SlideShare a Scribd company logo
Angewandte Netzwerkgrundlagen reloaded
Von Layer 1 bis 3
FrOSCon 15 - Cloud Edition
Falk Stern, Maximilian Wilhelm
1 / 64
Agenda
1. Who's who
2. Models
3. Layer 1
4. Layer 2 (Ethernet)
1. LAGs / Bonding
2. VLANs
5. Layer 3 (IP)
2 / 64
Who's who Falk Stern
Full Stack Infrastructure Engineer
IPv6 fanboy
Runs his own Kubernetes cluster in his basement
Consultant @ Profi Engineering Systems AG
Contact
@wrf42
falk@fourecks.de
3 / 64
Who's who Maximilian Wilhelm
Infrastructure Engineer
OpenSource Hacker
Fanboy of
(Debian) Linux
IPv6
Occupation:
By day: Senior Infrastructure Architect, Uni Paderborn
By night: Infrastructure Archmage, Freifunk Hochstift
In between: Freelance Solution Architect for hire
Contact
@BarbarossaTM
max@sdn.clinic
4 / 64
Who's who
Models
Layer models - ISO/OSI, TCP/IP & Hybrid
5 / 64
Who's who
Models
Layer models - ISO/OSI, TCP/IP & Hybrid
Physical
Wires, Wireless - 802.3 & 802.11 (Bit)
Data Link
Addressing stations on the same physical medium (Ethernet MAC) (Frame)
Network
Adressing stations somewhere in the entire network (IPv4, IPv6) (Packet)
Transport
How to transport data? (Datagram, Segment)
Session, Presentation, Application
Which data to transport? (SSH, IRC, HTTP, etc.)
6 / 64
Who's who
Models
Layer 1
Layer 1 - Physical networking*
* for Ethernet 7 / 64
Who's who
Models
Layer 1
Air
802.11ac
802.11ax
Real copper cables
Usually Category 7 today
Category 6a is usually fine
Fiber
Multi mode fiber (MMF)
Single mode fiber (SMF)
Specials
Direct Attached Cable (DAC)
Active Optical Cable (AOC) Source: Wikimedia commons
The medium is the message
8 / 64
Who's who
Models
Layer 1
Wireless
Looks like Ethernet (802.3) but isn't
Differentiates between Stations (STA) and Access Points (AP)
Generation Max Linkrate Frequency
Wi-Fi 1 (802.11b) 1 - 11 Mbit/s 2.4 GHz
Wi-Fi 2 (802.11a) 1.5 - 54 Mbit/s 5 GHz
Wi-Fi 3 (802.11g) 3 - 54 Mbit/s 2.4 GHz
Wi-Fi 4 (802.11n) 72 - 400 Mbit/s 2.4 & 5 GHz
Wi-Fi 5 (802.11ac) 433 - 6933 Mbit/s 2.4 & 5 GHz
Wi-Fi 6 (802.11ax) 600 - 9608 Mbit/s 2.4 & 5 GHz, 1-6 GHz ISM
9 / 64
Who's who
Models
Layer 1
Wireless
Channels between 20 and 160 MHz
Channels usually overlap
2.4 GHz is dead, as well as 802.11abg
Problem with 5 GHz Channels is Radar DFS (Dynamic Frequency Selection)
Channelwidths above 20 MHz only usable in 5 GHz bands
10 / 64
Who's who
Models
Layer 1
Wireless Encryption
Started with a 40 Bit WEP key, 104 bit did cost extra
Currently WPA3 with PSK or EAP
EAP usually authenticates against a RADIUS server
PSK is "safe enough" for home use
11 / 64
Who's who
Models
Layer 1
Twisted Pair copper cables
https://en.wikipedia.org/wiki/2.5GBASE-T_and_5GBASE-T 12 / 64
Who's who
Models
Layer 1
Types of fibers
Multi mode fiber
Single mode fiber
Form factors of connectors
ST
SC
LC
E2000
MTO/MTP
Contact of connectors
PC
APC
Let's talk about bers
13 / 64
Who's who
Models
Layer 1
Usually used at 850nm
Attenuation between 1,5 - 3dB/km
Only suited for shorter ranges
Light is bouncing off the "edges"
Category Color code Fiber type
OM1 orange G62,5/125
OM2 orange G50/125
OM3 aqua G50/125
OM4 violet G50/125
OM5 lime G50/125
Acceptance
cone
Cladding
Cladding
Core
Multi mode ber (MMF)
https://de.wikipedia.org/wiki/Lichtwellenleiter#Multimodefaser 14 / 64
Who's who
Models
Layer 1
Usually used between 1270nm &
1610nm
Attenuation 0,4 - 1,0dB/km
Suited for long range connections
Light travels "straight"
Category Color code Fiber type
OS1 yellow E9/125
OS2 yellow E9/125
Single mode ber (SMF)
15 / 64
Who's who
Models
Layer 1
Maximum ber lengths*
Multi mode values depending on category!
The following values ignore
Use of amplifiers
Use of WDM
Number of patches
Connector types
Contact types
Speed Multi mode Single mode
1Gb/s ≤1000m ≤ 1km
10Gb/s ≤ 500m ≤ 80km
40Gb/s ≤ 150m ≤ 80km
100Gb/s ≤ 100m ≤ 80km
* This is a very rough overview 16 / 64
Who's who
Models
Layer 1
ST / Straight Tip (1992)
Still seen in the wild
Legacy infrastructure
SC / Standard connector (1993)
Used on older optics
Still in wide use on panels
24 duplex ports per RU
LC / Lucent/Little connector (2002)
De facto standard today
In wide use on optics & panels
48 duplex ports per RU
Common optical ber connectors
17 / 64
Who's who
Models
Layer 1
E2000 / LSH (1997)
Dust caps included
prevents you from looking into
the beam
More expensive
Usually used for MAN/WAN links
Multiple-Fiber Push-On/Pull-off
(MPO/MTP)
Connects up to 24 cores
Usually used within data centers
e.g. rear connection for panels
Source (MTP): Wikimedia commons
Common optical ber connectors (contd.)
18 / 64
Who's who
Models
Layer 1
Physical contact (PC)
Slightly convex surface
Mostly blue connectors bodies
Angled physical contact (APC)
Fiber end face polished at 8° angle
Green connector body
Contact type usually denoted as suffix:
LC/PC
E2000/APC
Common optical connectors / contact
https://en.wikipedia.org/wiki/Optical_fiber_connector#Contact 19 / 64
Who's who
Models
Layer 1
Transceivers
1Gb/s
GBIC
SFP
10Gb/s
Xenpak
X2
XFP
SFP+
25Gb/s
SFP28
40Gb/s
QSFP+
100Gb/s
CFP
QSFP28
400Gb/s
DD-QSFP
Transceivers - It's not all GBICs
20 / 64
Who's who
Models
Layer 1
Transceivers
Gigabit interface converter (GBIC)
old and busted (1995)
obsoleted by SFP
connector
RJ45
SC
proprietary
supported speeds:
1Gb/s
Transceivers - GBICs
21 / 64
Who's who
Models
Layer 1
Transceivers
Small form-factor pluggable (SFP)
introduced 2001
aka Mini-GBIC
connector
RJ45
LC
supported speeds
100Mb/s
1Gb/s
Transceivers - SFPs
https://en.wikipedia.org/wiki/Small_form-factor_pluggable_transceiver 22 / 64
Who's who
Models
Layer 1
Transceivers
introduced 2001
obsoleted by X2, XFP, SFP+
connectors
SC
CX4
converter to SFP+
supported speeds:
10Gb/s
Transceivers - XENPAK
23 / 64
Who's who
Models
Layer 1
Transceivers
introduced 2002
slightly smaller than XENPAK
consume less power than XENPAK
obsoleted by XFP, SFP+
connectors
SC
CX4
converter to SFP / SFP+
supported speeds:
1Gb/s (via converter)
10Gb/s
Transceivers - X2
24 / 64
Who's who
Models
Layer 1
Transceivers
introduced 2002/2003
much smaller than X2
slightly larger than SFP(+)
obsoleted by SFP+
connectors
LC
supported speeds:
10Gb/s
Source: Wikimedia commons
Transceivers - XFP
25 / 64
Who's who
Models
Layer 1
Transceivers
introduced 2006
much smaller than XENPAK, X2
slightly smaller than XFP
same size as SFP
compatible to SFP
connectors:
RJ45
LC
DAC
AOC
supported speeds:
1Gb/s
10Gb/s
Transceivers - SFP+
26 / 64
Who's who
Models
Layer 1
Transceivers
Quad SFP+
4 channels of 10Gb/s
slightly larger than SFP
fanout possible to 4x 10Gb/s
connectors:
LC
MTO/MTP
DAC
AOC
supported speeds:
10Gb/s
40Gb/s
Transceivers - QSFP+
27 / 64
Who's who
Models
Layer 1
Transceivers
4 channels of 28Gb/s
same size as QSFP(+)
compatible to QSFP+
fanout possible to
4x 10Gb/s
4x 25Gb/s
connectors:
LC
MTO/MTP
DAC
AOC
supported speeds:
10Gb/s
25Gb/s
40Gb/s
100Gb/s
Transceivers - QSFP28
28 / 64
Who's who
Models
Layer 1
Transceivers
one channel of 28Gb/s
same size as SFP(+)
compatible to SFP+
connectors:
LC
DAC
AOC
supported speeds:
1Gb/s
10Gb/s
25Gb/s
Transceivers - SFP28
29 / 64
Who's who
Models
Layer 1
Transceivers
Double-density Quad-SFP
8 channel of 50Gb/s
same size as QSFP*
fanout possible to
4x 100Gb/s
connectors:
LC
DAC
AOC
MTO/MTP
supported speeds:
400Gb/s
Transceivers - DD-QSFP
30 / 64
Who's who
Models
Layer 1
Outlook - CWDM
Coarse Wavelength Division Multiplexing
Using different wavelength on the same fiber
https://community.fs.com/de/blog/wdm-technology-basis-cwdm-vs-dwdm.html 31 / 64
Who's who
Models
Layer 1
Outlook - CWDM
Coarse Wavelength Division Multiplexing
Using different wavelength on the same fiber
Requires transceiver with specific "color"
https://community.fs.com/de/blog/wdm-technology-basis-cwdm-vs-dwdm.html 32 / 64
Who's who
Models
Layer 1
Copper based cable of fixed length
Transceiver permanently attached
SFP+/SFP28
QSFP/QSFP28
Available from 1Gb/s to 400Gb/s
Pros:
Much cheaper than fiber link
Simple
Cons:
Only useful within one / between
adjacent racks
Slightly higher latency
Susceptible for EM interference
Specials - Direct Attached Cable (DAC)
33 / 64
Who's who
Models
Layer 1
Specials - Active Optical Cable (AOC)
Fiber based cable of fixed length
Transceiver permanently attached
SFP+/SFP28
QSFP+/QSFP28
DD-QSFP
Available from 10Gb/s to 400Gb/s
Pros:
Slightly less attenuation than manual optical connection
At higher bandwidth cheaper than transceiver + cable
Cons:
Only useful within one / between adjacent racks
34 / 64
Who's who
Models
Layer 1
Layer 2 Layer 2 - Ethernet
35 / 64
Who's who
Models
Layer 1
Layer 2
Ethernet
Developed between 1973 and 1974 at Xerox
Inspired by ALOHAnet, the Packet Radio Network on Hawaii
At first available with 2,94 Mbps, 10 Mbps available commercially since 1980
Further development lead to IEEE standard 802.3 in 1983
CSMA/CD - "Carrier Sense, Multiple Access, Collision Detect"
Ethernet today:
Common access port speed: 1 Gbit/s
Common uplink/server interfaces speed: 10 - 40 Gbit/s
Up to 400-Gbit/s available commercially
Interfaces for copper or multi-mode / single-mode fiber
Preamble SFD
Source
MAC
Address
Destination
MAC
Address
EtherType FCSPayload
Source: Wikimedia Commons
36 / 64
Who's who
Models
Layer 1
Layer 2
Ethernet Technology
Repeater
Maximum Segmentlength in on network segment around 100m
Repeater amplify and repeat signals
Extend broadcast domains
Extend collision domains
Bridges
Extend broadcast domains
Limit collision domains
Important Rule: Frames must not be send out on port where they were received
37 / 64
Who's who
Models
Layer 1
Layer 2
Ethernet Devices
Hubs
Repeater with many ports
Switches
Bridges with many ports
Three possible actions to happen with any frame:
Forward
Replicate
Drop
38 / 64
Who's who
Models
Layer 1
Layer 2
Addresses
Format: AA:BB:CC:DD:EE:FF
Identify stations on the same physical medium
Should be unique (on the medium)
1st octet 2nd octet 3rd octet 4th octet 5th octet 6th octet
6 octets
or
Organisationally Unique
Identifier (OUI)
Network Interface Controller
(NIC) Specific
3 octets 3 octets
b7 b6 b5 b4 b3 b2 b1 b0
8 bits
0:
1:
unicast
multicast
0:
1:
globally unique (OUI enforced)
locally administered
Source: Wikipedia Commons
39 / 64
Who's who
Models
Layer 1
Layer 2
Linux command line example
