Download Cisco.300-535.ExamLabs.2020-01-09.26q.vcex

Local Packet Transport Services (LPTS) maintains tables describing all packet flows destined for the secure domain router (SDR), making sure that packets are delivered to their intended destinations. The Low Latency Queueing feature brings strict priority queueing to Class-Based Weighted Fair Queueing (CBWFQ).

The Low Latency Queueing feature brings strict priority queueing to Class-Based Weighted Fair Queueing (CBWFQ).

Differentiated Services Traffic Engineering MPLS Differentiated Services (Diff-Serv) Aware Traffic Engineering (DS-TE) is an extension of the regular MPLS-TE feature. Regular traffic engineering does not provide bandwidth guarantees to different traffic classes. A single bandwidth constraint is used in regular TE that is shared by all traffic. To support various classes of service (CoS), users can configure multiple bandwidth constraints. These bandwidth constraints can be treated differently based on the requirement for the traffic class using that constraint. MPLS diff-serv traffic engineering provides the ability to configure multiple bandwidth constraints on an MPLSenabled interface. Available bandwidths from all configured bandwidth constraints are advertised using IGP. TE tunnel is configured with bandwidth value and class-type requirements. Path calculation and admission control take the bandwidth and class-type into consideration. RSVP is used to signal the TE tunnel with bandwidth and class-type requirements. Diff-Serv TE can be deployed with either Russian Doll Model (RDM) or Maximum Allocation Model (MAM) for bandwidth calculations.  TE Class Mapping Each of the eight available bandwidth values advertised in the IGP corresponds to a TE Class. Because the IGP advertises only eight bandwidth values, there can be a maximum of only eight TE classes supported in an IETF DS-TE network. TE class mapping must be exactly the same on all routers in a DS-TE domain. It is the responsibility of the operator configure these settings properly as there is no way to automatically check or enforce consistency. The operator must configure TE tunnel class types and priority levels to form a valid TE class. When the TE class map configuration is changed, tunnels already up are brought down. Tunnels in the down state, can be set up if a valid TE class map is found. Table 4 TE Classes and Priority     The default mapping includes four classes types.

Hierarchical policing is also supported. In such a configuration, both parent and child policies have class-maps containing policing statements, as in the following example:! policy-map child class gold police rate percent 50 conform-action set precedence immediate exceed-action drop ! ! policy-map parent class match_all police rate 10000 kbps burst 15000 exceed-action drop service-policy child

Comparison of Cisco IOS QoS and Cisco IOS-XR QoS The Cisco IOS-XR software implementation of QoS is basically the same as the QoS implementation on Cisco IOS software, with the following exceptions:On Cisco IOS-XR software, the bandwidth command can be configured only in egress policies. The following changes have been made to the class-map command on Cisco IOS-XR software:Supports 4K per logical router. Maximum number of match criteria configurable in one class map is eight. When a class is marked as high priority using the priority command on Cisco IOS-XR software, we recommend that you configure a policer to limit the priority traffic. Limiting the priority traffic will ensure that the priority traffic does not starve all of the other traffic on the line card. Use the police command to explicitly configure the policer. On Cisco IO-XR software, only one conform-action, exceed-action, or violate-action command can be configured at a time. To configure traffic policing, use the police command. On Cisco IOS-XR software, policy modifications cannot be made on existing policies. Use the policy-map command to remove the policy from all attached interfaces, delete the policy map, and redefine a new policy. When configuring a policy map on Cisco IOS-XR software, the maximum number of classes configurable in one policy map is 16, which includes both Level 1 and Level 2 classes. To configure a policy map, use the policy-map command. When WRED is configured on Cisco IOS-XR software, the mark probability in the random-detect command is not configurable—it is always set to 1. When the random-detect exp command is used on Cisco IOS-XR software, the exponential weighting constant is not configurable and will be programmed automatically by Cisco IOS-XR software. When access control lists (ACLs) are used in QoS class maps, the underlying deny or permit actions associated with access control entries (ACEs) are ignored. ACEs are used as a classification mechanism in order to provide appropriate QoS behavior as specified in class maps. Use ACLs that include ACEs with permit actions only.

http://www.cisco.com/en/US/technologies/tk648/tk872/technologies_white_paper0900aecd8026004d.pdfCisco Systems.             IPv6 QoS                                     AT-A-GLANCE RFC 2460/3697 Currently IPv6 provides support for QoS marking via a field in the IPv6 header. Similar to the type of service (ToS) field in the IPv4 header, the traffic class field (8 bits) is available for use by originating nodes and for forwarding routers to identify and distinguish between different classes or priorities of IPv6 packets.      Current Cisco IOS Software support for IPv6 QoS includes:Packet classification Queuing (includes LLQ; excludes legacy PQ/CQ) Traffic shaping WRED IPv6 also has a 20-bit field known as the flow label field (RFC 3697). The flow label enables per flow processing for differentiation at the IP layer. It can be used for special sender requests and is set by the source node. The flow label must be modified by an intermediate mode. Planned Cisco IOS Software support for IPv6 QoS includes:Compressed Real-Time Protocol (cRTP) Network-based application recognition (NBAR) Committed access rate (CAR)

QoS Policy Propagation via BGP (QPPB), is a mechanism that allows propagation of quality of service (QoS) policy and classification by the sending party based on access lists, community lists and autonomous system paths in the Border Gateway Protocol (BGP), thus helping to classify based on destination instead of source address.

http://www.cisco.com/en/US/tech/tk543/tk545/technologies_tech_note09186a008017405e.shtmlThe qos pre-classify command When packets are encapsulated by tunnel or encryption headers, QoS features are unable to examine the original packet headers and correctly classify the packets. Packets traveling across the same tunnel have the same tunnel headers, so the packets are treated identically if the physical interface is congested. With the introduction of the Quality of Service for Virtual Private Networks (VPNs) feature, packets can now be classified before tunneling and encryption occur. In this example, tunnel0 is the tunnel name. The qos pre-classify command enables the QoS for VPNs feature on tunnel0:Router(config)# interface tunnel0 Router(config-if)# qos pre-classify