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CIS 185 Advanced Routing Protocols EIGRP Part 2

CIS 185 Advanced Routing Protocols EIGRP Part 2

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CIS 185 Advanced Routing Protocols EIGRP Part 2

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  1. CIS 185 Advanced Routing ProtocolsEIGRP Part 2 Rick Graziani Cabrillo College graziani@cabrillo.edu Fall 20101

  2. EIGRP Part 2 • EIGRP over Frame Relay • EIGRP over MPLS • EIGRP Load Balancing • EIGRP Bandwidth across WAN Links • Authentication • EIGRP Scalability in Large Networks

  3. Materials • Book: • Implementing Cisco IP Routing (ROUTE) Foundation Learning Guide: Foundation learning for the ROUTE 642-902 Exam • By Diane Teare • Book • ISBN-10: 1-58705-882-0 • ISBN-13: 978-1-58705-882-0 • eBook • ISBN-10: 0-13-255033-4 • ISBN-13: 978-0-13-255033-8

  4. Configuring and Verifying EIGRP in an Enterprise WAN Physical Frame-Relay Multipoint and point-to-point Frame-Relay subinterfaces Multiprotocol Label Switching (MPLS) virtual private networks (VPNs) Ethernet over Multiprotocol Label Switching (EoMPLS)

  5. Frame Relay Basics • Frame Relay Basics • A switched WAN technology • Virtual circuits (VCs) are created by a Service Provider (SP) • Multiple logical VCs to be multiplexed over a single physical interface. • Typically PVCs identified by a locally significant data link connection identifier (DLCI). • For IP connectivity: A mapping between IP addresses and DLCIs must be defined, either dynamically or statically.

  6. Frame Relay Basics • By default, a Frame Relay network is an NBMA network. • Like multiaccess networks (Ethernet LANs) All routers are on the same subnet • But broadcast (and multicast) packets CANNOT be sent just once as they are in a broadcast environment such as Ethernet. • Cisco IOS implements pseudo-broadcasting • Router creates a copy of the broadcast or multicast packet for each neighbor reachable through the WAN media (over the PVC). • Sends the copy of the broadcast or multicast packet over the appropriate PVC for that neighbor.

  7. EIGRP over Frame Relay: Physical Interface with Dynamic Mapping R1 Same Subnet DLCI 100 DLCI 130 • Inverse ARP is on by default • Automatically maps the IP address of the devices at the other end of the PVCs to the local DLCI number. • Split horizon is disabled by default on Frame Relay physical interfaces. • Routes from Router R2 can be sent to Router R3, and vise-versa. • Note: Inverse ARP does not provide dynamic mapping for the communication between routers R2 to R3 because they are not connected with a PVC; this must be configured (mapped) manually

  8. EIGRP over Frame Relay: Physical Interface with Dynamic Mapping • R1 forms the adjacency with router R2 and R3 over the serial0/0 physical interface. • R3 (and R2) forms an adjacency with router R1. • No EIGRP relationship exists between routers R2 and R3.

  9. EIGRP over Frame Relay: Physical Interface with Static Mapping R1 interface Serial 0/0 encapsulation frame-relay ip address 192.168.1.103 255.255.255.0 frame-relay map ip 192.168.1.101 130 broadcast router eigrp 110 network 192.168.1.0 R3 • Using static mapping disables Inverse ARP • No changes to the basic EIGRP configuration. • Manual IP-to-DLCI mapping commands on the serial 0/0 interface are necessary on all three routers. • Again, because split horizon is disabled by default on Frame Relay physical interfaces, routes from R2 can be sent to R3, and vise-versa. • Note: R1 includes a Frame Relay map to its own IP address so it can ping its own interface.

  10. EIGRP over Frame Relay: Physical Interface with Static Mapping interface Serial 0/0 encapsulation frame-relay ip address 192.168.1.103 255.255.255.0 frame-relay map ip 192.168.1.101 130 broadcast frame-relay map ip 192.168.1.102 130 broadcast router eigrp 110 network 192.168.1.0 R3 • The adjacencies formed on R1 using static mapping are the same as those formed using dynamic mapping. • R2 and R3 also form an adjacency with router R1. • R2 and R3 can also form an EIGRP adjacency to each other if the IP-to-DLCI mapping for that connectivity is provided. • Output shows that R3 has two neighbors (router R1 and R2), indicating that this mapping was provided on R3 (but not required between R2 and R3).

