Advanced
Telecommunication
Networks
Chapter 10
Contents
1.
Ethernet Local Area Networks
2.
Network Segmentation and Interconnection
3.
Quality of Service (QoS)
4.
Network Design
5.
Routing Algorithms
6.
Routing Protocols
7.
Security
8.
High Availability Environments
9.
Network Management
10.
Multi-service Network
11.
SDN
12.
Evolution of LAN Networks
Advanced Telecommunication Networks
Ethernet
local
area
networks
1. Ethernet local area networks
General concepts
➢ Based on the control and management of the access of the different
actors to a common medium.
➢ Materialisation of OSI layers 1 and 2.
➢ Standardised by the IEEE through the 802.3 project.
1. Ethernet local area networks
General concepts
➢ Defines the physical (layer 1) and link (layer 2) layers
➢ Specifies media access technology: CSMA/CD
➢ Unique interface identifier: MAC (Media Access Control)
➢ Set of operation protocols: ARP, STP,...
1. Ethernet local area networks
Physical Elements
➢ Network Interfaces (NIC)
➢ Repeaters
➢ Twisted Pair Cable (UTP)
➢ Network connectors
1. Ethernet local area networks
Architecture and equipment
ROUTER
LAYER 3
SWITCHES
LAYER 2
LAYER 1
1. Ethernet local area networks
Access to the environment
➢ Packet Collision: Occurs when a node wants to transmit information
to the medium at the same time as another node in the network.
➢ Collision Domain: Network segment in which data packets can
"collide" with other packets when using a shared medium.
➢ CSMA/CD: Media access control protocol that resolves these collisions.
✓ Each node monitors the medium to detect if someone is
transmitting.
✓ In case a node starts transmitting and detects that the medium is
already occupied by other information, it aborts the transmission
and waits for a random time to try again.
1. Ethernet local area networks
Hubs and Switches
➢ Hubs
✓ They relay packets on all their ports except the ingress port.
✓ They do nothing to reduce the number of collisions in the network.
✓ Simple, no configuration required
✓ Fast and inexpensive
➢ Switches
✓ Learn which equipment (MAC) is reachable on each port
✓ Reduce collisions
✓ They bring new functions: remote management, port aggregation,
virtual networks, ...
1. Ethernet local area networks
Wiring
➢ There are different standards for the physical medium in Ethernet
networks, using either optical fiber or copper cable as support. The
most widespread are the following:
Standard
Medium
Distance
100Base-T
UTP (Cat5, Cat5e, Cat6, Cat7)
100 meters
1000Base-T
UTP (Cat5, Cat5e, Cat6, Cat7)
100 meters
1000Base-LX
Multimode Optical Fiber
550 meters
1000Base-LX
Singlemode Optical Fiber
5 kilometers
1000Base-LX10
Singlemode OF @ 1310 nm
10 kilometers
1000Base-EX
Singlemode OF @ 1310 nm
40 kilometers
1000Base-ZX
Singlemode OF @ 1550 nm
70 kilometers
10GBase-T
UTP (Cat5e, Cat6, Cat6e)
45, 55, 100 meters
1. Ethernet local area networks
Wiring
➢ Specific standards for copper cabling:
Standard
Type
Bandwidth
Applications
Category 5
UTP
100 MHz
100Base-T, 1000Base-T
Category 5e
UTP
100 MHz
100Base-T, 1000Base-T
Category 6
UTP
250 MHz
10GBase-T
Category 5e
STP/UTP
550 MHz
10GBase-T
➢ Depending on the type of connection, it is necessary that the cables
are either crossed or straight. As a general rule:
✓ Straight cables: Terminal equipment vs. switches.
✓ Crossover cables: Between terminating equipment (routers, servers)
✓ Auto MDI/MDIX technology. Negotiates the connection automatically.
1. Ethernet local area networks
ARP (Address Resolution Protocol)
➢ Link layer protocol (Ethernet) that is able to find the physical address
(MAC) of a device and its corresponding IP address.
➢ To do this, an ARP request packet is sent to the broadcast address
asking for the IP address of which the MAC address is to be found.
➢ Any machine on the network responds with an ARP reply packet,
since all machines keep an arp table with the addresses they know.
1. Ethernet local area networks
STP (Spanning Tree Protocol)
➢ Link layer protocol handling the presence of loops.
➢ Connections are activated or deactivated to undo loops automatically.
➢ To know which ports need to be disabled, equipment communicates
via messages called BPDUs (Bridge Protocol Data Units).
1. Ethernet local area networks
STP (Spanning Tree Protocol)
➢ Operation:
✓ A root switch (Root Bridge) is established: Configurable priority + MAC
✓ The least cost paths to the root bridge are calculated:
❖ The cost of each link can be manually configured.
❖ The path cost is the sum of the costs of each individual link.
❖ Each switch remembers the port through which the minimum cost is achieved (Root
Port)
❖ All switches in a segment agree on the switch through which the minimum path is
accessed. The port that connects that switch to the network segment is marked as a
Desginated Port
❖ Any port that is not a Root Port or Designated Port is blocked (Blocked Port)...
1. Ethernet local area networks
STP (Spanning Tree Protocol)
Advanced Telecommunication Networks
Network
Segmentation
and
Interconnection
2. Network Segmentation and Interconnection
Network Segmentation: 802.1 Q VLANS
➢ VLAN = Virtual LAN
➢ Logical separation of Layer 2 networks over the same physical
infrastructure.
