EIGRP unique load balancing

• Feature chi co trong gia thuc dinh tuyen IGRP va BGP (DMZ bandwidth)

• Share tai khong can bang giua cac link

• Mo hinh test  nhu sau:

• Adver mangj 8.8.8.0/24 tren R4 vao mang

• Chinh "  metric weights 0 0 0 1 0 0 " => k3 = 1--> metric = 256* tong delay /10

R1#show ip ei to 8.8.8.0/24

IP-EIGRP (AS 1): Topology entry for 8.8.8.0/24

  State is Passive, Query origin flag is 1, 1 Successor(s), FD is 76800

  Routing Descriptor Blocks:

  10.1.13.3 (FastEthernet0/1), from 10.1.13.3, Send flag is 0x0

      Composite metric is (89601/51200), Route is Internal

      Vector metric:

        Minimum bandwidth is 10000 Kbit

        Total delay is 3500 microseconds

        Reliability is 255/255

        Load is 1/255

        Minimum MTU is 1500

        Hop count is 2

  10.1.12.2 (FastEthernet0/0), from 10.1.12.2, Send flag is 0x0

      Composite metric is (115200/89600), Route is Internal

      Vector metric:

        Minimum bandwidth is 10000 Kbit

        Total delay is 4500 microseconds

        Reliability is 255/255

        Load is 1/255

        Minimum MTU is 1500

        Hop count is 2

Cac thong so nhu sau:

Path 1:  R1-R2-R4:    FD = 115200; AD = 89600

Path 2:  R1-R3-R4:    FD = 89601;   AD = 51200

Path 2 co gia tri FD nho hon => Path 2 la successor

Path 1 co gia tri AD < FD path 2 => Path 1 la PS

De dua path 1 len bang dinh tuyen thi ta cau hinh gia tri varian sao cho:

AD*variance > FD (path 1)

Hay 89600*variance > 89601

Chon variace = 2

R1#show ip route 8.8.8.0

Routing entry for 8.8.8.0/24

  Known via "eigrp 1", distance 90, metric 89601, type internal

  Redistributing via eigrp 1

  Last update from 10.1.12.2 on FastEthernet0/0, 00:00:54 ago

  Routing Descriptor Blocks:

  * 10.1.13.3, from 10.1.13.3, 00:00:54 ago, via FastEthernet0/1

      Route metric is 89601, traffic share count is 240

      Total delay is 3500 microseconds, minimum bandwidth is 10000 Kbit

      Reliability 255/255, minimum MTU 1500 bytes

      Loading 1/255, Hops 2

    10.1.12.2, from 10.1.12.2, 00:00:54 ago, via FastEthernet0/0

      Route metric is 115200, traffic share count is 187

      Total delay is 4500 microseconds, minimum bandwidth is 10000 Kbit

      Reliability 255/255, minimum MTU 1500 bytes

      Loading 1/255, Hops 2

• Ti le share count = 240/187

• Co the su dung offsetlist hoac distribute list + route-map de chinh gia tri metric thay doi ti le share count

EX: ti le share count = 1.5

      -> (115200 + x) / 89601 =  1.5

      -> x = 19201

Ta nen tang gia tri LD  metric cua path 1, neu tang gia tri AD path 1 thi co the xay ra truong hop AD > FD (path 2) luc do path 2 khong con la FS.

Cau hinh R1:

R1#show run | se router eigrp 1

router eigrp 1

 variance 2

 offset-list 0 in 19201 FastEthernet0/0

 offset-list 0 in 12801 FastEthernet0/1

 network 0.0.0.0

 metric weights 0 0 0 1 0 0

 no auto-summary

R1#show ip route 8.8.8.0

Routing entry for 8.8.8.0/24

  Known via "eigrp 1", distance 90, metric 89601, type internal

  Redistributing via eigrp 1

  Last update from 10.1.12.2 on FastEthernet0/0, 00:00:06 ago

  Routing Descriptor Blocks:

  * 10.1.13.3, from 10.1.13.3, 00:00:06 ago, via FastEthernet0/1

      Route metric is 89601, traffic share count is 3

      Total delay is 3500 microseconds, minimum bandwidth is 10000 Kbit

      Reliability 255/255, minimum MTU 1500 bytes

      Loading 1/255, Hops 2

    10.1.12.2, from 10.1.12.2, 00:00:06 ago, via FastEthernet0/0

      Route metric is 134401, traffic share count is 2

      Total delay is 5250 microseconds, minimum bandwidth is 10000 Kbit

      Reliability 255/255, minimum MTU 1500 bytes

      Loading 1/255, Hops 2

• Share count = 3/2

• Luy y: co the su dung distribute-list + route-map de modify gia tri mectric (chi co trong EIGRP) 

