Sunday 30 August 2015

Layer 2 Final Revision

This weekend I consolidated my Layer 2 knowledge by finishing off the first 3 chapters of the Official CCIE Study Guide. I was pretty confident in Layer 2 stuff, but I still managed to pick up a few reminders of gotchas below.

Etherchannel Notes from this weekend:

To check the load balancing accross the links use the following command:
show port-channel traffic

Reminder - for Layer 3 port-channels, configure 'no switchport' on the physical interfaces first before configuring the port-channel

Layer 2 reminders:

Ethernet V2 and IEEE802.3 frames are different.
Ethernet V2 have a 2-byte Type field.
IEEE802.3 have a 2-byte Length field & 3 x 1-byte fields - Destination Service Access Point (DSAP), Source Service Access Point (SSAP) and Control. These are called LLC fields.

VTP gotchas this weekend -

without any configuration, the default is server mode
without any domain name a switch will assume the domain name of the first received VTP update
Although VTPv3 supports extended vlans, it does not prune them :O
VLAN database mode ALWAYS only allows manipulating normal range VLANs, regardless of the VTP version and VTP mode

PPP header = 2 bytes
PPPoE header = 6 bytes

Private VLANs can always communicate with trunk ports

STP: port costs are only applied to RECEIVED BPDUs, not sent BPDUs

Here are my results from the post chapter quizzes... not stunning, but mostly just misreading questions or forgetting something small:

Switched Networking Basics Quiz

Virtual LANs and VLAN Trunking Quiz

Spanning Tree Protocol Quiz