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Simple net pinging Date 03/06/2007 Hanan Ohana
Motivation   <ul><li>This presentation shows the flow of events for a PING request in a brand new net with static IP confi...
Net introduction <ul><li>Net containing: </li></ul><ul><ul><li>4 end units  </li></ul></ul><ul><ul><li>2 switches </li></u...
Net introduction <ul><li>The net is configured this way: </li></ul><ul><ul><li>The circled letters A,…,H represents MAC ID...
IP packet release algorithm <ul><li>This block diagram describes the algorithm used by a network device for frame structur...
PING chain of events <ul><li>PING request from station A to station H:  </li></ul><ul><li>Following PING request: </li></u...
PING chain of events <ul><li>A:>ping 30.0.0.3 </li></ul><ul><li>Ping request is to be released from station A, the “IP pac...
PING chain of events <ul><li>ARP request is sent from station A: </li></ul><ul><li>ARP packet: </li></ul><ul><li>The ARP p...
PING chain of events <ul><li>ARP packet arrives to station B and green router: </li></ul><ul><li>Station B receives the AR...
PING chain of events <ul><li>ARP reply is sent from green router: </li></ul><ul><li>ARP packet: </li></ul><ul><li>ARP pack...
PING chain of events <ul><li>PING packet is sent from station A: </li></ul><ul><li>Now that station A knows the MAC of sta...
PING chain of events <ul><li>PING packet is arrives to green router from side C: </li></ul><ul><li>Green router checks des...
PING chain of events <ul><li>ARP request is sent from green router through D: </li></ul><ul><li>ARP packet: </li></ul><ul>...
PING chain of events <ul><li>Another PING packet is sent from station A: </li></ul><ul><li>The packet goes through the lef...
PING chain of events <ul><li>PING packet is arrives to blue router from side E: </li></ul><ul><li>Blue router checks desti...
PING chain of events <ul><li>ARP request is sent from blue router through F: </li></ul><ul><li>ARP packet: </li></ul><ul><...
PING chain of events <ul><li>ARP packet arrives to station G and station H: </li></ul><ul><li>Station G receives the ARP p...
PING chain of events <ul><li>ARP reply is sent from station H: </li></ul><ul><li>ARP packet: </li></ul><ul><li>ARP packet ...
PING chain of events <ul><li>Another PING packet is sent from station A: </li></ul><ul><li>The packet goes through the lef...
PING chain of events <ul><li>PING reply packet is sent from station H to station A: </li></ul><ul><li>The packet goes thro...
The net in steady state <ul><li>After a little traffic the net should look like that: </li></ul><ul><li>All the ARP and CA...
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Ping Presentation

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Transcript of "Ping Presentation"

  1. 1. Simple net pinging Date 03/06/2007 Hanan Ohana
  2. 2. Motivation <ul><li>This presentation shows the flow of events for a PING request in a brand new net with static IP configured to the devices and blank ARP tables to begin with. </li></ul><ul><li>The PING request is sent from one computer in the IP net to another computer. </li></ul><ul><li>Taking in consideration: routers do not use buffers so IP packets get lost if ARP request needed. </li></ul>
