Maintaining and Troubleshooting Routing Solutions

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
<notice>...OUTPUT OMITTED...</notice>
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#<input>show ip cef exact-route 172.16.4.16 192.168.22.73</input>
172.16.4.16 -> 192.168.22.73 => IP adj out of Vlan1, addr 172.16.4.16

Route-maps

Example

ip access-list extended ISP-CON1
 remark Internally used nets denied. They should be routed by the FIB
 deny   ip 192.168.1.0 0.0.0.255 10.0.0.0 0.255.255.255
 deny   ip 192.168.1.0 0.0.0.255 192.168.0.0 0.127.255.255
 permit ip 192.168.1.0 0.0.0.255 any
!
ip prefix-list DEFAULT seq 5 permit 0.0.0.0/0
!
route-map HETH permit 5
 match ip address ISP-CON1
 set ip next-hop 10.0.0.30
!
route-map HETH permit 10
 match ip address prefix-list DEFAULT
 set ip next-hop 10.0.0.34

prefix lists

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

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 are 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.

Neighbor states

OSPF Neighbor states
State	Description
Attempt	This state is only valid for manually configured neighbors in an NBMA environment. In Attempt state, the router sends unicast hello packets every poll interval to the neighbor, from which hellos have not been received within the dead interval.
Init	This state specifies that the router has received a hello packet from its neighbor, but the receiving router's ID was not included in the hello packet. When a router receives a hello packet from a neighbor, it should list the sender's router ID in its hello packet as an acknowledgment that it received a valid hello packet.
2-Way	This state designates that bi-directional communication has been established between two routers. Bi-directional means that each router has seen the other's hello packet. This state is attained when the router receiving the hello packet sees its own Router ID within the received hello packet's neighbor field. At this state, a router decides whether to become adjacent with this neighbor. On broadcast media and non-broadcast multiaccess networks, a router becomes full only with the designated router (DR) and the backup designated router (BDR); it stays in the 2-way state with all other neighbors. On Point-to-point and Point-to-multipoint networks, a router becomes full with all connected routers. At the end of this stage, the DR and BDR for broadcast and non-broadcast multiacess networks are elected. For more information on the DR election process, refer to DR Election. Note: Receiving a Database Descriptor (DBD) packet from a neighbor in the init state will also a cause a transition to 2-way state.
Exstart	Once the DR and BDR are elected, the actual process of exchanging link state information can start between the routers and their DR and BDR. In this state, the routers and their DR and BDR establish a master-slave relationship and choose the initial sequence number for adjacency formation. The router with the higher router ID becomes the master and starts the exchange, and as such, is the only router that can increment the sequence number. Note that one would logically conclude that the DR/BDR with the highest router ID will become the master during this process of master-slave relation. Remember that the DR/BDR election might be purely by virtue of a higher priority configured on the router instead of highest router ID. Thus, it is possible that a DR plays the role of slave. And also note that master/slave election is on a per-neighbor basis.
Exchange	In the exchange state, OSPF routers exchange database descriptor (DBD) packets. Database descriptors contain link-state advertisement (LSA) headers only and describe the contents of the entire link-state database. Each DBD packet has a sequence number which can be incremented only by master which is explicitly acknowledged by slave. Routers also send link-state request packets and link-state update packets (which contain the entire LSA) in this state. The contents of the DBD received are compared to the information contained in the routers link-state database to check if new or more current link-state information is available with the neighbor.
Loading	In this state, the actual exchange of link state information occurs. Based on the information provided by the DBDs, routers send link-state request packets. The neighbor then provides the requested link-state information in link-state update packets. During the adjacency, if a router receives an outdated or missing LSA, it requests that LSA by sending a link-state request packet. All link-state update packets are acknowledged.
Full	In this state, routers are fully adjacent with each other. All the router and network LSAs are exchanged and the routers' databases are fully synchronized. Full is the normal state for an OSPF router. If a router is stuck in another state, it's an indication that there are problems in forming adjacencies. The only exception to this is the 2-way state, which is normal in a broadcast network. Routers achieve the full state with their DR and BDR only. Neighbors always see each other as 2-way.

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

BGP has two maintables

BGP Tables
Table	Description
Neighbor table	List all neighbors configured on the router. Contains AS, state, time up/down, and how many prefixes exchanged
BGP table	Also called BGP RIB stores all locally injected routes and all routes received from neighbors/peers and routing info such as Nexthop, AS, MED, metric origin etc.

Troubleshooting commands

show commands

show ip bgp summary
show ip bgp neighbors [ip-address]
show ip bgp [prefix]

debug commands

debug ip bgp
debug ip bgp updates

Navigation menu

CCNP TSHOOT Learning Guide/Chapter 5

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

Route-maps

prefix lists

Troubleshooting EIGRP

Monitoring EIGRP

show commands

debug commands

Examples

Troubleshooting OSPF

Neighbor states

INSERT TABLE 5.2 and FIGURE 5.3 from page 168

Cisco IOS OSPF commands

Show commands

debug commands

Troubleshooting BGP

Troubleshooting commands

show commands

debug commands