Chapter 10 673
19
Is there a limit to the number of subinterfaces that are allowed on a router when using
Frame Relay?
Because there can be only 992 DLCIs, you would reach that limit before the subinterface
limit.
20
What does an increase in the number of FECN and BECN packets mean?
The provider is probably experiencing congestion in the network.
21
In order for a DLCI on a subinterface to be "active," does the DLCI also have to be up at
the remote end?
Yes. The remote DLCI must be up in order for a DLCI on a subinterface to be active.
22
With two subinterfaces on the same router, can there be two different Frame Relay
encapsulations?
No. The parent interface can be configured with only one encapsulation.
23
Does OSPF use split horizon for an interface?
OSPF does not use split horizon, because it is a link-state routing protocol.
24
What is LMI used for?
The Frame Relay LMI conveys the DLCI status from the switch to the router.
25
By default, is a subinterface point-to-point or multipoint?
Multipoint.
26
Does LAPB provide error recovery?
Yes. However, this slows down performance. Cisco's HDLC does not do error recovery.
It simply drops the packet. But performance is faster.
27
To which layer do the X.25 parameters window size and packet size belong?
Layer 3 of the X.25 spec.
28
Does Frame Relay guarantee delivery of data?
No. Frame Relay relies on upper-layer protocols to correct errors.
29
Does X.25 guarantee delivery of data?
Yes. It relies on the LAPB protocol to check for errors on the line and request
retransmission for errors on the link.
30
Which companies comprise the Gang of Four?
Stratacom, Northern Telecom, Cisco Systems, Digital Equipment Corporation.
87200333.book Page 673 Wednesday, August 22, 2001 1:41 PM