Advanced IP Routing. Policy Routing QoS RVSP

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1 Advanced IP Routing Policy Routing QoS RVSP

2 Traditional Routing What is traditional routing? Best effort. All routing is a destination driven process. Router cares only about the destination address when making a decision on where to forward the packet.

3 Policy Routing What is Policy Routing? If routing decision is based on: TOS field Source address Incoming interface Fwmark values for matching IP protocols and transport ports Packet payload, etc.

4 Why Policy Routing? Traditional IPv4 Routing Problems Quality of Service Different treatment for different packets Control the usage of network resource Setting of packet delivery priorities Services availability and data security

5 Policy Routing Structures The three Policy Routing Elements: Address Route Rule

6 Address For traditional Ipv4 routing, only the destination address matters. For Policy routing, both the source and destination address (and other fields in the IP header) may affect the routing decision and routing path

7 Route Still destination based, plus alternate criteria Method of actually selecting a route is changed, but the method of using the route once obtained is the same More versatility and flexibility in specification and destination options e.g. See targets for the route object in Liunx

8 Rule Allows you to specify the filters that match packets Which route structure to select for a match Multiple independent routing tables RPDB Routing Policy DataBase in Linux primary provides the internal structure and mechanism for implementing the rule element of Policy Routing and the multiple routing tables (supports 255 routing tables and 2^32 rules)

9 Linux Implementation Policy routing with iproute2 At startup, the Linux kernel configures a default RPDB consisting of three rules: 0: from all lookup local 32766: from all lookup main 32767: from all lookup default The above rules point to the local, main and default routing tables

10 iproute2 What is iproute2? Tool used in Linux for implementing Policy Routing The ip utility Written by Alexey N. Kuznetsov

11 ip utility objects link network device addr IP Address route routes rule rules neigh ARP neighbors table tunnel IP tunnels multicast IP multicast monitor Debug and tracking

12 ip link Used to modify NIC parameters and/or get information about a NIC except for the IP address 1: lo: <LOOPBACK,UP> mtu qdisc noqueue link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 2: eth0: <BROADCAST,MULTICAST,NOTRAILERS,UP> mtu 1500 qdisc pfifo_fast qlen 1000 link/ether 00:11:09:85:d2:fb brd ff:ff:ff:ff:ff:ff 3: sit0: <NOARP> mtu 1480 qdisc noop link/sit brd : eth1: <BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast qlen 1000 link/ieee :00:01:00:00:0e:16:96 brd ff:ff:ff:ff:ff:ff:ff:ff

13 ip addr Provide the similar function as the ifconfig command. Use to modify, delete, or add IP addresses to a NIC. Supports multiple addresses assignment to a single NIC and Ipv6. $ip addr show eth0 2: eth0: <BROADCAST,MULTICAST,NOTRAILERS,UP> mtu 1500 qdisc pfifo_fast qlen 1000 link/ether 00:11:09:85:d2:fb brd ff:ff:ff:ff:ff:ff inet /24 brd scope global eth0 inet6 fe80::211:9ff:fe85:d2fb/64 scope link valid_lft forever preferred_lft forever

14 ip neigh Provide similar function as the arp command. linuxmind:~ # ip neigh dev eth0 lladdr 00:11:95:0c:b3:94 REACHABLE dev eth0 lladdr 00:09:6b:d8:da:a3 REACHABLE dev eth0 lladdr 00:08:74:e6:84:ff REACHABLE

15 ip route Provides similar function as the route command but more capable and flexible. Used to list, modify, delete, or add entries to any of the routing tables on the system. linuxmind:~ # ip route /24 dev eth0 proto kernel scope link src /16 dev eth0 scope link /8 dev lo scope link default via dev eth0

16 ip rule New. Used to show and maintain the routing policy database. linuxmind:~ # ip rule show 0: from all lookup local 32766: from all lookup main 32767: from all lookup default

17 Add ip rules linuxmind:~ # ip ru add from /24 table 101 priority 250 linuxmind:~ # ip ru add from /24 table 102 priority 300 linuxmind:~ # ip ru show 0: from all lookup local 250: from /24 lookup : from /24 lookup : from all lookup main 32767: from all lookup default

18 Add ip route tables linuxmind:~ # ip route add default via dev eth1 table Eng linuxmind:~ # ip route add default via dev eth0 table Sales linuxmind:~ # ip route list /24 dev eth1 proto kernel scope link src /24 dev eth0 proto kernel scope link src /16 dev eth0 scope link /8 dev lo scope link default via dev eth0 linuxmind:~ # ip route list table Sales default via dev eth0 linuxmind:~ # ip route list table Eng default via dev eth1

19 Quality of Service Quality of Service (IPv4) routing and queueing of data packets based on TOS (type of service) tag on IP header and The service provided Assign a defined percentage of the available bandwidth Congestion avoidance and preferential packet paths

20 RSVP One of the two protocols developed by IETF to provide QoS. RSVP is a signaling protocol: An endpoint uses RSVP to request a simplx flow through an IP inter net to a destination endpoint with specified QoS bounds. If all the routers along the path agree to honor the request, the sender get a positive reply. If an application needs QoS in both directions, each endpoint must use RSVP to request a separate flow.

21 COPS Another protocol developed by IETF to provide Qos. IntServ Enforcement Common Open Policy Services Protocol (COPS): The COPS protocol defines the client server interaction between a QoS enabled router and a PDP (Policy Decision Point) Server. For approved QoS requests, the router must operate as a Policy Enforcement Point (PEP) to ensure traffic does not exceed the policy.

22 IntServ The implementation of RVSP (IntServ Resource Reservation Protocol) requires changes to the basic network infrastructure: All routers must be able to response to requests for reserving resources (bandwidth) for each flow between a pair of endpoints. As datagrams traverse the flow, the routes must be able to monitor and control traffic forwarding.

23 QoS Traffic Monitoring Also called traffic policing To ensure that the traffic sent on a flow does not exceed the specified QoS bounds Monitoring/Policing mechanism: Leaky bucket: uses a counter to control the packet rate. The counter is incremented periodically according to the approved QoS data rate, and decremented by the size of the traffic

24 QoS Traffic forwarding The QoS enabled router must be able to control the queueing and forwarding of data packets: Queueing policy that meets the QoS bounds on delay The router must smooth packet bursts (traffic shaping). For example, reshapes a 3 Mbps of traffic for a millisecond followed by no traffic for two milliseconds to a steady rate of 1 Mbps for three milliseconds on a guarantee average throughput of 1 Mbps QoS.

25 Reference Policy Routing Using Linux Matthew G. Marsh ISBN Sams Publishing Internetworking with TCP/IP, Principles, Protocols, and Architecture Douglas E. Comer ISBN Prentice Hall Linux TCP/IP Network Administration Scott Mann ISBN Prentice Hall

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