  11. EIGRP over Frame Relay: Multipoint Subinterfaces Same Subnet DLCI 100 • Separating a physical interface into multipoint subinterfaces allows each subinterface to be on a separate network. • Multipoint subinterfaces are configured with the command: interface serial number.subinterface-numbermultipoint DLCI 103 DLCI 130

  12. EIGRP over Frame Relay: Multipoint Subinterfaces R1 interface Serial 0/0 no ip address encapsulation frame-relay interface serial 0/0/0.1 multipoint ip address 192.168.1.101 255.255.255.0 no ip split-horizon eigrp 110 frame-relay map ip 192.168.1.102 102 broadcast frame-relay map ip 192.168.1.103 103 broadcast router eigrp 110 network 192.168.1.0 network 172.16.1.0 0.0.0.255 R3 interface Serial 0/0 no ip address encapsulation frame-relay interface serial 0/0/0.1 multipoint ip address 192.168.1.103 255.255.255.0 frame-relay map ip 192.168.1.101 130 broadcast router eigrp 110 network 192.168.1.0 • IP address-to-DLCI mapping on multipoint subinterfaces is done by either: • Specifying the local DLCI value (frame-relay interface-dlci dlci) and relying on Inverse ARP • Using manual IP address-to-DLCI mapping. • The physical interface serial 0/0 is configured for Frame Relay encapsulation and does not have an IP address assigned to it. • Note: The spoke router does not have a multipoint-subinterface.

  13. EIGRP over Frame Relay: Multipoint Subinterfaces R1 interface Serial 0/0 no ip address encapsulation frame-relay interface serial 0/0/0.1 multipoint ip address 192.168.1.101 255.255.255.0 no ip split-horizon eigrp 110 frame-relay map ip 192.168.1.102 102 broadcast frame-relay map ip 192.168.1.103 103 broadcast router eigrp 110 network 192.168.1.0 network 172.16.1.0 0.0.0.255 R3 interface Serial 0/0 no ip address encapsulation frame-relay interface serial 0/0/0.1 multipoint ip address 192.168.1.103 255.255.255.0 frame-relay map ip 192.168.1.101 130 broadcast router eigrp 110 network 192.168.1.0 • Split horizon is enabled by default on Frame Relay multipoint interfaces. • R2 and R3 need to provide connectivity between their connected networks so… • EIGRP split horizon is disabled on the multipoint subinterface of router R1 with the no ip split-horizon eigrp as-number command.

  14. EIGRP over Frame Relay: Multipoint Subinterfaces • Verify with show ip eigrp neighbors • R1 forms an adjacency with routers R2 and R3 over the serial0/0.1 multipoint subinterface. • R2 and R3 form the adjacency with R1 • Note: R2 and R3 could form an adjacency between each other if the IP address-to-DLCI mapping for that connectivity is provided. (not required)

  15. EIGRP over Frame Relay: Unicast Neighbors R1 R2 • Not all Frame Relay service providers support multicasts/broadcasts so routing information must be sent as unicasts. • router configuration command: neighbor {ip-address | ipv6-address} interface-type interface-number • Defines a neighboring router to exchange EIGRP routing information. • Instead of using multicast packets, EIGRP exchanges routing information with the specified neighbor using unicast packets.

  16. EIGRP over Frame Relay: Unicast Neighbors R1 R2 • EIGRP does not process any multicast packets coming inbound on that interface • EIGRP stops sending multicast packets on that interface.

  17. unicast EIGRP over Frame Relay: Unicast Neighbors multicast R1 R2 • R1 is configured with a neighbor command for R2. • R1 will therefore not accept multicast packets on Serial 0/0.1 anymore. • R2 must also be configured with a neighbor command for R1 to establish an adjacency. • R1 and R3 are not configured with a neighbor command for each other. • Therefore, R1 and R3 will not form an adjacency.

