Alcatel-Lucent 7750 SR Manual page 1239

egress
Syntax egress
Context cconfig>service>vprn>if>spoke-sdp
config>service>vprn>red-if>spoke-sdp
Description This command configures an SDP context.
hash-label
Syntax [no] hash-label
Context config>service>vprn
config>service>vprn>spoke-sdp
config>service>vprn>interface>spoke-sdp
Description This command enables the use of the hash label on a VLL, VPLS, or VPRN service bound to LDP or
RSVP SDP as well as to a VPRN service using the autobind mode with the with the ldp, rsvp-te, or
mpls options. This feature is not supported on a service bound to a GRE SDP or for a VPRN service
using the autobind mode with the gre option..
When this feature is enabled, the ingress data path is modified such that the result of the hash on the
packet header is communicated to the egress data path for use as the value of the label field of the
hash label. The egress data path appends the hash label at the bottom of the stack (BoS) and sets the
S-bit to 1 to indicate that.
In order to allow for applications whereby the egress LER infers the presence of the Hash Label
implicitly from the value of the label, the Most Significant Bit (MSB) of the result of the hash is set
before copying into the Hash Label. This means that the value of the hash label will always be in the
range [524,288 - 1,048,575] and will not overlap with the signaled/static LSP and signaled/static
service label ranges. This also guarantees that the hash label will not match a value in the reserved
label range.
The (unmodified) result of the hash continues to be used for the purpose of ECMP and LAG spraying
of packets locally on the ingress LER. Note however that for VLL services, the result of the hash is
overwritten and the ECMP and LAG spraying will be based on service-id when ingress SAP shared
queuing is not enabled. However, the hash label will still reflect the result of the hash such that an
LSR can use it to perform fine grained load balancing of VLL PW packets.
Packets that are generated in CPM and forwarded labeled within the context of a service (for
example, OAM packets) must also include a Hash Label at the BoS and set the S-bit accordingly.
The TTL of the Hash Label is set to a value of 1.
The no form of this command disables the use of the hash label.
Default no hash-label
7750 SR OS Services Guide
Virtual Private Routed Network Services
Page 1239