Information Technology Reference
In-Depth Information
encapsulation frame-relay
!
interface Serial1/0.100 point-to-point
ip address 10.1.1.1 255.255.255.0
frame-relay interface-dlci 100
class slow-wan-class
You can calculate the fragment size as follows:
Fragment size (bytes) = (PVC speed [Kbps] * Max allowed jitter [ms]) / 8
Using a maximum allowed jitter of 10 ms (the Cisco recommendation), the fragment size for a 768-Kbps PVC works out as 960 bytes.
Before finishing this section, note that MLP can also be used to enable fragmentation when deploying Frame Relay/ATM FRF.8
service interworking. In this case, Frame Relay and ATM networks are connected, and to help to ensure end-to-end QoS, packets can
be sent across the connection using MLP over Frame Relay (MLPoFR) and MLP over ATM (MLPoATM).
MLPoFR and MLPoATM were introduced in IOS 12.1(5)T.
Compressed Real-Time Transport Protocol
cRTP compresses IP/UDP/RTP headers of packets as they are sent over low-speed links and therefore saves bandwidth. Cisco
recommends enabling cRTP on low-speed WAN lines (less than or equal to 768 Kbps).
cRTP can be configured on an interface using the
ip rtp header-compression
command. cRTP must be enabled at both ends of the
link.
cRTP can also be configured via the MQC using the
compression header ip rtp
command, as shown in the following example:
policy-map
crtp-map
class
voice-traffic
compression header ip rtp
priority percent
30
class class-default
fair-queue
More information about cRTP can be found in the section, “RTP and cRTP,” later in this e-book.