➢ Each virtual network is assigned an identifier called a tag, which is
encoded within a 32-bit field in the Ethernet frame. Increasing the
maximum frame size from 1518 bytes to 1522 bytes.
2. Network Segmentation and Interconnection
Network Segmentation: 802.1 Q VLANS
2. Network Segmentation and Interconnection
Network Segmentation: VLANS Concepts
➢ They are usually configured on switch ports.
➢ There are different types of ports that behave differently:
✓ Access ports:
❖ Receive an untagged packet: label it with the configured label
❖ Receive a labelled packet: they change the label*
❖ Distribute the packets that are sent to them.
❖ Distribute packets arriving at the switch that have the same configured label. They
remove the label at the output.
✓ Trunk ports:
❖ They are configured with the labels to distribute.
❖ Any packet with these labels is distributed over the port as is (without removing the
label).
❖ Any packet entering the switch on a trunk port is processed as usual.
2. Network Segmentation and Interconnection
Network Segmentation: VLAN QinQ
➢ An access port can be instructed to stack labels. This way when a
tagged packet arrives, instead of overwriting the tag, it nests a
second one.
➢ The maximum frame size grows again, up to 1526 bytes.
➢ This can be done through external cabling between a trunk and an
access port.
2. Network Segmentation and Interconnection
Network Interconnection: General Concepts
➢ Each device must have a unique IP address.
➢ There must be at least one Layer 3 device: Router.
➢ Default Gateway: Layer 3 equipment through which traffic going
outside the local network goes out. It is configured in each terminal
equipment.
➢ Packets going to equipment on the subnet itself do not go through
the default gateway.
➢ The level 3 equipment of the local network must know how to reach
the other networks → Routing Protocols (EIGRP, BGP, OSPF,...)
➢ When the router routes a packet to another network, the original
Ethernet header is completely replaced.
2. Network Segmentation and Interconnection
Network Interconnection: General Concepts
2. Network Segmentation and Interconnection
Network Interconnection: Examples
➢ Ethernet Local Network
2. Network Segmentation and Interconnection
Network Interconnection: Examples
➢ Ethernet Local Network + IP
2. Network Segmentation and Interconnection
Network Interconnection: Examples
➢ Ethernet Local Network + IP
2. Network Segmentation and Interconnection
Network Interconnection: Examples
➢ Ethernet Local Network + IP + SDH
2. Network Segmentation and Interconnection
Network Interconnection: Overview
➢ Overview
2. Network Segmentation and Interconnection
Network Interconnection: Network Address Translation
➢ Translation of IP network addresses as they pass through a router. It is a
useful mechanism for connecting privately addressed networks to
public networks.
➢ Static one-to-one NAT (basic NAT)
✓ The address to which each internal IP address is to be translated is manually
configured in the router.
✓ The router changes the source/destination IP of the packets according to the
configured translation table.
2. Network Segmentation and Interconnection
Network Interconnection: Network Address Translation
➢ Dynamic NAT:
✓ The translation address is chosen from a pool of addresses automatically.
➢ PAT (Port Address Translation): NAT Overload
✓ When there are not enough addresses in the pool, several computers in the
same network share a public address.
✓ The router uses the connection ports (TCP, UDP) to establish which machine
each packet belongs to.
2. Network Segmentation and Interconnection
Network Interconnection: Basic NAT
➢ Basic NAT:
2. Network Segmentation and Interconnection
Network Interconnection: Basic NAT
➢ Basic NAT:
2. Network Segmentation and Interconnection
Network Interconnection: NAT Overload (PAT)
➢ NAT Overload (PAT):
2. Network Segmentation and Interconnection
Network Interconnection: NAT Overload (PAT)
➢ NAT Overload (PAT):
2. Network Segmentation and Interconnection
Network Interconnection: NAT Overload (PAT)
➢ NAT Overload (PAT):
2. Network Segmentation and Interconnection
Network Interconnection: NAT Overload (PAT)
➢ NAT Overload (PAT):
Advanced Telecommunication Networks
Quality
of
service (QoS)
3. Quality of service (QoS)
Quality of service (QoS): General Concepts
➢ The different services that can be integrated in a network have
particular requirements that need to be fulfilled in order to function
properly.
➢ The parameters to be controlled are the following:
✓ Delay: time it takes for a packet to reach its destination.
✓ Loss: packets that are discarded in the network (due to congestion).
✓ Bandwidth: total transfer rate
✓ Jitter: fluctuation of the delay period
➢ QoS seeks to classify traffic and assign appropriate priorities that keep
the above parameters within tolerable limits for each type of traffic.
3. Quality of service (QoS)
Quality of service (QoS): General Concepts
➢ QoS can be applied at different levels. Specifically for IP over Ethernet
networks:
✓ Layer 2 Ethernet: Class of Service (CoS) → 802.1p
✓ Layer 3 IP: Quality of Service (QoS) → Diffserv, Intserv
➢ Behaviour of the different services in relation to network parameters:
Service
Bandwidth
Delay
Jitter
Loss
Web browsing
Medium
Low
Low
High
E-mail
Low
Low
Low
High
Video streaming
High
Low
High
Low
Voice
Low
High
High
Medium
Telecontrol
Medium
High
Medium / High
High
3. Quality of service (QoS)
Quality of service (QoS): General Concepts
➢ Service-Level Agreement (SLA): In order to guarantee the correct
operation of the services within their recommended parameters, an
agreement is signed between the network provider and the owner of
the services.