$ ip link show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue
state UNKNOWN mode DEFAULT group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: eth0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast
state DOWN mode DEFAULT group default qlen 1000
link/ether 70:5a:0f:cf:21:f3 brd ff:ff:ff:ff:ff:ff
3: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq
state UP mode DORMANT group default qlen 1000
link/ether 64:80:99:cf:66:6f brd ff:ff:ff:ff:ff:ff
11: tun0: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1400 [...]
link/none
40 / 64
Who's who
Models
Layer 1
Layer 2
Spanning Tree
Protocol for loop prevention within ethernet networks
Create logical tree of network topology based on BPDUs
Will block connections which will produce loops
Only deactivate STP if you really know better
Seriously!
41 / 64
Who's who
Models
Layer 1
Layer 2 Layer 2 / LAGs
42 / 64
Who's who
Models
Layer 1
Layer 2
LAGs
Link Aggregation
Combine one or more physical links between two peers to one virtual link, to
increase over-all bandwidth
create a redundant Layer 2 link
both
Also know as:
LAG
Bonding (Linux)
Aggregated Ethernet (Juniper)
Port-Channel (Cisco)
Trunk (3Com, HP?)
NIC-Teaming
43 / 64
Who's who
Models
Layer 1
Layer 2
LAGs
Link Aggregation - Simple Linux bonding
Just use multiple links and hope the peer does, too.
Drawbacks:
If media converters are involved a link-down event may not propagate
No way to tell it the peer is configured the same way
44 / 64
Who's who
Models
Layer 1
Layer 2
LAGs
Link Aggregation - LACP
Link Aggregation Control Protocol (802.3ad / 802.1AX)
De-facto standard within networking world
Use LACP signalling to set up LAG with peer
Maximum of 8 interface per LAG
Keep alive every 1s (fast) or every 30s (slow)
An interface can be on one of two modes:
active: send out LACP packets to activly form the LAG
passive: wait for and only then reply to LACP packets
45 / 64
Who's who
Models
Layer 1
Layer 2
LAGs
Multi-Chassis Link Aggregation Groups
Link Aggregation between more than two peers
At least on peer has to do magic to make this work
Also know as:
MC-LAG
MLAG
Virtual Port-Channel (vPC)
Source: Wikipedia
46 / 64
Who's who
Models
Layer 1
Layer 2
LAGs
Loadbalancing Tra c over LAGs
Round-Robin
One packet on link 1, one on link 2, ..., and repeat
Hashing of header elds
Layer 2 (src MAC + dst MAC)
Only useful if communication is to multiple stations within local subnet
Layer 2+3 (src MAC + dst MAC + src IP + dst IP)
Might be more useful for communication without local subnet
Layer 3+4 (src IP + dst IP + src Port + dst Port)
Probably most useful when communicating with multiple peers
47 / 64
Who's who
Models
Layer 1
Layer 2
LAGs
Layer 2 / VLANs
48 / 64
Who's who
Models
Layer 1
Layer 2
LAGs
VLANs
Virtual Local Area Networks (VLANs)
Used to separate broadcast domains in LANs
VLAN transport between switches standardized as IEEE 802.1q
after proprietary standards from Cisco, 3COM
12 bit VLAN Identifier
only 4096 possible VLANs, ~100 reserved for internal switch functions
1 2 3 4 5 6
Destination MAC
1 2 3 4 5 6
Source MAC
1 2 3 4
802.1Q Header
TPID=0x8100 PCP/DEI/VID
1 . . . n
Payload
1 2
EtherType/
Size
1 2 3 4
CRC / FCS
1 2 3 4 5 6
Inter Frame Gap
7 8 9 10 11 12
1 2 3 4 5 6
Destination MAC
1 2 3 4 5 6
Source MAC
1 . . . n
Payload
1 2
EtherType/
Size
1 2 3 4
CRC / FCS
1 2 3 4 5 6
Inter Frame Gap
7 8 9 10 11 12
n = 42–1500
n = 46–1500
1 2 3 4 5 6
Preamble
7 8
SFD
1 2 3 4 5 6
Preamble
7 8
SFD
49 / 64
Who's who
Models
Layer 1
Layer 2
Layer 3
Layer 3 / IPv4
50 / 64
Who's who
Models
Layer 1
Layer 2
Layer 3
IPv4 Adresses
Identify stations within and beyond subnets
Up to - but not limited to - the Internet
32bit long
Composed of 4 octets
127.0.0.1
192.168.178.42
Subdived into network and host part
What is now known as the Internet started as a research project in the 1970s to
design and develop a set of protocols that could be used with many different
network technologies to provide a seamless, end- to-end facility for
interconnecting a diverse set of end systems.
Source: RFC4632, Section 2
51 / 64
Who's who
Models
Layer 1
Layer 2
Layer 3
Network Classes (historical!)
Deprecated since 1993 (RFC1519)!!1!
Long live CIDR / VLSM
Correct and complete definition given for historical attribution only!
DO NOT USE IN REAL LIFE ANYMORE! SRSLY!
Class Binary Prefix IP Space Default Mask
A 0... 0.0.0.0 - 127.255.255.255 /8
B 10.. 128.0.0.0 - 191.255.255.255 /16
C 11.. 192.0.0.0 - 223.255.255.255 /24
D 1110 224.0.0.0 - 239.255.255.255
E 1111 240.0.0.0 - 255.255.255.255
52 / 64
Who's who
Models
Layer 1
Layer 2
Layer 3
Subnetting - CIDR / VLSM
Classless Interdomain Routing
Variable Length Subnet Mask
Introduced in 1993, RFC4632 (original RFC1519)
Prefix Notation -> Number of bits in network part of address
255.255.255.0 == 24 Bit netmask == /24
53 / 64
Who's who
Models
Layer 1
Layer 2
Layer 3
Pre xes to know/ Private stu
Loopback
127.0.0.0/8
RFC1918 - Private Address Space
10.0.0.0/8, 172.16.0.0/12 und 192.168.0.0/16
RFC3927 - APIPA / Link-Local
169.254.0.0/16
RFC6598 - Shared Address Space (CGN)
100.64.0.0/10
RFC5737 - Documentation prefixes
192.0.2.0/24, 198.51.100.0/24, 203.0.113.0/24
RFC8190 - Special-Purpose IP Address Registries
Complete list of special prefixes
54 / 64
Who's who
Models
Layer 1
Layer 2
Layer 3
Linuxcommand line example
$ ip addr show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 state UNKNOWN [...]
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: eth0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 state DOWN [...]
link/ether 70:5a:0f:cf:21:f3 brd ff:ff:ff:ff:ff:ff
3: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 state UP [...]
link/ether 64:80:99:cf:66:6f brd ff:ff:ff:ff:ff:ff
inet 192.168.178.5/24 brd 192.168.178.255 scope global dynamic wlan0
valid_lft 2450sec preferred_lft 2450sec
inet6 fe80::668:0cff:fecf:666f/64 scope link
valid_lft forever preferred_lft forever
11: tun0: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1400 [...]
link/none
inet 10.23.42.8/25 brd 10.23.42.127 scope global ffho-ops
valid_lft forever preferred_lft forever
inet6 fe80::3f59:2a39:b0e1:92ec/64 scope link flags 800
valid_lft forever preferred_lft forever
55 / 64
Who's who
Models
Layer 1
Layer 2
Layer 3
ARP - Address Resolution Protocol
Glue between Ethernet and IPv4
Simple protocol to resolve MAC address of IP peer
Two messages types
who-has
is-at
A B
ARP WHO-HAS 192.168.178.8
192.168.178.8 IS-AT 64:80:99:CF:66:6F
A B
56 / 64
Who's who
Models
Layer 1
Layer 2
Layer 3
Routing
Every device speaking IP has a routing table
German translation according to IBM: "Leitwegtabelle"
Packets are forwarded according to longest prefix match
Default Gateway or Gateway of last resort used if no entry matches
Hot Potato principle
Packets forwarded to next hop w/o knowledge of their routing table
Asymmetric routing
Path to destination and return path don't have to be identical
57 / 64
Who's who
Models
Layer 1
Layer 2
Layer 3
Routing table
Possible routing table of your laptop when using company VPN:
Prefix Iface Next-hop
10.0.0.0/8 tun0 10.23.42.1
10.23.42.0/25 tun0
192.168.178.0/24 wlan0
0.0.0.0/0 wlan0 192.168.178.1
58 / 64
Who's who
Models
Layer 1
Layer 2
Layer 3
Source Address Selection
With every routing decision for a locally originated connection a source address is
selected based on the routing table.
Usually the (primary) IP configured on the outgoing interface
May be explicitly set to any IP
For example IP on loopback interface
Prefix Iface Next-hop Src address
10.0.0.0/8 tun0 10.23.42.1
10.23.42.0/25 tun0 10.23.42.8
192.168.178.0/24 wlan0 192.168.178.5
0.0.0.0/0 wlan0 192.168.178.1  
59 / 64
Who's who
Models
Layer 1
Layer 2
Layer 3
MTU/MSS
Maximum Transmission Unit
Maximum size of a frame
Usually 1500 Bytes in Ethernet networks
Usually >= 9000 Bytes in service provider backbones (Jumbo Frames)
Maximum Segment Size
Maximum size of a segment which fits into a TCP packet
MTU - 60 Bytes
60 / 64
Who's who
Models
Layer 1
Layer 2
Layer 3
ICMP - Ping
Echo request / Echo reply messages
Time between request and reply is measured
measures round trip latency
paths can differ
$ ping -c 3 www.heise.de
PING www.heise.de (193.99.144.85): 56 data bytes
64 bytes from 193.99.144.85: icmp_seq=0 ttl=247 time=14.149 ms
64 bytes from 193.99.144.85: icmp_seq=1 ttl=247 time=29.102 ms
64 bytes from 193.99.144.85: icmp_seq=2 ttl=247 time=30.070 ms
--- www.heise.de ping statistics ---
3 packets transmitted, 3 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 14.149/24.440/30.070/7.288 ms
61 / 64
Who's who
Models
Layer 1
Layer 2
Layer 3
ICMP - Traceroute
Sends echo requests with increasing TTL
Expects ICMP TTL Exceeded in Transit notifications
$ traceroute kilbeggan.fourecks.de
traceroute to kilbeggan.fourecks.de (88.198.54.132), 64 hops max, 52 byte packets
1 fritz.box (192.168.178.1) 2.243 ms 4.264 ms 14.443 ms
2 192.0.0.1 (192.0.0.1) 8.315 ms 8.309 ms 7.171 ms
3 62.214.38.173 (62.214.38.173) 7.167 ms 10.843 ms 14.588 ms
4 62.214.37.134 (62.214.37.134) 13.658 ms
62.214.37.130 (62.214.37.130) 11.569 ms
62.214.37.134 (62.214.37.134) 14.127 ms
5 versatel-gw.hetzner.com (213.239.239.45) 13.212 ms 12.322 ms 17.035 ms
6 core1.fra.hetzner.com (213.239.245.125) 19.927 ms 22.543 ms
core5.fra.hetzner.com (213.239.224.218) 13.700 ms
7 core23.fsn1.hetzner.com (213.239.229.74) 27.851 ms *
core24.fsn1.hetzner.com (213.239.252.42) 50.545 ms
8 ex9k1.dc13.fsn1.hetzner.com (213.239.245.242) 14.976 ms
ex9k1.dc13.fsn1.hetzner.com (213.239.245.238) 16.691 ms 15.347 ms
9 kilbeggan.fourecks.de (88.198.54.132) 17.902 ms 47.793 ms 22.902 ms
62 / 64
Who's who
Models
Layer 1
Layer 2
Layer 3
More?
Future Reading
FrOSCon Network Track 2018:
https://myfirst.network/
Introduction to networking by Ben Eater:
https://www.youtube.com/playlist?
list=PLowKtXNTBypH19whXTVoG3oKSuOcw_XeW
How Autonegotiation works:
https://daemons.net/networking/ethernet/auto-negotiation.html
Alles was ihr schon immer über Glasfasern wissen wolltet:
https://media.ccc.de/v/gpn18-13-alles-was-ihr-schon-immer-ber-glasfasern-wissen-
wolltet
Wie kommt eigentlich das Internet von Hamburg nach Stuttgart
https://media.ccc.de/v/gpn17-8524-
wie_kommt_eigentlich_das_internet_von_hamburg_nach_stuttgart
63 / 64
Who's who
Models
Layer 1
Layer 2
Layer 3
Questions
Questions?
64 / 64

