Linksys SRW 224G4, Cisco Catalyst 3650G and management via trunk

[wojciech.penar]

I have couple of Linksys SRW 224G4 and SRW 2024 connected together with Cisco C3650 switches. For my part of network VLAN100 is used as administrative vlan and VLAN1 as defult (on trunks or unused ports).

Altrough most of switches work fine, on all older models of SRW224G4 (hw 1.0, various firmware versions) there is no connectivity to management utilities (also ping won't work) via trunk (where of course VLAN100 is present). At the same time there is no problem with access from "local" ports (assigned to VLAN100) and there are no problems with traffic on VLAN 100 along the network.

For example:

Two computers (A and B), two switches (sw1 - old SRW224G4 and sw2 - Cisco switch), are connected as follow:

A--VLAN100--sw1--TRUNK--sw2--VLAN100--B

Swicthes have VLAN100 as management VLAN, computers are connected to access ports (untagged).

A has access to management on sw1 and sw2 and connectivity with B

B has access to management on sw2 and connectivity with B but has no access to management on sw1...

If sw1 and sw2 are same, old SRW224G4 - everything works fine.

Newer versions of SRW224G4, SRW2024 and SLM2024 works OK.

Why it doesn't work?

Thank for your attention.

[Alejandro Gallego]

In your example:

A--VLAN100--sw1--TRUNK--sw2--VLAN100--B

Is VLAN 100 tagged?

One thing to remember is that the Native VLAN (regardless of its ID) is always untagged. If one switch has a native of VLAN 1 and the other a native of VLAN 100, there is no problem; YET! Because, since native is always untagged there is no VLAN info that we care about.

But now here is the problem, If SW1 native is 1 and SW2 native is 100, but 100 is not really the Native, its just what we chose to use for our "Management" VLAN, we would have no other option but to tag 100 accross the Trunk. Now, VLAN 100 is a different subnet than VLAN 1 NATIVE on SW1 and SW1 is left to look for VLAN 100 subnet that is now in conflict with its Native VLAN1 subnet. This is because the switch expects VLAN 1 traffic to be un-tagged.

So when you say "Management" VLAN do you mean "Native"; or is "Native" what you refer to as "Default" Vlan?

The reason for the rant was this statement:

"If sw1 and sw2 are same, old SRW224G4 - everything works fine."

This leads me to beleive that VLAN 1 is still NATIVE on the SRWs (by factory default) and the Cisco switches are on NATIVE VLAN 100. Since VLAN 100 has to be created on the SRWs we will need to tag it accross the Trunk.

If you could clarify this, it would be very helpful.

[wojciech.penar]

It was two years ago and for some reason I forgot about this thread. Problem still exists and there are rather no new findings in the subject.

All trunks use VLAN 1 as native (untagged) member and VLAN100 (used for management purposes) is always tagged within trunks.

Some switches are daisy-chained using trunks:

C3560G-trunk-SRW224G4v1.1-trunk-SRW224G4v1.1-trunk-SRW224G4v1.0

Management station is connected to C3560G (via SLM2024, trunk between SLM and Catalyst), VLAN100 is always tagged and still - no connectivity with management on SRW224G4v1.0, but all vlans works OK - even access ports on VLAN100 on SRW224G4v1.0 has connectivity with VLAN100 across whole network.

We use two Cisco C3560G switches as "core" switches for our LAN and about thirty various SRW (SG300) Linksys/Cisco Small Business as access switches. There are also one SG200 and one SLM switch. It seems, that only SRW224G4v1.0 series is affected with problems with access to management interface through the trunk.

Regards,

Wojciech