07 - Routing Flashcards
Router
- Forwards packets based on IP
- works at network layer
Switch that works at more than one layer
MLS
- Multi-layer Switch
Layer 3 Switch
Handles IP traffic as well (routing)
Routing Table
Tells the router exactly where to send packets based on IP
Columns of a routing table
Destination LAN IP - defined network ID
Subnet Mask - network ID
Gateway - IP for next hop router
Interface - LAN or WAN
What does 0 mean on routing tables
Anything - wildcard
Routing table default route
Tells the router what to do with every incoming packet unless another line in the tables gives a route
View routing table windows CLI
route print
or
netstat -r
View routing table Linux & Mac CLI
netstat -r
routing table metric
defines “cost” of using a particular route
- lower values are better
SNAT
Static NAT
-
DNAT
Dynamic NAT
-
hop
Each time a packet goes through a router
Most common criteria for routing metrics
hop count -
bandwidth -
delay -
cost -
MTU
Maximum Transmission Unit
- The largest frame a particular technology can handle
Convergence
- updating of routing tables for all routers has been completed
- also called steady state
RIP
Routing Information Protocol
- first is RIPv1
- current is RIPv2
AS
Autonomous System
- one or more networks that are governed by a sigle dynamic routing protocol
- do not use IPs, but use Autonomous System Number (ASN) assigned by IANA
- 2 16 bit numbers separated by a dot (32 bits total)
- use either Exterior Gateway Protocol (EGP) or Interior Gateway Protocol (IGP)
BGP
Border Gateway Protocol
- hybrid routing protocol
- uses route aggregation
Edge Routers
Routers for AS-to-AS communication
OSPF
Open Shortest Path First
- most commonly used IGP in the world
Link State Routing Protocols
Instead of updating an entire routing table at regular intervals, routers announce and forward individual route changes as they appear
- two kinds are