More Related Content

What's hot

Building your own CGN boxes with Linux
Building your own CGN boxes with LinuxBuilding your own CGN boxes with Linux
Building your own CGN boxes with Linux
Maximilan Wilhelm
 
Overlays & IP-Fabrics - viele Wege führen nach Rom und warum Layer2 keine Lös...
Overlays & IP-Fabrics - viele Wege führen nach Rom und warum Layer2 keine Lös...Overlays & IP-Fabrics - viele Wege führen nach Rom und warum Layer2 keine Lös...
Overlays & IP-Fabrics - viele Wege führen nach Rom und warum Layer2 keine Lös...
Maximilan Wilhelm
 
Fun with PRB, VRFs and NetNS on Linux - What is it, how does it work, what ca...
Fun with PRB, VRFs and NetNS on Linux - What is it, how does it work, what ca...Fun with PRB, VRFs and NetNS on Linux - What is it, how does it work, what ca...
Fun with PRB, VRFs and NetNS on Linux - What is it, how does it work, what ca...
Maximilan Wilhelm
 
Best Current Operational Practices - Dos, Don’ts and lessons learned
Best Current Operational Practices - Dos, Don’ts and lessons learnedBest Current Operational Practices - Dos, Don’ts and lessons learned
Best Current Operational Practices - Dos, Don’ts and lessons learned
Maximilan Wilhelm
 
6.Routing
6.Routing6.Routing
6.Routing
phanleson
 
OpenNebulaConf2018 - Scalable L2 overlay networks with routed VXLAN / BGP EVP...
OpenNebulaConf2018 - Scalable L2 overlay networks with routed VXLAN / BGP EVP...OpenNebulaConf2018 - Scalable L2 overlay networks with routed VXLAN / BGP EVP...
OpenNebulaConf2018 - Scalable L2 overlay networks with routed VXLAN / BGP EVP...
OpenNebula Project
 
Building your own sdn with debian linux salt stack and python
Building your own sdn with debian linux salt stack and pythonBuilding your own sdn with debian linux salt stack and python
Building your own sdn with debian linux salt stack and python
Maximilan Wilhelm
 
Demystifying EVPN in the data center: Part 1 in 2 episode series
Demystifying EVPN in the data center: Part 1 in 2 episode seriesDemystifying EVPN in the data center: Part 1 in 2 episode series
Demystifying EVPN in the data center: Part 1 in 2 episode series
Cumulus Networks
 
CCNA DUMPS 640-802
CCNA DUMPS 640-802CCNA DUMPS 640-802
CCNA DUMPS 640-802
rahul kumar verma
 
VXLAN BGP EVPN: Technology Building Blocks
VXLAN BGP EVPN: Technology Building BlocksVXLAN BGP EVPN: Technology Building Blocks
VXLAN BGP EVPN: Technology Building Blocks
APNIC
 
VXLAN Distributed Service Node
VXLAN Distributed Service NodeVXLAN Distributed Service Node
VXLAN Distributed Service Node
David Lapsley
 
Building DataCenter networks with VXLAN BGP-EVPN
Building DataCenter networks with VXLAN BGP-EVPNBuilding DataCenter networks with VXLAN BGP-EVPN
Building DataCenter networks with VXLAN BGP-EVPN
Cisco Canada
 
6 Lo Wpan Tutorial 20080206
6 Lo Wpan Tutorial 200802066 Lo Wpan Tutorial 20080206
6 Lo Wpan Tutorial 20080206
pauldeng
 
Rpl2016
Rpl2016Rpl2016
Linux Bridging: Teaching an old dog new tricks
Linux Bridging: Teaching an old dog new tricksLinux Bridging: Teaching an old dog new tricks
Linux Bridging: Teaching an old dog new tricks
Stephen Hemminger
 
