FlexWAN and Enhanced FlexWAN Modules Installation and Configuration Guide
Multilink Feature Support
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Multilink Feature Support

Table Of Contents

Multilink Feature Support

Multilink Feature Support

Table 4-1 shows the combination of features supported on multilink interfaces on the FlexWAN, Enhanced FlexWAN, and SIP/SPA modules on the Cisco 7600 series router.

For additional details about multilink features on the FlexWAN and Enhanced FlexWAN modules, see Chapter 3, "FlexWAN and Enhanced FlexWAN Software Features Configuration Information.".

For additional details about multilink features on SIP/SPA modules, see the Cisco 7600 Series Router SIP, SSC, and SPA Software Configuration Guide at:


Table 4-1 Multilink Feature Support on FlexWAN, Enhanced FlexWAN, and SIP/SPA Modules 

QoS 1
High Availability

distributed Multilink Point-to-Point


Note cRTP is not supported
with MPLS.


Supported in core and access networks.

PPPoMPLS is not supported on dMLP. 2


distributed Multilink Frame Relay

Not supported.


FRoMPLS is supported between CE and PE.

RPR+ is supported.

SSO is not supported.

distributed Link Fragmentation
and Interleaving
(dLFI) over:

Frame Relay

Leased lines

Supported only on multilink interface
with a single
member link. 3


MPLS is not supported with dLFI.

MPLS-VPN is supported between the CE and PE. VRF is also supported between CE and PE.

PPPoMPLS is not supported with dLFI. 2

Supported on dLFIoLL.

Not supported on dLFIoFR or dLFIoATM.

Link fragmentation and interleaving (LFI) is always done in the software. 4

In addition, the following guidelines apply to fragmentation:

For software-based dMLP (which is performed at the line card), the ppp multilink interleave command is required to enable fragmentation. For hardware-based MLP (on the SPA), fragmentation can be enabled through the ppp multilink fragmentation command.

For dMLFR, fragmentation on the TX side is not supported.

1 QoS is always handled at the line card.

2 PPPoMPLS is not supported with dMLP and dLFI. This is because PPPoMPLS must be configured end-to-end, while dMLP and dLFI are terminated (since they use point-to-point protocol).

3 cRTP and dLFI can be used together only if the multilink interface has a single link. On an interface with multiple links, dLFI distributes priority packets (such as VoIP) across all of the links. Since priority packets do not contain the MLP header and sequence number, the packets could arrive out of sequence. cRTP does not support out-of-sequence packets; therefore, cRTP and dLFI cannot be used on a multilink interface with multiple links.

4 LFI is always done in the software with the exception of dLFIoATM on a SIP-100/ATM-SPA, in which case LFI is done in the SPA.
In addition, when running dLFIoLL with a single member link in the bundle on a SIP-200 SPA, LFI is done at the hardware level.