3D Connexion OL-6415-03 Owner's Manual
Contents
1. 1 policy map priority_queue class ip_dscp_40_47 set cos 5 1 interface Dot11Radio 0 2 0 no ip address service policy output priority_queue Cisco Wireless Router and HWIC Configuration Guide Ta E OL 6415 03 Chapter7 Configuring QoS on an Access Point Configuration Guidelines W Cisco Wireless IP Phone 7920 Support The Wireless IP Phone 7920 phone uses Cisco CDP message with Appliance VLAN ID TLV to inform the access point of its presence The access point intercepts the CDP messages sent from the client and if it contains the Appliance VLAN ID TLY it should flag the client as VoIP phone client If VLAN is enabled all phone clients should be associated to a single Voice VLAN If VLAN is not enabled we advise that all the VoIP packets be classified by using the same user_priority value 6 The access point always uses DIFS with minimum contention window CW value derived from the CWmax and CWmin range parameters to prioritize voice traffic Radio Interface Transmit Queues The radio maintains four priority queues one for each traffic category and 802 1 le Enhanced DCF EDCF to provide differentiate Distributed Coordination Function DCF access to the wireless medium An EDCF aware access point is assigned distinct pairs of CWmin and CWmax parameters for each traffic category The CWmin and CWmax parameters can be modified through the CLI Adjusting Radio Access Categories The access point uses the radio ac2. Configuring QoS on an Access Point This chapter describes how to configure quality of service QoS on an access point QoS provides preferential treatment to certain traffic at the expense of other traffic Without QoS the access point offers best effort service to each packet regardless of the packet contents or size It sends the packets without any assurance of reliability delay bounds or throughput Recommended Reading The following information is recommended for gaining a better understanding of QoS as it applies to voice deployments in a wireless environment Wireless Quality of Service Deployment Guide http www cisco com en US products hw wireless ps430 prod_technical_reference09186a008014449 8 html Cisco Wireless IP Phone 7920 Design and Deployment Guide http www cisco com en US products hw phones ps379 products_implementation_design_guide_boo k09186a00802a029a html Understanding QoS for Wireless LANs Typically networks operate on a best effort delivery basis that means that all traffic has equal priority and an equal chance of being delivered in a timely manner When congestion occurs all traffic has an equal chance of being dropped When QoS is configured on an access point you can select specific network traffic prioritize it and use congestion management and congestion avoidance techniques to provide preferential treatment Implementing QoS in a wireless LAN makes network performance more predictable and bandwi
3. anded range Allow or deny packet forwarding based on IP source or destination addresses Cisco Wireless Router and HWIC Configuration Guide a OL 6415 03 Chapter7 Configuring QoS on an Access Point Configuration Guidelines W Table 7 4 Access Control List Numbers 700 799 MAC address access list Allow or deny packet forwarding based on Ethernet packet MAC source or destination addresses 200 299 Protocol type code access list Allow or deny packet forwarding based on packet protocol type code in the case of Ethernet it is either DIX SAP or SNAP type The radio interface supports the following access lists lt 1 99 gt IP standard access list e lt 100 199 gt IP extended access list e lt 700 799 gt MAC address access list lt 200 299 gt Protocol type code access list The rest of the access lists can be applied but it is not recommended Applying Access Control Lists An access control list can be applied to an the ingress or egress of the interface The type of access control list determines the best place to apply the list Table 7 5 summarizes where the access control lists should be applied Table 7 5 Access Control List Recommended Location ACL Range Location lt 1 99 gt Apply to interface ip access group lt acl_num gt lt in lt 100 199 gt onie lt 200 299 gt Apply to interface bridge group lt x gt lt input lsap list input type list gt lt acl_nu
4. applied to VLAN sub interface to match packet on a particular VLAN the keywords match any should be used class map lt name gt match any Policy Map Keyword for Set COS Value A packet that matches the classifier specified in the class parameter is assigned the Class of Service CoS value specified in set cos command policy map lt policy_name gt class lt class_name gt set cos lt 0 7 gt Configure Contention Windows Values To Traffic Classes Set cw min cw max and the fixed slot times parameters for a particular traffic class to radio The values for cw min and cw max are power of 2 The actual value of cw min and cw max are power of 2 1 If the parameter zero is configured for cw min and cw max the effective cw min and cw max value will be zero traffic class lt 0 7 gt cw min lt gt cw max lt gt fixed slot lt cnt gt I OL 6415 03 Cisco Wireless Router and HWIC Configuration Guide jg Chapter7 Configuring QoS onan Access Point W End User Interface Cisco Wireless Router and HWIC Configuration Guide