6lowpan
6lowpan6lowpan
Operationalizing EVPN in the Data Center: Part 2
Operationalizing EVPN in the Data Center: Part 2Operationalizing EVPN in the Data Center: Part 2
Operationalizing EVPN in the Data Center: Part 2
Cumulus Networks
 
AS201701 - Building an Internet backbone with pure 1he servers and Linux
AS201701 - Building an Internet backbone with pure 1he servers and LinuxAS201701 - Building an Internet backbone with pure 1he servers and Linux
AS201701 - Building an Internet backbone with pure 1he servers and Linux
Maximilan Wilhelm
 
Ipv6 cheat sheet
Ipv6 cheat sheetIpv6 cheat sheet
Ipv6 cheat sheet
julianlz
 
Scaling the Web to Billions of Nodes: Towards the IPv6 “Internet of Things” b...
Scaling the Web to Billions of Nodes: Towards the IPv6 “Internet of Things” b...Scaling the Web to Billions of Nodes: Towards the IPv6 “Internet of Things” b...
Scaling the Web to Billions of Nodes: Towards the IPv6 “Internet of Things” b...
gogo6
 

What's hot (20)

Building your own CGN boxes with Linux
Building your own CGN boxes with LinuxBuilding your own CGN boxes with Linux
Building your own CGN boxes with Linux
 
Overlays & IP-Fabrics - viele Wege führen nach Rom und warum Layer2 keine Lös...
Overlays & IP-Fabrics - viele Wege führen nach Rom und warum Layer2 keine Lös...Overlays & IP-Fabrics - viele Wege führen nach Rom und warum Layer2 keine Lös...
Overlays & IP-Fabrics - viele Wege führen nach Rom und warum Layer2 keine Lös...
 
Fun with PRB, VRFs and NetNS on Linux - What is it, how does it work, what ca...
Fun with PRB, VRFs and NetNS on Linux - What is it, how does it work, what ca...Fun with PRB, VRFs and NetNS on Linux - What is it, how does it work, what ca...
Fun with PRB, VRFs and NetNS on Linux - What is it, how does it work, what ca...
 
Best Current Operational Practices - Dos, Don’ts and lessons learned
Best Current Operational Practices - Dos, Don’ts and lessons learnedBest Current Operational Practices - Dos, Don’ts and lessons learned
Best Current Operational Practices - Dos, Don’ts and lessons learned
 
6.Routing
6.Routing6.Routing
6.Routing
 
OpenNebulaConf2018 - Scalable L2 overlay networks with routed VXLAN / BGP EVP...
OpenNebulaConf2018 - Scalable L2 overlay networks with routed VXLAN / BGP EVP...OpenNebulaConf2018 - Scalable L2 overlay networks with routed VXLAN / BGP EVP...
OpenNebulaConf2018 - Scalable L2 overlay networks with routed VXLAN / BGP EVP...
 
Building your own sdn with debian linux salt stack and python
Building your own sdn with debian linux salt stack and pythonBuilding your own sdn with debian linux salt stack and python
Building your own sdn with debian linux salt stack and python
 
Demystifying EVPN in the data center: Part 1 in 2 episode series
Demystifying EVPN in the data center: Part 1 in 2 episode seriesDemystifying EVPN in the data center: Part 1 in 2 episode series
Demystifying EVPN in the data center: Part 1 in 2 episode series
 
CCNA DUMPS 640-802
CCNA DUMPS 640-802CCNA DUMPS 640-802
CCNA DUMPS 640-802
 
VXLAN BGP EVPN: Technology Building Blocks
VXLAN BGP EVPN: Technology Building BlocksVXLAN BGP EVPN: Technology Building Blocks
VXLAN BGP EVPN: Technology Building Blocks
 
VXLAN Distributed Service Node
VXLAN Distributed Service NodeVXLAN Distributed Service Node
VXLAN Distributed Service Node
 
Building DataCenter networks with VXLAN BGP-EVPN
Building DataCenter networks with VXLAN BGP-EVPNBuilding DataCenter networks with VXLAN BGP-EVPN
Building DataCenter networks with VXLAN BGP-EVPN
 
6 Lo Wpan Tutorial 20080206
6 Lo Wpan Tutorial 200802066 Lo Wpan Tutorial 20080206
6 Lo Wpan Tutorial 20080206
 
Rpl2016
Rpl2016Rpl2016
Rpl2016
 
Linux Bridging: Teaching an old dog new tricks
Linux Bridging: Teaching an old dog new tricksLinux Bridging: Teaching an old dog new tricks
Linux Bridging: Teaching an old dog new tricks
 
6lowpan
6lowpan6lowpan
6lowpan
 
Operationalizing EVPN in the Data Center: Part 2
Operationalizing EVPN in the Data Center: Part 2Operationalizing EVPN in the Data Center: Part 2
Operationalizing EVPN in the Data Center: Part 2
 
AS201701 - Building an Internet backbone with pure 1he servers and Linux
AS201701 - Building an Internet backbone with pure 1he servers and LinuxAS201701 - Building an Internet backbone with pure 1he servers and Linux
AS201701 - Building an Internet backbone with pure 1he servers and Linux
 
Ipv6 cheat sheet
Ipv6 cheat sheetIpv6 cheat sheet
Ipv6 cheat sheet
 
Scaling the Web to Billions of Nodes: Towards the IPv6 “Internet of Things” b...
Scaling the Web to Billions of Nodes: Towards the IPv6 “Internet of Things” b...Scaling the Web to Billions of Nodes: Towards the IPv6 “Internet of Things” b...
Scaling the Web to Billions of Nodes: Towards the IPv6 “Internet of Things” b...
 

Similar to Angewandte Netzwerkgrundlagen reloaded - von Layer 1 bis 3

05. DF - Latest Trends in Optical Data Center Interconnects
05. DF - Latest Trends in Optical Data Center Interconnects05. DF - Latest Trends in Optical Data Center Interconnects
05. DF - Latest Trends in Optical Data Center Interconnects
Dimitris Filippou
 
Wi max
Wi maxWi max
Wi max
Ali Kamil
 
Mod9
Mod9Mod9
Data center interconnects multimode vs. single mode
Data center interconnects multimode vs. single modeData center interconnects multimode vs. single mode
Data center interconnects multimode vs. single mode
Angelina Li
 
Networking
NetworkingNetworking
Networking
Swapnil Kapate
 
Networking Concepts Lesson 07 - Architectures - Eric Vanderburg
Networking Concepts Lesson 07 - Architectures - Eric VanderburgNetworking Concepts Lesson 07 - Architectures - Eric Vanderburg
Networking Concepts Lesson 07 - Architectures - Eric Vanderburg
Eric Vanderburg
 
Fddi & Gigabit Ethernet
Fddi & Gigabit EthernetFddi & Gigabit Ethernet
Fddi & Gigabit Ethernet
Utkarsh Verma
 
Multiply the capacity of your LAN by 400
Multiply the capacity of your LAN by 400Multiply the capacity of your LAN by 400
Multiply the capacity of your LAN by 400
Kourosh Matloubi
 
100G QSFP28 Optical Transceiver Data Sheet By JTOPTICS
100G QSFP28 Optical Transceiver Data Sheet By JTOPTICS100G QSFP28 Optical Transceiver Data Sheet By JTOPTICS
100G QSFP28 Optical Transceiver Data Sheet By JTOPTICS
Jayani Technologies Ltd
 
Sorrento Networks DMM
Sorrento Networks DMMSorrento Networks DMM
Sorrento Networks DMM
Phil Bartlett
 
Intro To Networking
Intro To NetworkingIntro To Networking
Intro To Networking
Phil Ashman
 
5 IEEE standards
5  IEEE standards5  IEEE standards
5 IEEE standards
Rodgers Moonde
 
Network engg
Network enggNetwork engg
Network engg
thetechnicalzone
 
Ethernet 802.3.pptx
Ethernet 802.3.pptxEthernet 802.3.pptx
Ethernet 802.3.pptx
TanveerAthar1
 
Chap.1 ethernet introduction
Chap.1 ethernet introductionChap.1 ethernet introduction
Chap.1 ethernet introduction
東原 李
 
Twisted Pair Ethernet
Twisted Pair EthernetTwisted Pair Ethernet
Twisted Pair Ethernet
Prof Ansari
 
SIS_LineCard_2016
SIS_LineCard_2016SIS_LineCard_2016
SIS_LineCard_2016
Melanie Miller
 
Next-generation-Interconnects-the-Critical-Importance-of-Cables-and-Connectors
Next-generation-Interconnects-the-Critical-Importance-of-Cables-and-ConnectorsNext-generation-Interconnects-the-Critical-Importance-of-Cables-and-Connectors
Next-generation-Interconnects-the-Critical-Importance-of-Cables-and-Connectors
ssuser6d7b1f3
 
PLNOG16: Coping with Growing Demands – Developing the Network to New Bandwidt...
PLNOG16: Coping with Growing Demands – Developing the Network to New Bandwidt...PLNOG16: Coping with Growing Demands – Developing the Network to New Bandwidt...
PLNOG16: Coping with Growing Demands – Developing the Network to New Bandwidt...
PROIDEA
 
Wired Broadband Communication
Wired Broadband CommunicationWired Broadband Communication
Wired Broadband Communication
Dilum Bandara
 

Similar to Angewandte Netzwerkgrundlagen reloaded - von Layer 1 bis 3 (20)

05. DF - Latest Trends in Optical Data Center Interconnects
05. DF - Latest Trends in Optical Data Center Interconnects05. DF - Latest Trends in Optical Data Center Interconnects
05. DF - Latest Trends in Optical Data Center Interconnects
 
Wi max
Wi maxWi max
Wi max
 
Mod9
Mod9Mod9
Mod9
 
Data center interconnects multimode vs. single mode
Data center interconnects multimode vs. single modeData center interconnects multimode vs. single mode
Data center interconnects multimode vs. single mode
 
