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1NW’2000 Paris © 2000, Cisco Systems, Inc.
The Integrated IS-IS routing protocol
The Integrated IS-IS routing protocol
Gerry [email protected]
Gerry [email protected]
2NW’2000 Paris © 2000, Cisco Systems, Inc.
Agenda Agenda
• Link-state protocol fundamentals
• Overview of IS-IS
• Areas and levels
• NSAPs and LSP identifiers
• CLNS routing principles
• LSP Flooding
3NW’2000 Paris © 2000, Cisco Systems, Inc.
AgendaAgenda
• IP routing specifics
• Configuration Commands
• Show Commands
• Debug Commands
4NW’2000 Paris © 2000, Cisco Systems, Inc.
Link-state protocol fundamentals
Link-state protocol fundamentals
4
5NW’2000 Paris © 2000, Cisco Systems, Inc.
About link-state protocolsAbout link-state protocols
• In a link-state protocol, the network can be viewed as a jigsaw puzzle
• Each jigsaw piece holds one router
• Each router creates a packet which represents its own jigsaw piece
This packet is called a Link State PDU (LSP)
6NW’2000 Paris © 2000, Cisco Systems, Inc.
About link-state protocolsAbout link-state protocols
• These packets are flooded everywhere
• Therefore each router receives all pieces of the jigsaw puzzle
• Each routers compute SPF algorithm to put the pieces together
Input: all jigsaw puzzle pieces (LSPs)
Output: Area or network topology tree Shortest Path Tree
7NW’2000 Paris © 2000, Cisco Systems, Inc.
The jigsaw puzzleThe jigsaw puzzle
LSP for router-A
LSP for router-B
LSP for router-CLSP for router-D
to B
to Eto D
to C
to A
to D to C
to BLSP for routerE
to A to B
to A
to E
8NW’2000 Paris © 2000, Cisco Systems, Inc.
All routers have same viewAll routers have same view
• All routers exchange all LSPs
via a reliable flooding mechanism
• All routers store all LSPs in a so-called link-state database (LSPDB)
separate from the routing table (RIB)
all routers should have exactly the same LSPDB, but different RIBs
9NW’2000 Paris © 2000, Cisco Systems, Inc.
What to do with LSPs ?What to do with LSPs ?
• Each router ‘composes the jigsaw puzzle’ by executing Dijkstra’s Shortest Path First algorithm (SPF)
the topology is calculated as a Shortest Path Tree (SPT), with itself as root
each router computes a different SPT
• From the SPT the RIBs are calculated
10NW’2000 Paris © 2000, Cisco Systems, Inc.
All routers have same LSPDBAll routers have same LSPDB
RouterA’s LSPDB
RouterB’s LSPDB
RouterC’s LSPDB
RouterE’s LSPDB
RouterD’s LSPDB
lspA lspB
lspC lspDlspE
lspA lspB
lspC lspDlspE
lspA lspB
lspC lspDlspE
lspA lspB
lspC lspDlspE
lspA lspB
lspC lspDlspE
11NW’2000 Paris © 2000, Cisco Systems, Inc.
Brief Overview of IS-ISBrief Overview of IS-IS
11
12NW’2000 Paris © 2000, Cisco Systems, Inc.
What is IS-IS ?What is IS-IS ?
• IS stands for Intermediate System
• IS is “OSI speak” for router
• IS-IS is the Intermediate System to Intermediate System intra-domain routing protocol
• IS-IS was defined in 1992 in the ISO/IEC recommendation 10589
13NW’2000 Paris © 2000, Cisco Systems, Inc.
IS-IS for IP routingIS-IS for IP routing
• IS-IS was designed for OSI routing
• IS-IS is easily extendable
• Extensions for IP routing in rfc1195
Also called “Integrated IS-IS”or “Dual IS-IS”
• Easy to extend for other protocols mainly IPv6
14NW’2000 Paris © 2000, Cisco Systems, Inc.
Only 4 types of IS-IS packetsOnly 4 types of IS-IS packets
• IS-IS Hello packet (IIH)
• Link State Packet (LSP)
• Partial Sequence Number Packet (PSNP)
• Complete Sequence Number Packet (CSNP)
• Packets are sometimes called Protocol Data Units (PDU in OSI)
15NW’2000 Paris © 2000, Cisco Systems, Inc.
IS-IS Hello PDUsIS-IS Hello PDUs
• Also called IIHs
• Used for maintaining adjacencies
• Different on p2p links and LANs
• Different from ISHs and ESHs (ESIS)
• IIHs are padded to full MTU size
16NW’2000 Paris © 2000, Cisco Systems, Inc.
Link State PDUsLink State PDUs
• Called LSPs
• Contains all info about one router
adjacencies, connected IP prefixes, OSI endsystems, area addresses, etc.
• One LSP per router (plus fragments)
• One LSP per LAN network
17NW’2000 Paris © 2000, Cisco Systems, Inc.
Sequence Number PDUsSequence Number PDUs
• Partial (PSNP) and Complete (CSNP)
• Used when flooding the LSPDB
• PSNPs are like ACKs on p2p links
• CSNPs are used for LSPDB synchronization over LANs
• CSNP are also used to sync LSPDB over new p2p adjacencies
18NW’2000 Paris © 2000, Cisco Systems, Inc.
