Alcatel-Lucent 7710 SR OS, Interface Configuration Manual

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Interface Configuration
7710 SR OS Interface Configuration Guide Page 33
A separate fragmentation context is used by each FR SAP. FR SAPs of the same scheduling class
share the same egress FR scheduling class queue with fragments of each SAP packets stored
contiguously. The fragments from each scheduling class queue are then sprayed over the member
links. Furthermore, the user may select the option to not fragment but spray the FR frames with
the fragmentation header included over the member links.
Received fragments over the member links are re-assembled on a per SAP basis to re-create the
original FR frame.
A user is not allowed to add an FR SAP with FRF.12 e2e fragmentation enabled to an MLFR
bundle. Conversely, the user cannot enable FRF.12 e2e fragmentation on an FR SAP configured
on an MLFR bundle. If an FR frame with the e2e fragmentation header is received on a bundle, it
is forwarded if the FR SAP is part of an fpipe service. It will be discarded if the FR SAP is part of
any other service.
Note that the operator must disable LMI before adding a link to an MLFR bundle. Also, the
operator must shut down the bundle in order to change the value of the fragmentation threshold.
An FR SAP configured on an MLFR bundle can be part of a VLL, VPLS, IES, or VPRN service.
MLFR Bundle Link Integrity Protocol
FRF.16.1 defines a MLFR Bundle Link Integrity Protocol which verifies the serviceability of a
member link. If a problem is found on the member link the link integrity protocol will identify the
problem, flag the link as unusable, and adjust the Bundle’s available bandwidth. For MLFR
Bundles the link integrity protocol is always enabled.
For each member link of a bundle the link integrity protocol will do the following:
• Confirm frame processing capabilities of each member link.
• Verify membership of a link to a specific remote bundle.
• Report to the remote end of the member link the bundle to which the link belongs
• Detect loopbacks on the member link. This is always enabled on the 7710 SRThe near-end
monitors the magic number Information Element (IE) sent by the far-end and if its value
matches the one it transmitted in ten consecutive control messages, it sends a remove_link
message to the far-end and brings the link down. The near-end will attempt to add the link
until it succeeds.
• Estimate propagation delay on the member link. The differential delay is calculated as
follows in the 7710 SR implementation. Every time the near-end sends an add_link or
Hello message to the far-end, it includes the Timestamp Information Element (IE) with
the local time the packet was sent. FRF16.1 standard requires that the remote equipment
includes the timestamp IE and copies the received timestamp value unchanged if the
sender included this IE. When the far-end node sends back the ACK for these messages,
the near-end calculates the round trip time. The 7710 SR implementation maintains a