Networking
NetworkingNetworking
Networking
 
Networking Concepts Lesson 07 - Architectures - Eric Vanderburg
Networking Concepts Lesson 07 - Architectures - Eric VanderburgNetworking Concepts Lesson 07 - Architectures - Eric Vanderburg
Networking Concepts Lesson 07 - Architectures - Eric Vanderburg
 
Fddi & Gigabit Ethernet
Fddi & Gigabit EthernetFddi & Gigabit Ethernet
Fddi & Gigabit Ethernet
 
Multiply the capacity of your LAN by 400
Multiply the capacity of your LAN by 400Multiply the capacity of your LAN by 400
Multiply the capacity of your LAN by 400
 
100G QSFP28 Optical Transceiver Data Sheet By JTOPTICS
100G QSFP28 Optical Transceiver Data Sheet By JTOPTICS100G QSFP28 Optical Transceiver Data Sheet By JTOPTICS
100G QSFP28 Optical Transceiver Data Sheet By JTOPTICS
 
Sorrento Networks DMM
Sorrento Networks DMMSorrento Networks DMM
Sorrento Networks DMM
 
Intro To Networking
Intro To NetworkingIntro To Networking
Intro To Networking
 
5 IEEE standards
5  IEEE standards5  IEEE standards
5 IEEE standards
 
Network engg
Network enggNetwork engg
Network engg
 
Ethernet 802.3.pptx
Ethernet 802.3.pptxEthernet 802.3.pptx
Ethernet 802.3.pptx
 
Chap.1 ethernet introduction
Chap.1 ethernet introductionChap.1 ethernet introduction
Chap.1 ethernet introduction
 
Twisted Pair Ethernet
Twisted Pair EthernetTwisted Pair Ethernet
Twisted Pair Ethernet
 
SIS_LineCard_2016
SIS_LineCard_2016SIS_LineCard_2016
SIS_LineCard_2016
 
Next-generation-Interconnects-the-Critical-Importance-of-Cables-and-Connectors
Next-generation-Interconnects-the-Critical-Importance-of-Cables-and-ConnectorsNext-generation-Interconnects-the-Critical-Importance-of-Cables-and-Connectors
Next-generation-Interconnects-the-Critical-Importance-of-Cables-and-Connectors
 
PLNOG16: Coping with Growing Demands – Developing the Network to New Bandwidt...
PLNOG16: Coping with Growing Demands – Developing the Network to New Bandwidt...PLNOG16: Coping with Growing Demands – Developing the Network to New Bandwidt...
PLNOG16: Coping with Growing Demands – Developing the Network to New Bandwidt...
 
Wired Broadband Communication
Wired Broadband CommunicationWired Broadband Communication
Wired Broadband Communication
 

Recently uploaded

manuaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaal
manuaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaalmanuaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaal
manuaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaal
wolfsoftcompanyco
 
不能毕业如何获得(USYD毕业证)悉尼大学毕业证成绩单一比一原版制作
不能毕业如何获得(USYD毕业证)悉尼大学毕业证成绩单一比一原版制作不能毕业如何获得(USYD毕业证)悉尼大学毕业证成绩单一比一原版制作
不能毕业如何获得(USYD毕业证)悉尼大学毕业证成绩单一比一原版制作
bseovas
 
[HUN][hackersuli] Red Teaming alapok 2024
[HUN][hackersuli] Red Teaming alapok 2024[HUN][hackersuli] Red Teaming alapok 2024
[HUN][hackersuli] Red Teaming alapok 2024
hackersuli
 
办理毕业证(NYU毕业证)纽约大学毕业证成绩单官方原版办理
办理毕业证(NYU毕业证)纽约大学毕业证成绩单官方原版办理办理毕业证(NYU毕业证)纽约大学毕业证成绩单官方原版办理
办理毕业证(NYU毕业证)纽约大学毕业证成绩单官方原版办理
uehowe
 
一比一原版(USYD毕业证)悉尼大学毕业证如何办理
一比一原版(USYD毕业证)悉尼大学毕业证如何办理一比一原版(USYD毕业证)悉尼大学毕业证如何办理
一比一原版(USYD毕业证)悉尼大学毕业证如何办理
k4ncd0z
 
成绩单ps(UST毕业证)圣托马斯大学毕业证成绩单快速办理
成绩单ps(UST毕业证)圣托马斯大学毕业证成绩单快速办理成绩单ps(UST毕业证)圣托马斯大学毕业证成绩单快速办理
成绩单ps(UST毕业证)圣托马斯大学毕业证成绩单快速办理
ysasp1
 
快速办理(Vic毕业证书)惠灵顿维多利亚大学毕业证完成信一模一样
快速办理(Vic毕业证书)惠灵顿维多利亚大学毕业证完成信一模一样快速办理(Vic毕业证书)惠灵顿维多利亚大学毕业证完成信一模一样
快速办理(Vic毕业证书)惠灵顿维多利亚大学毕业证完成信一模一样
3a0sd7z3
 
Gen Z and the marketplaces - let's translate their needs
Gen Z and the marketplaces - let's translate their needsGen Z and the marketplaces - let's translate their needs
Gen Z and the marketplaces - let's translate their needs
Laura Szabó
 
办理毕业证(UPenn毕业证)宾夕法尼亚大学毕业证成绩单快速办理
办理毕业证(UPenn毕业证)宾夕法尼亚大学毕业证成绩单快速办理办理毕业证(UPenn毕业证)宾夕法尼亚大学毕业证成绩单快速办理
办理毕业证(UPenn毕业证)宾夕法尼亚大学毕业证成绩单快速办理
uehowe
 
快速办理(新加坡SMU毕业证书)新加坡管理大学毕业证文凭证书一模一样
快速办理(新加坡SMU毕业证书)新加坡管理大学毕业证文凭证书一模一样快速办理(新加坡SMU毕业证书)新加坡管理大学毕业证文凭证书一模一样
快速办理(新加坡SMU毕业证书)新加坡管理大学毕业证文凭证书一模一样
3a0sd7z3
 
怎么办理(umiami毕业证书)美国迈阿密大学毕业证文凭证书实拍图原版一模一样
怎么办理(umiami毕业证书)美国迈阿密大学毕业证文凭证书实拍图原版一模一样怎么办理(umiami毕业证书)美国迈阿密大学毕业证文凭证书实拍图原版一模一样
怎么办理(umiami毕业证书)美国迈阿密大学毕业证文凭证书实拍图原版一模一样
rtunex8r
 
留学挂科(UofM毕业证)明尼苏达大学毕业证成绩单复刻办理
留学挂科(UofM毕业证)明尼苏达大学毕业证成绩单复刻办理留学挂科(UofM毕业证)明尼苏达大学毕业证成绩单复刻办理
留学挂科(UofM毕业证)明尼苏达大学毕业证成绩单复刻办理
uehowe
 
Ready to Unlock the Power of Blockchain!
Ready to Unlock the Power of Blockchain!Ready to Unlock the Power of Blockchain!
Ready to Unlock the Power of Blockchain!
Toptal Tech
 
HijackLoader Evolution: Interactive Process Hollowing
HijackLoader Evolution: Interactive Process HollowingHijackLoader Evolution: Interactive Process Hollowing
HijackLoader Evolution: Interactive Process Hollowing
Donato Onofri
 
Discover the benefits of outsourcing SEO to India
Discover the benefits of outsourcing SEO to IndiaDiscover the benefits of outsourcing SEO to India
Discover the benefits of outsourcing SEO to India
davidjhones387
 
办理新西兰奥克兰大学毕业证学位证书范本原版一模一样
办理新西兰奥克兰大学毕业证学位证书范本原版一模一样办理新西兰奥克兰大学毕业证学位证书范本原版一模一样
办理新西兰奥克兰大学毕业证学位证书范本原版一模一样
xjq03c34
 
存档可查的(USC毕业证)南加利福尼亚大学毕业证成绩单制做办理
存档可查的(USC毕业证)南加利福尼亚大学毕业证成绩单制做办理存档可查的(USC毕业证)南加利福尼亚大学毕业证成绩单制做办理
存档可查的(USC毕业证)南加利福尼亚大学毕业证成绩单制做办理
fovkoyb
 
Design Thinking NETFLIX using all techniques.pptx
Design Thinking NETFLIX using all techniques.pptxDesign Thinking NETFLIX using all techniques.pptx
Design Thinking NETFLIX using all techniques.pptx
saathvikreddy2003
 
Should Repositories Participate in the Fediverse?
Should Repositories Participate in the Fediverse?Should Repositories Participate in the Fediverse?
Should Repositories Participate in the Fediverse?
Paul Walk
 

Recently uploaded (19)

manuaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaal
manuaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaalmanuaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaal
manuaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaal
 
不能毕业如何获得(USYD毕业证)悉尼大学毕业证成绩单一比一原版制作
不能毕业如何获得(USYD毕业证)悉尼大学毕业证成绩单一比一原版制作不能毕业如何获得(USYD毕业证)悉尼大学毕业证成绩单一比一原版制作
不能毕业如何获得(USYD毕业证)悉尼大学毕业证成绩单一比一原版制作
 
[HUN][hackersuli] Red Teaming alapok 2024
[HUN][hackersuli] Red Teaming alapok 2024[HUN][hackersuli] Red Teaming alapok 2024
[HUN][hackersuli] Red Teaming alapok 2024
 
办理毕业证(NYU毕业证)纽约大学毕业证成绩单官方原版办理
办理毕业证(NYU毕业证)纽约大学毕业证成绩单官方原版办理办理毕业证(NYU毕业证)纽约大学毕业证成绩单官方原版办理
办理毕业证(NYU毕业证)纽约大学毕业证成绩单官方原版办理
 
