network_stuff:cisco:qos
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| network_stuff:cisco:qos [2021/09/06 19:41] – created jotasandoku | network_stuff:cisco:qos [2023/11/02 14:38] (current) – external edit 127.0.0.1 | ||
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| * ignore ENC for marking (2 bits). | * ignore ENC for marking (2 bits). | ||
| * QoS EF(101110) is one and is above AF (is twelve possible values) ; The CS is for backwards compatibility with IPP (3 bits) | * QoS EF(101110) is one and is above AF (is twelve possible values) ; The CS is for backwards compatibility with IPP (3 bits) | ||
| + | |||
| + | * Common values: | ||
| + | * 48: Network Control | ||
| + | * 46: EF | ||
| + | * 32: Real-time | ||
| + | * 0 : BE | ||
| \\ | \\ | ||
| Marking Example: Cs6 network critical ; EF voice ; Afxx for other important traffic ; BE rest | Marking Example: Cs6 network critical ; EF voice ; Afxx for other important traffic ; BE rest | ||
| ---- | ---- | ||
| + | |||
| + | __CONGESTION AVOIDANCE__ | ||
| + | |||
| + | * Policing | ||
| + | * Shaping | ||
| + | |||
| + | Shapers can only be used on **outbound traffic**. You can’t shape traffic arriving on an interface. **__It’s already arrived__**. There is no “buffer” to work with). | ||
| + | |||
| + | ---- | ||
| + | __CONGESTION MANAGEMENT__\\ | ||
| + | Now, the network device has a reason to consider which packet to send next.\\ | ||
| + | * **CBWFQ**: FQ is just some level of fairness for example don't let elephant flows choke the rest. | ||
| + | * CBW is to obey the markings and apply whatever. policies we define. So Class here is obeying the Markings | ||
| + | * **LLQ**: Means Priority Queue with a Policer: priority up to a max rate | ||
| + | * Rule of thumb do not allocate more than 33% to the LLQ (note is singular) | ||
| + | |||
| + | |||
| + | ---- | ||
| + | ---- | ||
| + | Advanced stuff:\\ | ||
| + | FQ_CoDel: | ||
| + | * CoDel measures how long long a packet has been in the queue, which it calls the “sojourn time.” When the sojourn time is too long, CoDel drops the packet. | ||
| + | * This aggressive drop approach allows TCP to back off to an appropriate rate, and you end up with a more consistent flow rate, more even utilization of the interface, and better sharing among traffic flows. | ||
| + | * CoDel per queue [https:// | ||
| + | |||
| + | ---- | ||
| + | TCP disciplines: | ||
| + | * CUBIC: BIC and CUBIC TCP variants use math to compute how much to open or close the sliding window based on round trip time and how much data was lost in a given acknowledgement cycle. That’s different from default TCP behavior, which slides the window shut and starts all over again to ramp up the unacknowledged transfer amount whenever there’s packet loss. | ||
| + | * BBR gives nominal TCP performance improvements over CUBIC, but when you operate at Google’s scale, every little bit matters. | ||
| + | |||
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