The pseudowire template concept used for BGP AD is re-used for BGP VPWS to dynamically instantiate pseudowires (SDP-bindings) and the related SDPs (provisioned or automatically instantiated).
The settings for the L2-Info extended community in the BGP update sent by the system are derived from the pseudowire-template attributes. The following rules apply:
If multiple pseudowire-template-bindings (with or without import-rt) are specified for the VPWS instance, the first (numerically lowest ID) pseudowire-template entry is used.
Both Ethernet VLAN and Ethernet Raw Mode Encaps Types are supported; these are selected by configuring the vc-type in the pseudowire template to be either vlan or ether, respectively. The default is ether.
The same value must be used by the remote BGP VPWS instance to ensure that the related pseudowire comes up.Layer 2 MTU – derived from service VPLS service-mtu parameter.
The same value must be used by the remote BGP VPWS instance to ensure that the related pseudowire comes up.Control Flag C – can be 0 or 1, depending on the setting of the controlword parameter in the PW template 0.
Control Flag S – always 0.
On reception, the values of the parameters in the L2-Info extended community of the BGP update are compared with the settings from the corresponding pseudowire-template. The following steps are used to determine the local pseudowire-template:
The route-target values are matched to determine the pseudowire-template. The binding configured with the first matching route target is chosen.
If a match is not found from the previous step, the lowest pw-template-binding (numerically) without any route-target configured is used.
If the values used for Encaps Type or Layer 2 MTU do not match, the pseudowire is created but with the operationally down state.
To interoperate with existing implementations, if the received MTU value = 0, then MTU negotiation does not take place; the related pseudowire is set up ignoring the MTU.If the value of the S flag is not zero, the pseudowire is not created.
The following pseudowire template parameters are supported when applied within a BGP VPWS service; the remainder are ignored:
configure service pw-template policy-id [use-provisioned-sdp |
[prefer-provisioned-sdp] [auto-sdp]] [create] [name name]
accounting-policy acct-policy-id
no accounting-policy
[no] collect-stats
[no] controlword
egress
filter ipv6 ipv6-filter-id
filter ip ip-filter-id
filter mac mac-filter-id
no filter [ip ip-filter-id] [mac mac-filter-id] [ipv6 ipv6-filter-id]
qos network-policy-id port-redirect-group queue-group-name instance instance
id
no qos [network-policy-id]
[no] force-vlan-vc-forwarding
hash-label [signal-capability]
no hash-label
ingress
filter ipv6 ipv6-filter-id
filter ip ip-filter-id
filter mac mac-filter-id
no filter [ip ip-filter-id] [mac mac-filter-id] [ipv6 ipv6-filter-id]
qos network-policy-id fp-redirect-group queue-group-name instance instance-id
no qos [network-policy-id]
[no] sdp-exclude
[no] sdp-include
vc-type {ether | vlan}
vlan-vc-tag vlan-id
no vlan-vc-tag
For more information about this command, see the 7450 ESS, 7750 SR, 7950 XRS, and VSR Services Overview Guide.
The use-provisioned-sdp option is permitted when creating the pseudowire template if a pre-provisioned SDP is to be used. Pre-provisioned SDPs must be configured whenever RSVP-signaled transport tunnels are used.
When the prefer-provisioned-sdp option is specified, if the system finds an existing matching SDP that conforms to any restrictions defined in the pseudowire template (for example, sdp-include/sdp-exclude group), it uses this matching SDP (even if the existing SDP is operationally down); otherwise, it automatically creates an SDP.
When the auto-gre-sdp option is specified, a GRE SDP is automatically created.
The tools perform command can be used in the same way as for BGP-AD to apply changes to the pseudowire template using the following format:
tools perform service [id service-id] eval-pw-template policy-id [allow-service-impact]
If a user configures a service using a pseudowire template with the prefer-provisioned-sdp option, but without an applicable SDP being provisioned, and the system binds to an automatic SDP, and the user subsequently provisions an appropriate SDP, the system does not automatically switch to the new provisioned SDP. This only occurs if the pseudowire template is re-evaluated using the tools perform service id service-id eval-pw-template command.