一比一原版(USYD毕业证)悉尼大学毕业证如何办理
一比一原版(USYD毕业证)悉尼大学毕业证如何办理一比一原版(USYD毕业证)悉尼大学毕业证如何办理
一比一原版(USYD毕业证)悉尼大学毕业证如何办理
 
成绩单ps(UST毕业证)圣托马斯大学毕业证成绩单快速办理
成绩单ps(UST毕业证)圣托马斯大学毕业证成绩单快速办理成绩单ps(UST毕业证)圣托马斯大学毕业证成绩单快速办理
成绩单ps(UST毕业证)圣托马斯大学毕业证成绩单快速办理
 
快速办理(Vic毕业证书)惠灵顿维多利亚大学毕业证完成信一模一样
快速办理(Vic毕业证书)惠灵顿维多利亚大学毕业证完成信一模一样快速办理(Vic毕业证书)惠灵顿维多利亚大学毕业证完成信一模一样
快速办理(Vic毕业证书)惠灵顿维多利亚大学毕业证完成信一模一样
 
Gen Z and the marketplaces - let's translate their needs
Gen Z and the marketplaces - let's translate their needsGen Z and the marketplaces - let's translate their needs
Gen Z and the marketplaces - let's translate their needs
 
办理毕业证(UPenn毕业证)宾夕法尼亚大学毕业证成绩单快速办理
办理毕业证(UPenn毕业证)宾夕法尼亚大学毕业证成绩单快速办理办理毕业证(UPenn毕业证)宾夕法尼亚大学毕业证成绩单快速办理
办理毕业证(UPenn毕业证)宾夕法尼亚大学毕业证成绩单快速办理
 
快速办理(新加坡SMU毕业证书)新加坡管理大学毕业证文凭证书一模一样
快速办理(新加坡SMU毕业证书)新加坡管理大学毕业证文凭证书一模一样快速办理(新加坡SMU毕业证书)新加坡管理大学毕业证文凭证书一模一样
快速办理(新加坡SMU毕业证书)新加坡管理大学毕业证文凭证书一模一样
 
怎么办理(umiami毕业证书)美国迈阿密大学毕业证文凭证书实拍图原版一模一样
怎么办理(umiami毕业证书)美国迈阿密大学毕业证文凭证书实拍图原版一模一样怎么办理(umiami毕业证书)美国迈阿密大学毕业证文凭证书实拍图原版一模一样
怎么办理(umiami毕业证书)美国迈阿密大学毕业证文凭证书实拍图原版一模一样
 
留学挂科(UofM毕业证)明尼苏达大学毕业证成绩单复刻办理
留学挂科(UofM毕业证)明尼苏达大学毕业证成绩单复刻办理留学挂科(UofM毕业证)明尼苏达大学毕业证成绩单复刻办理
留学挂科(UofM毕业证)明尼苏达大学毕业证成绩单复刻办理
 
Ready to Unlock the Power of Blockchain!
Ready to Unlock the Power of Blockchain!Ready to Unlock the Power of Blockchain!
Ready to Unlock the Power of Blockchain!
 
HijackLoader Evolution: Interactive Process Hollowing
HijackLoader Evolution: Interactive Process HollowingHijackLoader Evolution: Interactive Process Hollowing
HijackLoader Evolution: Interactive Process Hollowing
 
Discover the benefits of outsourcing SEO to India
Discover the benefits of outsourcing SEO to IndiaDiscover the benefits of outsourcing SEO to India
Discover the benefits of outsourcing SEO to India
 
办理新西兰奥克兰大学毕业证学位证书范本原版一模一样
办理新西兰奥克兰大学毕业证学位证书范本原版一模一样办理新西兰奥克兰大学毕业证学位证书范本原版一模一样
办理新西兰奥克兰大学毕业证学位证书范本原版一模一样
 
存档可查的(USC毕业证)南加利福尼亚大学毕业证成绩单制做办理
存档可查的(USC毕业证)南加利福尼亚大学毕业证成绩单制做办理存档可查的(USC毕业证)南加利福尼亚大学毕业证成绩单制做办理
存档可查的(USC毕业证)南加利福尼亚大学毕业证成绩单制做办理
 
Design Thinking NETFLIX using all techniques.pptx
Design Thinking NETFLIX using all techniques.pptxDesign Thinking NETFLIX using all techniques.pptx
Design Thinking NETFLIX using all techniques.pptx
 
Should Repositories Participate in the Fediverse?
Should Repositories Participate in the Fediverse?Should Repositories Participate in the Fediverse?
Should Repositories Participate in the Fediverse?
 

