Archive for the ‘headers’ tag
ONT Notes – QoS On Wireless Networks
- Wireless LANs (WLANs)
- Extensions to wired LANs
- Carrier sense multiple access collision avoidance (CSMA/CA) as media access method
- Uses distributed coordinated function (DCF) for collision avoidance
- DCF is based on RF carrier sense, inter-frame spacing (IFS), and random wait timers
- Wifi QoS standards
- 802.11e
- IEEE standard
- 0-7 priority levels
- Wifi Multimedia (WMM)
- Four access categories
- Platinum (voice) – 6 or 7 802.11e
- Gold (video) – 4 or 5 802.11e
- Silver (BE) – 0 or 3 802.11e
- Bronze (Background) – 1 or 2 802.11e
- Four access categories
- WMM and 802.11e replace DCF with EDCF
- 802.11e
- Cisco Split-MAC
- Splits functions between Lightweight access points (LWAPs) and WLAN controllers (WLCs)
- LWAPs handle real-time functions
- Beacon generation
- Probe transmission and response
- Power management
- 802.11e/WMM scheduling and queuing
- Packet buffering
- Encryption/decryption
- Control frame/message processing
- WLCs handle non-real-time functions
- Association/disassociation/reassociation
- 802.11e/WMM resource reservation
- 802.1x EAP
- Key management
- Authentication
- Fragmentation
- Ethernet-WLAN bridging
- End-to-end QoS
- Step 1: WLC copies DSCP from switch to outer DSCP and outer 802.1p and sends to LWAP over LWAPP tunnel
- Step 2: LWAP copies outer DSCP from WLC to 802.11e/WMM field and sent to client
- Step 3: LWAP copies 802.11e/WMM value from the client to outer DSCP and sends it to WLC
- Step 4: WLC copies outer DSCP from WLAP to 802.1p (CoS) fields and sends it to the switch
- Web interface (do you even need to know this?)
- Controller>QoS Profiles
- Per-User Bandwidth Contracts – set avg data rate, burst data rate, avg real-time rate, and burst real-time rate
- Over the Air QoS
- Maximum RF usage per AP (%)
- Queue Depth – queue size before dropping packets
- Wired QoS Protocol – 802.1p or None
- Controller>WLANs>Edit
- For each WLAN ID, set the QoS value: plat, gold, silver, bronze
- WMM Policy
- Disabled – 802.11e/WMM QoS requests are ignored
- Allowed – 802.11e/WMM QoS requests are sent
- Required – 802.11e/WMM QoS requests are required
- Controller>QoS Profiles
ONT Notes – AutoQoS
- AutoQoS benefits
- Automates QoS for most deployments
- Protects business-critical apps to maximize availability
- Simplifies QoS deployments
- Reduces configuration errors
- Cheaper, faster, and simpler deployments
- Follows DiffServ
- Allows complete control over QoS configs
- Allows modification of auto-generated configs
- AutoQoS phases of evolution
- AutoQoS VOIP – Early version that configures the basics without discovery
- AutoQoS for Enterprise – Second version that only runs on routers and uses two-step process
- Autodiscovery using NBAR
- Generation of class maps
- AutoQoS key elements
- Application classification
- Policy generation
- Configuration
- Monitoring and reporting
- Consistency
- Interfaces that you can configure AutoQoS on
- Serial ifs with PPP and HDLC
- FR point-to-point subifs (NOT multipoint)
- ATM point-to-point subifs
- FR-to-ATM links
- Prerequsites
- No Qos policy already configured on if
- CEF enabled on if
- Correct bandwidth configured on if
- IP address on low-speed if
- Configuring AutoQoS Enterprise on a router (NOT a switch)
- auto qos discovery – begins discovery process
- auto qos – generates and applies MQC-based policies
- Configuring AutoQoS VOIP
- auto qos voip [ trust | cisco-phone ]
- Verifying AutoQoS on router
- show auto discovery qos – get autodiscovery results
- show auto qos – examine configuration generated
- Number of classes
- Classification options
- Marking options
- Queuing mechanisms
- Other QoS mechanisms
- If, subif, PVC where policy is applied
- show policy-map interface – look at if stats
- Verify AutoQoS VOIP
- show auto qos
- show policy-map interface
- show mls qos maps – shows CoS to DSCP mappings
- Possible issues with AutoQoS
- Too many traffic classes – manually consolidate some
- Configuration doesn’t change – rerun AutoQoS
- Configuration may not fit your situation – fine-tune it by hand
- Fine-tuning AutoQoS
- Use QPM
- CLI
- copy policy into editor, change, reapply
- AutoQoS can match on characteristics besides ACLs and NBAR
- match input interface
- match cos
- match ip precedence
- match ip dscp
- match ip rtp
ONT Notes – Pre-classify and End-to-end QoS
- VPNs (Didn’t ISCW cover this?)
- Provide
- Confidentiality
- Integrity
- Authentication
- Types
- Remote-access
- Client-initiated
- NAS-initiated
- Site-to-site
- LAN-to-LAN
- Extranet
- Remote-access
- Provide
- L3 Tunneling protocols
- GRE
- IPSec
- Pre-classify allows traffic to be classified before being sent across a tunnel or crypto-ed.
- qos pre-classify
- Provides a view into the original IP headers
- To classify on pre-tunnel header, apply the policy to the tunnel interface WITHOUT pre-classify.
- To classify on post-tunnel header, apply the policy to the physical interface WITHOUT pre-classify.
- To classify on pre-tunnel header, apply the policy to the physical interface WITH pre-classify.
- SLA – agreement with provider to guarantee QoS mechanisms across their network based on your markings.
- Assures availability, loss, throughput, delay, and jitter.
- End-to-end QoS
- To be effective, each hop in the path must have QoS configured similarly.
- Necessary in three locations
- Campus – within the customer network
- The edges – customer facing the provider, provider facing customer
- On the provider network
- QoS tasks
- Campus access switches
- Speed/duplex settings
- Classification
- Trust
- Phone/access switch configs
- Multiple queues on switch ports, including priority for VOIP
- Campus distribution
- L3 policing and marking
- Multiple queues on switch ports, including priority for VOIP
- WRED
- WAN edge
- SLA definitions
- LLQ
- LFI
- WRED
- Shaping
- Provider cloud
- Capacity planning
- PHB
- LLQ
- WRED
- Campus access switches
- Enterprise campus QoS implementation
- Implement multiple queues to avoid congestion
- Assign VOIP and video to highest priority queue
- Esablish trust boundaries
- Use policing to rate-limit excess traffic
- Use hardware QoS when possible
- Control Plane Policing (CoPP)
- Applies QoS policy to traffic destined for the router
- Routing protocols
- Management protocols
- Can be used to avoid DOS attacks
- Applied to control-plane in global config
- Applies QoS policy to traffic destined for the router