  18. EIGRP over Frame Relay: Unicast Neighbors R1 R3 interface Serial 0/0 no ip address encapsulation frame-relay interface serial 0/0/0.1 multipoint ip address 192.168.1.103 255.255.255.0 frame-relay map ip 192.168.1.101 130 broadcast router eigrp 110 network 192.168.1.0 • Because R3 is not using the neighbor command it tries to communicate with multicast packets on its Serial 0/0/.1. • However, neighborship is not established because neither R1 nor Router R2 is accepting multicast packets.

  19. EIGRP over Frame Relay: Point-to-Point Subinterfaces Same Subnet DLCI 100 DLCI 103 DLCI 130 • Point-to-point subinterfaces are logical interfaces: • Emulates a leased line network • Provide a routing equivalent to point-to-point physical interfaces • As with physical point-to-point interfaces, each interface requires its own subnet. • Frame Relay point-to point is applicable to hub and spoke topologies.

  20. EIGRP over Frame Relay: Point-to-Point Subinterfaces • R1 and R3: • The physical interface serial 0/0 is configured for Frame Relay encapsulation • The physical interface does not have an IP address assigned to it

  21. EIGRP over Frame Relay: Point-to-Point Subinterfaces • Point-to-point subinterfaces are created with the command: interface serialnumber.subinterface-number point-to-point • IP address-to-DLCI mapping on point-to-point subinterfaces with: frame-relay interface-dlci dlci • R1 has two point-to-point subinterfaces, one for each subnet and DLCI. • Note: R3 does not need a subinterface.

  22. EIGRP over MPLS • MPLS (Multiprotocol Label Switching) is an IETF standard. • Combines the: • Advantages of Layer 3 routing • Benefits of Layer 2 switching • Short fixed-length labels are assigned to each packet at the edge of the MPLS network. • Allows for scalable VPNs, end-to-end QoS, and other IP services that allow efficient utilization of existing networks with simpler configuration, management, and quicker fault correction.

  23. What is MPLS? • New WAN technology originally defined in RFC 3031 by: • Cisco Systems • Force 10 Networks • Juniper networks • Started out as Tag Switching introduced by Ipsilon (now part of Nokia)

  24. What is the problem MPLS is trying to solve? • Layer 3 End-to-end circuits • Advantages • IP routing provides dynamic, automatic path setup • Provides best path and backup paths • Provides QoS • Disadvantages • Latency in hop-by-hop Layer 3 lookup • Latency in routing – switching – packet forwarding process

  25. What is the problem MPLS is trying to solve? • Layer 2 End-to-end circuits (ATM, Frame Relay) • Advantages • Circuits (SVC or PVC) means destinations are pre-established at switches • Less latency, switched only - no Layer 3 lookups • Disadvantages • Circuits difficult to manage - must use management software or human configuration. • QoS and SLAs are individually managed

  26. MPLS WAN Connectivity • MPLS extends Layer 2 or Layer 3 natively between sites. • The MPLS network although owned by a service provider but is an extension of the enterprise network. • MPLS network is like a single router or switch with multiple interfaces. • MPLS philosophy is that the Layer 3 header contains significantly more information than is necessary to forward the packet.

  27. MPLS Terms • MPLS domain – A contiguous set of nodes performing MPLS routing and forwarding. • These are typically in one routing or administrative domain. • Label Switching Router (LSR) – An MPLS node that is capable of forwarding labeled packets. • Label – A short, fixed-length, physically contiguous identifier used to identify a group of networks sharing a common destination, usually of local significance. • MPLS Ingress Node – An MPLS node that handles traffic entering an MPLS domain. • MPLS Egress Node – An MPLS node that handles traffic leaving an MPLS domain.

