Revision as of 17:09, 18 June 2010

Maintaining and Troubleshooting Routing Solutions

1 Maintaining and Troubleshooting Routing Solutions
2 Redistributiuon
- 2.1 Redistribute from OSPF to EIGRP
3 IOS Commands to verify Routing Functions
4 redistribution cavets
- 4.1 Routing loops
  - 4.1.1 redistribute RIP into OSPF example
    - 4.1.1.1 Avoiding Routing loop
  - 4.1.2 redistribute RIP into EIGRP example
5 Distribute lists
6 prefix lists
7 Example
8 PBR: Policy Based Routing
9 Seed metric
10 Troubleshooting EIGRP
- 10.1 Monitoring EIGRP
11 Troubleshooting OSPF
- 11.1 INSERT TABLE 5.2 and FIGURE 5.3 from page 168
- 11.2 Cisco IOS OSPF commands
  - 11.2.1 Show commands
  - 11.2.2 debug commands
12 Troubleshooting BGP

Redistributiuon

Redistribution metrics
Protocol	Default Seed Metric
RIP	Infinity
IGRP/EIGRP	Infinity
OSPF	20 except from BGP then 1
ISIS	0
BGP	IGP

Redistribute from OSPF to EIGRP

Example

router eigrp 1
 redistribute ospf 100 metric 64 10000 255 1 1500

IOS Commands to verify Routing Functions

Verifying and Troubleshooting Route Propagation

Debug ip routing

R1#<input>debug ip routing</input>
IP routing debugging is on
R1#<input>clear ip eigrp 1 neighbors</input>
R1#
Jun 18 12:45:44: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: <notice>Nei 10.1.2.1 (Fa0/1) is down: manually cleared</notice>
Jun 18 12:45:44: RT: delete route to 10.1.10.0 via 10.1.2.1, eigrp metric [90/28416]
Jun 18 12:45:44: RT: no routes to 10.1.10.0
Jun 18 12:45:44: RT: NET-RED 10.1.10.0/24
<notice>...OUTPUT OMITTED...</notice>
Jun 18 12:45:44: RT: NET-RED 10.1.200.0/24
Jun 18 12:45:46: RT: NET-RED 0.0.0.0/0
Jun 18 12:45:47: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: <notice>Nei 10.1.2.1 (Fa0/1) is up: new adjacency</notice>
Jun 18 12:45:47: RT: network 10.0.0.0 is now variably masked
Jun 18 12:45:47: RT: add 10.1.10.0/24 via 10.1.2.1, eigrp metric [90/28416]
Jun 18 12:45:47: RT: NET-RED 10.1.10.0/24
Jun 18 12:45:47: RT: add 10.1.20.0/24 via 10.1.2.1, eigrp metric [90/28416]
<notice>...OUTPUT OMITTED...</notice>
Jun 18 12:45:47: RT: add 10.1.203.1/32 via 10.1.2.1, eigrp metric [90/158976]
Jun 18 12:45:47: RT: NET-RED 10.1.203.1/32
R1#<input>no debug ip routing</input>
IP routing debugging is off

Route Profiling

R1(config)#<input>ip route profile</input>
R1(config)#<input>^Z</input>
Jun 18 12:46:41.803: %SYS-5-CONFIG_I: Configured from console by console
R1#<input>sh ip route profile</input>
IP routing table change statistics:
Frequency of changes in a 5 second sampling interval
-------------------------------------------------------------
Change/   Fwd-path  Prefix   Nexthop  Pathcount  Prefix
interval  change    add      change   change     refresh
-------------------------------------------------------------
0         2         2        2        2          1
1         0         0        0        0          1
2         0         0        0        0          0
3         0         0        0        0          0
4         0         0        0        0          0
5         0         0        0        0          0
10        0         0        0        0          0
15        0         0        0        0          0
20        0         0        0        0          0
25        0         0        0        0          0
30        0         0        0        0          0
55        0         0        0        0          0
80        0         0        0        0          0
105       0         0        0        0          0
130       0         0        0        0          0
155       0         0        0        0          0
280       0         0        0        0          0
405       0         0        0        0          0
-------------------------------------------------------------
Change/   Fwd-path  Prefix   Nexthop  Pathcount  Prefix
interval  change    add      change   change     refresh
-------------------------------------------------------------
530       0         0        0        0          0
655       0         0        0        0          0
780       0         0        0        0          0
1405      0         0        0        0          0
2030      0         0        0        0          0
2655      0         0        0        0          0
3280      0         0        0        0          0
3905      0         0        0        0          0
7030      0         0        0        0          0
10155     0         0        0        0          0
13280     0         0        0        0          0
Overflow  0         0        0        0          0
R1#<input>conf t</input>
R1(config)#<input>no ip route profile</input>

show ip cef

SW1#show ip cef exact-route 172.16.4.16 192.168.22.73
172.16.4.16 -> 192.168.22.73 => IP adj out of Vlan1, addr 172.16.4.16

show ip prot

remember

Route-maps

prefix lists

redistribution cavets

Routing loops

redistribute RIP into OSPF example

Consider the network below and follow the red update path.