5. cess categories to calculate backoff times for each packet As a rule high priority packets have short backoff times The default values in the minimum and maximum contention window fields and in the slot time fields are based on settings recommended in IEEE Draft Standard 802 1 le For detailed information on these values consult the standard We recommend that you use the default settings Changing these values can lead to unexpected blockages of traffic on your wireless LAN and the blockages might be difficult to diagnose If you change these values and find that you need to reset them to the default values The values listed in Table 7 2 are to the power of 2 The access point computes contention window values by using the equation CW 2 X minus 1 where X is the value in Table 7 3 Table 7 3 CWmin and CWmax Default Parameters Priority Fixed slottime Number CW min CW max 0 6 15 1023 1 2 15 1023 2 1 7 15 3 1 3 7 Cisco Wireless Router and HWIC Configuration Guide I OL 6415 03 a Chapter7 Configuring QoS onan Access Point Hs Configuration Guidelines Ethernet Interface Transmit Queue Since the Ethernet interface always has a larger bandwidth than radio interface there is no need to maintain priority queues for Ethernet interface There will be only one transmit queue per Ethernet interface 802 1Q Untagged Voice Packets If VLAN is enabled IOS bridging code adds 802 11q tags into the unta
6. clients when the QoS Element for Wireless Phones feature is enabled To contrast the wireless LAN QoS implementation with the QoS implementation on other Cisco network devices see the Cisco IOS Quality of Service Solutions Configuration Guide at this URL http www cisco com univercd cc td doc product software ios 122 122cgcr fqos_c index htm Impact of QoS ona Wireless LAN Wireless LAN QoS features are a subset of the proposed 802 1 1e draft QoS on wireless LANs provides prioritization of traffic from the access point over the WLAN based on traffic classification Just as in other media you might not notice the effects of QoS on a lightly loaded wireless LAN The benefits of QoS become more obvious as the load on the wireless LAN increases keeping the latency jitter and loss for selected traffic types within an acceptable range QoS on the wireless LAN focuses on downstream prioritization from the access point The radio downstream flow is traffic transmitted out the access point radio to a wireless client device This traffic is the main focus for QoS on a wireless LAN The radio upstream flow is traffic transmitted out the wireless client device to the access point QoS for wireless LANs does not affect this traffic The Ethernet downstream flow is traffic sent from a switch or a router to the Ethernet port on the access point If QoS is enabled on the switch or router the switch or router might prioritize and rate limit tra
7. dth utilization more effective Configuring QoS creates and applies policies to the VLANs configured on the access point If VLANs are not used on the network QoS policies can be applied to the Ethernet and radio ports QoS for Wireless LANs Versus QoS on Wired LANs The QoS implementation for wireless LANs differs from QoS implementations on other Cisco devices With QoS enabled access points perform the following Does not classify packets it prioritizes packets based on Differentiated Services Code Point DSCP value client type such as a wireless phone or the priority value in the 802 1q or 802 1p tag I OL 6415 03 Cisco Wireless Router and HWIC Configuration Guide gg Chapter7 Configuring QoS onan Access Point HI Understanding QoS for Wireless LANs Does not construct internal DSCP values it only supports mapping by assigning IP DSCP precedence or protocol values to Layer 2 CoS values Table 7 1 lists the class of service CoS values as they map to DSCP values Table 7 1 CoS Values Mapped to DSCP Values CoS Value DSCP Value 1 10 2 18 3 26 4 34 5 46 6 48 7 56 Carries out Enhanced DCF EDCF like queuing on the radio egress port only Support only 802 1Q P tagged packets Access points do not support ISL Support only Cisco Modular QoS CLI MQC policy map set cos action Prioritize the traffic from voice clients such as Symbol phones over traffic from other
