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L3 or L2 switching on Catalyst3550-SMI

Answered Question
Apr 9th, 2003
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Hi all,

I am planning to use Catalyst 3550-SMI-24 to separate net_1 (192.168.1.x/24) & net_2 (192.168.2.x/24). With following assignment:

1. port 1-23 for net_1 & port 24 for net_2. Gateway will be positioned in net_1, so net_1 & net_2 users must pass through net_1 to the router/internet.

2. I have tried to enable L3 switching on port 24, set it up as gateway for net_2 users. And also I have tried VLAN (L2) for this port too.

Although net_1 & net_2 are able to ping each other, messaging application like ipmsg (even I have set broadcast setting to both networks broadcast addresses)can not communicate between them. Client on net_2 seems like to be isolated from net_1. Do I need to enable any features (like bridging, etc)?

Any ideas and helps will be greatly appreciated.



Correct Answer by Prashanth Krishnappa about 14 years 4 months ago

Have you enabled ip routing? It is disabled by default. You cannot bridge on this box

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Correct Answer
Prashanth Krishnappa Thu, 04/10/2003 - 05:16
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Have you enabled ip routing? It is disabled by default. You cannot bridge on this box

b.go Thu, 04/10/2003 - 19:44
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Hi thanks for the reply, yes I have enabled ip routing so the client in net_2 can do the ping to gateway in net_1. The client in net_2 is able to connect to the internet without any problem. But I (net_1) use ipmsg to communicate with other users on net_1 and net_2 (using TCP/IP with broadcast to net_1 & net_2 being set).

I am not able to 'see' any users on net_2 except net_1 users, so this makes net_2 seems to be 'isolated'. Do I need to enable directed broadcast ?

Another questions are:

1. all ports for net_1 are running in switchport mode, and port for net_2 is running in no switchport mode. Is there any problems to communicate to each other networks within this condition ?

2. Does Catalyst3550-SMI support InterVLAN routing (without router) ?

Many thanks for any helps and suggestions.



aan_k76 Fri, 05/02/2003 - 04:24
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Catalyst3550-SMI has standard routing capability using RIP protocol. So, it supports interVLAN communication. To make interVLAN communication, configure SVI (Switch Virtual Interface). You have it everytime you make a VLAN. To configure itu, it's much easier using Cluster Management Software than using command-line interface. After configuring VLANs, to make SVIs work, you must configure routing protocol in menu Device-Routing and then check the option ip-routing, select the network you have, click Advance and select interfaces you want to make them communicate one another.

b.go Mon, 05/12/2003 - 17:51
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Hi many thanks for the reply,

I think this should be very helpful to me. Since some people told me that 3550-SMI is 'not L3 switch', but I doubt it. Routing command is available so it should be able to do routing.

I'm glad that I didn't make 'wrong' suggestion to purchase 3550-SMI...maybe we will consider to upgrade to EMI later (to provide more redundancy with HSRP or VRRP). I think we don't have it in 3550-SMI.

Once again, many thanks for the help.

Best regards,



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