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Mar 16, 2024 330 likes •529 views

Lab Course RouterLab VLAN, Routing Information Protocol Miscellaneous Your feedback on work sheet 1? Don't reserve more time than you need! Check that inferfaces are no shutdown Lab -k if devices not accessible

SLIDE 1

Lab Course „RouterLab“

VLAN, Routing Information Protocol

SLIDE 2

Miscellaneous

❒ Your feedback on work sheet 1? ❒ Don't reserve more time than you need! ❒ Check that inferfaces are „no shutdown“ ❒ Lab -k if devices not accessible

❍ Please terminate a session ...

❒ Router XXX-rj1 require password

❍ Login: root ❍ Password: router

SLIDE 3

Virtual LAN

(VLAN)

SLIDE 4

Definitions

❒ LAN

❍ broadcast domain ❍ Hubs or switches „connect“ different LAN

segments

❍ Ethernet

❒ Virtual LAN (VLAN)

❍ Group of devices can communicate with each

ther as if they were on the same LAN

❍ configured on switches (and routers)

SLIDE 5

VLAN Example

SLIDE 6

Port-based VLANs

❒ Each switchport

❍ can be assigned to a VLAN ❍ accepts incoming traffic from a specific VLAN ❍ forwards packets to ports that belong to same

VLAN ❒ Configuration

❍ (config-if) switchport access vlan <vlan-id> ❍ (config-if) switchport mode access

SLIDE 7

Importance of Native VLANs

Trunking

SLIDE 8

Trunking (802.1Q)

❒ Needed if multiple VLANs on same link ❒ Switch

❍ (config-if) switchport trunk encapsulation dot1q ❍ (config-if) switchport trunk allowed vlan 500,501 ❍ (config-if) switchport mode trunk

❒ Subinterface on Cisco, e.g., f0/0.100

❍ (config-subif) encapsulation dot1Q <vlan_id>

❒ Extra unit on Juniper

❍ vlan-tagging ❍ unit 500 {vlan-id 500}

SLIDE 9

RIP

(Routing Information Protocol)

SLIDE 10

Routing Algorithm classification

Global or decentralized information?

Global:

❒ all routers have complete

topology, link cost info

❒ “link state” algorithms

Decentralized:

❒ router knows physically-

connected neighbors, link costs to neighbors

❒ iterative process of

computation, exchange of info with neighbors

❒ “distance vector”

algorithms

Static or dynamic?

Static:

❒ routes change slowly

ver time

Dynamic:

❒ routes change more

quickly

❍ periodic update ❍ in response to link

cost changes

SLIDE 11

RIP (Routing Information Protocol)

❒ Distance vector algorithm ❒ Included in BSD-UNIX Distribution in 1982 ❒ Distance metric: # of hops (max = 15

hops)

❒ RFC 2453

SLIDE 12

Distance Vector Routing

Decentralized algorithm:

❒ router knows its neighbors and link costs to

neighbors

❒ iterative computation, exchange of info with

neighbors Bellman-Ford Equation (dynamic programming) Define dx(y) := cost of least-cost path from x to y Then dx(y) = min {c(x,v) + dv(y)} where min is taken over all neighbors v of x

SLIDE 13

Distance Vector Algorithm

Iterative, asynchronous:

❒ each local iteration

caused by:

❍ local link cost change ❍ DV update message from

neighbor

Distributed:

❒ each node notifies

neighbors only when its Distance Vector changes

❍ neighbors then notify their

neighbors if necessary

wait for (change in local link

cost of msg from neighbor)

recompute estimates

if Distance Vector to any dest has changed, notify neighbors

Each node:

SLIDE 14

Distance Vector: link cost changes

Link cost changes:

❒ good news travels fast ❒ bad news travels slow

SLIDE 15

x y z x from cost to y 4 0 1 z 5 1 0 time node y table node z table

z

1 4 50

1 x y z x from cost to y 4 0 1 z 5 1 0 x y z x from cost to y 1 0 1 z 5 1 0 1 x y z x from cost to y 1 0 1 z 5 1 0 2 x y z x from cost to y 1 0 1 z 2 1 0 x y z x from cost to y 1 0 1 z 2 1 0

„Good news travel fast“

SLIDE 16