Pseudonodes and network LSAs Pseudonodes and network LSAs
• For SPF, the whole network must look like a collection of nodes and point-to-point links
Multi-access networks are different
• Assume a virtual node for the LAN
this virtual node is called pseudonode. It is not a real router, but just an extra LSP in the LSPDB
19NW’2000 Paris © 2000, Cisco Systems, Inc.
A pseudonode on a LAN A pseudonode on a LAN
Logical view
LAN
Physical view
DIS
Pseudonode
DIS
20NW’2000 Paris © 2000, Cisco Systems, Inc.
Who creates the pseudonodeWho creates the pseudonode
• Created by Designated Router (DIS)
• No Backup Designated Router in IS-IS
• The DIS reports all LAN neighbors in the pseudonode LSP; with metric 0
• All LAN routers report connectivity to the pseudonode in their LSPs
21NW’2000 Paris © 2000, Cisco Systems, Inc.
Identifying nodesIdentifying nodes
• In IS-IS SystemIDs are 6 bytes. Nodes are identified by 7 bytes.
A normal node (non-pseudonode) is identified by 6 bytes systemID plus a zero (e.g. 00c0.0040.1234.00-00 )
A pseudonode is identified by the systemID of the DIS, plus 1 byte from the circuitID of the interface of the DIS
(e.g. 00c0.0040.1234.01-00 )
22NW’2000 Paris © 2000, Cisco Systems, Inc.
Areas and levelsAreas and levels
22
23NW’2000 Paris © 2000, Cisco Systems, Inc.
Hierarchy Hierarchy
• IS-IS has 2 layers of hierarchy
the backbone is called level-2
areas are called level-1
• Same algorithms apply for L1 and L2
• A router can take part in L1 and L2
inter-area routing (or inter-level routing)
24NW’2000 Paris © 2000, Cisco Systems, Inc.
Level-1 RoutersLevel-1 Routers
• Neighbors only in the same area
• L1 has information about own area
• L1-only routers look at the attach-bit (ATT) in L1 LSPs to find the closest L1L2 router
• L1-only routers install a default route to the closest L1L2 router in the area
25NW’2000 Paris © 2000, Cisco Systems, Inc.
Level-2 routers Level-2 routers
• May have neighbors in other areas
• L2 has information about L2 topology
• L2 has information what L1 destinations are reachable and how to reach them via the L2 topology
• L2 routers often do also L1 routing
so called L1L2 routers
26NW’2000 Paris © 2000, Cisco Systems, Inc.
Adjacency levels
L1-Adjacency L2-Adjacency
L2-AdjacencyL2-Adjacency
L1L2Adjacency
L1L2Adjacency
Router with adjacencies within the same area.
However, needs to have a L2 database as well since it is a transit node
Therefore L1L2 adjacency is required
27NW’2000 Paris © 2000, Cisco Systems, Inc.
Level-1, Level-2 & Level-1-2 Routers
• Backbone MUST BE L2 contiguous
L1-only
L1-only
L1-only
L1-only
L1-L2
L1-L2
L2-only
L1-only
L1-L2
L1-L2
L1-only
This router has to behave as level-2 as well in order to guarantee backbone continuity
28NW’2000 Paris © 2000, Cisco Systems, Inc.
Level-1, Level-2 & Level-1-2 Routers
• Backbone MUST BE L2 contiguous
L1-only
L1-only
L1-only
L1-L2
L1-L2
L2-only
L1-L2
L1-L2
L1-only
This router has to behave as level-2 as well in order to guarantee backbone continuity
L1-L2
29NW’2000 Paris © 2000, Cisco Systems, Inc.
NSAPs and LSPidsNSAPs and LSPids
29
30NW’2000 Paris © 2000, Cisco Systems, Inc.
NSAPs and AddressingNSAPs and Addressing
• Network Service Access Point
• The NSAP is the network layer address for CLNS packets
• One NSAP per box, not per interface (similar to DECnet)
• SNPA means SubNetwork Point of Attachment, which is the layer2 or MAC address
31NW’2000 Paris © 2000, Cisco Systems, Inc.
How do I read an NSAP ?How do I read an NSAP ?
• An NSAP consists of 3 parts
area-address, systemID and n-selector
• Total length between 8 and 20 bytes
example: 49.0001.0000.0000.0007.00
32NW’2000 Paris © 2000, Cisco Systems, Inc.
NETs versus NSAPsNETs versus NSAPs
• A NET is an NSAP with n-selector 0
• A NET implies the routing layer of the IS itself (no transport layer)
• On routers we always deal with NETs
We haven’t implemented TP4 (or another transport layer)
33NW’2000 Paris © 2000, Cisco Systems, Inc.
Do I need an NSAP if I want to use IS-IS for IP routing ?
Do I need an NSAP if I want to use IS-IS for IP routing ?
• Yes, still needed for IP routing only
• Area address is like OSPF area nr
• SystemID is like an OSPF routerID
LSP identifier is derived from systemID
34NW’2000 Paris © 2000, Cisco Systems, Inc.
Creating unique systemIDsCreating unique systemIDs
• SystemID is 6 bytes
• Start numbering 1, 2, 3, 4 …. etc
• Convert your loopback IP address
192.31.231.16 -> 192.031.231.016 -> systemID 1920.3123.1016
35NW’2000 Paris © 2000, Cisco Systems, Inc.
Creating area addressesCreating area addresses
• If you do CLNS routing, request an official NSAP prefix
• If you do just IP routing, use AFI 49
• AFI 49 denotes private address space
like network 10.0.0.0 in IP
• Just number your areas 49.0001… 49.0002…., 49.0003,… etc
36NW’2000 Paris © 2000, Cisco Systems, Inc.