➢ In this agreement, the provider undertakes to comply with
established requirements as long as the traffic generated by the
client conforms to a pre-established form (Traffic Shaping).
3. Quality of service (QoS)
Quality of service (QoS): Traffic Shaping
➢ Traffic Shaping: Algorithms to adapt the traffic of a given application to
predefined parameters (bandwidth, bursts, silences...). They are used
in a multitude of technologies: MPLS, FR, ATM...
➢ Leaky Bucket: Regulates the
maximum
number
of
packets injected into the
network per unit of time.
➢ Token
Bucket:
Regulates
outbound traffic but allows
bursts to a certain extent.
3. Quality of service (QoS)
Quality of service (QoS): Class of Service (CoS)
➢ Quality of Service at level 2. Specified in the 802.1p standard.
➢ Defines eight classes of service that can be assigned via the existing
3-bit PCP field in 802.1Q tags.
➢ The way traffic is handled is left to the choice of the manufacturer.
The IEEE makes certain recommendations:
PCP
Priority
Acronym
Traffic Type
1
0
BK
Background
0
1
BE
Best Effort
2
2
EE
Excelent Effort
3
3
CA
Critical Applications
4
4
VI
Video < 100 ms latency and jitter
5
5
VO
Voice < 10 ms latency and jitter
6
6
IC
Internet Control
7
7
NC
Network Control
3. Quality of service (QoS)
Quality of service (QoS)
➢ DiffServ: Differentiated Services
✓ Uses the 6 DSCP bits in the IP packet to classify traffic.
✓ Traffic is classified at the entrance of the network, according to several
parameters:
❖ Source address
❖ Destination address
❖ Type of traffic
✓ Advantages:
❖ Simple to implement
❖ Approximate quality of service is achieved
❖ Scalable solution (requires configuration only at the endpoints)
✓ Problems:
❖ The way routers act on headers is dependent on their configuration. It is difficult to
predict the behaviour of the routers.
3. Quality of service (QoS)
Quality of service (QoS)
➢ IntServ: Integrated Services
✓ For each application that requires a certain QoS, a reservation of resources
must be produced in the network routers. The resources are basically
bandwidth, CPU cycles and buffers..
❖ Flow Specs: describes how resource reservation is done.
▪ Defines the type of traffic: bit rate and queue size.
▪ Establishes what guarantees the traffic needs (best effort, controlled load,
guaranteed).
▪ Resource Reservation Protocol (RSVP): makes the reservation of resources along
the entire circuitDestination address
✓ Advantages:
❖ Achieve more accurate quality of service than DiffServ
✓ Problems:
❖ It is not a scalable solution as each router must support IntServ and must also be able
to store a large amount of state information.
Advanced Telecommunication Networks
Network
Design
4. Network design
Network design
➢ What do we need?
✓ To establish connectivity mainly between some central equipment and
some equipment at remote sites.
✓ We define it at a logical level, we are interested in the equipment
communicating, not the path it takes.
4. Network design
Network design
➢ How are we going to do it?
✓ We always need a physical level, a transmission medium that we can share
or not.
✓ It is necessary to choose between a physical and a logical view of the
network. For example, if we choose a physical view:.
❖ We need the availability of the physical medium to be 100% of the time, we can use
time multiplexing techniques but invisible to the eye, sdh, pdh.
❖ We need other services not to interfere with our services.
❖ VLANs are used to separate traffic, it's almost like having physical circuits associated
with the logical ones we need.
❖ Still, it is unavoidable in the current context to use only these concepts, it is necessary
to include the network level.
4. Network design
Network design
➢ Example: Wind farm network design
WIND FARM
Wind turbine line #1
COMPANY
NETWORK
Wind turbine line #2
Post #1 Local Operator
Switch
manufacturer
RADIO LINK
PDH
Telecontrol Router
E1
SCADA server
UCC
Counters /
Recorders
E1
IP Telephone
E1
4. Network design
Network design
➢ Example: Wind farm network design
4. Network design
Network design
➢ Example: Wind farm network design
VLAN #3
VLAN #2
MAIN
CONTROL
CENTER
VLAN #4
VLAN #5
VLAN #6
VLAN #1
SECONDARY
CONTROL
CENTER
VLAN #7
VLAN #8
Advanced Telecommunication Networks
Routing
Algoritms
5. Routing Algorithms
Routing Algorithms: Concepts
➢ Network metrics
✓ Hops required to get from node to node
✓ Transit delay between neighbouring nodes
✓ Bandwidth.
5. Routing Algorithms
Static Routing Algorithms
➢ Shortest path, Dijkstra's algorithm
✓ Dijkstra's algorithm allows to know the shortest path from one
node to another.
5. Routing Algorithms
Static Routing Algorithms
➢ Shortest path, Dijkstra's algorithm
5. Routing Algorithms
Static Routing Algorithms
➢ Shortest path, Dijkstra's algorithm
5. Routing Algorithms
Static Routing Algorithms
➢ Shortest path, Dijkstra's algorithm
5. Routing Algorithms
Static Routing Algorithms
➢ Flooding algorithm
✓ Sends packets through all possible paths
✓ Loop problem
✓ Possible network saturation
5. Routing Algorithms
Static Routing Algorithms
➢ Flow-based algorithm
✓ If the capacity and average traffic are known, the average packet
delay can be estimated.
✓ Queuing theory is used to achieve the lowest average delay.
