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Community Member

Questions on dot1q-tunnel

Hello,

I'm getting lots of problems with dot1q-tunnel on my test lab.

In fact i receive traffic on a one client per vlan basis (traffic is PPPoE), i receive all this traffic on a router, collecting all these vlan on a bridge where the pppoe packets are treated.

When I use a transeiver to convert operator fiber arrival to my router copper media interface, i have no problem....

When I use dot1q-tunnel to make the same on my 3750, packets seems to be corrupted...

I get PPPoE timeouts and packet loss, not regulary, totally stochastic...

I made dozen of tests and different settings, without success.

I first thougt of MTU issues... it doesn't seems to be the problem.... If somebody has any idea... please let me know.

Here is an extract of the config:

interface GigabitEthernet1/0/1

description ROUTER

switchport trunk encapsulation dot1q

switchport trunk allowed vlan 108

switchport mode trunk

no cdp enable

end

interface GigabitEthernet1/0/28

description OPERATOR-VLANS

switchport access vlan 108

switchport mode dot1q-tunnel

no cdp enable

end

I made tests with system MTU and/or system jumbo MTU above 1500, without success...

I didn't found any known caveats on 3750 running Version 12.2(25r)SEE4 related to dot1q-tunnel...

Thank you for your help

Regards

Everyone's tags (3)
7 REPLIES
Hall of Fame Super Blue

Questions on dot1q-tunnel

Gig 1/0/1 is a Dot1Q trunk while Gig 1/0/28 is an access port.  Is this correct?

Community Member

Questions on dot1q-tunnel

No, Gi1/0/28 is a dot1q-tunnel port ( switchport mode dot1q-tunnel )

Anyway i made lots of search and it seems to be the correct settings:

http://www.cisco.com/en/US/docs/switches/lan/catalyst3550/software/release/12.1_13_ea1/configuration/guide/swtunnel.html

Thanks anyway

Hall of Fame Super Blue

Re: Questions on dot1q-tunnel

No, Gi1/0/28 is a dot1q-tunnel port ( switchport mode dot1q-tunnel )

If that is the case, then Gi 1/0/28 is missing a line:  switchport mode trunk

When you enter this command, the line "switchport access vlan 108" will be replaced by the command "switchport mode trunk".

To verify, use the command "sh interface trunk".

By the way, that's a very ancient and archaic IOS code.

Community Member

Questions on dot1q-tunnel

If the port is in dot1q-tunnel mode it couldn't be in trunk mode at the same time...

So i tend to say, according to cisco's documentations refered previously, that the "switchport mode dot1q-tunnel" is correct... except if you can give me more informations...

Hall of Fame Super Blue

Re: Questions on dot1q-tunnel

Uh-oh ... Looks like I made a big boo-boo.

Did you run this command "vlan dot1q tag native"?

Community Member

Questions on dot1q-tunnel

No problem, thank you for your tries

I tried but except crashing my trunks it didn't changed the packet corruptions problem...

And in fact i don't think that is the origin of the problem because all packets coming on interface are tagged, so there's no posible hesitation for the switch on how to manage untagged packets ( hesitation that the tag native vlan is made to solve)...

And worse, my test lab, sometimes work quite well ( except some loss ) and some other times some vlan don't get anymore traffic, and some other work quite well. All vlan are no running the same way at the same moment, that's totally random, stochastic...

Hall of Fame Super Blue

Questions on dot1q-tunnel

Try upgrading the firmware and test again.

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