Comp 343/443-001 Week 2 notes

Assignment 1
    Chapter 1 exercises 1.0, 4.0, 5.0, 7.0, 9.0 (not 8)
    Chapter 2 exercises 2.0, 3.0, 6.0
    Due Thurs, Sept 16

1.10: IP

Routing on network prefix only

    local delivery

hierarchical routing


IP address assignment

why does IP support fragmentation?
    virtual circuits

Here is the routing table for my previous laptop, when at home and connected to both Ethernet and Wi-Fi. It's from the route command (very similar to netstat -r).

Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
default         asgard61         UG    100    0        0 enp0s25
default         asgard         UG    600    0        0 wlp3s0   U     600    0        0 wlp3s0   U     100    0        0 enp0s25   U     0      0        0 tap0
link-local     U     1000   0        0 enp0s25

The destinations are at left. Only the first two have the G flag, and thus have a gateway; the last four are link-level routes. The Gateway column lists the next_hop, where applicable; for non-G route entries, there is no next_hop and everything must be delivered directly. The prefix length for each Destination address is specified by Genmask, where you count the number of 1-bits. Note that the two valid next_hop entries are listed by hostname.

From the newer ip route list command:

default via dev enp0s25 proto dhcp                  metric 100
default via dev wlp3s0  proto dhcp                  metric 600 dev wlp3s0  proto kernel scope link src metric 600 dev enp0s25 proto kernel scope link src metric 100 dev tap0    proto kernel scope link src linkdown dev enp0s25           scope link              metric 1000

Here, destinations are listed as destaddr/mask. The link-level routes are listed as "scope link". The metric values are arbitrary; smaller is better. The src values represent the IP address of this machine on the given subnet. Some spaces have been added in an attempt to get similar values to line up.

1.11: DNS

1.12: Transport
    TCP goals
    TCP interface

1.13: Firewalls

Ethernet: start Chapter 2

10 Mbps classic Ethernet
broadcast bus
collisions: meant to be normal
physical v logical layer
Network Interfaces and packet delivery
multicast addresses

Ethernet diagram with NIs

Ethernet collision timeline

scaling Ethernet to 100 Mbps, etc
    scaling problems
    switched full duplex => collision-free!

basic Ethernet-switch learning algorithm

Back to Ethernet:
    Spanning-tree algorithm
    Brief look at SDN

Chapter 3:

3.1: VLANs      
3.2: Carrier Ethernet
3.3: VPNs

(skip Virtual Circuits and ATM for now)

3.6: Radioland
3.7: Wi-Fi (3.7.1-3.7.4; maybe some 3.7.5-3.7.7)
    collision basics