Angewandte Netzwerkgrundlagen reloaded - von Layer 1 bis 3

  • 1. Angewandte Netzwerkgrundlagen reloaded Von Layer 1 bis 3 FrOSCon 15 - Cloud Edition Falk Stern, Maximilian Wilhelm 1 / 64
  • 2. Agenda 1. Who's who 2. Models 3. Layer 1 4. Layer 2 (Ethernet) 1. LAGs / Bonding 2. VLANs 5. Layer 3 (IP) 2 / 64
  • 3. Who's who Falk Stern Full Stack Infrastructure Engineer IPv6 fanboy Runs his own Kubernetes cluster in his basement Consultant @ Profi Engineering Systems AG Contact @wrf42 falk@fourecks.de 3 / 64
  • 4. Who's who Maximilian Wilhelm Infrastructure Engineer OpenSource Hacker Fanboy of (Debian) Linux IPv6 Occupation: By day: Senior Infrastructure Architect, Uni Paderborn By night: Infrastructure Archmage, Freifunk Hochstift In between: Freelance Solution Architect for hire Contact @BarbarossaTM max@sdn.clinic 4 / 64
  • 5. Who's who Models Layer models - ISO/OSI, TCP/IP & Hybrid 5 / 64
  • 6. Who's who Models Layer models - ISO/OSI, TCP/IP & Hybrid Physical Wires, Wireless - 802.3 & 802.11 (Bit) Data Link Addressing stations on the same physical medium (Ethernet MAC) (Frame) Network Adressing stations somewhere in the entire network (IPv4, IPv6) (Packet) Transport How to transport data? (Datagram, Segment) Session, Presentation, Application Which data to transport? (SSH, IRC, HTTP, etc.) 6 / 64
  • 7. Who's who Models Layer 1 Layer 1 - Physical networking* * for Ethernet 7 / 64
  • 8. Who's who Models Layer 1 Air 802.11ac 802.11ax Real copper cables Usually Category 7 today Category 6a is usually fine Fiber Multi mode fiber (MMF) Single mode fiber (SMF) Specials Direct Attached Cable (DAC) Active Optical Cable (AOC) Source: Wikimedia commons The medium is the message 8 / 64
  • 9. Who's who Models Layer 1 Wireless Looks like Ethernet (802.3) but isn't Differentiates between Stations (STA) and Access Points (AP) Generation Max Linkrate Frequency Wi-Fi 1 (802.11b) 1 - 11 Mbit/s 2.4 GHz Wi-Fi 2 (802.11a) 1.5 - 54 Mbit/s 5 GHz Wi-Fi 3 (802.11g) 3 - 54 Mbit/s 2.4 GHz Wi-Fi 4 (802.11n) 72 - 400 Mbit/s 2.4 & 5 GHz Wi-Fi 5 (802.11ac) 433 - 6933 Mbit/s 2.4 & 5 GHz Wi-Fi 6 (802.11ax) 600 - 9608 Mbit/s 2.4 & 5 GHz, 1-6 GHz ISM 9 / 64
  • 10. Who's who Models Layer 1 Wireless Channels between 20 and 160 MHz Channels usually overlap 2.4 GHz is dead, as well as 802.11abg Problem with 5 GHz Channels is Radar DFS (Dynamic Frequency Selection) Channelwidths above 20 MHz only usable in 5 GHz bands 10 / 64
  • 11. Who's who Models Layer 1 Wireless Encryption Started with a 40 Bit WEP key, 104 bit did cost extra Currently WPA3 with PSK or EAP EAP usually authenticates against a RADIUS server PSK is "safe enough" for home use 11 / 64
  • 12. Who's who Models Layer 1 Twisted Pair copper cables https://en.wikipedia.org/wiki/2.5GBASE-T_and_5GBASE-T 12 / 64
  • 13. Who's who Models Layer 1 Types of fibers Multi mode fiber Single mode fiber Form factors of connectors ST SC LC E2000 MTO/MTP Contact of connectors PC APC Let's talk about bers 13 / 64
  • 14. Who's who Models Layer 1 Usually used at 850nm Attenuation between 1,5 - 3dB/km Only suited for shorter ranges Light is bouncing off the "edges" Category Color code Fiber type OM1 orange G62,5/125 OM2 orange G50/125 OM3 aqua G50/125 OM4 violet G50/125 OM5 lime G50/125 Acceptance cone Cladding Cladding Core Multi mode ber (MMF) https://de.wikipedia.org/wiki/Lichtwellenleiter#Multimodefaser 14 / 64
  • 15. Who's who Models Layer 1 Usually used between 1270nm & 1610nm Attenuation 0,4 - 1,0dB/km Suited for long range connections Light travels "straight" Category Color code Fiber type OS1 yellow E9/125 OS2 yellow E9/125 Single mode ber (SMF) 15 / 64
  • 16. Who's who Models Layer 1 Maximum ber lengths* Multi mode values depending on category! The following values ignore Use of amplifiers Use of WDM Number of patches Connector types Contact types Speed Multi mode Single mode 1Gb/s ≤1000m ≤ 1km 10Gb/s ≤ 500m ≤ 80km 40Gb/s ≤ 150m ≤ 80km 100Gb/s ≤ 100m ≤ 80km * This is a very rough overview 16 / 64
  • 17. Who's who Models Layer 1 ST / Straight Tip (1992) Still seen in the wild Legacy infrastructure SC / Standard connector (1993) Used on older optics Still in wide use on panels 24 duplex ports per RU LC / Lucent/Little connector (2002) De facto standard today In wide use on optics & panels 48 duplex ports per RU Common optical ber connectors 17 / 64
  • 18. Who's who Models Layer 1 E2000 / LSH (1997) Dust caps included prevents you from looking into the beam More expensive Usually used for MAN/WAN links Multiple-Fiber Push-On/Pull-off (MPO/MTP) Connects up to 24 cores Usually used within data centers e.g. rear connection for panels Source (MTP): Wikimedia commons Common optical ber connectors (contd.) 18 / 64
  • 19. Who's who Models Layer 1 Physical contact (PC) Slightly convex surface Mostly blue connectors bodies Angled physical contact (APC) Fiber end face polished at 8° angle Green connector body Contact type usually denoted as suffix: LC/PC E2000/APC Common optical connectors / contact https://en.wikipedia.org/wiki/Optical_fiber_connector#Contact 19 / 64
  • 21. Who's who Models Layer 1 Transceivers Gigabit interface converter (GBIC) old and busted (1995) obsoleted by SFP connector RJ45 SC proprietary supported speeds: 1Gb/s Transceivers - GBICs 21 / 64
  • 22. Who's who Models Layer 1 Transceivers Small form-factor pluggable (SFP) introduced 2001 aka Mini-GBIC connector RJ45 LC supported speeds 100Mb/s 1Gb/s Transceivers - SFPs https://en.wikipedia.org/wiki/Small_form-factor_pluggable_transceiver 22 / 64
  • 23. Who's who Models Layer 1 Transceivers introduced 2001 obsoleted by X2, XFP, SFP+ connectors SC CX4 converter to SFP+ supported speeds: 10Gb/s Transceivers - XENPAK 23 / 64
  • 24. Who's who Models Layer 1 Transceivers introduced 2002 slightly smaller than XENPAK consume less power than XENPAK obsoleted by XFP, SFP+ connectors SC CX4 converter to SFP / SFP+ supported speeds: 1Gb/s (via converter) 10Gb/s Transceivers - X2 24 / 64
  • 25. Who's who Models Layer 1 Transceivers introduced 2002/2003 much smaller than X2 slightly larger than SFP(+) obsoleted by SFP+ connectors LC supported speeds: 10Gb/s Source: Wikimedia commons Transceivers - XFP 25 / 64
  • 26. Who's who Models Layer 1 Transceivers introduced 2006 much smaller than XENPAK, X2 slightly smaller than XFP same size as SFP compatible to SFP connectors: RJ45 LC DAC AOC supported speeds: 1Gb/s 10Gb/s Transceivers - SFP+ 26 / 64
  • 27. Who's who Models Layer 1 Transceivers Quad SFP+ 4 channels of 10Gb/s slightly larger than SFP fanout possible to 4x 10Gb/s connectors: LC MTO/MTP DAC AOC supported speeds: 10Gb/s 40Gb/s Transceivers - QSFP+ 27 / 64
  • 28. Who's who Models Layer 1 Transceivers 4 channels of 28Gb/s same size as QSFP(+) compatible to QSFP+ fanout possible to 4x 10Gb/s 4x 25Gb/s connectors: LC MTO/MTP DAC AOC supported speeds: 10Gb/s 25Gb/s 40Gb/s 100Gb/s Transceivers - QSFP28 28 / 64
  • 29. Who's who Models Layer 1 Transceivers one channel of 28Gb/s same size as SFP(+) compatible to SFP+ connectors: LC DAC AOC supported speeds: 1Gb/s 10Gb/s 25Gb/s Transceivers - SFP28 29 / 64
  • 30. Who's who Models Layer 1 Transceivers Double-density Quad-SFP 8 channel of 50Gb/s same size as QSFP* fanout possible to 4x 100Gb/s connectors: LC DAC AOC MTO/MTP supported speeds: 400Gb/s Transceivers - DD-QSFP 30 / 64
  • 31. Who's who Models Layer 1 Outlook - CWDM Coarse Wavelength Division Multiplexing Using different wavelength on the same fiber https://community.fs.com/de/blog/wdm-technology-basis-cwdm-vs-dwdm.html 31 / 64
  • 32. Who's who Models Layer 1 Outlook - CWDM Coarse Wavelength Division Multiplexing Using different wavelength on the same fiber Requires transceiver with specific "color" https://community.fs.com/de/blog/wdm-technology-basis-cwdm-vs-dwdm.html 32 / 64
  • 33. Who's who Models Layer 1 Copper based cable of fixed length Transceiver permanently attached SFP+/SFP28 QSFP/QSFP28 Available from 1Gb/s to 400Gb/s Pros: Much cheaper than fiber link Simple Cons: Only useful within one / between adjacent racks Slightly higher latency Susceptible for EM interference Specials - Direct Attached Cable (DAC) 33 / 64
  • 34. Who's who Models Layer 1 Specials - Active Optical Cable (AOC) Fiber based cable of fixed length Transceiver permanently attached SFP+/SFP28 QSFP+/QSFP28 DD-QSFP Available from 10Gb/s to 400Gb/s Pros: Slightly less attenuation than manual optical connection At higher bandwidth cheaper than transceiver + cable Cons: Only useful within one / between adjacent racks 34 / 64
  • 35. Who's who Models Layer 1 Layer 2 Layer 2 - Ethernet 35 / 64
  • 36. Who's who Models Layer 1 Layer 2 Ethernet Developed between 1973 and 1974 at Xerox Inspired by ALOHAnet, the Packet Radio Network on Hawaii At first available with 2,94 Mbps, 10 Mbps available commercially since 1980 Further development lead to IEEE standard 802.3 in 1983 CSMA/CD - "Carrier Sense, Multiple Access, Collision Detect" Ethernet today: Common access port speed: 1 Gbit/s Common uplink/server interfaces speed: 10 - 40 Gbit/s Up to 400-Gbit/s available commercially Interfaces for copper or multi-mode / single-mode fiber Preamble SFD Source MAC Address Destination MAC Address EtherType FCSPayload Source: Wikimedia Commons 36 / 64
  • 37. Who's who Models Layer 1 Layer 2 Ethernet Technology Repeater Maximum Segmentlength in on network segment around 100m Repeater amplify and repeat signals Extend broadcast domains Extend collision domains Bridges Extend broadcast domains Limit collision domains Important Rule: Frames must not be send out on port where they were received 37 / 64
  • 38. Who's who Models Layer 1 Layer 2 Ethernet Devices Hubs Repeater with many ports Switches Bridges with many ports Three possible actions to happen with any frame: Forward Replicate Drop 38 / 64
  • 39. Who's who Models Layer 1 Layer 2 Addresses Format: AA:BB:CC:DD:EE:FF Identify stations on the same physical medium Should be unique (on the medium) 1st octet 2nd octet 3rd octet 4th octet 5th octet 6th octet 6 octets or Organisationally Unique Identifier (OUI) Network Interface Controller (NIC) Specific 3 octets 3 octets b7 b6 b5 b4 b3 b2 b1 b0 8 bits 0: 1: unicast multicast 0: 1: globally unique (OUI enforced) locally administered Source: Wikipedia Commons 39 / 64