5. Routing Algorithms
Dynamic routing algorithms
➢ Vector distance, Bellman-Ford algorithm
✓ Each node knows its distance to all its neighbours.
✓ Packets with distance data are exchanged, so each node updates
its table and knows the distances to the other nodes in the
network.
5. Routing Algorithms
Dynamic routing algorithms
➢ Vector distance
✓ It takes a long time to converge (minutes).
✓ RIP (version 1 and 2) uses this algorithm
5. Routing Algorithms
Dynamic routing algorithms
➢ Vector distance
5. Routing Algorithms
Dynamic routing algorithms
➢ Link status
✓ Each node knows the entire network topology and the costs
associated with the links.
✓ With the data, each node calculates the shortest path.
✓ OSPF uses this algorithm
5. Routing Algorithms
Dynamic routing algorithms
➢ Link status
✓ Each node knows the entire network topology and the costs
associated with the links.
✓ With the data, each node calculates the shortest path.
✓ OSPF uses this algorithm
Advanced Telecommunication Networks
Routing
Protocols
6. Routing Protocols
Routing Protocols
➢ IGP: Internal Gateway, to maintain routes in an autonomous system,
for example in an internal network RIP, EIGRP and OSPF are used.
➢ EGP: External gateway, to link independent or autonomous systems,
in this case it is called BGP which is used for the Internet.
➢ Special case: Tunnels and VPNs.
6. Routing Protocols
Routing Protocols IGP
➢ RIP (Routing Information Protocol)
✓ It is a Distance Vector protocol
✓ The metric is the number of hops
✓ The limit is 15, 16 is considered an unreachable or undesirable route.
• RFC 1058. Does not support variable
length masks (VLSM)
RIPv1
• RFC 1723 and RFC 4822. Supports subnets,
the 15-hop limitation was maintained
RIPv2
• RFC 2080 Next generation RIP has
RIPng support for IPv6.
6. Routing Protocols
Routing Protocols IGP
➢ RIP (Routing Information Protocol)
✓ Operation mode
START
I request
a copy of
the
routing
table
ACTIVE
MODE
Send
routing
table
every 30
seconds
WHEN I
RECEIVE
A
REPLAY
Update
routing
table if
necessary
6. Routing Protocols
Routing Protocols IGP
➢ OSPF (Open Shortest Path First)
✓ It builds an identical database on all routers describing the network
topology, thus it is a link-state protocol.
✓ The metric is bandwidth
✓ It can be broken down into smaller regions or areas.
❖ These areas are logical groups of routers whose information can be
summarised for the rest of the network.
❖ There is a special area called the backbone area which forms the central
part of the network and where other areas are connected to it.
❖ Routes between different areas always circulate through the backbone,
therefore all areas must connect to the backbone..
6. Routing Protocols
Routing Protocols IGP
➢ OSPF (Open Shortest Path First)
✓ To transmit the network topology, several types of packets are sent by IP
multicast.
❖ Hello packets: Contains the list of neighbours recognised by the router,
indicating the type of relationship it has with each one every 10 seconds
via multicast to ip address 224.0.0.5 initially.
❖ Link State Advertisements (LSA) packets :Changes in the state of a
router's links are notified to the network by sending LSA messages.
❖ DataBase Description Packets (DDP): Are used in the database exchange
between two nodes in the first instance.
6. Routing Protocols
Routing Protocols IGP
➢ OSPF (Open Shortest Path First)
✓ Operation mode
START
I discover my
neighbours
with HELLO
packets
every 10
seconds
ONCE THE
HEIGHBOURS
ARE KWON
I send the
data I have
and receive
the data that
others have
with DDP
packets
WHEN I HAVE
ALL THE
INFORMATION
Each node
executes
Dijkstra to
complete the
routing table.
WHEN THERE IS
A CHANGE IN
THE NETWORK
I send LSA
packet
describing
the change
in the
network
6. Routing Protocols
Routing Protocols IGP
➢ EIGRP (Enhanced Interior Gateway Routing Protocol)
✓ It builds an identical database on all routers describing the network
topology, thus it is a link-state protocol.
✓ EIGRP uses the following metric calculation:
❖ Metric=[K1*bandwidth+((K2*bandwidth)/(256-load))+(K3* delay)]*[K5/(reliability + K4)].
❖ The default values of the constants are : K1=1, K2=0, K3=1, K4=0, K5=0.
Metric = Bandwidth+delay
6. Routing Protocols
Routing Protocols IGP
➢ EIGRP (Enhanced Interior Gateway Routing Protocol)
✓ EIGRP maintains the following three tables:
❖ Neighbour table: Each EIGRP router maintains a neighbour table that
lists adjacent routers.
❖ The topology table: It consists of all EIGRP routing tables received from
neighbours and calculates the least-cost routes to each destination.
❖ EIGRP Routing Table: Contains the best routes to a destination.
6. Routing Protocols
Routing Protocols IGP: RIP vs OSPF vs EIGRP
➢ RIP vs OSPF vs EIGRP
RIP
OSPF
EIGRP
Easy to configure
Complex to configure
Uses OSPF advantages
Open
Can tag
Simple to configure
Only takes into account
the number of hops
Most widely used
Improves OSPF
convergence
Public
Cisco proprietary
6. Routing Protocols
Routing Protocols EGP
➢ BGP
✓ It is external
✓ It seeks to traverse as few other networks or stand-alone systems as
possible.
✓ It has to be configured manually:
6. Routing Protocols
Special Cases: Tunnels
➢ Tunnels
✓ Encapsulate an IP packet and add another network header to it.