  3. 3. Net introduction <ul><li>Net containing: </li></ul><ul><ul><li>4 end units </li></ul></ul><ul><ul><li>2 switches </li></ul></ul><ul><ul><li>2 routers </li></ul></ul>
  4. 4. Net introduction <ul><li>The net is configured this way: </li></ul><ul><ul><li>The circled letters A,…,H represents MAC ID’s of the devices when the routers have one MAC ID for each leg (port). </li></ul></ul><ul><ul><li>IP address and Gate Way for each station and device is written beside the unit. </li></ul></ul><ul><ul><li>The switches legs are numbered in circles 1,2,3. </li></ul></ul><ul><li>The ARP and CAM tables are empty, as the initial condition of the devices. </li></ul>1 1 2 3 3 2 A B C D E F G H IP 10.0.0.1 GW 10.0.0.3 IP 10.0.0.2 GW 10.0.0.3 IP 10.0.0.3 IP 20.0.0.1 IP 20.0.0.2 IP 30.0.0.1 IP 30.0.0.2 GW 30.0.0.1 IP 30.0.0.3 GW 30.0.0.1 GW 20.0.0.2 GW 20.0.0.1 A ARP B ARP G ARP H ARP R ARP R ARP CAM CAM
  5. 5. IP packet release algorithm <ul><li>This block diagram describes the algorithm used by a network device for frame structure decision, when IP packet has to be sent. </li></ul>Local Destination IP? ARP Target MAC Known? Send to Gateway Send to destination Send to destination Yes No Yes No Decision needed
  6. 6. PING chain of events <ul><li>PING request from station A to station H: </li></ul><ul><li>Following PING request: </li></ul><ul><ul><li>A:>ping 30.0.0.3 </li></ul></ul>1 1 2 3 3 2 A B C D E F G H IP 10.0.0.1 GW 10.0.0.3 IP 10.0.0.2 GW 10.0.0.3 IP 10.0.0.3 IP 20.0.0.1 IP 20.0.0.2 IP 30.0.0.1 IP 30.0.0.2 GW 30.0.0.1 IP 30.0.0.3 GW 30.0.0.1 GW 20.0.0.2 GW 20.0.0.1 A ARP B ARP G ARP H ARP R ARP R ARP CAM CAM
  7. 7. PING chain of events <ul><li>A:>ping 30.0.0.3 </li></ul><ul><li>Ping request is to be released from station A, the “IP packet release algorithm” is used. </li></ul><ul><li>For non local destination IP and unknown target MAC, an ARP request is sent to GW, as a broadcast. </li></ul>1 1 2 3 3 2 A B C D E F G H IP 10.0.0.1 GW 10.0.0.3 IP 10.0.0.2 GW 10.0.0.3 IP 10.0.0.3 IP 20.0.0.1 IP 20.0.0.2 IP 30.0.0.1 IP 30.0.0.2 GW 30.0.0.1 IP 30.0.0.3 GW 30.0.0.1 GW 20.0.0.2 GW 20.0.0.1 A ARP B ARP G ARP H ARP R ARP R ARP CAM CAM
  8. 8. PING chain of events <ul><li>ARP request is sent from station A: </li></ul><ul><li>ARP packet: </li></ul><ul><li>The ARP packet is a broadcast so the left switch is flooding and send the same packet to the rest of the connected legs. </li></ul><ul><li>The left switch updates the CAM table with A-leg1 relation. </li></ul>FCS TRAILER 10.0.0.3 000000 10.0.0.1 A 0001 4 6 0800 1 0806 A FFFF 1 1 2 3 3 2 A B C D E F G H IP 10.0.0.1 GW 10.0.0.3 IP 10.0.0.2 GW 10.0.0.3 IP 10.0.0.3 IP 20.0.0.1 IP 20.0.0.2 IP 30.0.0.1 IP 30.0.0.2 GW 30.0.0.1 IP 30.0.0.3 GW 30.0.0.1 GW 20.0.0.2 GW 20.0.0.1 A ARP B ARP G ARP H ARP R ARP R ARP A-leg1 CAM CAM