LSP IdentifierLSP Identifier
• LSP identifier consists of 3 parts• Source ID
SystemID of router or DIS (if pseudonode)
• Pseudonode IDRouter LSP = zero, Pseudonode LSP = non-zero
• LSP numberFragmentation number
• Example: 00c0.0040.1234.02-00
PN-ID Frag-Nr SystemID
37NW’2000 Paris © 2000, Cisco Systems, Inc.
CLNS routing principlesCLNS routing principles
37
38NW’2000 Paris © 2000, Cisco Systems, Inc.
OSI protocol familyOSI protocol family
• CLNS is datagram delivery protocol
like bare IP service
actually called CLNP
• ESIS is like ARP, ICMP, HSRP, IRDP
between routers and hosts
• IS-IS and ISO-IGRP are the IGPs
39NW’2000 Paris © 2000, Cisco Systems, Inc.
OSI protocol familyOSI protocol family
• IS-IS is not encapsulated in CLNS
and not encapsulated in IP (yet)
• Encapsulated directly in layer2
• Protocol family is OSI
usually values like 0xFE or 0xFEFE
(ppp uses 0x0023 and 0x8023)
40NW’2000 Paris © 2000, Cisco Systems, Inc.
Encapsulation of IS-ISEncapsulation of IS-IS
Datalink header (OSI family 0xFEFE)
ISIS fixed header (first byte is 0x82)
ISIS TLVsISIS:
Datalink header (OSI family 0xFEFE)
ESIS fixed header (first byte is 0x81)
ESIS TLVsESIS:
Datalink header (OSI family 0xFEFE)
CLNS header (with NSAPs) (first byte is 0x80)
User dataCLNS:
41NW’2000 Paris © 2000, Cisco Systems, Inc.
Level-1 routingLevel-1 routing
• L1-only routers know only topology of their own area (including all ISs and ESs in the area)
• Traffic to other areas is sent via the closest L2 IS
• L1L2 ISs set the “attached-bit” in their L1 LSP
42NW’2000 Paris © 2000, Cisco Systems, Inc.
Area addressesArea addresses
• An area address is like a summary
• All L1 ISs and ESs in an area must have NSAPs that start with the same area-address
• L1L2 routers advertise their area-addresses to L2 routers in other areas
• Multiple area-adresses possible
43NW’2000 Paris © 2000, Cisco Systems, Inc.
Level-2 RoutingLevel-2 Routing
• L2 routers know about other areas
L2 area addresses and L2 routers
• When doing OSI routing, the L2 ISs must know their own area. Therefore never use L2-only on OSI routers
L2-only is possible when doing just IP
44NW’2000 Paris © 2000, Cisco Systems, Inc.
Level-2 RoutingLevel-2 Routing
• Transit traffic requires routers inside the area to know about other areas
routers in transit paths must be L1L2 routers to have the full L2 LSDB
similar to pervasive BGP requirement
• L2 routers must be contiguous
45NW’2000 Paris © 2000, Cisco Systems, Inc.
The BackboneThe Backbone
• A router can’t tell whether it is a transit node
Therefore the cisco default is to be L1L2
This will make the backbone larger then necessary
So always configure L1-only or L2-only when possible
• L1L2 in one area is less scalable
Especially with ISIS for IP
46NW’2000 Paris © 2000, Cisco Systems, Inc.
ISIS router cannot determine if they need to be L1 or L1L2Therefore By default all cisco routers will behave as L1L2
Area 4
Can an IS determine its level ? Can an IS determine its level ?
Area 3
Area 2
Area 1“I’m in area 2 and ALL my neighbors are in thesame area. I must be a L1-only router ?”
!! NO !!Rtr C must have a full L2 LSDB to route between areas 1, 3 and 4. Remember, the backbone must be contiguous.
47NW’2000 Paris © 2000, Cisco Systems, Inc.
The Attached bit The Attached bit
Area 2 Area 1
rtr A
rtr D
• L1L2 routers set the ATT bit in their L1 LSP
• L1 routers use ATT bit found in L1-LSDB as possible area exit point
ISIS for IP: level-1 router will install a 0.0.0.0/0 route towards the L1L2 with ATT-bit set
• Shortest metric to the L1L2 who sets the ATT bit wins
L2-LSDBrtrA.00-00rtrD.00-00
L1-LSDBrtrA.00-00 ATT-bitrtrB.00-00rtrC.00-00
L1-LSDBrtrD.00-00 ATT-bitrtrE.00-00rtrF.00-00
48NW’2000 Paris © 2000, Cisco Systems, Inc.
LSP floodingLSP flooding
48
49NW’2000 Paris © 2000, Cisco Systems, Inc.
Why do we need floodingWhy do we need flooding
• All routers generate an LSP
• All LSPs need to be flooded to all routers in the network
if LSPDB is not synchronised, routing loops or blackholes might occur
• IS-IS’ two components are the SPF computation and reliable flooding
50NW’2000 Paris © 2000, Cisco Systems, Inc.
What triggers a new LSP ?What triggers a new LSP ?
• When something changes …
Adjacency came up or went down
Interface up/down (connected IP prefix !)
Redistributed IP routes change
Inter-area IP routes change
An interface is assigned a new metric
Most other configuration changes
Periodic refresh
51NW’2000 Paris © 2000, Cisco Systems, Inc.
What to do with a new LSP ?What to do with a new LSP ?