✓ The resulting packet is longer
✓ Allows IP traffic to travel across multiple networks without configuring
routing protocols.
✓ Can add security by encrypting data.anually:
6. Routing Protocols
Special Cases: Tunnels
➢ Tunnels Types
✓ IPSec
✓Act at the network layer, layer 3
✓Mandatory for IPv6 and optional for IPv4
✓Endpoint authentication services → Authentication Header (AH)
✓Security Services → Encapsulating Security Payload (ESP)
❖ Encrypting traffic
❖ Integrity validation
❖ Authenticate endpoints
❖ Anti-replay
6. Routing Protocols
Special Cases: Tunnels
➢ Tunnels Types
✓ GRE (Generic Routing Encapsulation)
❖ Developed by Cisco
❖ Non-encrypting
❖ Works at Layer 3 layer
✓ OPC Tunneller
❖ Application layer
❖ Helps to make DCOM independent
❖ In a typical installation, an OPC Tunneller application is installed on each
server.
▪
Each OPC Tunneller communicates locally with the installed OPC application
(Using COM).
▪
Each pair of Tunneller applications communicate and transfer OPC data using
TCP/IP, eliminating the need for DCOM.
6. Routing Protocols
Special Cases: VPNs
➢ VPN’s (Virtual Private Network)
✓ Connections of mobile users via remote access
❖ Use of the Internet
❖ Data needs to be encrypted
❖ Using keys
❖ Using certificates
❖ Authentication of endpoints is required (e.g. Radius servers)
❖ A specific IP address is assigned to the local private network.
❖ Software is required on the user's PC
✓ Office interconnection
❖ Generally uses an operator-provided service
❖ Operator's remote equipment must be able to support the technology,
typically IPSec, VPLS tunnels
Advanced Telecommunication Networks
Security
7. Security
Security Cycle
➢ Identify assets that are vulnerable and potential threats.
➢ Quantify the impact of a threat materialising.
➢ Weight the most likely threats.
➢ Risk: combination of impact and vulnerability, will be high if both
factors are high.
Assets
Threats
Impact
Vulnerabilities
Risk
Safeguards
7. Security
Security Cycle
➢ Threats:
✓ By origin: People, elements of the environment, water
✓ By
target:
Physical
resources,
reduction
of
availability,
theft/modification of stored or in-transit information, image and
reputation
➢ Security services:
✓ Access control: both physical access by people and logical access
by authentication and firewall.
✓ Information protection: cryptography, public keys, SSL application
level security, IPSec tunnels.
7. Security
Security Cycle
➢ Network architectures with firewalls
7. Security
Security Cycle
➢ Implementing security on a Cisco router
✓ Using access lists or ACL (access control list)
A list of source and destination IP addresses, protocols and ports is defined.
Lists are applied to interfaces
Problem, Cisco no longer supports and considers it obsolete.
✓ By defining security zones
Safety zones are defined
Pairs describing how the zones interact are defined.
Define security policies to be applied
Apply the policies to the zone pairs
And finally, each interface is included in a single security zone.
Advanced Telecommunication Networks
High
Availability
Environments
8. High Availability Environments
High Availability Environments
➢ The aim is to minimise the impact of the failure of a single network
element.
➢ Ideally, system failure would only occur in the event of a chain failure
of several elements.
➢ It is necessary to find a cost/protection compromise.
➢ To achieve these objectives, a multitude of technologies are
employed at various levels:
✓
Redundancy of network equipment
✓
Hot Standby protocols in layer 3 equipment: HSRP/VRRP
✓
Dynamic routing protocols: OSPF, EIGRP, BGP
✓
Link Redundancy/Aggregation: LACP, NIC Teaming
✓
Mesh or ring network topologies
✓
Redundant power systems
✓
Real-time monitoring systems: SNMP, FO monitoring,...
8. High Availability Environments
High Availability Environments
8. High Availability Environments
High Availability Environments: HSRP (Hot Standby
Router Protocol)
➢ HSRP is a CISCO proprietary protocol that acts at layer 3 of the OSI
model to provide the network with a fail-safe default gateway.
➢ A group or cluster of routers is created in which one of them acts as
the master, routing traffic, and the others act as backups waiting for
the master to fail.
➢ A virtual IP address is assigned to the cluster, which will be the
default gateway for the network equipment.
➢ Only the master router will be active and will answer for the cluster
IP.
8. High Availability Environments
High Availability Environments: HSRP (Hot Standby
Router Protocol)
➢ When the master router fails, another router within the cluster will
become the active router, transparently to the rest of the network
equipment.
➢ The convergence times will depend on the configuration of the
timers for the cluster and the convergence time of the routing
protocol used.
8. High Availability Environments
High Availability Environments: HSRP (Hot Standby
Router Protocol)
➢ Operation
✓ HSRP is enabled on the routers that will be part of the cluster and
a cluster identifier (group ID) will be configured.
✓ There are two possible states for the routers that are part of the
cluster: master or backup.
✓ The routers exchange HSRP hello messages, which allow each
router to know the status of the other. These messages use the
multicast address 224.0.0.2 and UDP port 1985.
8. High Availability Environments
High Availability Environments: HSRP (Hot Standby
Router Protocol)
➢ Operation
✓ The administrator can configure priorities for the routers. The
router with the highest priority becomes the master. This router
will have the virtual IP address of the cluster and will respond with
a preconfigured MAC (0000.0C07.ACXX, where XX is the ID
assigned to the cluster).