EIGRP auto-summary

R1 <----> R2 <----> R3

R1 config "no auto-summary"

R2 config " auto-summary"

R3 config "auto-summary"

R3#show ip route ei

     1.0.0.0/24 is subnetted, 1 subnets

D       1.1.1.0 [90/435200] via 10.1.23.2, 00:03:41, FastEthernet0/0

D    2.0.0.0/8 [90/409600] via 10.1.23.2, 00:03:52, FastEthernet0/0

     3.0.0.0/8 is variably subnetted, 2 subnets, 2 masks

D       3.0.0.0/8 is a summary, 00:00:44, Null0

     10.0.0.0/8 is variably subnetted, 4 subnets, 2 masks

D       10.1.12.0/24 [90/307200] via 10.1.23.2, 00:03:52, FastEthernet0/0

D       10.0.0.0/8 is a summary, 00:00:44, Null0

=> chi summary nhung routes local router.

EIGRP advertise default-route

==============================EIGRP adver_default route==========

   1.         ip route 0.0.0.0 0.0.0.0 null0

              Router eigrp 100

        Network 0.0.0.0

          = >> In this case the default route will show as an "internal" Eigrp route.

======================================================================

   2.         Ip route 0.0.0.0 0.0.0.0 null0

              Router eigrp 100

        Redistribute static

          =>> In this case the default route will show as an "external" Eigrp route "EX".

======================================================================

   3.          " under a given interface ":

              # ip summary-address eigrp 1 0.0.0.0 0.0.0.0

           =>> In this case the default route will show as an "internal" Eigrp route

Note : creat null0 with AD = 5 in routing table

 

Để không thấy route null 0 trong routing table thì khi summary ta cho AD = 255

# ip summary-address eigrp 1 0.0.0.0 0.0.0.0 255

=======================================================================

   4.         IP default-network 1.0.0.0

>> note : The network can be any network,but must be a classful network and NOT a subnet

Loopback interface or any interface

         Router eigrp 100

         Network 1.0.0.0

+++++++++++++++++++++++++

+ show ip route eigrp   +

+                        +

+  D*   1.0.0.0/8        +

+++++++++++++++++++++++++

          >> Note : the "*" after the letter D.==> " candidate default "

         * Your need to have access to network 1.0.0.0, but it

not want to use it as a candidate default

should be configured as follows:

+----------------------------------- ------------+

           +Router eigrp 100                                     +

+                                                       +

           + No default-information allowed in   +

+------------------------------------------------+

*After the above configuration, if you check your routing table it should

look like the following:

+++++++++++++++++++++++++

+ show ip route eigrp   +

+                        +

+  D   1.0.0.0/8        +

+++++++++++++++++++++++++

          >> Note : the "*" is gone and network 1.0.0.0 is no longer used as the candidate

default.

==================================================================

    Gateways of last resort selected using the ip default-network

    command are propagated differently depending on which routing protocol

    is propagating the default route. For IGRP and EIGRP to propagate the

    route, the network specified by the ip default-network command

    must be known to IGRP or EIGRP. This means the network must be an IGRP-

    or EIGRP-derived network in the routing table, or the static route used

    to generate the route to the network must be redistributed into IGRP or

    EIGRP, or advertised into these protocols using the network command.

EIGRP Filter

=====================  EIGRP FILTER  ========================================

1. offset-list

- the offset-list feature in EIGRP is used to modify the metric on a per_route basis or a per-interface basis.

+ Only apply theo chieu " in "

+ Only increases delay value.

+ accesslist used "permit"

+ change value delay

+ Metric increase = K3 * offset * (K5 / (reliability + K4))

+ In Eigrp it’s used to add to the existing delay value                

#offset-list [ACL] {in|out} {offset} {interface}

router eigrp 1

offset-list 1 in 2147483647 s0/0

!

access-list 1 permit 1.1.1.0 0.0.0.255

=============================================================================

2. distribute-list

- Filters all routes matching the ACL or prefix-list

distribute-list {ACL | prefix} {in|out}

std acl:

router eigrp 1

distribute-list 1 in Serial0/0

!

access-list 1 permit 1.1.1.0 0.0.0.255

extended acl:

In R2 :

access-list 100 deny ip host 1.1.1.1 host 10.1.12.1

access-list 100 deny ip host 1.1.2.1 host 10.1.12.1

access-list 100 deny ip host 1.1.3.1 host 10.1.12.1

access-list 100 permit ip any any

!

