Juniper JUNOSE SOFTWARE FOR E SERIES 11.3.X - POLICY MANAGEMENT CONFIGURATION GUIDE 2010-10-04 Configuration Manual page 86

JunosE 11.3.x Policy Management Configuration Guide
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token counts are reduced, making them more likely to make other packets conformed
or exceeded. Transmit unconditional is not allowed as an exceeded action.
After the transmit-unconditional completes, the packet traverses to the end of the
hierarchy. Because ownership of the packet has been retained, no rate limit further
down can apply its actions to it. Some of the later rate limits might already have very
low token counts, which must still be decremented when processing a
transmit-unconditional packet (if necessary, by making the token count negative).
Negative token counts enable the remaining rate limits to restrict the total traffic
through them to their peak rate (over a large enough averaging interval, which is a
function of rates and burst sizes only). Transmit unconditional packets traversing the
rate-limit hierarchy reduce the number of tokens available for other packets.
A rate limit has one of the four preceding actions configured for each possible result:
committed, conformed, and exceeded. (Transmit unconditional is not allowed as an
exceeded action.) The action taken depends only on the result of that rate limit, its rates,
burst sizes, and current token state. In addition, the rate limit assigns a color to the packet,
depending on both the result of the rate limit and the packet's incoming color. The final
color after a packet has finished traversing a rate-limit hierarchy is a function of all the
rate limits that owned the packet.
Policy actions are processed in the following order:
log
1.
filter
2.
traffic class
3.
user packet class
4.
next hop
5.
rate limit
6.
color status
7.
color action
8.
parent group
9.
mark
10.
The mark action is the last action that occurs, after parent-group, so that the color-mark
profile can mark the packet with the final color from the hierarchy.
NOTE: To avoid saturation when using dual token buckets, the total amount
of yellow transmit unconditional traffic should be less than the peak rate
minus the committed rate; the green transmit unconditional traffic should
be less than the committed rate.
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