  • 40. Who's who Models Layer 1 Layer 2 Linux command line example $ ip link show 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 2: eth0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN mode DEFAULT group default qlen 1000 link/ether 70:5a:0f:cf:21:f3 brd ff:ff:ff:ff:ff:ff 3: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP mode DORMANT group default qlen 1000 link/ether 64:80:99:cf:66:6f brd ff:ff:ff:ff:ff:ff 11: tun0: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1400 [...] link/none 40 / 64
  • 41. Who's who Models Layer 1 Layer 2 Spanning Tree Protocol for loop prevention within ethernet networks Create logical tree of network topology based on BPDUs Will block connections which will produce loops Only deactivate STP if you really know better Seriously! 41 / 64
  • 42. Who's who Models Layer 1 Layer 2 Layer 2 / LAGs 42 / 64
  • 43. Who's who Models Layer 1 Layer 2 LAGs Link Aggregation Combine one or more physical links between two peers to one virtual link, to increase over-all bandwidth create a redundant Layer 2 link both Also know as: LAG Bonding (Linux) Aggregated Ethernet (Juniper) Port-Channel (Cisco) Trunk (3Com, HP?) NIC-Teaming 43 / 64
  • 44. Who's who Models Layer 1 Layer 2 LAGs Link Aggregation - Simple Linux bonding Just use multiple links and hope the peer does, too. Drawbacks: If media converters are involved a link-down event may not propagate No way to tell it the peer is configured the same way 44 / 64
  • 45. Who's who Models Layer 1 Layer 2 LAGs Link Aggregation - LACP Link Aggregation Control Protocol (802.3ad / 802.1AX) De-facto standard within networking world Use LACP signalling to set up LAG with peer Maximum of 8 interface per LAG Keep alive every 1s (fast) or every 30s (slow) An interface can be on one of two modes: active: send out LACP packets to activly form the LAG passive: wait for and only then reply to LACP packets 45 / 64
  • 46. Who's who Models Layer 1 Layer 2 LAGs Multi-Chassis Link Aggregation Groups Link Aggregation between more than two peers At least on peer has to do magic to make this work Also know as: MC-LAG MLAG Virtual Port-Channel (vPC) Source: Wikipedia 46 / 64
  • 47. Who's who Models Layer 1 Layer 2 LAGs Loadbalancing Tra c over LAGs Round-Robin One packet on link 1, one on link 2, ..., and repeat Hashing of header elds Layer 2 (src MAC + dst MAC) Only useful if communication is to multiple stations within local subnet Layer 2+3 (src MAC + dst MAC + src IP + dst IP) Might be more useful for communication without local subnet Layer 3+4 (src IP + dst IP + src Port + dst Port) Probably most useful when communicating with multiple peers 47 / 64
  • 48. Who's who Models Layer 1 Layer 2 LAGs Layer 2 / VLANs 48 / 64
  • 49. Who's who Models Layer 1 Layer 2 LAGs VLANs Virtual Local Area Networks (VLANs) Used to separate broadcast domains in LANs VLAN transport between switches standardized as IEEE 802.1q after proprietary standards from Cisco, 3COM 12 bit VLAN Identifier only 4096 possible VLANs, ~100 reserved for internal switch functions 1 2 3 4 5 6 Destination MAC 1 2 3 4 5 6 Source MAC 1 2 3 4 802.1Q Header TPID=0x8100 PCP/DEI/VID 1 . . . n Payload 1 2 EtherType/ Size 1 2 3 4 CRC / FCS 1 2 3 4 5 6 Inter Frame Gap 7 8 9 10 11 12 1 2 3 4 5 6 Destination MAC 1 2 3 4 5 6 Source MAC 1 . . . n Payload 1 2 EtherType/ Size 1 2 3 4 CRC / FCS 1 2 3 4 5 6 Inter Frame Gap 7 8 9 10 11 12 n = 42–1500 n = 46–1500 1 2 3 4 5 6 Preamble 7 8 SFD 1 2 3 4 5 6 Preamble 7 8 SFD 49 / 64
  • 50. Who's who Models Layer 1 Layer 2 Layer 3 Layer 3 / IPv4 50 / 64
  • 51. Who's who Models Layer 1 Layer 2 Layer 3 IPv4 Adresses Identify stations within and beyond subnets Up to - but not limited to - the Internet 32bit long Composed of 4 octets 127.0.0.1 192.168.178.42 Subdived into network and host part What is now known as the Internet started as a research project in the 1970s to design and develop a set of protocols that could be used with many different network technologies to provide a seamless, end- to-end facility for interconnecting a diverse set of end systems. Source: RFC4632, Section 2 51 / 64
  • 52. Who's who Models Layer 1 Layer 2 Layer 3 Network Classes (historical!) Deprecated since 1993 (RFC1519)!!1! Long live CIDR / VLSM Correct and complete definition given for historical attribution only! DO NOT USE IN REAL LIFE ANYMORE! SRSLY! Class Binary Prefix IP Space Default Mask A 0... 0.0.0.0 - 127.255.255.255 /8 B 10.. 128.0.0.0 - 191.255.255.255 /16 C 11.. 192.0.0.0 - 223.255.255.255 /24 D 1110 224.0.0.0 - 239.255.255.255 E 1111 240.0.0.0 - 255.255.255.255 52 / 64
  • 53. Who's who Models Layer 1 Layer 2 Layer 3 Subnetting - CIDR / VLSM Classless Interdomain Routing Variable Length Subnet Mask Introduced in 1993, RFC4632 (original RFC1519) Prefix Notation -> Number of bits in network part of address 255.255.255.0 == 24 Bit netmask == /24 53 / 64
  • 54. Who's who Models Layer 1 Layer 2 Layer 3 Pre xes to know/ Private stu Loopback 127.0.0.0/8 RFC1918 - Private Address Space 10.0.0.0/8, 172.16.0.0/12 und 192.168.0.0/16 RFC3927 - APIPA / Link-Local 169.254.0.0/16 RFC6598 - Shared Address Space (CGN) 100.64.0.0/10 RFC5737 - Documentation prefixes 192.0.2.0/24, 198.51.100.0/24, 203.0.113.0/24 RFC8190 - Special-Purpose IP Address Registries Complete list of special prefixes 54 / 64
  • 55. Who's who Models Layer 1 Layer 2 Layer 3 Linuxcommand line example $ ip addr show 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 state UNKNOWN [...] link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo valid_lft forever preferred_lft forever inet6 ::1/128 scope host valid_lft forever preferred_lft forever 2: eth0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 state DOWN [...] link/ether 70:5a:0f:cf:21:f3 brd ff:ff:ff:ff:ff:ff 3: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 state UP [...] link/ether 64:80:99:cf:66:6f brd ff:ff:ff:ff:ff:ff inet 192.168.178.5/24 brd 192.168.178.255 scope global dynamic wlan0 valid_lft 2450sec preferred_lft 2450sec inet6 fe80::668:0cff:fecf:666f/64 scope link valid_lft forever preferred_lft forever 11: tun0: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1400 [...] link/none inet 10.23.42.8/25 brd 10.23.42.127 scope global ffho-ops valid_lft forever preferred_lft forever inet6 fe80::3f59:2a39:b0e1:92ec/64 scope link flags 800 valid_lft forever preferred_lft forever 55 / 64
  • 56. Who's who Models Layer 1 Layer 2 Layer 3 ARP - Address Resolution Protocol Glue between Ethernet and IPv4 Simple protocol to resolve MAC address of IP peer Two messages types who-has is-at A B ARP WHO-HAS 192.168.178.8 192.168.178.8 IS-AT 64:80:99:CF:66:6F A B 56 / 64
  • 57. Who's who Models Layer 1 Layer 2 Layer 3 Routing Every device speaking IP has a routing table German translation according to IBM: "Leitwegtabelle" Packets are forwarded according to longest prefix match Default Gateway or Gateway of last resort used if no entry matches Hot Potato principle Packets forwarded to next hop w/o knowledge of their routing table Asymmetric routing Path to destination and return path don't have to be identical 57 / 64
  • 58. Who's who Models Layer 1 Layer 2 Layer 3 Routing table Possible routing table of your laptop when using company VPN: Prefix Iface Next-hop 10.0.0.0/8 tun0 10.23.42.1 10.23.42.0/25 tun0 192.168.178.0/24 wlan0 0.0.0.0/0 wlan0 192.168.178.1 58 / 64
  • 59. Who's who Models Layer 1 Layer 2 Layer 3 Source Address Selection With every routing decision for a locally originated connection a source address is selected based on the routing table. Usually the (primary) IP configured on the outgoing interface May be explicitly set to any IP For example IP on loopback interface Prefix Iface Next-hop Src address 10.0.0.0/8 tun0 10.23.42.1 10.23.42.0/25 tun0 10.23.42.8 192.168.178.0/24 wlan0 192.168.178.5 0.0.0.0/0 wlan0 192.168.178.1   59 / 64
  • 60. Who's who Models Layer 1 Layer 2 Layer 3 MTU/MSS Maximum Transmission Unit Maximum size of a frame Usually 1500 Bytes in Ethernet networks Usually >= 9000 Bytes in service provider backbones (Jumbo Frames) Maximum Segment Size Maximum size of a segment which fits into a TCP packet MTU - 60 Bytes 60 / 64
  • 61. Who's who Models Layer 1 Layer 2 Layer 3 ICMP - Ping Echo request / Echo reply messages Time between request and reply is measured measures round trip latency paths can differ $ ping -c 3 www.heise.de PING www.heise.de (193.99.144.85): 56 data bytes 64 bytes from 193.99.144.85: icmp_seq=0 ttl=247 time=14.149 ms 64 bytes from 193.99.144.85: icmp_seq=1 ttl=247 time=29.102 ms 64 bytes from 193.99.144.85: icmp_seq=2 ttl=247 time=30.070 ms --- www.heise.de ping statistics --- 3 packets transmitted, 3 packets received, 0.0% packet loss round-trip min/avg/max/stddev = 14.149/24.440/30.070/7.288 ms 61 / 64
  • 62. Who's who Models Layer 1 Layer 2 Layer 3 ICMP - Traceroute Sends echo requests with increasing TTL Expects ICMP TTL Exceeded in Transit notifications $ traceroute kilbeggan.fourecks.de traceroute to kilbeggan.fourecks.de (88.198.54.132), 64 hops max, 52 byte packets 1 fritz.box (192.168.178.1) 2.243 ms 4.264 ms 14.443 ms 2 192.0.0.1 (192.0.0.1) 8.315 ms 8.309 ms 7.171 ms 3 62.214.38.173 (62.214.38.173) 7.167 ms 10.843 ms 14.588 ms 4 62.214.37.134 (62.214.37.134) 13.658 ms 62.214.37.130 (62.214.37.130) 11.569 ms 62.214.37.134 (62.214.37.134) 14.127 ms 5 versatel-gw.hetzner.com (213.239.239.45) 13.212 ms 12.322 ms 17.035 ms 6 core1.fra.hetzner.com (213.239.245.125) 19.927 ms 22.543 ms core5.fra.hetzner.com (213.239.224.218) 13.700 ms 7 core23.fsn1.hetzner.com (213.239.229.74) 27.851 ms * core24.fsn1.hetzner.com (213.239.252.42) 50.545 ms 8 ex9k1.dc13.fsn1.hetzner.com (213.239.245.242) 14.976 ms ex9k1.dc13.fsn1.hetzner.com (213.239.245.238) 16.691 ms 15.347 ms 9 kilbeggan.fourecks.de (88.198.54.132) 17.902 ms 47.793 ms 22.902 ms 62 / 64
  • 63. Who's who Models Layer 1 Layer 2 Layer 3 More? Future Reading FrOSCon Network Track 2018: https://myfirst.network/ Introduction to networking by Ben Eater: https://www.youtube.com/playlist? list=PLowKtXNTBypH19whXTVoG3oKSuOcw_XeW How Autonegotiation works: https://daemons.net/networking/ethernet/auto-negotiation.html Alles was ihr schon immer über Glasfasern wissen wolltet: https://media.ccc.de/v/gpn18-13-alles-was-ihr-schon-immer-ber-glasfasern-wissen- wolltet Wie kommt eigentlich das Internet von Hamburg nach Stuttgart https://media.ccc.de/v/gpn17-8524- wie_kommt_eigentlich_das_internet_von_hamburg_nach_stuttgart 63 / 64
  • 64. Who's who Models Layer 1 Layer 2 Layer 3 Questions Questions? 64 / 64