• Create new LSP, install in your own LSPDB and mark it for flooding
• Send the new LSP to all neighbors
• Neigbors flood the LSP further
52NW’2000 Paris © 2000, Cisco Systems, Inc.
Basic flooding rulesBasic flooding rules
• When receiving an LSP, compare with old version of LSP in LSPDB
• If newer:
install it in the LSPDB
Acknowledge the LSP with a PSNP
Flood to all other neighbors
Check if need to run SPF
53NW’2000 Paris © 2000, Cisco Systems, Inc.
Basic flooding rulesBasic flooding rules
• If same age:
Acknowledge the LSP with a PSNP
• If older:
Acknowledge the LSP with a PSNP
Send our version of the same LSP
Wait for PSNP
54NW’2000 Paris © 2000, Cisco Systems, Inc.
Sequence numberSequence number
• Each LSP (and LSP fragment) has its own sequence number
• When router boots, set seqnr to one
• When there is a change, the seqnr is incremented, a new version of the LSP is generated with the new seqnr
• Higher seqnr means newer LSP
55NW’2000 Paris © 2000, Cisco Systems, Inc.
Remaining lifetimeRemaining lifetime
• Used to age out old LSPs
• Periodic refresh needed to keep stable LSPs valid
• IS-IS counts down from 1200 sec to 0
we allow start at 65535 sec (18.7h)
• When lifetime expires, the LSP is purged from the network
Header with lifetime = 0 is flooded
56NW’2000 Paris © 2000, Cisco Systems, Inc.
Flooding on a P2P LinkFlooding on a P2P Link
RouterARouterB
Received ackClear SRMbit
Received it. Local copy has seqNr = 21.So the received one is newer. Install it in LSDB. Acknowledge it. Maybe flood further.id=x seqnr=22
PSNP
Now flood it:Set SRM bit.Send over p2p.
id=x seqnr=22LSP
Receives LSPid=x seqNr=22 It’s new. Put it in the LSPDB
id=x seqnr=22LSP
57NW’2000 Paris © 2000, Cisco Systems, Inc.
The Designated RouterThe Designated Router
• DIS is like the DR in OSPF
• DIS is only on LANs, not on p2p
• DIS has two tasks
create/update pseudonode LSP
conduct flooding over the LAN
• DIS sends periodic CSNPs
LSPid, SeqNr, Checksum, Lifetime of all LSPs present in the LSPDB
58NW’2000 Paris © 2000, Cisco Systems, Inc.
The Designated ISThe Designated IS
• No Backup DIS in ISIS
not necessary, no LSPDB resync
• DIS is elected by priority and MAC
actually is “self-elected”
• LAN circuitID shows who is DIS
use show clns interface
59NW’2000 Paris © 2000, Cisco Systems, Inc.
Flooding on a LANFlooding on a LAN
Periodic CSNPevery 10 secs
id=y seqnr=...id=x seqNr=22id=z ...
CSNP
LAN
DISRtr-A
Got it. Install andrun SPF
Local copies of LSP-y and LSP-z are up-to-date but local copy of LSP-x is older.Request latest LSP-x via PSNP
id=x seqNr=21PSNP
!!! Problem !!!Dropped LSP
LSP
Received new LSPid=x seqNr=22Install in LSPDB.Flood the LSP.
id=x seqNr=22LSP
Neighbor has an old LSP, better resend him latest
id=x seqNr=22LSP
60NW’2000 Paris © 2000, Cisco Systems, Inc.
IP routing specificsIP routing specifics
60
61NW’2000 Paris © 2000, Cisco Systems, Inc.
L1 advertised into L2L1 advertised into L2
• All L1L2 routers advertise all the IP prefixes they learn via L1 into L2
• Only advertise routes you use
(inter-level routing goes via the RIB)
• Summarization possible
- At L1->L2
- when redistributing
62NW’2000 Paris © 2000, Cisco Systems, Inc.
L1 advertised into L2L1 advertised into L2
• Level-1 preferred over Level-2
In case of SAME routes (same prefix and same mask)
• Internal equal to external route type
(TLV 128 versus TVL 130)
• Internal over external metric-type
63NW’2000 Paris © 2000, Cisco Systems, Inc.
ISIS routing LevelsISIS routing Levels
L1
L1L2
L1
L1L2L12. Level-1 LSP withIP prefix: 10.1.0.0/16
2. Level-1 LSP withIP prefix: 10.10.0.0/16
L1
1. Level-1 LSP withAttached-bit (used as a default route by all level-1routers
3. Level-2 LSP withIP prefix: 10.1.0.0/16IP prefix: 10.10.0.0/16
Routers within an area do not have any routing information about prefixes originated outside the area. Default routing (ATT-bit or explicit 0.0.0.0/0) is used to reach destinations outside the area.
64NW’2000 Paris © 2000, Cisco Systems, Inc.
ISIS routing LevelsISIS routing Levels
L1L2
L1
L2L2
L1L2L1
L1L2
L11. Level-1 LSP withIP prefix: 10.1.0.0/16
4. At this point the prefix 10.1.0.0/16 will NOT be inserted in the L1 LSP (no route leaking by default)
2. Level-2 LSP withIP prefix: 10.1.0.0/16 2. Level-2 LSP with
IP prefix: 10.1.0.0/16
3. Level-2 LSP withIP prefix: 10.1.0.0/16
3. Level-2 LSP withIP prefix: 10.1.0.0/16
2. At this point prefix 10.1.0.0/16 will be inserted in L2 LSP
2. At this point prefix 10.1.0.0/16 is inserted in L2 LSP
0. Level-1 LSP with ATT bit set
0. Level-1 LSP with ATT bit set
0. Level-1 LSP with ATT bit set
65NW’2000 Paris © 2000, Cisco Systems, Inc.
