ISP_QoS Study Notes & lt; incomplete & gt;

ISP_QoS learning notes <incomplete>
1-The Implementation of QS1-1CLI traditional method, no modular, no classification idea when using auto qs can be fine-tuned using 1-2MQCClass map definition classification Policy map contains multiple class map + default class map, 1-3 Auto QS is called on interfaces in two categories. VOIP/enterprise classifies voip traffic, with low latency and low jitter. One command is used to handle Enterprise: different types of application traffic are divided into different categories. different treatments are made for each type: 1-4 QPMQos policy manager, graphical Management of QS. The actual use of the 2-QS model Best-Effort is relatively small: no QoS is applied to packets. intServ: Applications signal to the network that they require special QoS. diffServ: The network recog Nizes classes that require special QoS.2-1 IntServ integrated router simulates the host to send RSVP messages, allowing network devices to allocate resources (based on the stream mode) ip rsvp sender-host 11.1.1.1 44.1.1.1 UDP 60000 50000 20 2000ip rsvp reservation-host 11.1.1.3 44.1.1.2 UDP 60000 50000 ff rate 20 2000 \ note that the original object information must be the same <interface> ip rsvp bandwidthdebug ip rsvp \ you can see that the RSVP session information of a stream is maintained during the two routes. If there are many traffic flows, CPU usage is required, at the same time, the bandwidth utilization is too low. 2-2 DiffServ is based on the node mode advantages: 1 Highly scalable 2 Many levels of quality possible disadvantages: complicated configuration because Configure based on each node 3-understand The trust boundary of the differential service model: recognizes devices that can use DSCP DiffServ field: The IP version 4 header ToS octet or the IPv6 traffic class octet, when interpreted in conformance with the definition given in RFC 2474 DSCP: The first six bits of the DiffServ field, used to select a PHB (forwarding and queuing method) each DSCP corresponds to a PHBDSCP selects PHB throughout the network. <the last digit is always 0>? <1> Default PHB (FIFO, tail drop) <all 0>? <1> EF Expedited Forwarding <only one EF type is used for VOIP>? <12> AF Assured Forwarding <there are four standard categories>? <8> Class-Selector (IP Precedence) PHB <the last three digits are 0, compatible with IPP> 3-1 ef phbef phb: <more VOIP traffic> 1-Ensures a minimum departure rate <ensure minimum latency> 2-Guarantees bandwidth (The class is guaranteed an amount of bandwidth with prioritized forwarding .) <allocate required bandwidth> 3-bandwidth es bandwidth (The class is not allowed to exceed the guaranteed amount-excess traffic is dropped .) <traffic monitoring is triggered when a congestion occurs.> DSCP value "101110": looks like IP Precedence 5 To non-DiffServ-compliant devicesBits 5 to 7: "101" = 5 (Same three bits used for IP Precedence) Bits 3 to 4: "11" = drop probability highBit 2: just "0" 3-2 af phbaf phb: 1-Guarantees bandwidth <bandwidth guarantee> 2-Allows access to extra bandwidth, if available <if the interface has other bandwidth, you can use> Four standard classes (af1, af2, af3, and af4) DSCP value range: "aaadd0"-Where "aaa" is a binary value of the class <there are four combinations>-Where "dd" Is drop probability <there are three combinations> <the greater the value, high possibility of discarding> AF has 12 combinations 3-3 CS PHBClass-Selector "xxx000" DSCP <compatible with IPP> Compatibility with current IP Precedence usage (RFC 1812) = maps IP Precedence to DSCPDifferentiates probability of timely forwarding (xyz000) >=( abc000) if xyz> abcIf a packet has DSCP = "011000, "it has a greater probability of timely forwarding than a packet with DSCP =" 001000. 4-QS mechanism 1-Classificat Ion: Each class-oriented QoS mechanic has to support some type of classification.2-Marking: Used to mark packets based on classification, metering, or both. <trust boundary tagging> 3-Congestion management <Congestion management mechanism>: Each interface must have a queuing mechanic to prioritize transmission of packets.4-Congestion avoidance <Congestion avoidance mechanism>: used to drop packets early to avoid congestion later in the network. use-> application's perception of network transmission quality Force, look at RTT, packet loss rate Buffer is not full, start packet loss 5-refreshing and shaping <traffic monitoring and shaping>: used to enforce a rate limit based on the metering (excess traffic is either dropped, marked, or delayed ). 