Per-destination or per-packet CEF load sharing?
Cisco Express Forwarding (CEF) can perform per-packet or per-destination (actually source/destination IP address pair) load-sharing with no performance degradation (without CEF, per-packet load-sharing requires process switching). Even though there is no performance impact on the router, per-packet load sharing will almost always result in out-of-order packets. The packet reordering might degrade TCP throughput in high-speed environments (in low-speed/few-flows scenarios, per-packet load-sharing actually improves the per-flow throughput) or severely impact applications that cannot survive out-of-order packet delivery, such as Fast Sequenced Transport for SNA over IP or voice/video streams.
To configure per-packet load-sharing, use the ip load-sharing per-packet interface configuration command (default is per-destination). This command has to be configured on all outgoing interfaces over which the traffic is load-shared.
To configure per-packet load-sharing, use the ip load-sharing per-packet interface configuration command (default is per-destination). This command has to be configured on all outgoing interfaces over which the traffic is load-shared.
The switch between the load-sharing modes is not immediate; sometimes you have to wait a few seconds for the ip load-sharing command to take effect, worst case a manual clearing of the CEF table (clear ip cef address) is required.
Ramya
Load sharing can be per-source-destination-pair (default), per-packet (strongly discouraged in this scenario, as the packets will be almost guaranteed to arrive out-of-order) or per-flow (see Per-port CEF load sharing).
I'm a bit unclear about this?
And especially if BGP is involved!
Thanks.
I have 4 running OK but was wondering if there was limit encase they want to add more?
Wayne
If you have significantly more than four parallel links, you might consider upgrading to a higher-speed solution.