✓ If the master router does not send hello messages to the backup
router within a certain period, the backup router assumes that the
master is out of service and becomes the master router. This
router takes the virtual IP address of the cluster.
8. High Availability Environments
High Availability Environments: HSRP (Hot Standby
Router Protocol)
➢ Operation
✓ The standby router takes the place of the master router, once the
holdtime timer expires (an equivalent of three hello packets not
coming from the active router, default hello timer set to 3 and
default holdtime set to 10).
8. High Availability Environments
High Availability Environments: VRRP (Virtual Router
Redundancy Protocol)
➢ It is the standardised alternative to Cisco's HSRP.
➢ Although similar in concept it is not compatible with HSRP.
➢ Defined in RFC 5798.
➢ Operation
✓ A virtual router is configured and assigned an IP address and the
following MAC address: 00-00-5E-00-01-XX. The last byte of the
address is the Virtual Router IDentifier (VRID), which is different for
each virtual router in the network.
✓ Physical routers that could potentially act as virtual routers must
communicate with each other using packets with IP multicast
address 224.0.0.18 and IP protocol number 112.
8. High Availability Environments
High Availability Environments: VRRP (Virtual Router
Redundancy Protocol)
➢ Operation
✓ The routers have a priority between 1 and 255. The router with the
highest priority is chosen as the master.
✓ Only the master sends multicast packets to signal that it is active.
✓ A failure to receive a multicast packet from the master for more
than three times the announcement time causes the backup
routers to assume that the master router is down. The virtual
router changes its status to "unstable" and an election process is
initiated to select the next master router from the backup routers.
✓ In the election phase the backup routers can broadcast multicast
traffic. The backup router with the highest priority is elected
master.
8. High Availability Environments
High Availability Environments: Port Aggregation
➢ An umbrella term for the various existing technologies for combining
multiple links in parallel to increase bandwidth and provide
connection redundancy.
➢ Link Aggregation Control Protocol (LACP): Standard in IEEE 802.ad to
form a single Ethernet link using two or more physical connections
between equipment.
✓ LACP must be enabled at both ends of the connection.
✓ It provides the necessary control mechanisms for negotiation
between both ends of the link parameters.
✓ LACP packets are exchanged between both ends to monitor the
link status. Polling time can be configured.
8. High Availability Environments
High Availability Environments: Port Aggregation
✓ Automatically adds
and
deletes links (in case of failures,
disconnections,...).
✓ Load sharing between the ports that make up the LACP group.
✓ Ports can be in two states:
❖ Active: negotiates connections through LACP packets.
❖ Passive: does not negotiate connections but responds to LACP
requests from an active one.
8. High Availability Environments
High Availability Environments: Port Aggregation
➢ In addition to LACP, there are a multitude of proprietary solutions to
implement similar functionalities: Cisco's EtherChannel, Huawei's
EtherTruk, Nortel's MultiLink Trunking,...
➢ When links are aggregated between a terminal equipment (server)
and a switch, network card pooling mechanisms are used: NIC
Teaming.
✓ Although LACP is a standard, each manufacturer implements NIC Teaming
differently.
✓ Not all Teaming solutions behave in the same way when dealing with link
aggregation.
✓ It is necessary to check with the manufacturer of the terminal equipment
that their driver is compatible with the network electronics. both ends to
monitor the link status. Polling time can be configured.
8. High Availability Environments
High Availability Environments: Port Aggregation
8. High Availability Environments
High Availability Environments: Switch Stacking
➢ Technology that allows multiple switches to be stacked so that they
operate as one.
➢ Proprietary solutions that do not allow interoperability between
vendors.
➢ Switch-to-switch connections are made between dedicated high-
capacity ports. They do not usually allow long cable runs.
➢ From a management point of view, they are seen as one device with
a single IP address.
➢ They make it easier to expand the network.
8. High Availability Environments
High Availability Environments: Switch Stacking
Advanced Telecommunication Networks
Network
Management
9. Network Management
3
2
1
Network diagnostics
Explain the
problem to
someone who
does not
understand or is
not aware of the
problem
Assume
nothing, test
everything, even
the physical
layer and log
actions →ping,
traceroute
6
Look for what
has changed →
alarms, physical
works
5
4
Collect all
available
information
Remain calm
Escalate if
necessary
9. Network Management
Network diagnostics: SNMP
➢ Find what has changed : SNMP (Simple Network Management
Protocol).
➢ It is an application layer protocol that facilitates the exchange of
management information between network devices. It allows
administrators to monitor network performance, find and resolve
network problems, and plan for network growth..
➢ Concepts:
9. Network Management
Network diagnostics: SNMP
➢ Operation:
✓ SNMP uses a non-connection-oriented service (UDP) to send
messages between managers and agents.
✓ These messages can be generated by the network manager or by
the managed devices, encapsulating for example an alarm when
certain events occur, such as an interface is down, a fan is broken...
9. Network Management
Network diagnostics: SNMP
GetRequest:
Through this message the
manager asks the agent for
the value of an object of
interest by its name.
GetNextRequest:
This message is used to
traverse a table of objects.
Once a GetRequest
message has been used to
collect the value of an
object, the
GetNextRequest message
can be used to repeat the
operation with the next
object in the table.
SetRequest:
This type of message is
used by the manager to
request an agent to modify
object values.