6-Link Efficiency: Used to improve bandwidth efficiency through compression, link fragmentation, and interleaving.5-learning CLIClass maps can operate in two modes: Match all: all conditions have to succeedMatch: at least one condition mu St succeedThe default mode is match all. class-map [match-all | match-any] class-map-namematch condition \ you can use match notdescription descriptionshow class-mapdefault class-map to modify only action, the Condition policy-map-nameclass {class-name | class-default} class-map-name conditiondescription descriptionshow policy-mapshow policy-map interface-name [input | output] // see details 6-learning classification and tagging classification: the comp Onent of a QoS feature that recognizes and distinguishes between different traffic streams. most fundamental QOS building block, a component for QoS to distinguish different traffic types. is the most basic module of QOS Without classification, all packets are treated the same. no classification, all packages are processed with The same tag: The QoS feature component that "colors" a packet (frame) so that it can be identified and distinguished from other packets (frames) in QoS treatment. commonly used markers inc Lude: CoS (802.1 p), DSCP, and IP precedence. l2 switching is implemented in PRI-bit (3bit) COS, FR switch, DE bit location, ATM, CLP location, discarding MPLS first: sitting in EXP bit, 3bit, 8 types of combined IP Packets: DSCP/IPP (TOS) end to end QoS makes sense. and the QOS must be consistent (QS consistency can be achieved through the QS tag ing) and this must be combined with the trust boundary to understand the 7-classification means Access listIP precedence valueIP DSCP valueQoS group number <not passed, qos-group, internal local label> MPLS experimental bitsProtocol (including NBAR) \ matching protocol Using another class map \ nested Frame Relay DE bitI EEE 802.1Q/ISL CoS/Priority valuesInput interfaceSource MAC address \ write MAC ACLDestination MAC addressRTP (UDP) port rangeAny packet \ matching mode: match all/match anyclass-map High-prioritymatch cos 4 6 7 \ This relationship is an OR relationship, although the matching mode is match allclass-map Voicematch ip dscp ef cs5! Class-map Mission-Criticalmatch ip dscp af31 af32 af33 cs3! Class-map Transactionalmatch ip dscp af21 af22 af23 cs2! Class-map Bulkmatch ip dscp af11 af12 af13 cs1! Class-map Best-Effortmatch ip dscp default prerequisites: CEF must be configured on the interface before the class-based packet marking feature can be used classification based on NBAR, PDLM fileNBAR also supports Protocol classification and detection of NBAR can classify applications that use :? Statically assigned TCP and UDP port numbers? Non-UDP and non-TCP/IP protocols? Dynamically assigned TCP and UDP port numbers negotiated during connection establishment (requires stateful inspection )? Subport classification: classification of HTTP (URLs, MIME, or host names) and Citrix applications (ICA traffic based on published application name )? Classification based on deep packet inspection and multiple application-specific butes (RTP payload classification) Router (config) # ip nbar pdlm-file Processing Protocol Discovery: router (config-if) # ip nbar protocol-discoveryshow ip nbar protocol-discoveryip nbar port-map protocol [tcp | udp] new-port [new-port...] 8-QoS PreclassifyQoS for VPNs (QoS preclassify) is a Cisco IOS feature that allows packets to be classified before tunneling and encryption authorization-QoS Policy Propagation Through BGP1-The QoS policy propagation via the qppb bgp fea Ture allows classifying packets based on access lists, BGP community lists, and bgp as paths.2-When using QPPB, qoS works independently from BGP routing.3-CEF switching with QoS packet marking will populate the FIB table with IP precedence and QoS group values.4-Route maps are used to set IP precedence and QoS group ID.5- bgp-policy Cisco IOS command (interface level) is used to mark the QoS po Licy via BGP. router (config) # route-map name permit seqmatch as-path-list-numbermatch ip address access-list-numbermatch community-listset ip precedence set ip qos-group groupDefines a route map to set IP precedence or QoS-groupSpecifies IP precedence and QoS group values in the routing table/FIB table entryrouter (config-router) # table-map route-map-name10-Understanding queue 1 Classification 2 insert or discard policies 3 Scheduling FIFO: one queue, tail discard, first-in-first-out PQ: multiple queues, tail discard, always scheduling high-priority classification, other categories starved to death status FQ: Round: multiple queues, tail discard, Weighted RoundRobin sent by queue wheel message: multiple queues and tail discard, which are scheduled based on the weight value. Two scheduling mechanisms are available: 1-packet size byte, 2-Number of packages DRR-solves the problem of inaccurate package size scheduling. The queue mechanism takes effect only when the hardware queue is full, in the software queue, if the bandwidth of the 11-FIFO/WFQ interface is less than 2.048, It is WFQ. Generally, the Ethernet port is FIFO. The (default) WFQ pair (Interactive Data Stream) packet is favorable for the WFQ classification: use 6 tuples to classify and generate different values to enter different queues. FT: Each package has an FT (finish time) value. The WFQ scheduling mechanism is related to the package length: the packet with the smallest FT always takes precedence over the WFQ insertion and discard mechanism: Hold-queue out limit: buffer size of the output interface Congestion d Iscard threshold: threshold for outgoing interface congestion (indicating interface congestion) less than CDT: normal incoming queue is greater than HQO: the packet with the largest FT loss may be discarded between CDT and HQO. The condition is met: the new data packet compares the data FT value in the buffer. If it is the worst FT, It is discarded. Otherwise, it is not lost. WFQ: the virtual packet length of FT is calculated based on the actual package length/IPP + 1WFQ configurable items: CDT/HQO/number of configurable queues/number of reserved queues (cannot be configured for classification) interface: fair-queue [cdt [dynamic-queues [reservable-queues] hold-queue max-limit outshow interface \ can view the corresponding values 12-CBWFQ and LLQCBWFQ available on different platforms the maximum bandwidth value is different, 7200 the maximum bandwidth ratio of the 99% outbound interface is related to the calculation of the bandwidth Digital Reference Value configured on the interface. The bandwidth after remaining is the actual bandwidth value minus the bandwidth allocated by PQ. Details: bandwidth: percent/specific number/remaining when the outbound interface is congested, the minimum bandwidth is provided to ensure that the outbound interface is not used for competition, A higher bandwidth value can be allocated <not included in the software queue>. When the outbound interface is congested The high bandwidth value occupies the excess bandwidth LLQ (CBWFQ + PQ) based on the minimum bandwidth value. Low-latency queues are mostly used for the EF placement of voice streams, IPP 5 is used to distinguish different types of data streams, and the bandwidth with the priority PQ is given without congestion, can be occupied by other queues ===== CBWFQ === Router (config) # access-list 101 permit udp host 10.10.10.10 host 10.10.20 range 16384 20000 Router (config-if) # access-list 101 permit udp host 10.10.10.10 host 10.10.20 range 53000 56000 Router (config) # class-map class1Router (config-cmap) # match access-group 101 Router (config-cm Ap) # exitRouter (config-cmap) # class-map class2Router (config-cmap) # match access-group 102 Router (config-cmap) # exitRouter (config) # policy-map policy1Router (config-pmap) # class class1Router (config-pmap-c) # bandwidth 3000 Router (config-pmap-c) # queue-limit 30 Router (config-pmap-c) # exitRouter (config-pmap) # class class2Router (config-pmap-c) # bandwidth 2000 Router (config-pmap-c) # exit ==== LLQ ===== class-m Ap voipmatch ip precedence 5! Class-map mission-criticalmatch ip precedence 3 4! Class-map transactionalmatch ip precedence 1 2! Policy-map Policy1class voippriority percent 10 class mission-criticalbandwidth percent 30random-detectclass transactionalbandwidth percent 20random-detectclass-defaultfair-queuerandom-detect the most common command: show policy-map interface interface13-congestion avoidance and RED: when there is no congestion avoidance, when the packet loss rate reaches 5%, the application layer throughput is reduced by 50% because of TCP retransmission mechanism (TCP synchronization ), (timeout retransmission and repeat ACK) in order to break TCP synchronization, a congestion avoidance mechanism is introduced. To achieve this mechanism when the outbound interface is not congested, the RED technology is introduced for a class, the packet is discarded randomly to reduce the TCP speed. The following concepts are introduced: minimum threshold (similar to CDT) and maximum CB-WRED for threshold values (similar to HQO) and discard likelihood: Based on DSCP and IPP. random-detect activates WREDIPP with a default N value of 9. WRED can be used with bandwidth and sharp for 14-Police and Shape to take effect before entering the software queue. In essence, it is used to limit traffic, such as Police and load shifting, if the buffer usage is small, you can mark Shaping, load shifting, and load shifting to take effect before entering the software queue. Flushing is a discard packet <load shifting>, while shaping is cached in the buffer. Token ing supports tagging, that is, it can be used in the outbound interface, or it can be used in the ingress interface to sort the bucket size/number, how to place tokens in the bucket, after classification, the flexibility card changes to single-rate single-bucket/single-rate dual-bucket (BC/BE), divided into three categories/Dual-rate dual-pass, divided into three types of Shaping only one bucket, apply to outbound interface 15-Wan compression technology <omitted>