Configuration, Show,& Debug CommandsConfiguration, Show,& Debug Commands
65
66NW’2000 Paris © 2000, Cisco Systems, Inc.
Command AgendaCommand Agenda
• Basic Configuration Commands
• Important Show Commands
• Useful Debug Commands
67NW’2000 Paris © 2000, Cisco Systems, Inc.
Basic ConfigurationCommands
Basic ConfigurationCommands
• Router sub-commandsrouter isis <tag name>
net <net>
is-type <L1 L2 L1L2>
default-information originate <route-map> (only for L2)
Hostname-dynamic
68NW’2000 Paris © 2000, Cisco Systems, Inc.
Basic ConfigurationCommands
Basic ConfigurationCommands
• Interface sub-commandsip router isis <tag name>
clns router isis <tag name>
isis metric <value>
isis priority <value>
isis circuit-type <L1 L2 L1L2>
isis hello-interval <seconds>
isis hello-multiplier <value>
69NW’2000 Paris © 2000, Cisco Systems, Inc.
Router-B--------------
interface Loopback0
ip address 192.168.1.1 255.255.255.255
!
Interface Serial0
ip address 192.168.120.10 255.255.255.0
ip router isis
!
interface Serial1
ip address 192.168.222.1 255.255.255.0
ip router isis
!
router isis
passive-interface Loopback0
net 49.0001.1921.6800.1001.00
Router-A--------------
interface Loopback0
ip address 192.168.1.5 255.255.255.255
!
interface Serial0
ip address 192.168.120.5 255.255.255.0
ip router isis
!
router isis
is-type level-1
passive-interface Loopback0
net 49.0001.1921.6800.1005.00
Basic ConfigurationBasic Configuration
Area 49.0001
Rtr-A
Rtr-B
L1L2 routers
L1router
Area 49.0002
Rtr-C
L1router
S0
S1
S0
S1
S0
S1
Rtr-D
70NW’2000 Paris © 2000, Cisco Systems, Inc.
Router-C--------------
interface Loopback0
ip address 192.168.2.2 255.255.255.255
!
interface Serial0
ip address 192.168.111.2 255.255.255.0
ip router isis
isis circuit-type level-1
!
interface Serial1
ip address 192.168.222.2 255.255.255.0
ip router isis
isis circuit-type level-2
!
router isis
passive-interface Loopback0
net 49.0002.1921.6800.2002.00
Router-D--------------
interface Loopback0
ip address 192.168.2.4 255.255.255.255
!
interface Serial1
ip address 192.168.111.4 255.255.255.0
ip router isis
!
router isis
is-type level-1
passive-interface Loopback0
net 49.0002.1921.6800.2004.00
Basic ConfigurationBasic Configuration
Area 49.0001
Rtr-A
Rtr-B
L1L2 routers
L1router
Area 49.0002
Rtr-C
L1router
S0
S1
S0
S1
S0
S1
Rtr-D
71NW’2000 Paris © 2000, Cisco Systems, Inc.
Rtr-B#show clnsGlobal CLNS Information: 2 Interfaces Enabled for CLNS NET: 49.0001.1921.6800.1001.00 Configuration Timer: 60, Default Holding Timer: 300, Packet Lifetime 64 ERPDU's requested on locally generated packets Running IS-IS in IP-only mode (CLNS forwarding not allowed)
Show clnsShow clns
Area 49.0001 Area 49.0002
Rtr-B
Rtr-D
L1L2 routers
L1routers
S0
S1 S0 S0 S1
S1
Rtr-C
Rtr-A
72NW’2000 Paris © 2000, Cisco Systems, Inc.
Rtr-B# show clns protocol
IS-IS Router: <Null Tag> System Id: 1921.6800.1001.00 IS-Type: level-1-2 Manual area address(es): 49.0001 Routing for area address(es): 49.0001 Interfaces supported by IS-IS: Serial1 - IP Serial0 - IP Redistribute: static (on by default) Distance for L2 CLNS routes: 110
Show clns protocolShow clns protocol
Area 49.0001
Rtr-A
Rtr-B
L1L2 routers
L1router
Area 49.0002
Rtr-C
L1router
S0
S1
S0
S1
S0
S1
Rtr-D
73NW’2000 Paris © 2000, Cisco Systems, Inc.
Rtr-B# show clns neighbors
System Id Interface SNPA State Holdtime Type ProtocolRtr-C Se0 *HDLC* Up 23 L2 IS-IS1921.6800.1005 Se1 *HDLC* Up 21 L1 IS-IS
show clns neighborsshow clns neighbors
Area 49.0001 Area 49.0002
Rtr-B
Rtr-D
L1L2 routers
L1routers
S0
S1 S0 S0 S1
S1
Rtr-C
Rtr-A
74NW’2000 Paris © 2000, Cisco Systems, Inc.
