TCP and RTP Header Compression


Scenario:

You are responsible for the WAN links at the company you work for. Your routers have a very low CPU load and the serial interfaces you have are pretty slow. You decide one day to run TCP and UDP header compression to get the most out of your connections…let’s squeeze some bits!

Goal:

  • All IP addresses have been preconfigured for you.
  • Enable TCP and RTP header compression on both routers.
  • Configure a maximum of 12 compressed TCP or RTP sessions.
  • Router Smaller should only use compression when it receives compressed traffic.

IOS:

c3640-jk9s-mz.124-16.bin

Topology:

TCP and RTP Header Compression

Video Solution:

Configuration Files

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Written by René Molenaar - CCIE #41726

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About the Author: Rene Molenaar

René - CCIE #41726 is the creator of GNS3Vault.com where he shares CCNA, CCNP and CCIE R&S labs. He also blogs about networking on http://networklessons.com

4 Comments

  1. why the copmress router showing the tcp and rtp compressing traffic although we just intiate the telnet traffick that affect on the tcp compression only

  2. Compress#sh ip rtp header-compression
    RTP/UDP/IP header compression statistics:
    Interface Serial0/0 (compression on, Cisco, RTP)
    Rcvd: 0 total, 0 compressed, 0 errors, 0 status msgs
    0 dropped, 0 buffer copies, 0 buffer failures
    Sent: 0 total, 0 compressed, 0 status msgs, 0 not predicted
    0 bytes saved, 0 bytes sent
    Connect: 12 rx slots, 12 tx slots,
    0 misses, 0 collisions, 0 negative cache hits, 12 free contexts

    —-showing zero rtp traffic

    Compress#sh ip tcp header-compression
    TCP/IP header compression statistics:
    Interface Serial0/0 (compression on, VJ)
    Rcvd: 6 total, 5 compressed, 0 errors, 0 status msgs
    0 dropped, 0 buffer copies, 0 buffer failures
    Sent: 8 total, 5 compressed, 0 status msgs, 0 not predicted
    180 bytes saved, 147 bytes sent
    2.22 efficiency improvement factor
    Connect: 12 rx slots, 12 tx slots,
    2 misses, 0 collisions, 0 negative cache hits, 12 free contexts
    75% hit ratio, five minute miss rate 0 misses/sec, 0 max
    showing in above that thre are tcp traffic

    1. Hi Nour,

      [code]Compress#sh ip rtp header-compression
      RTP/UDP/IP header compression statistics:
      Interface Serial0/0 (compression on, Cisco, RTP)
      Rcvd: 0 total, 0 compressed, 0 errors, 0 status msgs[/code]

      I don’t see any hits on the RTP compression?

      [code]Compress#sh ip tcp header-compression
      TCP/IP header compression statistics:
      Interface Serial0/0 (compression on, VJ)
      Rcvd: 6 total, 5 compressed, 0 errors, 0 status msgs[/code]

      And I do see hits on TCP compression…

      Rene

  3. Compress#sh ip tcp header se0/0
    TCP/IP header compression statistics:
    Interface Serial0/0 (compression on, VJ)
    Rcvd: 15 total, 14 compressed, 0 errors, 0 status msgs
    0 dropped, 0 buffer copies, 0 buffer failures
    Sent: 26 total, 24 compressed, 0 status msgs, 0 not predicted
    842 bytes saved, 239 bytes sent
    4.52 efficiency improvement factor
    Connect: 12 rx slots, 12 tx slots,
    1 misses, 0 collisions, 0 negative cache hits, 11 free contexts
    96% hit ratio, five minute miss rate 0 misses/sec, 0 max
    ========================================================
    Smaller(config)#do sh ip tcp header-compres se0/0
    TCP/IP header compression statistics:
    Interface Serial0/0 (compression on, VJ, passive)
    Rcvd: 26 total, 24 compressed, 0 errors, 0 status msgs
    0 dropped, 0 buffer copies, 0 buffer failures
    Sent: 15 total, 14 compressed, 0 status msgs, 0 not predicted
    461 bytes saved, 227 bytes sent
    3.03 efficiency improvement factor
    Connect: 12 rx slots, 12 tx slots,
    1 misses, 0 collisions, 0 negative cache hits, 12 free contexts
    93% hit ratio, five minute miss rate 0 misses/sec, 0 max

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