From 1ed2135f9bdccb7859ac53f031d3f7d697599ff8 Mon Sep 17 00:00:00 2001 From: Isaac Shoebottom Date: Mon, 22 Jan 2024 12:38:16 -0400 Subject: [PATCH] 2024-01-22 12:38:16 --- .obsidian/plugins/obsidian-git/data.json | 2 +- .obsidian/workspace.json | 20 +++---- UNB/Year 4/Semester 2/CS2333/2024-01-22.md | 0 UNB/Year 4/Semester 2/CS3873/2024-01-22.md | 56 ++++++++++++++++++++ UNB/Year 4/Semester 2/CS3873/CS2024-01-22.md | 8 --- 5 files changed, 67 insertions(+), 19 deletions(-) create mode 100644 UNB/Year 4/Semester 2/CS2333/2024-01-22.md create mode 100644 UNB/Year 4/Semester 2/CS3873/2024-01-22.md delete mode 100644 UNB/Year 4/Semester 2/CS3873/CS2024-01-22.md diff --git a/.obsidian/plugins/obsidian-git/data.json b/.obsidian/plugins/obsidian-git/data.json index a3b7fad..f2dabf0 100644 --- a/.obsidian/plugins/obsidian-git/data.json +++ b/.obsidian/plugins/obsidian-git/data.json @@ -1,7 +1,7 @@ { "commitMessage": "{{date}}", "commitDateFormat": "YYYY-MM-DD HH:mm:ss", - "autoSaveInterval": 1, + "autoSaveInterval": 10, "autoPushInterval": 0, "autoPullInterval": 0, "autoPullOnBoot": true, diff --git a/.obsidian/workspace.json b/.obsidian/workspace.json index adf1c76..564c4ce 100644 --- a/.obsidian/workspace.json +++ b/.obsidian/workspace.json @@ -4,16 +4,16 @@ "type": "split", "children": [ { - "id": "c0c8d0798199c14a", + "id": "7e1a8e1157b8660a", "type": "tabs", "children": [ { - "id": "38642519e0ef3cbe", + "id": "81e5aff710e811bc", "type": "leaf", "state": { "type": "markdown", "state": { - "file": "UNB/Year 4/Semester 2/CS3873/CS2024-01-22.md", + "file": "UNB/Year 4/Semester 2/CS2333/2024-01-22.md", "mode": "source", "source": false } @@ -85,7 +85,7 @@ "state": { "type": "backlink", "state": { - "file": "UNB/Year 4/Semester 2/CS3873/CS2024-01-22.md", + "file": "UNB/Year 4/Semester 2/CS2333/2024-01-22.md", "collapseAll": false, "extraContext": false, "sortOrder": "alphabetical", @@ -102,7 +102,7 @@ "state": { "type": "outgoing-link", "state": { - "file": "UNB/Year 4/Semester 2/CS3873/CS2024-01-22.md", + "file": "UNB/Year 4/Semester 2/CS2333/2024-01-22.md", "linksCollapsed": false, "unlinkedCollapsed": true } @@ -125,7 +125,7 @@ "state": { "type": "outline", "state": { - "file": "UNB/Year 4/Semester 2/CS3873/CS2024-01-22.md" + "file": "UNB/Year 4/Semester 2/CS2333/2024-01-22.md" } } }, @@ -156,10 +156,12 @@ "table-editor-obsidian:Advanced Tables Toolbar": false } }, - "active": "38642519e0ef3cbe", + "active": "81e5aff710e811bc", "lastOpenFiles": [ + "UNB/Year 4/Semester 2/CS2333/2024-01-22.md", + "UNB/Year 4/Semester 2/CS3873/2024-01-22.md", + "UNB/Year 4/Semester 2/CS3873/2024-01-19.md", "UNB/Year 4/Semester 2/STAT2593/2024-01-22.md", - "UNB/Year 4/Semester 2/CS3873/CS2024-01-22.md", "README.md", "UNB/UNB.md", "UNB.md", @@ -189,8 +191,6 @@ "Semester 1/CS3418/10-30-2023.md", "Semester 1/CS3418/10-27-2023.md", "Semester 1/CS2418/10-25-2023.md", - "Semester 1/CS2418/10-23-2023.md", - "Semester 1/CS3418/10-25-2023.md", "Semester 1/CS2418", "Semester 1/CS3418" ] diff --git a/UNB/Year 4/Semester 2/CS2333/2024-01-22.md b/UNB/Year 4/Semester 2/CS2333/2024-01-22.md new file mode 100644 index 0000000..e69de29 diff --git a/UNB/Year 4/Semester 2/CS3873/2024-01-22.md b/UNB/Year 4/Semester 2/CS3873/2024-01-22.md new file mode 100644 index 0000000..44d350d --- /dev/null +++ b/UNB/Year 4/Semester 2/CS3873/2024-01-22.md @@ -0,0 +1,56 @@ +Lecture Topic: Packet Switching Performance +# Packet Switching +## Congestion +A relevant example is air plane ticket overbooking. If an air plane has a capacity of 100 