8. er for the purpose of Providing QoS for Voice over IP VoIP phones e Mapping IP precedence values into 802 1P Q Class of Service CoS values for downlink traffic Providing Layer 2 and Layer 3 Access Control List features to the bridging path and access point host receive path 802 11 VOIP Phone Support The Symbol element is advertised by the access point This helps a Symbol phone to make an association decision if there are multiple access points serving the area The current packet rate is the calculation of average means of number of packets transmitted per second for the past 8 seconds After the normal 802 11 association process a Symbol phone sends a proprietary Symbol 802 11 phone registration message WNMP to the access point to complete the association The Symbol phone does not associate to an access point if the advertised packet rate is above the threshold of the access point The Symbol phone uses its Symbol Element as optional information Basic operation does not require an access point to send Symbol Elements Mapping IP Precedence Examples The QoS examples in this section show the mapping of IP precedence Matching IP Precedence class map match any ip_pres_5 match ip precedence 5 policy map priority_queue class ip_pres_5 set cos 5 interface Dot11Radio 0 2 0 ip address 30 5 0 105 255 255 0 0 service policy output priority_queue Matching IP DSCP class map match any ip_dscp_40_47 match ip dscp ef
9. ffic to the access point The Ethernet upstream flow is traffic sent from the access point Ethernet port to a switch or router on the wired LAN The access point does not prioritize traffic that it sends to the wired LAN based on traffic classification Figure 7 1 shows the upstream and downstream traffic flow Cisco Wireless Router and HWIC Configuration Guide 72 E OL 6415 03 Chapter7 Configuring QoS on an Access Point Configuration Guidelines W Figure 7 1 Upstream and Downstream Traffic Flow Radio Ethernet am downstream downstream lt Ga Wired 0000000000000 y gt Client Radio Access Ethernet 7 device upstream point upstream Precedence of QoS Settings When you enable QoS the access point queues packets based on the CoS value for each packet If a packet matches one of the filter types based on its current precedence the packet is classified based on the matching filter and no other filters are applied Table 7 2 shows the precedence of QoS filters Precedence number zero is the highest Table 7 2 Precedence of QoS Filters Precedence Filter Type 0 Dynamicly created VoIP client filter Traffic from voice clients takes priority over other traffic regardless of other policy settings This setting takes precedence over all other policies second only to previously assigned packet classifications 1 User configured class map match clause except match any QoS Policies configured f
10. gged voice packets The class of service CoS value should be part of the VLAN configuration For a voice VLAN the CoS should be 6 If VLAN is not enabled the access point relies on the DSCP to COS filter configured by the user to assign CoS value to the packet QoS on VLAN The default cos value for all the VLANs is zero best effort This ensures that the access point provides differentiate services based on VLAN IDs Packets sends to these clients are queued into the appropriate priority queue based on their VLAN CoS value If VLAN is enabled packets from a wireless client that must be forwarded to the wired network a 802 1q tag is added by the forwarding module Access Control Lists Table 7 4 shows the access control list number used to support access control features Table 7 4 Access Control List Numbers ACL number Usage 1 99 IP standard access list Allow or deny packet forwarding based on IP source or destination addresses 100 199 IP extended access list Allow or deny packet forwarding based on IP protocols and or protocol port numbers 1100 1199 Extended MAC address access list Allow or deny packet forwarding based on ethernet packet MAC addresses and or packets payload values on a given offset location and number of bytes extended 1300 1999 IP standard access list expanded range Allow or deny packet forwarding based on IP source or destination addresses 2000 2699 IP extended access list exp
11. ld be applied to the interfaces If VLAN is enabled the policy map should be applied to VLAN sub interfaces A policy map applied to an interface is ignored Enable 802 11 Phone Support Use the no dot11 phone command to configure the access point to advertise Symbol and QoS Basis Service Set QBSS information in the beacon and probe for response frames The access point processes incoming Symbol frames and Cisco CDP Appliance VLAN field to flag the client as a phone client Install IP Acess Control List To control access to an interface use the ip access group command in interface configuration mode To remove the specified access group use the no form of this command no ip access group lt 1 199 gt in out Access lists are applied on either outbound or inbound interfaces For standard inbound access lists after receiving a packet the Cisco IOS software checks the source address of the packet against the access list For extended access lists the router also checks the destination access list If the access list permits the address the software continues to process the packet If the access list rejects the address the software discards the packet and returns an ICMP host unreachable message Install MAC address Acess Control List To assign an access list to a particular interface use the bridge group input address list command in interface configuration mode This access list is used to filter packets received on that inte
