Autoqos on Aaron's Worthless Words

ONT Notes - AutoQoS

Wed, 10 Feb 2010 00:00:00 +0000

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 – Classification, Marking, and NBAR

Fri, 22 Jan 2010 00:00:00 +0000

Here’s another set of notes from my ONT studies. I’m sure someone will find it useful. Please help to correct dumbass mistakes.

Classification is done with traffic desriptors
- Ingress interface
- CoS value on ISL or 802.1P frames
- Source/destination IP address
- IP Precedence or DSCP value
- MPLS EXP
- Application type
Layer 3 QoS
- Type of Service (ToS) is 8-bit field.
- First 3 bits of ToS are the IP precedence.
- First 6 bits of ToS are the DSCP value.
- Last 2 bits of ToS are explicit congestion notification (ECN).
Layer 2 QoS

ONT Notes - Intro to QoS

Thu, 21 Jan 2010 00:00:00 +0000

I’ll try to keep it a little shorter this time.

Major issues for converged enterprise networks

Available bandwidth: competition among applications
- Fixes
  - Increase bandwidth: More power!
  - Properly queue based on classification and marking: QoS
  - Compress: cRTP, TCP header compression, etc.
Delay: Lead time to get a packet to the destination
- Types of delay
  - Processing delay: routing, switch delay
  - Queuing delay: how long a frame stays in an output queue
  - Serialization delay: how long to put the frame on the wire
  - Propagation delay: the time to cross the physical medium
Jitter (delay variation): Variation is the delay
- Different delays mean different arrival times
- De-jitter buffers save up packets to reduce jitter (like the old CD writers)
- Fixes
  - More bandwidth
  - Prioritize sensitive data and forward first
  - Remark (reclassify) packets based on sensitivity
  - Enable L2 payload compression: make sure compression delay isn’t worse than the jitter
  - Use header compression
Packet loss: Packets are lost in the network somewhere
- Fixes
  - More bandwidth
  - Increase buffers space: more room for the queue on the interface
  - Provide guaranteed bandwidth: Queuing and QoS
  - Congestion avoidance
    - Random Early Detection (RED) and weighted RED (WRED) drop packets before the queue is full
    - Selective dropping is better than FIFO or LIFO dropping

QoS History