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Configure a 3Com switch 4800G

Configure a 3Com switch 4800G

Configure a 3Com switch 4800G


I'm getting some difficulty to configure a 3Com switch 4800G.

This one is plugged in on 3Com switch 4228G with a category 5e patch cable.  The link light must become green for both ports except it is not the case.

The devices support autonegotiation and 10BASE-T/100BASE-TX transmissions.

The supplied RJ-45-to-DB-9 adapter cable is used to connect the console port PC. Using Hyperterminal, I succeed to configure an IP address and the netmask.
The "display vlan" display the Vlan configuration. All ports are assigned to VLAN 1  by default

Side 4228G, the port is configured to transmit untagged  frames on Vlan1 and tagged frames on Vlan2.

If I examine the MAC address table of 3Com switch 4228G, I don't find the MAC address of 3Com switch 4800G.

Thanks in advance for any help

RE: Configure a 3Com switch 4800G

Have you specified the ports which link to two switches together as trunk ports and allowed vlans 1 and 2?

'When all else fails.......read the manual'

RE: Configure a 3Com switch 4800G

Forgot to add the commands you need!

port link-type trunk
port trunk permit vlan 1 to 2

'When all else fails.......read the manual'

RE: Configure a 3Com switch 4800G

Thx so much.

To resume :

1) I select the mode system view


2) I select Ethernet port view

interface Ethernet1/0/1  

3) I change a port's link type from access to trunk because the link type of a port is access by default.

4) I assign the current port to VLANs 1 to 2

port trunk permit vlan 1 to 2

Some questions (newbie):

- I have set the interfaces on both switches. Isn't it ?

- How can I configure the link type for a specific port (17 for example) ?

interface Ethernet 1/0/17 (?)
I don't understand the interface number argument.

1 ?
0 ?

- Why do I have to create a trunk ? I have some switches behind the 3Com switch 4228G. The port for interconnection is untagged on Vlan1 and tagged on Vlan2.

RE: Configure a 3Com switch 4800G

Yes, you do this in system view. To select a specific interface is as you say, for example, interface Ethernet 1/0/17. The interface is as follows:

1 - The unit ID of the switch. When switches are in a stack they will have different unit ID's, so this could be 2/0/1, 3/0/1, etc.

0 - Actually not sure what relevance this has but it's always a 0 in the middle for ethernet/gigabit ethernet ports. It may in fact be to do with the particular controller card...for example the Cascade ports on a 5500 are interface Cascase 1/2/1 and 1/2/2....however, I digress!

17 - The port on the unit in question.

Your points 3 and 4 are correct. Use of trunk ports is standard practice for a switch to switch connection, although it is true on some units (especially layer 2 only, unmanaged, basic switches) that just plugging in a cable will work OK.

You need to set the trunk ports on both interfaces, one on each switch, as you said.


'When all else fails.......read the manual'

RE: Configure a 3Com switch 4800G


Side 4228G, It seems that I can't configure a trunk port.

RE: Configure a 3Com switch 4800G

--> Considering un access port packet processing (in reference to 3com Swicth 5500 Family configuration Guide):

1) By default, all Ethernet ports belong to Vlan 1, the port 17 (side 4800G) receive/match an untagged packet from 3Com switch 4228G (because the selected port is configured to transmit untagged packets on Vlan1 and tagged packets on Vlan2). It add the default Vlan tag to the packet.
For an outgoing packet, it strip the tag from the packet and send the packet. OK.

Why it does not work and the link light doesn't become green for both ports ?

Do I have to create a Vlan 2 and assign the specified port (17) to the Vlan2 ?

vlan 2
port Ethernet 1/0/17

How to specify a tagged port ?

2) If the port 17 (side 4800G) receive/match a tagged packet (Vlan id 2) from 3Com switch 4228G. The Vlan id is not the default Vlan and the packet will be discard.

It is not what I want !

--> Using 3com series 4200 switches, the ports for interconnection are untagged on Vlan1 and tagged on Vlan2 and everything is fine !

Any help will be greadly apprecied. Thanks in advance.

RE: Configure a 3Com switch 4800G

Two problems solved :

1) Port on 3Com switch 4800G was configured for full-duplex while trunk port on 3Com switch 4228G was defaulted to half-duplex.
2) Side 3Com switch 4800G, I had to configure the trunk port as active link (undo shutdown command)

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