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Configuring Serial Interfaces on Cisco IOS XR Software
How to Configure Serial Interfaces
HC-121
Cisco IOS XR Interface and Hardware Component Configuration Guide
Keepalives are independent between the two peers. One peer end can have keepalives enabled; the other
end can have them disabled. Even if keepalives are disabled locally, LCP still responds with ECHOREP
packets to the ECHOREQ packets it receives. Similarly, LCP also works if the period of keepalives at
each end is different.
When the interface has PPP encapsulation, if LCP sends three ECHOREQ packets without an
ECHOREP being received then it declares the link down and initiates full LCP negotiation again. If the
interface has HDLC encapsulation, the number of resends is only three before the link is taken down.
Only when LCP negotiation is complete (for example, when LCP is Open) are ECHOREQ packets sent
out.
How to Configure Serial Interfaces
After you have configured a channelized or clear channel T3/E3 controller, as described in the
Configuring Clear Channel T3/E3 Controllers and Channelized T3 Controllers on Cisco IOS XR
Software module earlier in this document, you can configure the Serial interfaces associated with that
controller. The following task describes how to configure a serial interface.
• Configuring the Serial Interfaces, page HC-121
Configuring the Serial Interfaces
Before you can use a serial interface, you must configure the IP address and bring the interface to the up
state, as described in the steps that follow.
Note All global commands are supported on serial interfaces. Only commands specific to serial interfaces are
described in this section. For more information about global interface commands, refer to the Global
Interface Commands on Cisco IOS XR Software module in Cisco IOS XR Interface and Hardware
Component Command Reference.
SUMMARY STEPS
1. configure
2. interface serial instance
3. ipv4 address ip-address
4. encapsulation [hdlc | ppp]
5. keepalive {seconds | disable}
6. serial
7. crc length
8. invert
9. scramble
10. transmit-delay hdlc-flags
11. exit
12. no shutdown