Hierarchical Rate Limits ! 85
Chapter 3: Creating Rate-Limit Profiles
host1(config)#policy-list mypolicy
host1(config-policy-list)#classifier-group A parent-group extrabw
host1(config-policy-list-classifier-group)#rate-limit-profile indiv
host1(config-policy-list-classifier-group)#exit
host1(config-policy-list)#classifier-group B parent-group extrabw
host1(config-policy-list-classifier-group)#rate-limit-profile indiv
host1(config-policy-list-classifier-group)#exit
host1(config-policy-list)#classifier-group C parent-group extrabw
host1(config-policy-list-classifier-group)#rate-limit-profile indiv
host1(config-policy-list-classifier-group)#exit
host1(config-policy-list)#parent-group extrabw
host1(config-policy-list-parent-group)#rate-limit-profile extrabw
host1(config-policy-list-parent-group)#rate-limit-profile indiv
host1(config-policy-list-parent-group)#exit
Aggregate Marking with Oversubscription
Figure 6 shows an aggregate rate limit that enables up to 2 Mbps of traffic to be sent
with ToS marking TOS1. Traffic above that rate is sent with marking TOS2 or TOS3
(depending on packet type) and traffic above 6 Mbps is dropped. The 2 Mbps of
TOS1 is oversubscribed among individual flows A, B, and C, each of which can have
up to 1 Mbps of TOS1 traffic. An individual flow can mark a packet TOS1, but if
there is insufficient bandwidth at the shared rate limit because of oversubscription,
the packet is demoted and remarked.
The demoted packets from flow A are marked as TOS2 but the demoted packets
from flows B and C are marked as TOS3. The shared rate limit determines whether
to demote the packet, in which case each individual rate limit selects the new ToS
marking. Individual flows are not required to mark demoted packets with the same
value.
The committed and conformed actions are transmit conditional so that all packets
also go through rate limit S, because rate limit S imposes the limit of 2 Mbps of
TOS1 traffic (total across A, B, and C).
Committed packets are transmitted conditionally to rate limit S, which has a peak
rate of 6 Mbps and a committed rate of 2 Mbps; these packets can be demoted by S
to Y (yellow), in which case they are remarked TOS2 or TOS3. If S leaves them as G
(green), they are marked as TOS1. All conformed packets from A, B, and C are also
transmitted conditionally to S but arrive as Y because rate limits do not promote
packets in color. S is color-aware so these Y packets do not take away G tokens,
leaving them reserved only for the G packets coming from A, B, and C.
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