GetResponse:
This message is used by
the agent to respond to a
GetRequest,
GetNextRequest, or
SetRequest message. In
the "Request Identifier"
field it has the same
identifier as the request it is
responding to.
9. Network Management
Network diagnostics: SNMP
➢ In order to use the above snmp messages to obtain information from
the MIB objects there is a nomenclature to identify each of them.
➢ For example in Cisco:
http://tools.cisco.com/Support/SNMP/do/BrowseOID.do?local=en
9. Network Management
Network diagnostics: SNMP
➢ Test it all: ICMP (Internet Control Message Protocol)
➢ Used to send error messages
➢ It operates at the network layer, at level 3.
➢ The only exception is the ping and traceroute tool.
✓ The traceroute command is implemented by transmitting UDP
datagrams with special TTL IP fields in the header, and looking for
the "Time to Live in transit" and "Destination unreachable"
messages generated in response.
✓ The ping tool is implemented using the ICMP "Echo request" and
"Echo reply" messages. Every host must respond to an Echo
Request with an Echo Reply containing exactly the same data as
the first one.
9. Network Management
Network diagnostics: SNMP
➢ Test it all: ICMP (Internet Control Message Protocol)
9. Network Management
Network diagnostics: SNMP
➢ Test it all: Ethereal (Wireshark)
9. Network Management
Network diagnostics: Network Management Center
➢ Scale it up if necessary: Network Management Center (NMC)
➢ NMC functions:
✓ Management of job scheduling
✓ Configuration of communications equipment for network modifications.
✓ Generation of reports on network status, availability and incidents as well as
network inventory.
✓ Troubleshooting of internal and external service failures on a 24/7 basis.
❖ Remote technical support to maintenance contractors to resolve
incidents.
❖ Opening of incidents to communications operators if necessary when
contracted services present a problem..
Advanced Telecommunication Networks
Multi-service
Network
10. Multi-service Network
Multi-service Network
➢ A telecommunications network is nowadays a Multi-service Network.
➢ It integrates voice, data, video services, which traditionally had their
own infrastructure in a single network.
➢ It is necessary to
✓ To have trunk links capable of transporting any type of service over any
infrastructure.
✓ Establish static addresses, unique for each device.
✓ Do not compromise voice and video services; QoS and security must be
established for data services.
✓ IPv6 solves some of these problems.
10. Multi-service Network
Multi-service Network
➢ Advantages
✓ Always on" offer content when and where you want it, 3g mobile
applications, video on demand, interactive games.
✓ One single device for all services, voice, data, etc.
✓ Bandwidth efficiency.
➢ The definition of Quality of Service or QoS levels and their assignment
according to the type of traffic to be transmitted is particularly
important.
➢ It must use the appropriate technology to be able to manage the
desired QoS, e.g. MPLS by means of labels and experimental bits
allows assigning priorities to different types of traffic.
10. Multi-service Network
Multi-service Network
Service
Bandwidth
Delay
Jitter
Loss
Web browsing
Medium
Low
Low
High
E-mail
Low
Low
Low
High
Video streaming
High
Low
High
Low
Voice
Low
High
High
Medium
Telecontrol
Medium
High
Medium / High
High
10. Multi-service Network
Public networks, Carrier MPLS, Satellite, GPRS, Internet
➢ VPN-IP
✓ The first access router tags and the last one untags.
✓ RPV-RFC 2547 bis model (IP-MPLS networking technology)
✓ VPN-IP
MOVISTAR
NetLan
(RIMA
transit
network)
http://www.movistar.es/rpmm/estaticos/negocios/fijo/soluciones/manuales/m
anual-usuario-netlan.pdf
✓ VPN-IP ONO
http://avancemgrup.com/blog/wp-content/uploads/2012/09/Servicio-MPLSono.pdf
✓ -VPN-IP Jazztel
http://www.slideshare.net/bobydiaz/presentacion-jazztel-empresas-5850556
✓ -VPN-IP Colt
http://www.colt.net/es/es/products-services/data-networking/ip-vpn-es.htm
10. Multi-service Network
Public networks, Carrier MPLS, Satellite, GPRS, Internet
➢ Ethernet
✓ MOVISTAR MacroLan
✓ ONO http://www.ono.es/empresas/serviciosdedatos.aspx
✓ JAZZTEL
✓ COLT http://www.colt.net/es/es/products-services/data-networking/
Advanced Telecommunication Networks
SDN
11. SDN
What is an SDN (Soft-Defined Network)?
➢ It is an approach to networking where, based on a separation
between the control plane and the data plane, resource optimisation
and capacity control plane is achieved and the ability to adapt very
quickly to new business adapt very quickly to new business,
application or traffic requirements.
➢ The control plane is based on SW applications that program the
network devices, whether they are HW or virtualised
➢ The objective is to facilitate the management of large and highly
distributed networks, establishing a centralised control of these
networks
11. SDN
What is an SDN (Soft-Defined Network)?
➢ Network planes
✓ Management
✓ Controlling
✓ Data / Forwarding
✓ Services
11. SDN
Benefits of SDN
➢ The objective of SDN is to reduce the complexity and cost of network
operations, accelerating resolving incidents and outages.
➢ Simplifying operations.
complete management
SDN provides a single pane of glass for
of the entire network,
reducing the
likelihood of human failures associated with individual device
management.
➢ Open infrastructure. Open APIs with standard technologies (REST) are
offered for integration with corporate systems, as well as open and
standard network protocols for integration with devices already in
the network.
