchport trunk allowed vlan XXX,YYY,ZZZ...

switchport mode trunk



Fa or Gi depending on interface type. You can ignore "183", as per Marshall

Jon Marshall Mon, 07/23/2007 - 00:14
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Hi Pavlo


I'm not sure the above config will achieve the same thing. Tim said that the port-channel was po1.2 and had an IP address assigned to it. If that's the case it is acting as a Layer 3 interface so he will need to create a layer 3 SVI on the new 4500.


The config you supplied will only create a layer 2 etherchannel.


Regards


Jon

Amit Singh Mon, 07/23/2007 - 01:31
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Jon,


The config pasted by the original poster was indeed for layer 2 ether-channel only. Cat4006 was layer 2 switch only with Sup2 running CatOS.As mentioned there was router card on the chassis which was 4232-L3 and was used for inter-vlan routing across the switch. I think the port-channel interface that the original poster was referring was only for inter-vlan routing across the switch backplane. It was a requirement for creating a port-channel on the internal gigabit ports between the sup and the routercard across backplane for interlvlan routing.


Please see the link below:


http://www.cisco.com/univercd/cc/td/doc/product/lan/cat4000/inst_nts/78_10164.htm#230108


-amit singh

Jon Marshall Mon, 07/23/2007 - 01:48
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Hi Amit



Okay now i am confused. I have used the 4006 switch in this mode before and an aware of having to create a port-channel interface for inter-vlan routing.


But isn't that the whole point. If there is a po1.2 with an ip address this means that there must be inter-vlan routing happening on the old 4006. So to replicate that onto the new 4500 with IOS you have to create a layer 3 SVI ??


Jon

Amit Singh Mon, 07/23/2007 - 02:28
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Jon,


Agree, with you on this. Yes, for inter-vlan routing, layer3-SVI's need to be created.


-amit singh

Thanks for the replies. I have created VLAN interfaces and the routing table is popuplated so I think that side is working OK. I need to start tracing fibre cables to work out what interfaces I need to confiure etherchannel on.


One thing I have noticed is that when I plug my laptop into the switch I get a DHCP address assigned by it with an IP address in the same range as the first VLAN. As far as I can see there is nothing in the config that mentions DHCP is this normal.

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