Answers to Review Questions

A network administrator observes that the MPC cannot develop a shortcut. An ATM analyzer attached to the network shows that the MPC never issues a shortcut request, even though the 10 frames per second threshold is crossed. Why doesn't the MPC issue a shortcut request? The show mpoa client command displays as shown in Example 10-20.

The MPC cannot issue a shortcut request because it cannot establish a relationship with an MPS. This results from the absence of an LEC to MPC binding. Notice in the last line of the output that no LANE clients are bound to mpc2. Assuming that a valid LEC exists, you can fix this with the lane client mpoa client command.

When might the ingress and egress MPS reside in the same router?

The ingress and egress MPS might reside in the same router whenever the ingress and egress MPCs are only one router hop away along the default path. That router can then service both the ingress and egress roles.

What creates the association of an MPC with a VLAN?

Because an LEC must be associated with an MPC in a Catalyst, the VLAN associated with the LEC also associates the MPC to the VLAN.

Example 10-6 has the following configuration statement in it: lane client ethernet elan_name. Where is the VLAN reference?

This is from an MPS configuration that resides on a router. The router does not associate VLANs like a Catalyst does. Only Catalyst client interfaces need a VLAN reference to bridge the VLAN to the ELAN. The router associates only with an ELAN.

The following lines appear in both Example 10-14 and Example 10-15: lane client ethernet 21 elan1 and lane client ethernet 22 elan2. Is there any problem with this? Could they both say ethernet 21? The values 21 and 22 combine those VLAN numbers to the correct ELANs (1 and 2). Both ELANs define different broadcast domains and support different IP subnetworks. Conventionally then, the VLAN numbers differ. However, the two VLAN numbers could be the same because they are isolated by a router. If, however, they were not isolated by a router, the VLAN values could not be the same because they would be bridged together merging the broadcast domains.

If a frame must pass through three routers to get from an ingress LEC to an egress LEC, do all three routers need to be configured as an MPS?

No. Only the ingress and egress routers need to be configured as an MPS. However, any other intermediate routers in the default path must have at least an NHS configured. Further, the NHS must be able to source and receive traffic through LECs.

Can you configure both an MPC and an MPS in a router?

Yes. The router may have both concurrently. You can elect to do this when the router functions as an intermediate router or as an ingress/egress router, while at the same time serving local Ethernet or other LAN connections as an MPC.