для Cisco Cisco IOS Software Release 12.2(33)SRE

The following parameters are exchanged using directed control protocol messages on pseudowires, but 
cannot be changed using the AToM Static Pseudowire feature introduced in Cisco IOS software Release 
12.33(SRB). Instead, the software has preconfigured defaults.

The maximum number of concatenated ATM cells is set to 1, which means no cell packing is 
available.

The Virtual Circuit Connectivity Verification (VCCV) options used for fault detection, isolation, 
and verification at both ends of the connection are set as follows:

Control channel type 1 sets the control word.

Control channel type 2 sets the Multiprotocol Label Switching (MPLS) router alert label.

Connectivity verification type 2 sets the label switched path (LSP) ping command.

Auto-sensing of the virtual circuit type for Ethernet over MPLS is not supported.

Additionally, the following functionality is not supported for static pseudowires:

Sequence number resynchronization—configured by the sequencing function in the Cisco IOS 
pseudowire-class command—is not supported because the sequence number resynchronization is 
done when the LDP software sends an LDP Label Release or Withdraw message followed by a Label 
Request or Mapping message, and static pseudowires do not use LDP.

Tunnel stitching, because it requires an extension of the Cisco IOS neighbor command to start the 
mode that allows configuring static pseudowire parameters such as remote and local labels, which 
is not supported in Cisco IOS software Release 12.33(SRB). Note that a tunnel switch point can be 
configured using a different static label command. The tunnel switch point will not process control 
words, but label swapping will occur.

Pseudowire redundancy, because it requires using a directed control protocol between the peer 
provider edge routers.

To provision an AToM static pseudowire, you should understand the following concepts:

In software prior to Cisco IOS software Release 12.33(SRB), pseudowires were dynamically 
provisioned using Label Distribution Protocol (LDP), or another directed control protocol such as 
Resource Reservation Protocol over traffic-engineered tunnels (RSVP-TE), to exchange the various 
parameters required for these connections. In environments that do not or cannot use directed control 
protocols, a means for provisioning the pseudowire parameters statically at the Cisco IOS CLI is 
provided by the AToM Static Pseudowire feature.

The AToM Static Pseudowire feature is platform-independent, but has been tested on only the 
Cisco 7600 series routers for Cisco IOS software Release 12.33(SRB).