12. m gt lt 700 799 gt Apply to interface bridge group lt x gt lt input address list output address list gt lt acl_num gt For each type of access list only one access list can applied to a direction We recommended that for IP access lists use only the extended IP access list numbers 100 through 199 because they can support multiple layers from Layer 3 to Layer 7 access control clauses in one access list Typical Layer 2 access control lists lt 200 299 gt and lt 700 799 gt only take effect inside the Layer 2 bridging path Packet received by the access point upper protocol stack are not be applied Cisco Wireless Router and HWIC Configuration Guide I OL 6415 03 E Chapter7 Configuring QoS onan Access Point HI End User Interface End User Interface The 802 1Q user_priority maps to radio transmit priority queues automatically VLAN default user_priority value must be explicitly assigned through the command line interface CLI or the default value zero is used for the VLAN For voice traffic whenever a 802 11 VOIP phone is associated with an access point a default traffic egress filter with user_priority value 6 is installed for all the voice traffic Cisco Modular QoS CLI MQC uses a class map clause to define traffic class and a policy map clause to define QoS policy A specific policy can be applied to an interface egress ingress or both If VLAN is not enabled the MQC the policy map shou
13. or and that apply to VLANs or to the access point interfaces are third in precedence after previously classified packets and the QoS Element for Wireless Phones setting 2 User configured class map match any clause match VLAN If a default classification for all packets on a VLAN is set that policy is fourth in the precedence list Configuration Guidelines Before configuring QoS on an access point you should be aware of this information Be familiar with the traffic on your wireless LAN If you know the applications used by wireless client devices the sensitivity of applications to delay and the amount of traffic associated with the applications configuring QoS improves performance QoS does not create additional bandwidth on a wireless LAN it helps control the allocation of bandwidth If there is enough of bandwidth on your wireless LAN it might not be necessary to configure QoS An access point is essentially a Layer 2 transparent bridge between wired and wireless networks Typically bandwidth on wireless side constrains the the wired side For example 802 1 1b offers 6 Mbps half duplex and 100baseT offers 100 Mbps full duplex Cisco Wireless Router and HWIC Configuration Guide I OL 6415 03 E Chapter7 Configuring QoS onan Access Point Hs Configuration Guidelines In addition a Cisco access point uses Access Control Lists for forwarding or blocking packets on selective basis as designated by the us
14. rface based on their MAC source addresses To remove an access list from an interface use the no form of this command bridge group bridge group input address list access list number Install Ethernet Type or SAP Acess Control List To filter Ethernet and Subnetwork Access Protocol SNAP encapsulated packets on input use the bridge group input type list command in interface configuration mode To disable this capability use the no form of this command bridge group bridge group input type list access list number Cisco Wireless Router and HWIC Configuration Guide _ Chapter 7 Configuring QoS on an Access Point End User Interface W Apply Layer 2 Acess Control List To Packet Received Sent Use the 12 filter bridge group acl configuration interface command to apply a Layer 2 access control list ACL filter to the bridge group incoming and outgoing packets between the access point and the host upper layer Use the no form of the command to disable the Layer 2 ACL filter no 12 filter bridge group acl If enabled and if any L2 ACLs are installed in ingress egress the same ACLs are applied to packets received or sent by AP host stack This example shows how to apply a Layer 2 ACL filter to the bridge group packets AP config if 12 filter bridge group acl This example shows how to activate a Layer 2 ACL filter AP config if no 12 filter bridge group acl Class Map Keyword for VLAN If a MQC policy map is
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