  28. MPLS Operation • A label identifies a flow of packets (for example, voice traffic between two nodes), also called a Forwarding Equivalence Class (FEC). • Grouping of packets which can be used for QoS requirements • Packets belonging to the same FEC receive the same treatment in the network. • Determined by various parameters including: • source or destination IP address • port numbers • IP protocol • IP precedence

  29. MPLS Operation • MPLS network nodes are called Label-Switched Routers (LSRs) • Use the label to determine the next-hop for the packet. • Do not need to examine the packet’s IP header • Forwards packets based on the label. • After a path has been established: • Packets destined to the same endpoint with the same requirements can be forwarded based on these labels without a routing decision at every hop. • Labels usually correspond to Layer 3 destination addresses, which makes MPLS equivalent to destination-based routing.

  30. MPLS Operation • A Label-Switched Path (LSP) must be defined for each FEC before packets can be sent. • Labels are locally significant to each MPLS node only • Therefore nodes must communicate what label to use for each FEC. • Label Distribution Protocol • Enhanced version of the Resource Reservation Protocol. • An interior routing protocol, such as OSPF or EIGRP is also used within the MPLS network to exchange routing information.

  31. MPLS Operation • Each of the MPLS nodes has previously communicated the labels it uses for each of the defined FECs to its neighboring nodes. • Packet A and Packet B represent different flows; for example, • Packet A might be from an FTP session, whereas • Packet B is from a voice conversation. • Without MPLS, these packets would take the same route through the network.

  32. R6 – Layer 3 Routed R5 – MPLS Switched 94 R4 – MPLS Switched 94 17 R3 – MPLS Switched 17 R1 – Layer 3 Routed 5 R2 – MPLS Switched (popped) 5

  33. MPLS Features • MPLS • Only one examination of the packet • Only one assignment to the FEC • This is done at the MPLS ingress node

  34. Service Provider Offerings • VPNs: • First built using leased lines with PPP and HDLC encapsulations. • Later, Layer 2 VPNs based on point-to-point data link layer connectivity, using ATM or Frame Relay virtual circuits. • MPLS VPNs were introduced to provide a unified network for Layer 3 VPN services. • Any Transport over MPLS (AToM) was introduced to facilitate this Layer 2 connectivity across an MPLS backbone.

  35. Layer 2 and Layer 3 MPLS VPN Solutions • Layer 2 MPLS VPN provides a Layer 2 service across the backbone • R1 and R2 are connected together on the same IP subnet. • Layer 3 MPLS VPN provides a Layer 3 service across the backbone • R1 and R2 are connected to ISP edge routers; on each side, a separate IP subnet is used.

  36. Layer 2 and Layer 3 MPLS VPN Solutions Site #3 • The network is divided into: • Customer-controlled part (C-network) • Provider-controlled part (P-network) • Contiguous portions of C-network are called sites and are linked to the P-network via Customer Edge routers (CE-routers). • The CE-routers are connected to the PE-routers (Provider Edge routers). • The core devices in the provider network (P-routers) provide transport across the provider backbone and do not carry customer routes. • The service provider connects customers using MPLS VPNs.

  37. Layer 2 and Layer 3 MPLS VPN Solutions Site #3 • Each customer is assigned an independent routing table - the virtual routing and forwarding (VRF) table in the PE router. • PE routers maintain separate routing tables for each customer. • Routing across the provider backbone is performed by another routing process that uses global IP routing table, the P-router.

  38. Layer 3 MPLS VPNs • In a Layer 3 MPLS VPN, the following requirements must be met: • The customer routers (the CE-routers) are not be MPLS VPN-aware • Run standard IP routing software. • The provider core routers (the P-routers) must not carry customer (VPN) routes, to make the MPLS VPN solution scalable. • The provider edge routers (PE-routers) must support MPLS VPN services and traditional IP services.

  39. Layer 3 MPLS VPNs L3 192.168.1.0/30 network 192.168.2.0/30 network • R1 and R2 are configured for EIGRP as if there were a corporate core network between them. • EIGRP parameters between R1 and R2 (such as the AS number, authentication password, and so on) are often governed/coordinated by the service provider.

