CEF
- Cisco Express Forwarding is enabled by default on most Cisco platforms running Cisco IOS software Release12.0 or later.
- When Cisco Express Forwarding is enabled on a router, the Route Processor (RP) performs the express forwarding.
Enabling or Disabling CEF or dCEF on a Router
[no] ip cef
[no] ip cef distributedWhen to Enable or Disable CEF on an Interface
The input interface determines the Cisco IOS switching path that a packet takes.
- CEF to be enabled on the incoming interface for packets to be CEF switched.Because CEF makes the forwarding decision on input, you need
! on the ingress interface
[no] ip route-cache cef
In contrast, because Cisco IOS builds a fast-switching cache entry after switching a packet, a packet coming in on a process-switched interface and going out through a fast-switched interface is fast switched. If you want to disable fast switching, use
! on the egress interface
no ip route-cache
Interface Bandwidth/ Delay:
| INTERFACE | bandwidth in kbits/s | Delay in microseconds (1 μs = 1/10^6 sec) |
| 10 Mbps Ethernet | 10'000 | 1000 |
| 100 Mbps Ethernet | 100'000 | 100 |
| 1000 Mbps Ethernet | 1'000'000 | 10 |
| 10000 Mbps Ethernet | 10'000'000 | 1 |
| Loopback | 8'000'000 | 5000 |
| Tunnel BW | 100 | 50000 |
| Tunnel
transmit/receive BW (only used with RBSCP - rate based satellite control protocol ) |
8'000 | |
| Token ring | 16000 | 630 |
| Fddi | 100000 | 100 |
| Serial | 1544 | 20000 |
Low-speed serial:
|
115 | 20000 |
WIC on 1600/2600/3600 series,
|
||
sync/async interfaces on 252x,
|
||
| sync/async serial modules on 2600/3600, etc.. | ||
| ISDN BRI & PRI | 64 | 20000 |
| Dialer | 56 | 20000 |
| Channelized T1 or E1 | n * 64 | 20000 |
| Async | tty line speed | 100000 |