Setting the MPLS EXP bits Spirent Test Center

Setting the MPLS EXP bits Spirent Test. Center Testing MPLS Qo. S PROPRIETARY AND CONFIDENTIAL

MPLS Traffic endpoints £ There are mainly 3 types of MPLS traffic endpoints in a test • IP Router running MPLS or IP Host /Network located behind an MPLS Router • Layer-3 CE Device/Network in an L 3 VPN • Layer-2 CE Device/Host in an L 2 VPN 2 £ The MPLS traffic endpoint can be an Emulated device (Host or Router) or a Simulated device (Route/Network Block or an LSP Tunnel Block) £ For simulated device endpoints, by default MPLS EXP = 0 b 000 and MPLS TTL =64 £ The MPLS traffic endpoints can be L 3 endpoints (e. g. IP addresses) or L 2 endpoints (e. g. Ethernet MAC addresses) £ For emulated device endpoints, MPLS EXP is set to the device interface Qo. S PROPRIETARY AND CONFIDENTIAL

MPLS Traffic endpoint is a Layer 3 device - Setting device interface Qo. S 3 £ Set the IPv 4 To. S or IPv 6 Traffic Class on the device interface by clicking “Edit Interface” in the Device Grid (next page) £ Control Plane protocols (like BGP, OSPF) use the IPv 4 To. S or IPv 6 Traffic Class specified on the interface to transmit control plane packets (OSPF Hellos, BGP Updates). £ Modifying the interface Qo. S settings should not be taken lightly. £ Lowering the Qo. S values on routers running routing protocols can cause critical control plane packets to be dropped. £ MPLS header if present in the interface stack cannot be edited. £ MPLS EXP bits and TTL are automatically set by the control plane protocols £ Control plane protocols running over MPLS tunnels (BGP or LDP Target) will copy the interface IP To. S and IP TTL to all the MPLS headers. PROPRIETARY AND CONFIDENTIAL

MPLS Traffic endpoint is a Layer 3 device 4 PROPRIETARY AND CONFIDENTIAL

MPLS Traffic Endpoint is a Layer 3 device - Importing Qo. S into the Traffic Wizard £ The Traffic Wizard will import the IPv 4 To. S or IPv 6 Traffic Class and the IP TTL specified on the device interface into the Frame tab when the stream-block is created (next page) £ Traffic Wizard automatically sets MPLS EXP bits to use the IPv 4 To. S or IPv 6 Traffic Class in the following IP header • For example: If an IPv 4 header immediately follows the MPLS headers then IP To. S will be copied to EXP in all MPLS headers 5 £ MPLS TTL is set to 64 by default. It is not copied from the following IP header in the Frame tab unlike the EXP bits. £ If there are multiple source endpoint devices in the same stream-block the IP Qo. S on the interface of the first endpoint will be imported into the Frame tab of the Traffic Wizard. £ If the Qo. S on the device interface is updated the stream-block will not be automatically updated. Stream-block will need to be re-created. PROPRIETARY AND CONFIDENTIAL

MPLS Traffic endpoint is a Layer 3 device (page 3) 6 PROPRIETARY AND CONFIDENTIAL

MPLS Traffic endpoint is a Layer 2 device - Setting device interface Qo. S 7 £ L 2 device is usually a CE device in a L 2 VPN test and is stacked behind an emulated PE device. £ If a VLAN interface is present then set the VLAN Priority on the device interface by clicking “Edit Interface” in the Device Grid (next page) £ If a control plane protocol (like STP, OSPF) is Active on the device(IP header may be added), then it would use the VLAN Priority specified on the interface to transmit control plane packets. £ Currently, for control plane protocols, the MPLS EXP is being set to 0 b 000 and MPLS TTL is being set to 255 by default. £ VLAN Priority and IP 4 To. S or IPv 6 Traffic Class are not being used to set the MPLS EXP bits for control plane protocols running on L 2 VPN CE devices. PROPRIETARY AND CONFIDENTIAL

MPLS Traffic endpoint is a Layer 2 device 8 PROPRIETARY AND CONFIDENTIAL

MPLS Traffic Endpoint is a Layer 2 device - Importing Qo. S into the Traffic Wizard £ The Traffic Wizard will import the VLAN Priority specified on the device interface into the Frame tab when the stream-block is created (next page) £ Traffic Wizard automatically sets MPLS EXP bits to use the VLAN Priority in the following Ethernet+VLAN header when present • For example: If an Ethernet+VLAN header immediately follows the MPLS headers then VLAN Priority bits will be copied to EXP bits in all MPLS headers £ If the VLAN header is not present on the L 2 device endpoint, MPLS EXP is set to a default value of 0 b 000 £ MPLS TTL is set to 64 by default. 9 PROPRIETARY AND CONFIDENTIAL

Setting MPLS Qo. S in the Traffic Wizard - L 3 endpoints with IP Qo. S £ A Layer 3 MPLS endpoint (Router/Host or Route/LSP Block) will have an IP header following the MPLS headers £ The IP Qo. S (To. S, DSCP or Traffic Class) of the IP header can be edited in the Frame tab £ MPLS EXP will be automatically mapped to the 3 higher order IP To. S bits of the IP Qo. S in the following IP header £ If a modifier is added to the IP Qo. S (To. S, DSCP or Traffic Class), then the modifier will automatically be copied to the EXP bits in all MPLS headers, provided that the Step only modifies the 3 higher order IP To. S bits. If the Step modifies other bits as well then the modifier is not copied to MPLS EXP and MPLS EXP bits are set to the 3 higher order To. S bits of the initial IP Qo. S. • Add an IP Diff. Serv/DSCP modifier: Start=AF 23 (0 x 58), Step=40, Count=2, § 1 st packet: IP DSCP=0 x 58, MPLS EXP=0 b 010 § 2 nd packet: IP DSCP=0 x 78, MPLS EXP=0 b 100 • Only 6 Modifiers are allowed per stream 10 PROPRIETARY AND CONFIDENTIAL

Setting MPLS QOS in the Traffic Wizard 11 PROPRIETARY AND CONFIDENTIAL

Setting MPLS Qo. S in the Traffic Wizard - Setting the MPLS EXP bits £ 12 To set the MPLS EXP bits directly, select “Show All Headers” at the “Endpoints” selection tab, and go the “Frame” tab. PROPRIETARY AND CONFIDENTIAL

Setting MPLS Qo. S in the Traffic Wizard - Setting the MPLS EXP bits 13 £ MPLS header is now viewable and fields are editable £ MPLS EXP bits for each header can be modified to override the defaults. £ MPLS EXP bits can be set to values different from the IP Qo. S or Vlan Priority £ A modifier can be added to MPLS EXP bits in one or more MPLS headers as needed £ MPLS TTL and Bottom of stack bit are also editable PROPRIETARY AND CONFIDENTIAL

Setting MPLS Qo. S in the Traffic Wizard - Setting the MPLS EXP bits 14 PROPRIETARY AND CONFIDENTIAL