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3COM 4250T with 3 vlans can't be ping from

Posted on 2004-08-20
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Last Modified: 2008-01-09
Hello,

I have a 4250T Superstack 3com switch,  with 2 VLANS created by me, with the native vlan 1 it makes a total of  3 vlans. I assigned  an IP address to the switch. This IP belongs to VLAN 2 (10.10.0.205). When it is created the switch assigns it to vlan 1 and I don't find a way to move it to vlan 2.

This is a scheme of how the switch is connected in my network:

 Foundry Switch  port  e 10 -------------->port e 10    3com switch
                           
port e 10 in the foundry belongs to vlan 2 and vlan 30 (tagged of course)
port e 10 in the 3com belongs to vlan 2 and vlan 30 (also tagged)

port 1 to 9, and port 11 to 40 of the 3com are untagged ports of vlan 2
port 40 to 50 are untagged ports of vlan 30


As you can see there is no physical port in vlan 1, cause I don't need it..The only way I can make it work (kind of) it's if I move one port to vlan 1 (lets say port 11) and then I cross connect port 11 with any untagged port of vlan 2.

The above method almost works ....the RTT of the ping starts in less than 10ms and keeps growing till it reaches 1.5 seconds. (I mean a ping to the managed IP, belonging to vlan 1 and generated from a host belonging to vlan 2).


Any help will be greatly appreciated,

Andres




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Question by:vandresv
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Expert Comment

by:PennGwyn
ID: 11857072
Don't know specifically about 3com gear, but many other switch models will ONLY take assignment of an IP address on VLAN 1.  You may have to rearrange your VLAN numbers so the switch can have the address you want to give it.

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Expert Comment

by:afurman
ID: 11859334
The Implementation Guide says:

------------
The Default VLAN

A new or initialized Switch contains a single VLAN, the Default VLAN.
This VLAN has the following definition:
- VLAN Name — Default VLAN
- 802.1Q VLAN ID — 1 (if tagging required)
All the ports are initially placed in this VLAN, and it is the only VLAN that allows you to access the management software of the Switch over the network, if using a Layer 2 environment only.

If you are using VLANs in a Layer 3 environment you can access the management software of the Switch and manage it via any IP interface that you have established.
------------

So you have to create router interfaces to each VLAN. Each router interface has an IP address and subnet mask. You will be able to manage the switch from any VLAN since you will have created these IP interfaces.
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Expert Comment

by:afurman
ID: 11859363
vandresv,

Sorry, I confused the model of your switch so my comment above corresponds to a switch 4050. In your case with a switch 4250 the only VLAN you are able to manage the switch with is VLAN 1.
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Author Comment

by:vandresv
ID: 11863764
afurman,
Is your last statement a definite answer ? So, If that is the case, and I have many 4250T on my network, Will I have to use vlan tagging on vlan 1 so I can manage the 4250s from anywhere where I get a vlan 1 port ?
Is it possible to tag the default vlan ?
Thanks a lot,
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Accepted Solution

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afurman earned 500 total points
ID: 11884283
Yes, for 4250 my answer is definite. You can manage it from any port of VLAN 1 (Default VLAN). It can be tagged or untagged as you like.
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