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V1910 (3com 2952) - Layer 3 routing on untagged (hybrid) ports

adn
Occasional Contributor

V1910 (3com 2952) - Layer 3 routing on untagged (hybrid) ports

Hello,

 

I hope this is the right place to post questions although it concerns a 3com labeled switch...

My problem is understanding the "untagged" feature for hybrid ports and Layer-3 routing between VLAN interfaces.

 

I am familiar with the concepts of routing and switching and I haven't considered a Layer-3 advertised switch to be an IP router - until now. Time probably let the switches evolve and now IP routing can possibly done in hardware...

 

We have two networks (192.168.1.0/192.168.2.0)  on the switch which are connected via a router.  I figuered it should be possible to let the switch handle the interconnection instead of the slow (100Mbit/s) router.

The different subnet members are scattered across all ports...

 

Starting out all switch ports belong to the same VLAN (1)  and its IP interface being 192.,168.1.1.

I set up an additional VLAN (2) with the IP 192.168..2.1.

 

Once I set the ports as untagged members of VLAN 1+2 the communication with IP clients in VLAN2 stopped working.

 

port  -- untagged -- PVID

            member

 1   --    1,2             --  1

 2   --    1,2             --  1

 3   --    1,2             --  1

...

48  --    1,2             --  1

 

According to the documentation the difference between a trunk port and a hybrid port is:

"A hybrid port allows traffic of multiple VLANs to pass through untagged."

"A trunk port allows only traffic of the default VLAN to pass through untagged."

 

Although my ports are hybrid ports, they seem to show trunk behavior.

 

When I assign PVID "2" to all the ports with IP clients of the 192.168.2.0 network routing is working (the switch is the default gateway for both networks). Yet this is very tedious and unflexible - what if there's a tiny workgroup switch attached with two devices in each network?

 

Can someone make sense of the "untagged" feature for hybrid ports?

 

Any hints are greatly appreciated!

 

Alex

3 REPLIES
MateusBuogo
Advisor

Re: V1910 (3com 2952) - Layer 3 routing on untagged (hybrid) ports

Hi

I use hybrid ports for IP phones.

VLAN29 = Voice Vlan
VLAN1 = Default Vlan (computers)

#
port link-type hybrid
port hybrid vlan 29 tagged
port hybrid vlan 1 untagged
#

The untagged ports in a hybrid port, are utilized for mark ports in default vlan or in a vlan necessary.

Other exemple

#
port hybrid vlan 29 tagged
port hybrid vlan 15 untagged
port hybrid pvid vlan 15
#

It's work.

Regards

Mateus Buogo
16again
Respected Contributor

Re: V1910 (3com 2952) - Layer 3 routing on untagged (hybrid) ports

I never understood hybrid ports  , afaik , they can use 2 VLANs for untagged.
In your example, (vlan1 untagged vlan29 tagged)  I'd go for well known trunk port instead

TuanPhanAnh
Visitor

Re: V1910 (3com 2952) - Layer 3 routing on untagged (hybrid) ports

I really don't understand the purpose the of hybrid port and how it work if more than 2 untagged vlans passed through.

I usually use trunk port with pvid. The pvid of a trunk port will be untagged vlan. 

Tuan