Area 49.0001
Rtr-A
Rtr-B
L1L2 routers
L1router
Area 49.0002
Rtr-C
L1router
S0
S1
S0
S1
S0
S1
Rtr-D
Rtr-B# show clns int serial1Serial1 is up, line protocol is up Checksums enabled, MTU 1500, Encapsulation HDLC ERPDUs enabled, min. interval 10 msec. CLNS fast switching enabled CLNS SSE switching disabled DEC compatibility mode OFF for this interface Next ESH/ISH in 47 seconds Routing Protocol: IS-IS Circuit Type: level-1-2 Interface number 0x2, local circuit ID 0x101 Level-1 Metric: 10, Priority: 64, Circuit ID: 1921.6800.1005.00 Number of active level-1 adjacencies: 1 Level-2 Metric: 10, Priority: 64, Circuit ID: Rtr-B.01 Number of active level-2 adjacencies: 0 Next IS-IS Hello in 6 seconds
Show clns interfaceShow clns interface
75NW’2000 Paris © 2000, Cisco Systems, Inc.
Rtr-B# show clns int serial0Serial0 is up, line protocol is up Checksums enabled, MTU 1500, Encapsulation HDLC ERPDUs enabled, min. interval 10 msec. CLNS fast switching enabled CLNS SSE switching disabled DEC compatibility mode OFF for this interface Next ESH/ISH in 30 seconds Routing Protocol: IS-IS Circuit Type: level-1-2 Interface number 0x1, local circuit ID 0x100 Level-1 Metric: 10, Priority: 64, Circuit ID: Rtr-C.01 Number of active level-1 adjacencies: 0 Level-2 Metric: 10, Priority: 64, Circuit ID: Rtr-B.00 Number of active level-2 adjacencies: 1 Next IS-IS Hello in 6 seconds
Show clns interfaceShow clns interface
Area 49.0001
Rtr-A
Rtr-B
L1L2 routers
L1router
Area 49.0002
Rtr-C
L1router
S0
S1
S0
S1
S0
S1
Rtr-D
76NW’2000 Paris © 2000, Cisco Systems, Inc.
Rtr-B# show isis database
IS-IS Level-1 Link State Database:LSPID LSP Seq Num LSP Checksum LSP Holdtime ATT/P/OLRtr-B.00-00 * 0x00000020 0x0C24 674 1/0/01921.6800.1005.00-00 0x00000023 0x909E 830 0/0/01921.6800.1005.01-00 0x00000017 0xC896 841 0/0/0
IS-IS Level-2 Link State Database:LSPID LSP Seq Num LSP Checksum LSP Holdtime ATT/P/OLRtr-B.00-00 * 0x00000024 0x7D98 748 0/0/0Rtr-C.00-00 0x00000028 0x1E01 1128 0/0/0
Show isis databaseShow isis database
Area 49.0001 Area 49.0002
Rtr-B
Rtr-D
L1L2 routers
L1routers
S0
S1 S0 S0 S1
S1
Rtr-C
Rtr-A
77NW’2000 Paris © 2000, Cisco Systems, Inc.
Rtr-B# show isis database 1921.6800.1001.00-00 detailIS-IS Level-1 LSP Rtr-B.00-00LSPID LSP Seq Num LSP Checksum LSP Holdtime ATT/P/OLRtr-B.00-00 * 0x00000020 0x0C24 424 1/0/0 Area Address: 49.0001 NLPID: 0xCC Hostname: Rtr-B IP Address: 192.168.1.1 Metric: 0 IP 192.168.1.1 255.255.255.255 Metric: 10 IP 192.168.222.0 255.255.255.0 Metric: 10 IP 192.168.120.0 255.255.255.0 Metric: 10 IS 1921.6800.1005.00
IS-IS Level-2 LSP Rtr-B.00-00LSPID LSP Seq Num LSP Checksum LSP Holdtime ATT/P/OLRtr-B.00-00 * 0x00000025 0x7B99 1186 0/0/0 Area Address: 49.0001 NLPID: 0xCC Hostname: Rtr-B IP Address: 192.168.1.1 Metric: 10 IS Rtr-C.00 Metric: 10 IP 192.168.120.0 255.255.255.0 Metric: 0 IP 192.168.1.1 255.255.255.255 Metric: 20 IP 192.168.1.5 255.255.255.255 Metric: 10 IP 192.168.222.0 255.255.255.0
Show isis database detailShow isis database detail
78NW’2000 Paris © 2000, Cisco Systems, Inc.
Rtr-B# show isis lsp-log
Level 1 LSP log When Count Interface Triggers01:50:44 1 CONFIG01:50:35 1 Loopback0 IPUP01:50:28 1 Serial0 IPUP01:50:20 1 Serial1 IPUP01:50:20 1 Serial1 NEWADJ01:50:18 1 ATTACHFLAG01:36:49 1 Loopback0 CONFIG
Level 2 LSP log When Count Interface Triggers01:50:46 1 CONFIG01:50:36 1 Loopback0 IPUP01:50:30 2 Serial0 NEWADJ IPUP01:50:22 1 Serial1 IPUP01:50:10 1 IPIA01:48:21 1 Serial0 DELADJ01:48:16 1 Serial0 NEWADJ01:36:51 1 Loopback0 CONFIG
Show isis lsp-logShow isis lsp-log
Area 49.0001
Rtr-A
Rtr-B
L1L2 routers
L1router
Area 49.0002
Rtr-C
L1router
S0
S1
S0
S1
S0
S1
Rtr-D
79NW’2000 Paris © 2000, Cisco Systems, Inc.
