3 - L2 Net Design, Large Nets and Static Routes Flashcards
Layer 2 good network design
Modular and Hierarchical
L2 what are the different separations of functions?
Core: resilient, high bandwidth
Distribution: Aggregation, redundancy
Access: Port density, affordability, security
Collision Domains
a network segment that is shared but not bridged or switched
Why are hubs dumb?
They broadcast every packet everywhere
How many hosts should a broadcast domain contain
Ideally no more than 250
What should you use between multiple switches?
Aggregation switch
Where should the aggregation switch be located?
Close to the building network entry point
Where should edge switches be?
Near users. Maximum 100m
VLAN Tagging
Used when a single link needs to carry traffic for more than one VLAN
VLAN Trunking
Tagged frames across different switches
VLAN Good reasons to use
Segment network with less switches
Separate control traffic from user traffic
VLAN Bad reasons to use
Just because.
As the sole method of security.
To extend the same IP net over multiple buildings
Why shouldn’t you use VLANs to extend an IP net over multiple buildings
Broadcast traffic is carried across all trunks
Broadcast storm can spread across the extent of the VLAN
Hard to maintain
IP Router - what to do when receiving a packet
Checks if dest addr is router - send to higher layers
Decrement TTL and discard if zero
Look up dest IP addr in forwarding table
Forwarding Table structure
COntains prefixes (network numbers)
If the first /n bits match, send that way.