  9. 9. PING chain of events <ul><li>ARP packet arrives to station B and green router: </li></ul><ul><li>Station B receives the ARP packet and updates the ARP table with A-10.0.0.1 relation. Station B does not send a reply. </li></ul><ul><li>The green router receives the ARP packet and updates the ARP table with A-10.0.0.1 relation, sends a reply and trashes the original packet. </li></ul>1 1 2 3 3 2 A B C D E F G H IP 10.0.0.1 GW 10.0.0.3 IP 10.0.0.2 GW 10.0.0.3 IP 10.0.0.3 IP 20.0.0.1 IP 20.0.0.2 IP 30.0.0.1 IP 30.0.0.2 GW 30.0.0.1 IP 30.0.0.3 GW 30.0.0.1 GW 20.0.0.2 GW 20.0.0.1 A ARP A-10.0.0.1 B ARP G ARP H ARP A-10.0.0.1 R ARP R ARP A-leg1 CAM CAM
  10. 10. PING chain of events <ul><li>ARP reply is sent from green router: </li></ul><ul><li>ARP packet: </li></ul><ul><li>ARP packet gets to the left switch. Switch recognizes destination MAC and pass it to leg1. CAM table is updated with C-leg3 relation. </li></ul><ul><li>Station A receives ARP response and updates its ARP table with C-10.0.0.3 relation. </li></ul>1 1 2 3 3 2 A B C D E F G H IP 10.0.0.1 GW 10.0.0.3 IP 10.0.0.2 GW 10.0.0.3 IP 10.0.0.3 IP 20.0.0.1 IP 20.0.0.2 IP 30.0.0.1 IP 30.0.0.2 GW 30.0.0.1 IP 30.0.0.3 GW 30.0.0.1 GW 20.0.0.2 GW 20.0.0.1 C-10.0.0.3 A ARP A-10.0.0.1 B ARP G ARP H ARP A-10.0.0.1 R ARP R ARP A-leg1 C-leg3 CAM CAM FCS TRAILER 10.0.0.3 C 10.0.0.1 A 0002 4 6 0800 1 0806 C A
  11. 11. PING chain of events <ul><li>PING packet is sent from station A: </li></ul><ul><li>Now that station A knows the MAC of station C (GW), a PING packet is sent. </li></ul><ul><li>PING packet: </li></ul><ul><li>PING packet is sent to GW because pinging to a non local IP. </li></ul>FCS PING 30.0.0.3 10.0.0.1 0800 A C 1 1 2 3 3 2 A B C D E F G H IP 10.0.0.1 GW 10.0.0.3 IP 10.0.0.2 GW 10.0.0.3 IP 10.0.0.3 IP 20.0.0.1 IP 20.0.0.2 IP 30.0.0.1 IP 30.0.0.2 GW 30.0.0.1 IP 30.0.0.3 GW 30.0.0.1 GW 20.0.0.2 GW 20.0.0.1 C-10.0.0.3 A ARP A-10.0.0.1 B ARP G ARP H ARP A-10.0.0.1 R ARP R ARP A-leg1 C-leg3 CAM CAM
  12. 12. PING chain of events <ul><li>PING packet is arrives to green router from side C: </li></ul><ul><li>Green router checks destination address and “IP packet release algorithm” is used. </li></ul><ul><li>For a non local destination IP and unknown target MAC, an ARP request is sent to GW as a broadcast through D. </li></ul><ul><li>REMARK: The routers in this example don’t have a buffer to keep the original PING request so it is lost. </li></ul>1 1 2 3 3 2 A B C D E F G H IP 10.0.0.1 GW 10.0.0.3 IP 10.0.0.2 GW 10.0.0.3 IP 10.0.0.3 IP 20.0.0.1 IP 20.0.0.2 IP 30.0.0.1 IP 30.0.0.2 GW 30.0.0.1 IP 30.0.0.3 GW 30.0.0.1 GW 20.0.0.2 GW 20.0.0.1 C-10.0.0.3 A ARP A-10.0.0.1 B ARP G ARP H ARP A-10.0.0.1 R ARP R ARP A-leg1 C-leg3 CAM CAM
  13. 13. PING chain of events <ul><li>ARP request is sent from green router through D: </li></ul><ul><li>ARP packet: </li></ul><ul><li>The ARP packet arrives to blue router. Blue router updates the ARP table with D-20.0.0.1 , sends reply and trashes the original packet. </li></ul><ul><li>The ARP reply arrives to green router. Green router updates the ARP table with E-20.0.0.2 . </li></ul>FCS TRAILER 20.0.0.2 000000 20.0.0.1 D 0001 4 6 0800 1 0806 D FFFF 1 1 2 3 3 2 A B C D E F G H IP 10.0.0.1 GW 10.0.0.3 IP 10.0.0.2 GW 10.0.0.3 IP 10.0.0.3 IP 20.0.0.1 IP 20.0.0.2 IP 30.0.0.1 IP 30.0.0.2 GW 30.0.0.1 IP 30.0.0.3 GW 30.0.0.1 GW 20.0.0.2 GW 20.0.0.1 C-10.0.0.3 A ARP A-10.0.0.1 B ARP G ARP H ARP A-10.0.0.1 E-20.0.0.2 R ARP D-20.0.0.1 R ARP A-leg1 C-leg3 CAM CAM