Rtr-B# show isis spf-log
Level 1 SPF log When Duration Nodes Count First trigger LSP Triggers02:16:52 0 1 1 Rtr-B.00-00 NEWLSP02:16:42 0 1 1 Rtr-B.00-00 TLVCODE02:16:32 0 1 2 Rtr-B.00-00 NEWADJ TLVCONTENT02:16:22 8 3 4 Rtr-B.00-00 ATTACHFLAG LSPHEADER
TLVCON TENT02:02:57 4 3 1 Rtr-B.00-00 TLVCONTENT02:01:52 8 3 1 PERIODIC01:46:52 8 3 1 PERIODIC01:31:53 8 3 1 PERIODIC01:16:52 8 3 1 PERIODIC01:01:52 8 3 1 PERIODIC00:46:52 8 3 1 PERIODIC00:31:51 8 3 1 PERIODIC00:16:51 8 3 1 PERIODIC00:01:50 64 3 1 PERIODIC
Show isis spf-logShow isis spf-log
Area 49.0001
Rtr-A
Rtr-B
L1L2 routers
L1router
Area 49.0002
Rtr-C
L1router
S0
S1
S0
S1
S0
S1
Rtr-D
80NW’2000 Paris © 2000, Cisco Systems, Inc.
Level 2 SPF log When Duration Nodes Count First trigger LSP Triggers02:16:54 0 1 1 Rtr-B.00-00 NEWLSP02:16:44 0 1 1 Rtr-B.00-00 TLVCODE02:16:34 8 2 3 Rtr-B.00-00 NEWADJ NEWLSP TLVCONTENT02:14:29 8 2 3 Rtr-B.00-00 NEWADJ TLVCONTENT02:14:23 4 2 1 Rtr-C.00-00 TLVCODE02:13:56 8 2 1 Rtr-C.00-00 TLVCONTENT02:02:59 4 2 1 Rtr-B.00-00 TLVCONTENT02:01:54 4 2 1 PERIODIC01:46:54 4 2 1 PERIODIC01:31:54 4 2 1 PERIODIC01:16:54 4 2 1 PERIODIC01:01:54 4 2 1 PERIODIC00:46:53 4 2 1 PERIODIC00:31:53 4 2 1 PERIODIC00:16:53 4 2 1 PERIODIC00:01:53 60 2 1 PERIODIC
Show isis spf-logShow isis spf-log
L1L2 routers
Area 49.0001
Rtr-A
Rtr-B
L1router
Area 49.0002
Rtr-C
L1router
S0
S1
S0
S1
S0
S1
Rtr-D
81NW’2000 Paris © 2000, Cisco Systems, Inc.
Show clns trafficShow clns traffic
• LSPs sourced indicates stability of IS
• LSP retransmissions should stay low
• PRCs can not be checked elsewhere
• LSP checksum errors are a bad sign
• Update queue should not stay full
• Update queue should not drop much
82NW’2000 Paris © 2000, Cisco Systems, Inc.
Show clns trafficShow clns traffic
Rtr-B# show clns trafficCLNS: Time since last clear: neverCLNS & ESIS Output: 669, Input: 4773CLNS Local: 0, Forward: 0CLNS Discards: Hdr Syntax: 0, Checksum: 0, Lifetime: 0, Output cngstn: 0 No Route: 0, Discard Route: 0, Dst Unreachable 0, Encaps. Failed: 0 NLP Unknown: 0, Not an IS: 0CLNS Options: Packets 0, total 0 , bad 0, GQOS 0, cngstn exprncd 0CLNS Segments: Segmented: 0, Failed: 0CLNS Broadcasts: sent: 0, rcvd: 0Echos: Rcvd 0 requests, 0 replies Sent 0 requests, 0 repliesESIS(sent/rcvd): ESHs: 0/0, ISHs: 669/660, RDs: 0/0, QCF: 0/0ISO-IGRP: Querys (sent/rcvd): 0/0 Updates (sent/rcvd): 0/0ISO-IGRP: Router Hellos: (sent/rcvd): 0/0ISO-IGRP Syntax Errors: 0
IS-IS: Time since last clear: neverIS-IS: Level-1 Hellos (sent/rcvd): 282/0
L1L2 routers
Area 49.0001
Rtr-A
Rtr-B
L1router
Area 49.0002
Rtr-C
L1router
S0
S1
S0
S1
S0
S1
Rtr-D
83NW’2000 Paris © 2000, Cisco Systems, Inc.
Show clns trafficShow clns traffic
IS-IS: Level-2 Hellos (sent/rcvd): 285/0IS-IS: PTP Hellos (sent/rcvd): 420/415IS-IS: Level-1 LSPs sourced (new/refresh): 8/2IS-IS: Level-2 LSPs sourced (new/refresh): 9/1IS-IS: Level-1 LSPs flooded (sent/rcvd): 5/8IS-IS: Level-2 LSPs flooded (sent/rcvd): 7/8IS-IS: LSP Retransmissions: 0IS-IS: Level-1 CSNPs (sent/rcvd): 1/1IS-IS: Level-2 CSNPs (sent/rcvd): 2/2IS-IS: Level-1 PSNPs (sent/rcvd): 7/4IS-IS: Level-2 PSNPs (sent/rcvd): 7/5IS-IS: Level-1 DR Elections: 1IS-IS: Level-2 DR Elections: 1IS-IS: Level-1 SPF Calculations: 7IS-IS: Level-2 SPF Calculations: 9IS-IS: Level-1 Partial Route Calculations: 1IS-IS: Level-2 Partial Route Calculations: 5IS-IS: LSP checksum errors received: 0IS-IS: Update process queue depth: 0/200IS-IS: Update process packets dropped: 0
L1L2 routers
Area 49.0001
Rtr-A
Rtr-B
L1router
Area 49.0002
Rtr-C
L1router
S0
S1
S0
S1
S0
S1
Rtr-D
84NW’2000 Paris © 2000, Cisco Systems, Inc.
