QoS Implementation Strategy
QoS for IPv6 in Cisco IOS includes packet allocation and marking, queuing, cartage shaping,
weighted accidental aboriginal apprehension (WRED), and policing. Each of these appearance is accurate for
both action switching and CEF switching in IPv6 in Cisco IOS.
Classification, Marking, and Queuing
Just as in IPv4, you charge analyze the arrangement cartage you appetite to amusement with QoS afore configuring
it. Once you accept done that, the aboriginal footfall is to actuate how a router can analyze the cartage of
interest; this is the allocation phase, which is done through Cisco IOS chic maps. If your
network is active the aforementioned protocols on IPv4 and IPv6, it makes faculty to allocate cartage based
on IP antecedence and DSCP. If not, you can amusement them apart application bout agreement ip
and bout agreement ipv6 instead. Cisco IOS has an added bout belief for cartage specified
in an IPv6 admission list, bout access-group name.
After you accept configured chic maps to bout the adapted traffic, you can mark the cartage in a
policy map. The accustomed set dscp and set antecedence commands abutment both IPv4 and IPv6 in
Cisco IOS.
Cisco IOS supports class-based and flow-based queuing for IPv6 traffic. Once you accept configured
classification and marking, which is covered in detail in Chapter 12, “Classification and Marking,”
you can chain the cartage application the aforementioned queuing accoutrement accessible for IPv4 and declared in Chapters
13 (“Congestion Management and Avoidance”) and 14 (“Shaping and Policing”). Please accredit to
those capacity for added details.
Some IPv6 QoS affection agreement differs from IPv4, either because of IPv6’s basic
implementation differences from IPv4 or for added reasons, accurately the following:
■ Because IPv6 admission lists cannot be numbered, but rather charge be named, Cisco IOS does not
support the bout access-group xxx command. Instead it supports the bout access-group
name command.
■ The bout ip rtp command identifies alone IPv4 RTP carriage packets. There is no
equivalent for analogous RTP packets in IPv6.
■ The bout cos and set cos commands for 802.1Q interfaces abutment alone CEF-switched
packets. They do not abutment process-switched or router-originated packets.
■ The bout cos and set cos commands do not abutment ISL interfaces, alike for CEF-switched
packets.
Congestion Avoidance
Like queuing, IPv6 WRED is identical to WRED for IPv4 both conceptually and in agreement of the
implementation commands. Cisco WRED supports both class- and flow-based (using DSCP or
precedence) operation.