CCIE Pursuit Blog

January 12, 2008

Internetwork Expert Volume II: Lab 4 – Section 3

Section 3 – HDLC/PPP – 3 Points

3.1 HDLC/PPP

A poem:

PPP
How I hate thee!

Actually, this task was easy because you are authenticating on both sides of the link.  You just have to watch out as one side uses clear-text password (PAP) and the other uses an MD5 hash (CHAP).  The hardest part is figuring out which side to configure with which authentication.

3.2 Link Efficiency

“Configure r4 and r5 to maximize efficiency on this link by guessing character streams in frames sent over the link.”

I’m thinking that this describes compression.  “guessing character streams” = predictor?   YES!!!

compress

r5(config-if)#compress ?
  lzs        lzs compression type
  mppc       MPPC compression type
  predictor  predictor compression type
  stac       stac compression algorithm

  <cr>

r5#p 141.1.45.5 re 10 size 1500

Type escape sequence to abort.
Sending 10, 1500-byte ICMP Echos to 141.1.45.5, timeout is 2 seconds:
!!!!!!!!!!
Success rate is 100 percent (10/10), round-trip min/avg/max = 20/21/24 ms

r5#sh compress detail
 Serial0/1
         Software compression enabled
         uncompressed bytes xmt/rcv 31472/31478
         compressed bytes   xmt/rcv 4251/4268
         Compressed bytes sent:      4251 bytes   0 Kbits/sec  ratio: 7.403
         Compressed bytes recv:      4268 bytes   0 Kbits/sec  ratio: 7.375

         1  min avg ratio xmt/rcv 6.826/7.056
         5  min avg ratio xmt/rcv 5.575/6.513
         10 min avg ratio xmt/rcv 5.575/6.513
         no bufs xmt 0 no bufs rcv 0
         resyncs 0
         Compression   Protocol used: Predictor 1
         Decompression Protocol used: Predictor 1

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