Alcatel-Lucent 7750 SR OS, Interface Configuration Manual, Page: 36 / 444

Port Features
Page 36 7750 SR OS Interface Configuration Guide
Figure 3: Frame Sequence of Events
1. A low priority frame arrives in the low priority queue. At this particular instant, there are
no packets in the high priority queue so low priority frame is de-queued and passed to the
fragmentation mechanism for MLPPP (or MLFR in the future).
2. The original packet is divided into ‘n’ fragments based on the size of the packet and the
fragment threshold configuration.
3. The fragments are then transmitted out the egress port.
4. After the transmission of the fragments has begun, high priority frames arrive in the high
priority queue.
5. The transmission of the remaining fragments stops and the high priority packets are
transmitted out the egress interface. Note that high priority packets are not fragmented.
6. When the high priority traffic is transmitted, the remaining lower priority fragments are
then transmitted.
On the ingress side, LFI requires that the ingress port can receive non-fragmented packets within
the fragment stream and pass these packets directly on to the forwarding engine and then continue
with the reassembly process for the fragmented frames.
Fig_2
MLPPP
Fragmentation
High Priority Queue
Egress
Low Priority Queue
4
1 2 6 5 3