cbwfq-utils 0.1.1

CBWFQ calculation utilities

cbwfq-utils

cbwfq-utils is a Python library for automating the calculation of CBWFQ (Class-Based Weighted Fair Queuing) parameters and generating configuration commands for Cisco IOS.

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Features

• Aggregates flows into queues based on DSCP tags
• Calculates the minimum normalization coefficient Dmin
• Distributes bandwidth among queues
• Generates Cisco IOS configuration commands
• Convenient integration into Python projects
• Supports result visualization

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Library Overview

CBWFQ (Class-Based Weighted Fair Queuing) is a queue scheduling mechanism in Cisco network devices that distributes bandwidth among traffic classes.
The cbwfq-utils library automates CBWFQ parameter calculations and produces ready-to-use Cisco IOS commands.

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Installation

pip install cbwfq-utils

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Quick Start

import numpy as np
from cbwfq_utils import (
    parse_dscp, aggregate_flows, find_min_Dmin, calculate_bandwidths, generate_cisco_commands
)

# 1. Define the number of queues and flows
N = 3  # number of queues
M = 4  # number of flows

# 2. Set flow intensities (Mbps) and DSCP values
a = np.array([10, 20, 15, 30])
dscp_values = [0, 10, 18, 46]

# 3. Aggregate flows based on DSCP values
x2, kq = aggregate_flows(N, M, a, dscp_values)

# 4. Find the minimum Dmin for a valid solution
Dmin = find_min_Dmin(N, M, a, x2, kq, K=64, B=75, Dmin=11, max_Dmin=150)

# 5. Calculate bandwidth distribution and load coefficients
poo, x3, D_range = calculate_bandwidths(N, M, a, x2, kq, K=64, B=75, Dmin=Dmin)

# 6. Generate Cisco configuration commands
commands = generate_cisco_commands(N, M, x2, dscp_values, x3)

print("Cisco configuration commands:")
for cmd in commands:
    print(cmd)

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Function Descriptions

parse_dscp

parse_dscp(dscp: str | int) -> int

Converts a DSCP value into its numeric code. Supports both numeric and symbolic values (e.g., "ef", "af21", "default").

Example:

parse_dscp("ef")    # 46
parse_dscp("af21")  # 18
parse_dscp(10)      # 10

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aggregate_flows

aggregate_flows(N, M, a, dscp_values, K=64)

Aggregates flows into queues based on DSCP tags.

• N — number of queues
• M — number of flows
• a — flow intensity array
• dscp_values — array of DSCP values
• K — total number of DSCP labels (default is 64)

Returns:

• x2 — N x M flow-to-queue distribution matrix
• kq — average DSCP values per queue

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find_min_Dmin

find_min_Dmin(N, M, a, x2, kq, K, B, Dmin, max_Dmin)

Finds the minimum normalization coefficient Dmin that ensures a valid solution.

• K — number of DSCP values
• B — total bandwidth (Mbps)
• Dmin — starting value
• max_Dmin — maximum allowed value

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calculate_bandwidths

calculate_bandwidths(N, M, a, x2, kq, K, B, Dmin)

Computes bandwidth allocation and load coefficients per queue.

Returns:

• poo — load coefficients per queue
• x3 — bandwidth distribution
• D_range — D values used for calculations

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generate_cisco_commands

generate_cisco_commands(N, M, x2, dscp_values, x3)

Generates a list of Cisco IOS CLI commands for CBWFQ configuration.

Returns:

• List of command strings

class-map match-any q1
 match dscp default
 match dscp af11
 exit
class-map match-any q2
 match dscp af21
 exit
class-map match-any q3
 match dscp ef
 exit
policy-map pyauto
 class q1
  bandwidth 25000
  exit
 class q2
  bandwidth 15000
  exit
 class q3
  bandwidth 35000
  exit
int f0/1
 service-policy output pyauto
 exit
exit
wr

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Requirements

• Python >= 3.11
• numpy >= 1.24
• scipy >= 1.10

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License

MIT

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Author

Yaroslav WWFyb3NsYXYg
📧 [e-mail]

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Feedback & Contributions

• Report issues and request features via GitHub Issues
• Pull requests are welcome!

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Useful Links

• Cisco CBWFQ Documentation
• PyPI cbwfq-utils
• PyPI cisco_telnet