router eigrp 100

distribute-list 100 in Serial0/0

line : access-list 100 deny ip host 1.1.1.1 host 10.1.12.1

+ prevent R2 learn 1.1.1.1 from R1 ( 10.1.12.1 )

- Filters all routes to/from a neighbor

distribute-list gateway {prefix-list} {in|out} {interface}

- Filters prefix from a specific source from entering the routing table

distribute-list prefix {prefix-routes} gateway {prefix-source} {in|out}

- Changes the distance for both internal and external EIGRP routes

distance eigrp {ad-internal} {ad-external}

- Using Route-maps

  

router eigrp 100

distribute-list route-map FILTER_ON_TAGS in

!

route-map FILTER_ON_TAGS deny 10

match tag 4  { match length , match interface .... }

!

route-map FILTER_ON_TAGS permit 20

=====================================================================

3. Using Admin distance:

distance {AD} {address} {wildcard} {acl#|aclname}

- any source

• Filter route internal

Distance {AD} eigrp internal  external

• Filter all

access-list 1 permit 1.1.1.0 0.0.0.255

!

router eigrp 100

distance 255 0.0.0.0 255.255.255.255 1

-specific per neighbor

access-list 1 permit 1.1.1.0 0.0.0.255

!

router eigrp 100

distance 255 10.1.12.1 0.0.0.0 1

=======================================================================

4. Using redistribution with route-maps

router eigrp 100

redistribute rip metric 100000 100 255 1 1500 route-map RIP_TO_EIGRP

!

ip prefix-list VLAN_43 seq 5 permit 204.12.1.0/24

!

route-map RIP_TO_EIGRP permit 10

match ip address prefix-list VLAN_43

set tag 4

!

route-map RIP_TO_EIGRP permit 20

==================================================================

EIGRP RTP

• RTP protocol là giao thức reliable dùng để quản lý ,thu nhận EIGRP packet . Realiable delivery có nghĩa rằng phân phát đảm bảo và packet được phân phối đúng thứ tự.
• Sử dụng 224.0.0.10. mỗi neighbor receiving a reliably multicast packet unicast an ack.
• Mỗi packet có 2 sequence nummber:
• Sequence number assigned by the sending router
• Sequence number incremented by one each time the router send a new packet.

• Trong một số trường hợp, RTP may use unreliable delivery. No Ack is request, and no sequence number will be included for unreliable delivered EIGRP packet.
• EIGRP uses multiple packet types, all of which are indentify by protocol number 88 in IP header:
• Hello sử dụng discovery neighbor and recovery process. Hello packet are multicast and use unreliable delivery.
• ACK là hello packet với no data. ACK luôn luôn là unicast and use unreliable delivery.
• Update convey route information. Packet transmitted chỉ khi cần thiết , bao gồm những thông tin cần thiết, và gửi tới router yêu cầu thông tin. Khi update yêu cầu chỉ rõ router, they are unicast. Còn khi yêu cầu bởi multiple routers, such as upon a metric or topology change, they are multicast. Up date always use reliable delivery.
• Queries and replies are by DUAL finite state machine to manage its diffusing compitation.
• Queries can be multicast or unicast
• Replies always unicast

Both they use reliable delivery.

• Request were type of packet originally intended for use in route servers. This app was nerver implemented, and request packets are noted here only because they are mentioned in some older EIGRP documentation.

• If any packet is reliably multicast and an ACK is not received from neighbor, the packet will be retransmitted as a unicast to that unresponding neighbor. Nếu ACK không nhận sau 16 time khi unicast retransmit, neighbor wikk be declared dead.

EIGRP overview

1. Hybrid IGP using DUAL (Diffusing Update Algorithm).

2. Using RTP ( reliable transport protocol) , port 88

3. Multicast to destination 244.0.0.10 (TTL = 0 ) , using RTP , the receiving neighbor unicast an acknowedgment.
4. Unequal-cost load sharing up to 16 link.

5. EIGRP does't form neighbors over secondary network/Ips.

6. EIGRP su dung gia tri router-id de chong loop external.
1. IOS- router id highest
2. IOS-XR router id lowest

Advan :

+ mạng hội tụ nhanh.

+ support VLSM and CIDR.

+ support authentication.

Note :

• EIGRP sử dụng hello protocol giữa neighbr to enable early detection of neighbor and hội tụ nhanh. Bình thường distance-vetor protocols rely on routing update timeouts to detect this condition.

• EIGRP sử dụng RTP để gửi và nhận routing update, which eliminates the need for periodic full update.