From: san (san.study@gmail.com)
Date: Mon Dec 12 2005 - 04:04:14 GMT-3
Quote from book: CCIE practical studies, vol 2, Page 189
Cisco IOS software considers the precedence bits of the TOS field if
there is traffic that is queued in WFQ, WRED, or WRR (weighted round
robbin). The precedence bits are not considered when policy routing,
PQ, CQ, CBWFQ are configured.
How about DTRC bits (bits 3 - 6) of TOS field,. Does this have any
limitation like above ?
After few pages, Page 192, example 2-31.
Example sets "set ip tos min-delay", & says. In this model, because
you are setting TOS values, you need to configure WRED or WFQ on the
outbound interface. WFQ is not the default queuing method on Ethernet
interfaces. It is the default queuing method on serial interfaces
with 2.048 Mbps or less of bandwidth. This portion of the
configuration is not present in this example.
Example 2-31.. shows configuring PQ though (&says PQ for TOS
enforcement on sidenote). ....Can anyone check, if the example is
correct. If example is correct then DTRC bits can have different
queue requirements than Precedence bits ? Is this correct ?
Summary: (To act on the bits)
Precedence bits => needs WFQ, WRR, WRED on outbound interface + queue congestion
DTRC bits => any queue could work !?!
Thanks
SAN
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