  14. 14. PING chain of events <ul><li>Another PING packet is sent from station A: </li></ul><ul><li>The packet goes through the left switch according to the CAM table to the green router. </li></ul><ul><li>In the green router, based on “IP packet release algorithm”, for non local IP destination and known target MAC, sends a continuation IP packet to blue router (same IP packet, different header). </li></ul><ul><li>The blue router checks MAC destination and recognizes as its own. </li></ul>1 1 2 3 3 2 A B C D E F G H IP 10.0.0.1 GW 10.0.0.3 IP 10.0.0.2 GW 10.0.0.3 IP 10.0.0.3 IP 20.0.0.1 IP 20.0.0.2 IP 30.0.0.1 IP 30.0.0.2 GW 30.0.0.1 IP 30.0.0.3 GW 30.0.0.1 GW 20.0.0.2 GW 20.0.0.1 C-10.0.0.3 A ARP A-10.0.0.1 B ARP G ARP H ARP A-10.0.0.1 E-20.0.0.2 R ARP D-20.0.0.1 R ARP A-leg1 C-leg3 CAM CAM
  15. 15. PING chain of events <ul><li>PING packet is arrives to blue router from side E: </li></ul><ul><li>Blue router checks destination address and “IP packet release algorithm” is used. </li></ul><ul><li>For a local destination IP and unknown target MAC, an ARP request is sent as a broadcast through F. </li></ul>1 1 2 3 3 2 A B C D E F G H IP 10.0.0.1 GW 10.0.0.3 IP 10.0.0.2 GW 10.0.0.3 IP 10.0.0.3 IP 20.0.0.1 IP 20.0.0.2 IP 30.0.0.1 IP 30.0.0.2 GW 30.0.0.1 IP 30.0.0.3 GW 30.0.0.1 GW 20.0.0.2 GW 20.0.0.1 C-10.0.0.3 A ARP A-10.0.0.1 B ARP G ARP H ARP A-10.0.0.1 E-20.0.0.2 R ARP D-20.0.0.1 R ARP A-leg1 C-leg3 CAM CAM
  16. 16. PING chain of events <ul><li>ARP request is sent from blue router through F: </li></ul><ul><li>ARP packet: </li></ul><ul><li>The ARP packet is a broadcast so the right switch is flooding and send the same packet to the rest of the connected legs. </li></ul><ul><li>The right switch updates the CAM table with F-leg3 relation. </li></ul>1 1 2 3 3 2 A B C D E F G H IP 10.0.0.1 GW 10.0.0.3 IP 10.0.0.2 GW 10.0.0.3 IP 10.0.0.3 IP 20.0.0.1 IP 20.0.0.2 IP 30.0.0.1 IP 30.0.0.2 GW 30.0.0.1 IP 30.0.0.3 GW 30.0.0.1 GW 20.0.0.2 GW 20.0.0.1 C-10.0.0.3 A ARP A-10.0.0.1 B ARP G ARP H ARP A-10.0.0.1 E-20.0.0.2 R ARP D-20.0.0.1 R ARP A-leg1 C-leg3 CAM F-leg3 CAM FCS TRAILER 30.0.0.3 000000 30.0.0.1 F 0001 4 6 0800 1 0806 F FFFF
  17. 17. PING chain of events <ul><li>ARP packet arrives to station G and station H: </li></ul><ul><li>Station G receives the ARP packet and updates the ARP table with F-30.0.0.1 relation. Station G does not send a reply. </li></ul><ul><li>Station H receives the ARP packet and updates the ARP table with F-30.0.0.1 relation, sends a reply and trashes the original packet. </li></ul>1 1 2 3 3 2 A B C D E F G H IP 10.0.0.1 GW 10.0.0.3 IP 10.0.0.2 GW 10.0.0.3 IP 10.0.0.3 IP 20.0.0.1 IP 20.0.0.2 IP 30.0.0.1 IP 30.0.0.2 GW 30.0.0.1 IP 30.0.0.3 GW 30.0.0.1 GW 20.0.0.2 GW 20.0.0.1 C-10.0.0.3 A ARP A-10.0.0.1 B ARP F-30.0.0.1 G ARP F-30.0.0.1 H ARP A-10.0.0.1 E-20.0.0.2 R ARP D-20.0.0.1 R ARP A-leg1 C-leg3 CAM F-leg3 CAM
