VLAN User Priority Mapping to One PVC

Transcription

1 VLAN User Priority Mapping to One PVC Date: March 2008 Version: v1.0 Abstract: Applicability: Updates: This Application Notes describes the configuration of a specific feature of the Thomson Gateway: VLAN User Priority Mapping to One PVC. This feature is explained by integrating the Thomson Gateway in a scenario where untagged, priority-tagged or VLAN-tagged frames have to be bridged between the local Ethernet segment and the DSL line. The practical realization of the scenario is described using CLI commands. This Application Note applies to all Thomson DSL Gateways with R7.4 and higher. Thomson continuously develops new solutions, but is also committed to improving its existing products. For more information on Thomson's latest technological innovations, documents and software releases, visit us at

2 Chapter 1 1 Introduction Thomson Gateway as bridge To set up the scenario of this document, the Thomson Gateway is configured as bridge. This means that Ethernet frames are forwarded between the local Ethernet segment (LAN) and the WAN Ethernet segment (PVCs on which RFC 1483 LLC encapsulation is used) on the link layer. In other words, the Thomson Gateway does not terminate or route received Ethernet frames. VLANs The Ethernet frames that have to be forwarded may reside in different VLANs. This implies that all Ethernet frames contain a (802.1Q) VLAN ID. Communication between different VLANs is not allowed on the link layer. Only routers can make connections between different VLANs. VLANs create thus separated logical Ethernet segments within a single physical segment. Ethernet QoS Ethernet frames optionally contain a (802.1p) user priority indication. If Ethernet QoS is taken into account during bridging, it can be based on two steps: 1 Mapping the user priority of an incoming frame to an internal priority class. This classification can be based on: The type of the interface on which the frame is entering the bridge. The (802.1p) user priority value. The IP Type of Service octet (TOS-byte) for IP packets, using the Precedence or DSCP notation. 2 Sending out the frame while taking into account its internal priority class. This class can be used to: Perform priority queuing on a single PVC. Perform traffic multiplexing over a range of PVCs. Related documents For detailed information on the features, CLI commands and parameters used in this document, see: Thomson Gateway Ethernet Configuration Guide. Thomson Gateway VLAN Configuration Guide. Thomson Gateway Ethernet QoS Configuration Guide. 1

3 2 VLAN User Priority Mapping to One PVC 2.1 Scenario Overview Introduction In this scenario, the Thomson Gateway is intended to forward the incoming VLAN-tagged Ethernet frames to a single PVC. Based on the VLAN user priority available in the VLAN tag, high priority marked frames get priority when sending out the frames on the PVC. This scenario configures the Thomson Gateway as bridge with one PVC. Frames coming in on a local interface are checked on VLAN user priority. This priority is mapped to an internal priority class. Taking this internal priority class into account, the frames are sent out on the PVC. Following illustration shows the VLAN user priority mapping to one PVC scenario: Thomson Gateway DSLAM A 5 A 2 B 7 B 3 C 2 A 2 C 1 C 2 PVC1 B 3 A 5 B 7 C 1 VID 802.1p WAN interface Mechanisms To set up this scenario, we use following mechanisms: Disabled VLAN awareness: Ethernet frames coming in on the Thomson Gateway have a VLAN tag in their header. However, the VLAN ID should not be taken into account. If the Ethernet bridge is VLAN aware, we have to define all VLANs that have to pass through the Thomson Gateway. Otherwise, unknown VLANs are dropped. Ingress classification: this mechanism ensures that an internal priority class is assigned to a received frame. In this scenario, the classification criterion has to be the VLAN user priority value. Priority queuing: even in bridging mode, we can make advantage of the powerful Thomson Gateway IPQoS implementation. By enabling IPQoS on the used PVC, we enable the queuing mechanism, which is active on ATM interface level. This queuing mechanism handles incoming frames according to their internal priority class. This way, frames passing the bridge can be treated in the same way as packets that come from the IPQoS framework. 2

