Learning by Doing: CISCO Certified Network ... - SCN Research

28. CDPCP: O CONFACK [REQsent]
29. IPCP: I CONFACK [ACKsent]
30. IPCP: Address 200.200.200.1
31. IPCP: State is Open
32. CDPCP: I CONFACK [ACKsent]
33. CDPCP: State is Open
34. IPCP: Install route to 200.200.200.2
35. Line protocol on Interface Serial0/0, changed state to up
In lines 4-9 we can see what is involved with “tearing down” a connection
session. Obviously we would expect to have to re-create those to establish a new
PPP session. We see that IPCP went down, then CDPCP, then PPP and finally
LCP. Lastly the route was removed. We would expect to see the creation in the
reverse order.
In line 13 we see, after our serial line is re-connected, the beginning step of
establishing a PPP session.
In 15-18 we see our LCP negotiation phase:
1. a request from s0/0 to s0/1 (line 15),
2. the acknowledgement of that request from s0/1 that s0/0 wants to
establish LCP (line 16),
3. then the acknowledgement of s0/0 that s0/1 received the request from
s0/0 to establish an LCP (line 17).
4. Then LCP is “open” (line 18).
Then we see our PPP “phase” is set to up in line 19.
Then we see our IPCP and CDPCP being brought back up just about the same
time in the remainder of our script. During the IPCP:
1. We see s0/0 send it’s ip address (200.200.200.1) to s0/1 (lines 20-21)
2. Then s0/1 sends it’s ip address (200.200.200.2) to s0/0 (lines 23-24)
3. Then s0/0 sends an acknowledgement to s0/1 that it received the ip
address from s0/1 (lines 25-26)
4. Then s0/1 sends an acknowledgement to s0/0 that it received the ip
address from s0/0 (lines 29-30)
5. Finally the route is established (line 34)
During the CDPCP:
1. a CDPCP configuration request is sent from s0/0 to s0/1 (line 22/27)
2. an acknowledgement of receipt of that request is sent from s0/1 to s0/0
(line 28).
3. an acknowledgement of receiving that acknowledgement is sent from
s0/0 to s0/1 (line 32).
4. The CDPCP state is set to “open.”
Our order has reversed itself and our connection, via PPP encapsulation, is now
ready to communicate!
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