Q-in-Q with vlan remapping limitation

[James Lasky]

Hi

I understood that there is a limitation on ME 6524 regarding q-in-q vlan mapping on a single interface at 8 mapping maximum, in Cisco documentation was written ISL and not 802.1q...

Does anybody know if there is a fix ?

Or how can I bypass this limitation ?

Example of the Cisco 6500ME with vlan remapping:

QinQ trunk 802.1q with a MetroEthernet provider

interface GigabitEthernet1/31
description Provider MetroEthernet connection
switchport
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 120,180,260,309,340,370,864,935,1035
switchport mode trunk
switchport vlan mapping enable
switchport vlan mapping 864 309   <-------------- vlan remapping

switchport vlan mapping 935 120   <-------------- vlan remapping

etc

etc
switchport vlan mapping 370 180   <-------------- vlan remapping up to maximum 8
mtu 9216
no ip address

Tks

[James Lasky]

I understood that there is a limitation on ME 6524 regarding q-in-q vlan mapping on a single interface at 8 mapping maximum, in Cisco documentation was written ISL and not 802.1q...

Does anybody know if there is a fix ?

Or how can I bypass this limitation ?

Example of the Cisco 6500ME with vlan remapping:

QinQ trunk 802.1q with a MetroEthernet provider

interface GigabitEthernet1/31
description Provider MetroEthernet connection
switchport
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 120,180,260,309,340,370,864,935,1035
switchport mode trunk
switchport vlan mapping enable
switchport vlan mapping 864 309   <-------------- vlan remapping

switchport vlan mapping 935 120   <-------------- vlan remapping

etc

etc
switchport vlan mapping 370 180   <-------------- vlan remapping up to maximum 8
mtu 9216
no ip address

Tks

[rsimoni]

Hi There,

I think you are merging 2 different limitations regarding vlan mapping.

The 8 number you mentioned I believe refers to the max limit of 802.1Q VLANs to ISL VLANs mapping, which is indeed 8.

•You can configure up to eight 802.1Q-to-ISL VLAN mappings.

http://www.cisco.com/en/US/docs/switches/lan/catalyst6500/ios/12.2SX/configuration/guide/vlans.html#wp1045451

that is the feature which allows you to map dot1q vlans to ISL vlans and is configured via a global command:

Router(config)# vlan mapping dot1q dot1q_vlan_ID isl isl_vlan_ID

However in your interface configuration you are showing a different type of vlan mapping (also called vlan translation) which works at port level and rewrite (remap)  the vlan tag.

On this box an hardware limitation is causing packet loss (about 2%) on ports configured for vlan mapping indipendently by the number of mappings configured.

Bug CSCsr41168  "ME6524, 6148A-GE-TX VLAN Mapping causes packet loss" documents this and suggest a workaround, which is to use ports 25-32 for the mapping as the ASIC limitation affects ports 1-24 only on ME6524 (whereas it affects all the ports of the W6148A module if you happen to have it in a Cat6500/C7600 chassis).

However that was a temporary workaround before it was decided to disable the feature completely at hardware level via another internal bug I cannot disclose. So starting from 12.2(33)SXI3 12.2(33)SXH6 12.2(18)ZYA3 12.2(18)SXF17 the CLI does not allow vlan mappings anymore.

Regards,

Riccardo