seats, and the probability of of a passenger showing up to their flight is 80%, then you can overbook ticket sales due to the probability of passengers not showing up +- If 110 tickets are sold, the probability of more than 100 passengers is 0.0058% +- If 115 tickets are sold, the probability goes up to 1.94% +- If 120 tickets are sold, the probability is 15.17% +- If 130 tickets are sold, the probability is 78.12% + +## Performance +Throughput: Rate (bits/time) at which bits are transferred between sender/receiver +- Instantaneous: Receiving rate at any instant of time +- Average: Receiving rate over a longer period of time + +How fast a node (host or router) is transmitting depends on +1. How fast the sender is sending +2. How fast the link is transmitting + +End-to-end throughput is constrained by rate of bottleneck link (the link of the minimum rate on an end-to-end path). The weakest link in the chain (of nodes) determines the throughput of the entire link. + +## Delay and Loss +Packets queue in a router buffer (Store and Forward) +- They are delayed while waiting in the buffer for it's turn +- Slowed down while the queue keeps growing (congestion) +- Dropped (lost) if no free space in a full buffer + +There is four sources of nodal delay: +1. Node processing: Decoding the incoming electronic signal and accounting for distortion (e.g. wireless signal distortion), and verifying the correctness of the packet, and determining the output link. Usually very small ($10^{-6}$ secs) +2. Queuing: Time waiting at the output link for transmission. Amount depends on the congestion of the network. +3. Transmission: $L/R$, L = Packet length, R = Link bandwidth +4. Propagation: $m/s$ m = Physical distance of link (e.g. 100m wire), s = propagation speed of link (e.g. speed of electricity) + +The entire delay is the sum of all of these figures + +### Measuring queuing delay +Traffic intensity is a measure of congestion. +$$ \frac{L \times a}{R} $$ +a: Average packet arrive rate (packets/s) +L: Packet length/size (bits/packet) +R: Link bandwidth/rate (bps) + +If this figure is 0, the delay on average is very small +If this figure is 1, the delay is large +If this figure is > 1, then more work arriving than serviced (severe congestion) + +Note: There is a field called traffic engineering, and an important rule for this field is to not let the traffic intensity exceed 1. + +## Example: Delay +Consider only transmission delay and propagation delay. S sends 1 packet of length L to D over a single link of rate R and distance m. s is the speed of the link + +L = 1 kb +R = 100 kb/s +m = 100 km +s = $2\times10^8$ m/s + +$d_{prop} = m/s = 10^5/(2\times 10^8) = 5 \times 10^{-4}$ \ No newline at end of file diff --git a/UNB/Year 4/Semester 2/CS3873/CS2024-01-22.md b/UNB/Year 4/Semester 2/CS3873/CS2024-01-22.md deleted file mode 100644 index c6f21b9..0000000 --- a/UNB/Year 4/Semester 2/CS3873/CS2024-01-22.md +++ /dev/null @@ -1,8 +0,0 @@ -Lecture Topic: -# Packet Switching -## Congestion -A relevant example is air plane ticket overbooking. If an air plane has a capacity of 100 seats, and the probability of of a passenger showing up to their flight is 80%, then you can overbook ticket sales due to the probability of passengers not showing up -- If 110 tickets are sold, the probability of more than 100 passengers is 0.0058% -- If 115 tickets are sold, the probability goes up to 1.94% -- If 120 tickets are sold, the probability is 15.17% -- If 130 tickets are sold, the probability is 78.12% \ No newline at end of file