Rtr-B# debug isis adj-packetsIS-IS Adjacency related packets debugging is onRtr-B#05:45:21: ISIS-Adj: rcvd state UP, old state UP, new state UP05:45:21: ISIS-Adj: Action = ACCEPT05:45:24: ISIS-Adj: Sending serial IIH on Serial0, length 149905:45:26: ISIS-Adj: Rec serial IIH from *HDLC* (Serial1), cir type L1, cir id 00, length 149905:45:26: ISIS-Adj: rcvd state UP, old state UP, new state UP05:45:26: ISIS-Adj: Action = ACCEPT05:45:26: ISIS-Adj: Sending serial IIH on Serial1, length 149905:45:31: ISIS-Adj: Rec serial IIH from *HDLC* (Serial0), cir type L1L2, cir id01, length 1499
Debug isis adj-packetsDebug isis adj-packets
Area 49.0001 Area 49.0002
Rtr-B
Rtr-D
L1L2 routers
L1routers
S0
S1 S0 S0 S1
S1
Rtr-C
Rtr-A
85NW’2000 Paris © 2000, Cisco Systems, Inc.
Debug isis snp-packetsDebug isis snp-packets
Rtr-B# debug isis snp-packetsIS-IS CSNP/PSNP packets debugging is on
07:51:59: ISIS-Snp: Build L2 PSNP entry for 1921.6800.2002.00-00, seq 3507:51:59: ISIS-Snp: Sending L2 PSNP on Serial007:53:50: ISIS-Snp: Rec L1 PSNP from 1921.6800.1005 (Serial1)07:53:50: ISIS-Snp: PSNP entry 1921.6800.1001.00-00, seq 31, ht 119707:53:50: ISIS-Snp: Same entry 1921.6800.1001.00-00, seq 3107:54:26: ISIS-Snp: Build L1 PSNP entry for 1921.6800.1005.00-00, seq 2F07:54:26: ISIS-Snp: Sending L1 PSNP on Serial107:55:18: ISIS-Snp: Rec L2 PSNP from 1921.6800.2002 (Serial0)07:55:18: ISIS-Snp: PSNP entry 1921.6800.1001.00-00, seq 32, ht 119707:55:18: ISIS-Snp: Same entry 1921.6800.1001.00-00, seq 32
Area 49.0001 Area 49.0002
Rtr-B
Rtr-D
L1L2 routers
L1routers
S0
S1 S0 S0 S1
S1
Rtr-C
Rtr-A
86NW’2000 Paris © 2000, Cisco Systems, Inc.
Debug isis spf-triggersDebug isis spf-triggers
Rtr-B# debug isis spf-triggersIS-IS SPF triggering events debugging is onRtr-B#07:32:10: ISIS-Spf: L1 SPF needed, periodic SPF, from 0x356C8DC07:32:10: ISIS-Spf: L2 SPF needed, periodic SPF, from 0x356C8DCRtr-B#conf tRtr-B(config)#int serial0Rtr-B(config-if)#isis metric 15Rtr-B(config-if)# ^Z07:38:27: ISIS-Spf: L1 SPF needed, new metric, from 0x3560762Rtr-B(config)#int serial0Rtr-B(config-if)#shutRtr-B(config-if)# ^Z07:39:23: ISIS-Spf: L2, 1921.6800.1001.00-00 TLV contents changed, code 0x207:39:28: ISIS-Spf: L1 SPF needed, L2 attach changed, from 0x357CF3607:39:28: ISIS-Spf: L1, LSP fields changed 1921.6800.1001.00-00
L1L2 routers
Area 49.0001
Rtr-A
Rtr-B
L1router
Area 49.0002
Rtr-C
L1router
S0
S1
S0
S1
S0
S1
Rtr-D
87NW’2000 Paris © 2000, Cisco Systems, Inc.
Lab TopologyLab Topology
R1
R2
R4 R5
R3
49.0
001
49.0002
L1L2
L1L1
L1
L1L2
88NW’2000 Paris © 2000, Cisco Systems, Inc.
Lab InstructionsLab Instructions
1. Configure R1 and R2 to belong to the same area. Configure each to route CLNS and IP data. Configure the serial link to only form L1 adjacencies.
2. Configure R2 and R3 to form an L2 adjacency; IP only.
3. Configure R3, R4 and R5 to belong to the same area; IP only.
4. Configure R5 so its systemID will be used to build the Psuedonode for the ethernet segment.
89NW’2000 Paris © 2000, Cisco Systems, Inc.
Lab ExerciseLab Exercise
1. What command can be used to confirm the R1 and R2 are enabled to route IP and CLNS packets?
2. What command did you issue to verify that only an L2 adjacency was formed between R2 and R3?
3. Is the ATT bit set in area 49.0002? If so, what command should you use to confirm it has been set?
4. What command do you use to display the Pseudonode LSP of the ethernet segment? What is the metric to each of the nodes listed?
5. Determine if R1 displays the IP subnet of the ethernet segment in area 49.0002. If it does not display the route, why not?
90© 2000, Cisco Systems, Inc.
Course NumberPresentation_ID