Router A updates router B with RIP. Router B now learne the network 80.0.0.0/16.
1. Please note that the administrative distance for RIP is 120.
Router B now redistributes 80.0.0.0/16 into OSPF.
1. Note that OSPF has an administrative distance of 110.
Router B updates router C as an external OSPF route administrative distance 110
Router C updates router D as an external OSPF route administrative distance 110
Router D updates router E as an external OSPF route administrative distance 110
Router E now has two router to 80.0.0.0/16
1. Via RIP directly to Router A (Preferred route)
2. Via OSPF to router D - Path D->C->B->A.
Router E sends traffic to 80.0.0.0/16 to router D because OSPF(110) administrative distance is better than RIP's(120).

RIP redistribution into OSPF example

Avoiding Routing loop

redistribute RIP into EIGRP example

With EIGRP we avoid the routing loop seen from OSPF above. EIGRP has two different administrative distances. One for internal routes 90 and one for externally learned routes 170.
Consider the network below and follow the red update path.

Router A updates router B with RIP. Router B now learne the network 80.0.0.0/16.
1. Please note that the administrative distance for RIP is 120.
Router B now redistributes 80.0.0.0/16 into EIGRP.
1. EIGRP has an internal route administrative distance of 90. and
2. EIGRP has an external route administrative distance of 170.
Router B updates router C as an external EIGRP route administrative distance 170
Router C updates router D as an external EIGRP route administrative distance 170
Router D updates router E as an external EIGRP route administrative distance 170
Router E now has two router to 80.0.0.0/16
1. Via RIP directly to Router A (Preferred route)
2. Via EIGRP to router D - Path D->C->B->A.
Router E sends traffic to 80.0.0.0/16 to router A because RIP(120) administrative distance is better than EIGRP external(170).

RIP redistribution into EIGRP example

Distribute lists

You can filter updates with distribute lists. The exampe below shows filtering of incoming updates. You can also filter outgoing updates.

distribute list example

hostname B
!
router rip
 version 2
 distribute-list 23 in
!
access-list 23 deny 90.0.0.0 0.0.255.255
access-list 23 permit any

Router B Configuration of distribute list

hostname E
!
router rip
 version 2
 distribute-list 3 in
!
access-list 3 deny 80.0.0.0 0.0.255.255
access-list 3 permit any

Router E Configuration of distribute list

prefix lists

Routes in routetable

Address groups
Nr.	Network
1	10.0.0.0/8
2	10.128.0.0/9
3	10.1.1.0/24
4	10.1.2.0/24
5	10.128.10.4/30
6	10.128.10.8/30

Address groups
Prefix list	Matches in previos table
10.0.0.0/8	1
10.128.0.0/9	2
10.0.0.0/8 ge 9	2,3,4,5,6
10.0.0.0/8 ge 24 le 24	3,4
10.0.0.0/8 le 24	1,2,3,4
0.0.0.0/0	None
0.0.0.0/0 le 32	All

Example

Prefix-lists are numbered. In this example "secret net" are not announced.

Note: As with access-lists there are an implicit deny in the end.

ip prefix-list SECRET-NET seq 10 deny 172.16.0.0/16
ip prefix-list SECRET-NET seq 20 deny 192.168.22.0/24
ip prefix-list SECRET-NET seq 30 permit 0.0.0.0/0 le 32 !Permit all other nets
!
router bgp 100
  neighbor 10.1.2.3 remote-as 200
  neighbor 10.1.2.3 prefix-list SECRET-NET out

PBR: Policy Based Routing

PBR or Policy Based Routing gives more control and more options than distribute lists - see above. PBR introduces the set command which set the interface or next-hop address to which the packet should be sent. To select which packets should go where you can use the match command and match the based on for example source or destination addresses.

In the picture below the traffic from 192.168.1.0/24 on E0 interface must route to ISP1 and traffic from 172.16.1.0/24 on E1 must route to ISP1.

hostname RTA
!
access-list 37 permit 192.168.1.0 0.0.0.255
access-list 48 permit 172.16.1.0 0.0.0.255
!
route-map ISP1 permit 10
 match ip address 37
 set interface s0
!
route-map ISP2 permit 20
 match ip address 48
 set interface s1
!
interface e0
 ip policy route-map ISP1
!
interface e1
 ip policy route-map ISP2

Policy Based Routing example

Seed metric

Default Seed Metric

Default Seed Metric example (RIP=infinity default)

Administrative distance

Troubleshooting EIGRP

EIGRP uses three tables

interface table:

EIGRP Tables
Table	Description
Interface	Contains list of all interfaces that have been enabled for processing of EIGRP packets. Passive interfaces are not listed in this table.
Neighbor	Keeps track of all active EIGRP neighbors. Neighbours are added on the reception of hello packet and are removed when the hold-time expires or when the associated interface goes down or removed from the Interface table. This table also keeps track on status on Routing information exchanged.
Topology	Holds all Routes received from neighbors, locally injected or redistributed into EIGRP. EIGRP selects the best routes from this table based on the DUAL algorithm.

