PPP Notes - LFI

Thu, 23 Jun 2011 00:00:00 +0000

Link Fragmentation and Interleaving
A QoS tool to prevent smaller, higher-priority packets from waiting on larger packets to transmit
- For example, VoIP packets and FTP packets
Fragments the larger packets and interleaves them with the smaller packets
Only available in PPP with Multilink
- Can be a multilink bundle with a single link in it
Common to use with LLQ to interleave the delay-sensitive packets
fragment-delay allows you to change the fragment size
- In milliseconds
- size = fragment-delay * bandwidth of interface

R1(config)#interface Multilink 1
R1(config-if)#bandwidth 512
R1(config-if)#ppp multilink interleave
R1(config-if)#ppp multilink delay 10

-- Corrections, please.

Network Protocol Overhead

Mon, 10 Jan 2011 00:00:00 +0000

Here are some packet overhead numbers for a few popular protocols to help with doing bandwidth requirement calculations. This may be another add-as-we-go post, so please comment with additions or corrections.

Ethernet : 20 bytes
Frame Relay : 4 - 6 bytes
PPP : 6 bytes
MLPPP: 10 bytes
MPLS : 4 bytes

IP : 20 bytes

TCP : 20+ bytes
UDP : 8 bytes
GRE: 4 - 20+ bytes

Ppp on Aaron's Worthless Words

PPP Notes - LFI

Network Protocol Overhead