3COM_OS_SW8800_V3.01.32rc13_Release_Notes

3COM OS SW8800 V3.01.32rc13 Release Notes
April 25, 2013 Page 8 of 56
Limitation 4
【QOS】In MPLS L3VPN networking, the IP packets, which come from the Egress PE (i.e. the
packets with the MPLS tag header removed), cannot map the DSCP value of the IP packet according
to EXP value of the MPLS header. Instead, they adopt the DSCP value of the original IP packet. It is
suggested that the DSCP value of the IP packet be guaranteed by the initiator.
Limitation 5
【QOS】In MPLS L3VPN networking, for the non-TCP and non-UDP IP packets, the EXP value can
be set according to the mapping table from DSCP to EXP on the Ingress PE. However, for the TCP
and UDP packets, the EXP value only can be directly mapped according to the three low bits of DSCP,
instead of according to the three high bits of DSCP.
Limitation 6
【QOS】After the drop priority (DP) is remarked based on the customized DSCP mapping in traffic-
priority or remark-policed-service, the packets entering the same queue (except queue 2) are not
dropped by the set DP.
Limitation 7
【QOS】The boards with suffixes CA/DB only provide the parameter mapping of User Priority of
Traffic Class+Confrom-Level->COS, while the DSCP value in the mapping table is a default one. For
this reason, after remarking the COS of the packet, the DSCP value of the packet is modified as well.
Limitation 8
【QOS】On the same port, traffic shaping and WRR (Weighted Round Robin) cannot be enabled
simultaneously, or the WRR queue dispatching mode will not function.
Limitation 9
【QOS】Flow control and QoS functions cannot be enabled on a port at the same time. Otherwise,
after flow control is enabled on a port, there will be no guarantee for preferential processing of the
queues with high priorities, resulting in QoS failure.
Limitation 10
【QOS】The 100Base port can only dispatch 5 queues at one time. If it is required to send packets
from over 5 queues, please use the WRR (Weighted Round Robin) mode.
Limitation 11
【QOS】 The 3C17528/3C17532/3C17528A/3C17532A/3C17526 board do not support the WRR
mode, so do not enable the WRR mode on these boards. Instead, the SP (Strict-Priority) mode should
be used.