Information Technology Reference
In-Depth Information
Link Eficiency
Link efficiency mechanisms, such as link fragmentation and interleave (LFI) and compression, can alleviate issues involving
excessive serialization delay for large data packets and issues involving scarcity of bandwidth on network links. In addition, a
mechanism called Voice Activity Detection (VAD) can save bandwidth by ensuring that packets are not sent when a speaker is silent.
LFI, compression, and VAD are discussed in the following sections.
Link Fragmentation and Interleave
LFI mechanisms help ensure that voice packets are not unduly delayed by large data packets (because of the serialization delay
incurred by those large packets) as they are transmitted across low-bandwidth links.
LFI reduces the delay experienced by smaller packets, such as voice, by breaking larger (data) packets into fragments and interleaving
smaller voice packets with the fragments of these larger packets as they are queued for transmission on an interface. LFI is typically
required on WAN links with bandwidths of 768 Kbps or less.
There are various methods of provisioning LFI, including Multilink PPP LFI and Frame Relay Forum 12 (FRF.12).
Multilink PPP LFI on Slow-Speed Leased Lines (768 Kbps or Less)
Multilink PPP (MLP) LFI can be configured on either a single link or over several bundled links that are using Point-to-Point Protocol
(PPP) encapsulation.
The following example shows a configuration for MLP LFI:
interface Multilink
5
ip address
10.1.1.1 255.255.255.0
ppp multilink
ppp multilink fragment delay
10
ppp multilink interleave
ppp multilink group
5
!
interface serial 0/0
