lec10 - CprE 530 Lecture 10 Topics 1. 2. 3. 4. Addressing...

Info iconThis preview shows pages 1–7. Sign up to view the full content.

View Full Document Right Arrow Icon
CprE 530 Lecture 10 Topics • 1. Addressing • 2. Routing • 3. Packet Formats • 4. ICMP Internet Control Message Protocol
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Routing All hosts and gateways store routing tables Each row in the route table contains: – Destination address or address range – Next hop for that destination address range – The physical interface to use for that address range. (i.e.: which Ethernet card to use) Example: Destination Next Interface 129.186.4.0 129.186.5.254 en0 Routing In order to route a packet: 1 . IP layer finds the route table entry where the destination address where the destination address matches the range given in the table. 2 . If the next hop falls within the local network, the packet is sent directly to the destination. Otherwise the packet is sent to the next hop.
Background image of page 2
Next Hop Routing Routing Netmask – Determines which part of the IP address is network and which part is host – Allows for the ability to create subnetworks – Example: a netmask of 255.255.255.0 indicates that the first 3 bytes of the IP address is the network, and the last 8 bytes is the host. – The above netmask allows for 254 subnetworks each with up to 254 attached hosts. – The following are examples of subnetworks: • 129.186.5.0 129.186.15.0 129.186.55.0
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Routing We will study routing using three scenarios: 1 . A simple network with only one router 2 A network with multiple routers 2. A network with multiple routers 3 . A single network with multiple IP’s Host H1 Router Router Network 1 192.168.1.0/24 Network 2 192.168.5.0/24 192.168.1.20 192.168.1.30 192.168.5.254 192.168.5.250 Destination Next Hop Interface 192.168.1.0/24 192.168.1.30 eth0 192.168.5.0/24 192.186.5.250 eth1 127.0.0.1 127.0.0.1 lo0 default 192.168.5.254 eth1 Route Table Router R1 To Host H5 R1 Host H2 Host H3 R2 192.168.1.25 192.168.5.25 Destination Next Hop Interface 192.168.1.0/24 192.168.1.20 eth0 127.0.0.1 127.0.0.1 lo0 default 192.168.1.30 eth0 Route Table Host H1 Route Table Host H3 Destination Next Hop Interface 192.168.5.0/24 192.168.5.25 eth0 192.168.1.0/24 192.186.5.250 eth0 127.0.0.1 127.0.0.1 lo0 default 192.168.5.254 eth0 Host H4 192.168.5.75
Background image of page 4
Routing Scenario 1 1.20 1.25 1.30 192.168.1.0/24 en0 en1 192.168.5.0/24 router 5.250 Packet from H1 to H2 (same network) 5.25 IP Address Hardware Address SRC DEST SRC DEST H1 H2 H1 H2 Packet from H1 to H3 (Next door network) IP Address Hardware Address SRC DEST SRC DEST H1 H2 H1 R1 (EN0) H1 H2 R1 (EN1) H3 Routing Scenario 1 Steps involved in sending a packet from H1 to H2: Destination Next Hop 192.168.1.0/2 4 192.168.1.20 Default 192.168.1.30 1 . Route table is checked. 192.168.1.25/24 matches the 192.168.1.0 entry 2 . The next hop is the host itself (192.168.1.20). This means the destination is on the local network. 3 . H1 then sends an ARP packet to find the data link address of the destination 4 . Once the data link address is found, the packet is sent
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Routing Scenario 1 Steps involved in sending a packet from H1 to an address that is on another network: 1 . Route table is checked. The destination address matches the default entry in the table.
Background image of page 6
Image of page 7
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 18

lec10 - CprE 530 Lecture 10 Topics 1. 2. 3. 4. Addressing...

This preview shows document pages 1 - 7. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online