➢ Increased network uptime: Faster network troubleshooting results in
higher network uptime and improved user experience.
11. SDN
SDN Context
➢ SDN originated around Virtualisation technology, as a technology for
decoupling the physical resources of operating systems. This
technology, precursor of the Cloud, makes it possible to define virtual
IT resources using a shared infrastructure.
➢ SDN is based on network virtualisation (SW-based creation of
communication
between
virtual
systems).
It
is
subsequently
extended, within the Datacenter environment, to the control of the
network between HW devices and the virtual machines themselves
and new services (FW, service chaining, load balancing).
11. SDN
SDN Context
11. SDN
What is SD-WAN?
➢ A particular case of SDN is SD-WAN. This is an automated and
programmatic approach to managing corporate networks and
transport circuits.
➢ Traffic is automatically and dynamically routed over the most efficient
WAN path
based
on network
conditions,
security
requirements. The operator sets the routing policies.
and QoS
11. SDN
Benefits of SD-WAN
➢ Simplifies network operation thereby reducing OpEx and CapEx of
the WAN network
➢ Provides greater business agility and better response to adapt to IT
innovations
➢ Improves performance by enabling traffic load sharing between
different WAN paths and adjusting traffic flows to network conditions
➢ Enables automatic provisioning of advanced network services (Layer
2, Layer 3), FWs or application control
➢ Enables Zero Touch Provisioning
➢ Increases network security by encrypting traffic over the WAN and
segmenting the network to mitigate the impact of network security
breaches.
11. SDN
SDN Basic Concepts
➢ Underlay Traffic
✓ Corresponds to the connectivity between the SDN devices present
at each location
✓ It is the connectivity necessary for SDN equipment to build on top
of the networks that will be used by network users
✓ Typical examples: the MPLS network, layer 2 services, services
provided by an operator, a corporate FTTH connection, LTE
connectivity through private APNs
11. SDN
SDN Basic Concepts
➢ Underlay Traffic.
11. SDN
SDN Basic Concepts
➢ Overlay Traffic
✓ Corresponds to the networks dynamically created from the SDN
manager to be used by the users of the network
✓ These networks can be of Layer 2 or Layer 3 networks depending
on the specific use case required by the user
✓ -Typical examples: level 2 service between offices and data centres,
level 2 services between substations and data centres, or level 3
services between the electrical centers and the data centres.
11. SDN
SDN Basic Concepts
➢ Overlay Traffic.
Advanced Telecommunication Networks
Evolution
of
LAN Networks
12. Evolution of LAN Networks
Evolution of LAN networks: Future of Networks
➢ Trend:
✓ Increasingly consolidated services: virtualisation
✓ Continuously growing systems: need for flexibility at LAN and WAN level.
✓ Increasing energy and process efficiency.
✓ Merging of system and network environment.
➢ Evolution:
✓ Virtualisation of the communications network.
✓ Software Defined Networking (SDN)
✓ Decoupling of network electronics and network configuration: OpenFlow
✓ New companies betting on SDN: Big Switch, Nicira, Juniper, Embrane.
12. Evolution of LAN Networks
Evolution of LAN networks: Virtualisation Concept
➢ It seeks to consolidate services on the same hardware: several servers
running in parallel on the same machine.
➢ Hardware is seen as a set of resources (CPU, RAM, disk) that are
allocated to different services according to their particular needs.
➢ This fine-tuned allocation of resources is intended to increase the
overall efficiency of the system.
➢ The element on which the virtual machines run and which acts as an
interface with the physical resources is the hypervisor.
➢ There are a multitude of companies offering virtualisation products.
The best known are VMWare and Citrix.
12. Evolution of LAN Networks
Evolution of LAN networks: Services Virtualisation
12. Evolution of LAN Networks
Evolution
of
LAN
networks:
Consequences
of
Virtualisation
➢ Having virtual machines opens up a multitude of possibilities that did
not exist before:
✓ Hot-plugging machines
✓ Relocation of virtual machines
✓ Adding new machines almost instantaneously
✓ Creating copies of a machine to be activated in the event of a failure
➢ All this flexibility must be supported by network electronics.
➢ Each virtual machine has at least one virtual network interface
associated with it and has connection needs just like conventional
physical machines.
➢ So-called virtual switches are beginning to appear.
12. Evolution of LAN Networks
Evolution of LAN networks: Virtual Switches
➢ Run at the hypervisor and virtual manager level.
➢ They associate virtual machines to physical network segments via
network cards.
➢ Increase computational requirements: running on the hypervisor
consumes resources.
➢ Commercial examples:
✓ Nexus 1000V (CISCO and VMWare).
✓ Open vSwitch
✓ Hyper-V (Microsoft)
12. Evolution of LAN Networks
Evolution of LAN networks: Network Virtualisation
➢ Each manufacturer uses its own solution. There are few standards.
➢ There is the problem of how to efficiently configure the network
when mixing virtual switches with physical switches.
✓ Software Defined Networking (SDN)
✓ OpenFlow protocol
12. Evolution of LAN Networks
Evolution of LAN networks: Soft-Defined Networks
➢ Openflow Protocol.
✓ The configuration of packet flows moves from the switches to the servers.
✓ It is a protocol that is presented as firmware in the network electronics,
acting between its configuration interface on the server and the usual
network protocols.
✓ New network functions (firewalls, balancers,...) are built as pieces of software
on top of the driver.
Thank you!
Fernando de la Huerta
Email: Fernando.dhuerta@msmk.university