  40. Layer 3 MPLS VPNs L3 • R1 establishes an EIGRP neighbor relationship with the PE1 router, • R2 establishes an EIGRP neighbor relationship with the PE2 router. • Routers R1 and R2 do NOT establish an EIGRP neighbor relationship with each other.

  41. Layer 2 MPLS VPNs • Layer 2 MPLS VPN, an MPLS backbone provides a Layer 2 Ethernet port-to-port connection between the two customer routers R1 and R2. • R1 and R2 are exchanging Ethernet frames. • PE1 router: • Takes the Ethernet frame received from the directly connected R1 • Encapsulates it into an MPLS packet • Forwards it across the backbone to the PE2 router. • The PE2 router decapsulates the MPLS packet and reproduces the Ethernet frame on its Ethernet link to router R2. • This process is a type of AToM, called EoMPLS (a type of Metro Ethernet Service.

  42. Layer 2 MPLS VPNs 192.168.1.100/27 network • EIGRP over EoMPLS: No changes to the EIGRP configuration from the customer perspective. • EIGRP needs to be enabled with the same AS number on both routers. • network command includes the interface toward the PE router (PE1 and PE2) over which the routers R1 and R2 will form their neighbor relationship. • From the EIGRP perspective, the MPLS backbone and routers PE1 and PE2 are not visible.

  43. Layer 2 MPLS VPNs • A neighbor relationship is established directly between routers R1 and R2 over the MPLS backbone.

  44. EIGRP Load Balancing

  45. Variance command Router(config)# router eigrp 1 Router(config-router)# variance multiplier • Cisco IOS allows up to 16 equal-cost paths, 4 by default. • EIGRP does unequal cost load balancing, forwarding packets relative to the metric. • The variance command: • Instructs the router to include routes with a metric less than or equal to n times the minimum metric route for that destination • n is the number specified by the variance command (1 -128). • Default = 1 • The maximum-pathsnumber EIGRP is used to sent the number of load-balancing paths (up to 16 paths). • 1 disables load balancing • Note: If a path isn't a feasible successor, then it isn't used in load balancing. • Note: Load balancing is only performed on traffic that passes through the router, not traffic generated by the router.

  46. Variance command FS Succ FS • Successor: R3 with a FD of 20 • Feasible Successors: R2 and R5 • R2’s AD of 10 < R3’s FD of 20 • R5’s AD of 10 < R3’s FD of 20 • R4 is NOT a FS because it’s AD of 25 > R3’s FD of 20

  47. Variance command FS Succ x 2 = 40 R1(config)# router eigrp 110 R1(config-router)# variance 2 FS • Variance = 2 • R3’s FDv 2 x 20 (FD) = 40 • R2 is added as successor to R1’s routing table: R2’s FD of 30 < R3’s FDv of 40 • R5 is NOT added to R1’s routing table: R5’s FD of 50 > R3’s FDv of 40 • R5 would still be a Feasible Successor • Note: R4 is not considered even if it’s FD was < or = R3’s FDv of 40 because it is not a FS • The load in is balanced proportional to the bandwidth. • FD of the route via router R2 is 30 • FD of the route via router R3 is 20 • Ratio of traffic between the two paths is via R2: 3/5 and via R3: 2/5

  48. EIGRP Bandwidth Across WAN Links

  49. The bandwidth-percent command ip bandwidth-percent eigrp as-number percent interface serial 0/0/0  bandwidth 56   ip bandwidth-percent eigrp 209 75 • The bandwidth-percent command configures the percentage of bandwidth that may be used by EIGRP on an interface. • By default, EIGRP is set to use only up to 50% of the bandwidth of an interface to exchange routing information. • In order to calculate its percentage, the bandwidth-percent command relies on the value set by the bandwidth command. • Allows EIGRP to use up to 75 percent (42 kbps) of a 56-kbps serial link in autonomous system 209.

  50. Link Utilization on Frame Relay • Cisco IOS assumes that point-to-point Frame Relay subinterfaces are operating at the default speed of the interface. • In many implementations, however, only fractional speeds (such as a fractional T1) are available. • Therefore, when configuring these subinterfaces, set the bandwidth to match the contracted CIR (Committed Information Rate).