我们在 2960X 交换机上有一个传入的 QoS 配置，如下所示：

class-map match-any QOS_GL_TRUST
 match ip dscp 8 16 24 32 46 
class-map match-any QOS_GL_CITRIX
 match access-group name QOS_GL_CITRIX

policy-map QOS_LAN_IN
 class QOS_GL_TRUST
  trust dscp
 class QOS_GL_CITRIX
  set dscp 32
 class class-default
  set dscp default

所以基本上，这会接受数据包并保留 DSCP8、16、24、32 和 46 的标记。如果 DSCP32 尚未标记，Citrix 流量将匹配 ACL 并设置 DSCP32 标记。所有其他 DSCP 标记都被 DSCP0 覆盖。所以到目前为止效果很好。现在我们希望在 Cisco 3850 交换机上具有相同的配置。但是我们没有 trust 命令：

switch(config-pmap-c)#? 
Policy-map class configuration commands:
  bandwidth        Bandwidth
  drop             Drop all packets
  encap-sequence   MCMLP encapsulate sequence
  exit             Exit from class action configuration mode
  netflow-sampler  NetFlow action
  no               Negate or set default values of a command
  police           Police
  priority         Strict Scheduling Priority for this Class
  queue-buffers    queue buffer
  queue-limit      Queue Max Threshold for Tail Drop
  service-policy   Configure QoS Service Policy
  set              Set QoS values
  shape            Traffic Shaping

因此，如果我想实现与 2960X 交换机相同的工作，我必须执行以下操作：

class-map match-any QOS_GL_VOICERTP
 match ip dscp 46
class-map match-any QOS_GL_CITRIX
 match ip dscp 32
 match access-group name QOS_GL_CITRIX
class-map match-any QOS_GL_VOICESIP
 match ip dscp 24
class-map match-any QOS_GL_MANAGEMENT
 match ip dscp 16
class-map match-any QOS_GL_TRASH
 match ip dscp 8

policy-map QOS_LAN_IN
class QOS_GL_VOICERTP
  set dscp 46
 class QOS_GL_CITRIX
  set dscp 32
 class QOS_GL_VOICESIP
  set dscp 24
 class QOS_GL_MANAGEMENT
  set dscp 16
 class QOS_GL_TRASH
  set dscp 8
 class class-default
  set dscp default

所以你可以看到3850er配置的代码要多得多。那么有没有更好的解决方案来实现这一目标？我只是在谈论标记，这里没有实际的 QoS 优先级。