Monitoring EIGRP

show commands

show ip eigrp interface
show ip eigrp neighbors
show ip eigrp topology

debug commands

debug ip routing
debug eigrp packets - Many options here (terse - except hello packets)
debug ip eigrp neighbor as-number network mask
debug ip eigrp as-number network mask - limit info. from debug eigrp packets

Examples

R1#<input>sh ip protocols</input>
Routing Protocol is "eigrp 1"
  Outgoing update filter list for all interfaces is not set
  Incoming update filter list for all interfaces is not set
  Default networks flagged in outgoing updates
  Default networks accepted from incoming updates
  EIGRP metric weight K1=1, K2=0, K3=1, K4=0, K5=0
  EIGRP maximum hopcount 100
  EIGRP maximum metric variance 1
  Redistributing: static, eigrp 1
  EIGRP NSF-aware route hold timer is 240s
  Automatic network summarization is not in effect
  Maximum path: 4
  Routing for Networks:
    10.1.2.0/30
    192.168.1.1/32
  Passive Interface(s):
    FastEthernet0/0
    Service-Engine0/1
    Serial0/0/0
    Serial0/0/1
    ATM0/3/0
    NVI0
    Loopback0
  Passive Interface(s):
    VoIP-Null0
  Routing Information Sources:
    Gateway         Distance      Last Update
    10.1.2.1              90      00:07:33
  Distance: internal 90 external 170

Many options debugging eigrp

  R1#<input>debug eigrp packets ?</input>
  SIAquery  EIGRP SIA-Query packets
  SIAreply  EIGRP SIA-Reply packets
  ack       EIGRP ack packets
  hello     EIGRP hello packets
  ipxsap    EIGRP ipxsap packets
  probe     EIGRP probe packets
  query     EIGRP query packets
  reply     EIGRP reply packets
  request   EIGRP request packets
  retry     EIGRP retransmissions
  stub      EIGRP stub packets
  terse     Display all EIGRP packets except Hellos
  update    EIGRP update packets
  verbose   Display all EIGRP packets
  <cr>

Troubleshooting OSPF

OSPF tables
Table	Description
Interface table	List all interfaces enabled for OSPF. The directly connected subnets are included in the TYPE-1 Router LSA the Router injects into the OSPF link-state database. Passive-interfaces is listed in the tables
Neighbor table	Used to keep track of all OSPF neighbors. Neighbors are added on the reception of a hello packet and removed when the dead-time expires or when the associated interface goes down.
Link State database	Main data structure containing all network topology information for the OSPF process.
Routing Information Base	Contains results from the SPF algorithm. OSPF offers the contents of the RIB to the Routing Table.

INSERT TABLE 5.2 and FIGURE 5.3 from page 168

Cisco IOS OSPF commands

Show commands

show ip ospf interface
show ip ospf neighbor
show ip ospf datatbase
show ip ospf statistics

debug commands

debug ip routing
debug ip ospf packet
debug ip ospf adj
debug ip ospf monitor

Troubleshooting BGP

@@ Line 111: / Line 111: @@
 ==Route-maps==
 ==prefix lists==
+{{:Route_optimization#PBR:_Policy_Based_Routing}}
 {{Source cli}}
 =Troubleshooting EIGRP=
 EIGRP uses three tables

Navigation menu

Difference between revisions of "CCNP TSHOOT Learning Guide/Chapter 5"

Revision as of 17:09, 18 June 2010

Maintaining and Troubleshooting Routing Solutions

Contents

Redistributiuon

Redistribute from OSPF to EIGRP

IOS Commands to verify Routing Functions

Verifying and Troubleshooting Route Propagation

Debug ip routing

Route Profiling

show ip cef

show ip prot

Route-maps

prefix lists

redistribution cavets

Routing loops

redistribute RIP into OSPF example

Avoiding Routing loop

redistribute RIP into EIGRP example

Distribute lists

prefix lists

Example

PBR: Policy Based Routing

Seed metric

Troubleshooting EIGRP

Monitoring EIGRP

show commands

debug commands

Examples

Troubleshooting OSPF

INSERT TABLE 5.2 and FIGURE 5.3 from page 168

Cisco IOS OSPF commands

Show commands

debug commands

Troubleshooting BGP