  18. 18. PING chain of events <ul><li>ARP reply is sent from station H: </li></ul><ul><li>ARP packet: </li></ul><ul><li>ARP packet gets to the right switch. Switch recognizes destination MAC and pass it to leg3. CAM table is updated with H-leg2 relation. </li></ul><ul><li>Blue router receives ARP response and updates its ARP table with H-30.0.0.3 relation. </li></ul>1 1 2 3 3 2 A B C D E F G H IP 10.0.0.1 GW 10.0.0.3 IP 10.0.0.2 GW 10.0.0.3 IP 10.0.0.3 IP 20.0.0.1 IP 20.0.0.2 IP 30.0.0.1 IP 30.0.0.2 GW 30.0.0.1 IP 30.0.0.3 GW 30.0.0.1 GW 20.0.0.2 GW 20.0.0.1 C-10.0.0.3 A ARP A-10.0.0.1 B ARP F-30.0.0.1 G ARP F-30.0.0.1 H ARP A-10.0.0.1 E-20.0.0.2 R ARP D-20.0.0.1 H-30.0.0.3 R ARP A-leg1 C-leg3 CAM F-leg3 H-leg2 CAM FCS TRAILER 30.0.0.3 H 30.0.0.1 F 0002 4 6 0800 1 0806 H F
  19. 19. PING chain of events <ul><li>Another PING packet is sent from station A: </li></ul><ul><li>The packet goes through the left switch according to the CAM table to the green router. The green router sends a continuation IP packet to blue router. The blue router sends a continuation IP packet to station H. </li></ul><ul><li>The packet goes through the right switch according to the CAM table to station H. </li></ul>1 1 2 3 3 2 A B C D E F G H IP 10.0.0.1 GW 10.0.0.3 IP 10.0.0.2 GW 10.0.0.3 IP 10.0.0.3 IP 20.0.0.1 IP 20.0.0.2 IP 30.0.0.1 IP 30.0.0.2 GW 30.0.0.1 IP 30.0.0.3 GW 30.0.0.1 GW 20.0.0.2 GW 20.0.0.1 C-10.0.0.3 A ARP A-10.0.0.1 B ARP F-30.0.0.1 G ARP F-30.0.0.1 H ARP A-10.0.0.1 E-20.0.0.2 R ARP D-20.0.0.1 H-30.0.0.3 R ARP A-leg1 C-leg3 CAM F-leg3 H-leg2 CAM
  20. 20. PING chain of events <ul><li>PING reply packet is sent from station H to station A: </li></ul><ul><li>The packet goes through the right switch according to the CAM table to the blue router. The blue router sends a continuation IP packet to green router. The green router sends a continuation IP packet to station A. </li></ul><ul><li>The packet goes through the left switch according to the CAM table to station A. </li></ul>1 1 2 3 3 2 A B C D E F G H IP 10.0.0.1 GW 10.0.0.3 IP 10.0.0.2 GW 10.0.0.3 IP 10.0.0.3 IP 20.0.0.1 IP 20.0.0.2 IP 30.0.0.1 IP 30.0.0.2 GW 30.0.0.1 IP 30.0.0.3 GW 30.0.0.1 GW 20.0.0.2 GW 20.0.0.1 C-10.0.0.3 A ARP A-10.0.0.1 B ARP F-30.0.0.1 G ARP F-30.0.0.1 H ARP A-10.0.0.1 E-20.0.0.2 R ARP D-20.0.0.1 H-30.0.0.3 R ARP A-leg1 C-leg3 CAM F-leg3 H-leg2 CAM
  21. 21. The net in steady state <ul><li>After a little traffic the net should look like that: </li></ul><ul><li>All the ARP and CAM tables are full with the information that let them work correctly. </li></ul>1 1 2 3 3 2 A B C D E F G H IP 10.0.0.1 GW 10.0.0.3 IP 10.0.0.2 GW 10.0.0.3 IP 10.0.0.3 IP 20.0.0.1 IP 20.0.0.2 IP 30.0.0.1 IP 30.0.0.2 GW 30.0.0.1 IP 30.0.0.3 GW 30.0.0.1 GW 20.0.0.2 GW 20.0.0.1 C-10.0.0.3 B-10.0.0.2 A ARP A-10.0.0.1 C-10.0.0.3 B ARP F-30.0.0.1 H-30.0.0.3 G ARP F-30.0.0.1 G-30.0.0.2 H ARP A-10.0.0.1 E-20.0.0.2 B-10.0.0.2 R ARP D-20.0.0.1 H-30.0.0.3 G-30.0.0.2 R ARP A-leg1 C-leg3 B-leg2 CAM F-leg3 H-leg2 G-leg1 CAM
  22. 22. Thank You
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