4 2.2 Practical Realization Configuration overview You must perform following configuration steps to configure the Thomson Gateway for this scenario: 1 Define which PVC must be used by configuring an ATM interface. 2 Connect the ATM interface to the Ethernet bridge. 3 Define that the bridge is not VLAN aware. 4 Enable VLAN user priority mapping for incoming frames on the local interface. 5 Enable QoS on the PVC to activate priority queuing. 6 Save the configuration. Before you start Before you start to configure the Thomson Gateway, make following preparations: Reset the Thomson Gateway to the factory defaults and reboot the device. Make sure the telnet session with the Thomson Gateway never times out. Remove the factory default interfaces and settings that you do not need for the configuration. Make these changes permanent. Now, you can start from a clean situation. =>:system reset factory=yes proceed=yes =>:env set var=sessiontimeout value=0 =>:ppp relay flush =>:ppp flush =>:eth flush =>:atm flush =>:atm phonebook flush =>:saveall Configure an ATM interface To create a phonebook entry for the PVC that must be used, execute following CLI command (the VPI/VCI value is indicative): =>:atm phonebook add name=phone_pvc1 addr=0.35 To create, configure and connect an ATM interface on top of this phonebook entry, execute following CLI commands: =>:atm ifadd intf=atm_pvc1 =>:atm ifconfig intf=atm_pvc1 dest=phone_pvc1 encaps=llc ulp=mac =>:atm ifattach intf=atm_pvc1 3

5 Configure a bridge port To connect the ATM interface to the Ethernet bridge, execute following CLI commands: =>:eth bridge ifadd intf=bridge_pvc1 =>:eth bridge ifconfig intf bridge_pvc1 dest=atm_pvc1 =>:eth bridge ifattach intf=bridge_pvc1 Disable VLAN awareness of the bridge By default, the bridge is already not VLAN aware. To check the current status of the Ethernet bridge, execute following CLI command: =>:eth bridge config Ageing : 300 Filter : no_wan_broadcast VLAN : disabled... If necessary, disable the VLAN awareness of the Ethernet bridge executing following CLI command: =>:eth bridge config vlan=disabled Enable VLAN priority mapping In the scenario, we enable the mapping of the 802.1p user priority indication of VLAN-tagged frames to an internal priority class for Ethernet port 4. Several parameters of the :eth bridge ifconfig command are relevant to this scenario: prioconfig= overwrite: in this case, the medium the frame is received on is not taken into account to determine the internal priority class. Only the classification criterion is used. ipprec=disabled: in this case, the classification criterion is the 802.1p user priority of VLAN-tagged frames. This is the default parameter value. regenprio= : in this case, the mapping between the 802.1p user priority indication and the regenerated user priority is defined as follows: 0 is mapped to 2, 1 is mapped to 0,..., 7 is mapped to 7. priority=0: in this case, the regenerated user priority 0 is assigned to untagged frames, which have no 802.1p user priority indication. This is the default parameter value. Execute following CLI command to enable this: :eth bridge ifconfig intf=ethport4 prioconfig=overwrite regenprio= To verify the configuration of your bridge port, execute following CLI command: =>:eth bridge iflist intf ethport4 ethport4 : dest : ethif4 Connection State: connected Retry: 10 Port: ethport4 PortNr: 4 PortState: forwarding Interface: down Multicast filter: disabled VLAN: Default VLAN: default Ingressfiltering: disabled Acceptvlanonly: disabled VLAN: Priority: overwrite IP Prec: disabled Priority: 0 Regen table: RX bytes: 0 frames: 0 TX bytes: 0 frames: 0 dropframes: 0 4

6 The mapping between the regenerated user priority and the internal priority class is fixed. Enable QoS on the ATM interface To enable the queuing mechanism, execute following CLI commands. The ATM interface on which we enable the queuing mechanism has to be detached and re-attached before the QoS changes take effect. =>:ipqos config dest=phone_pvc1 state=enabled =>:eth bridge ifdetach intf=bridge_pvc1 =>:atm ifdetach intf=atm_pvc1 =>:atm ifattach intf=atm_pvc1 =>:eth bridge ifattach intf=bridge_pvc1 The mapping between the internal priority class and the IP QoS queue is fixed. Save the configuration To make your changes permanent, execute following CLI command: =>:saveall Expected result At this moment all frames containing a VLAN user priority indication are, priority-wise, bridged on one PVC. At the ingress side, frames received on a bridge port are checked for their VLAN user priority. This user priority is mapped to the regenerated user priority, which in its turn corresponds to an internal priority class. For example, VLAN user priority 1 is mapped to regenerated user priority 0, which corresponds to internal priority class 4. At the egress side, the internal priority class of a frame determines which queue is used. For example, frames with internal priority class 4 are put in the best-effort queue on PVC1. 5

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