ccnp - flashcards

BCMSN Stuff

IOS commands (RSM commands are the same) CatOS commandshostname <hostname> set system name <hostname>description <description> set port name <slot/port> <description>speed <speed> set port speed <slot/port> <speed>write erase clear config allenable [password|secret] set enablepasspassword <password> set passwordshow ip interface <interface> show interfaceip address <ip address mask> set interface sc0 <ip address mask>interface range <int range>switchport access vlan <vlan id>

set vlan 3 <slot/ports>eg. set vlan 3 3/1-12

show vtp status show vtp domainclear vtp pruneeligible <vlan>set spantree root [primary|secondary]

(config-if)#spanning-tree priority <priority>Check this as it could be “spantree priority”

set spantree backbonefast enableset spantree root

ip route 0.0.0.0 0.0.0.0 <next hop> set route default <next hop>set route 0.0.0.0 <next hop>

(config-if)#ip pim <pim method>spanning-tree vlan 1 root primary|secondaryspanning-tree vlan 1 priority <priority (incr of 4096)>

IEEE specsFast Ethernet 802.3uGigabit Ethernet 802.3zSTP 802.1dMST 802.1sRSTP 802.1wCST 802.1qSetting ToS on an ethernet frame 802.1p

© 2011. Terry Roswell – CCNP

VLAN Trunking ProtocolVLANs increase the number of broadcast domains. VLANs across interconnected switches require trunking. VLAN tagging involves adding another header to each frame that traverses the trunk and the header includes a VLAN identifier (VLAN ID).

To create VLAN [vlan #]In VLAN configuration mode add name [name name]In interface configuration mode: [switchport access vlan #][vtp pruning|password|domain]Show commands:[show vlan brief][show vlan #][show interface vlan #][show interface type # switchport|trunk][show vtp status|password][show cdp neighbors] <- can be helpful

Trunking protocols:o ISL – Proprietary, Full Encapsulation (adds 30 bytes to ethernet frame size – brings to 1548)o 802.1Q – Standardized, Only a header, Defines native VLAN and does not encapsulate for that VLAN

(1) (adds 4 bytes to ethernet frame size – brings to 1522)o Both support 4094 VLANs -- 1-1005 normal range, 1006+ extended range

VTP Period update messages (every 5 minutes) and when VLAN changes occur. VTP clients and servers react to updates based on VLAN database configuration revision number. Updates don’t start until VTP domain is configured.Three VTP Modes:

o Server -- Stores database in flash onlyo Client -- Cannot configure VTP, can receive updates, can pass them on, stores database in flash onlyo Transparent -- Allows VLAN configuration, Ignores VTP, passes advertisements and updates on, stores

database in running config and in flashThree types of messages:

Summary advertisements – periodic (every 5min), contain revision number, domain name, no database info Subset advertisements – only when change occurs, includes subset of VLAN database Advertisement requests – request updates as soon as trunk comes up or if local dbase is lost or corrupted

For VTP to work; encap (dot1q or isl), domain name and password must match throughout the domain

VLAN database stored in flash memory in vlan.dat file… (important command to clear file [delete flash:vlan.dat])Transparent bridging using VTP Version 2 does not check domain name or password, it will just forward the advertisements and messages as per usualVLAN pruning dynamically decides which trunks do not need updates…

VTP Configuration CommandsTo configure Trunking first set encapsulationThen set the administrative mode

switchport trunk encapsulation dot1q|isl|negotiate switchport mode access|trunk|dynamic desirable|dynamic auto

To configure which vlans are allowed to cross a trunk

switchport trunk allowed add|remove|except|all vlan-list

To trunk to CISCO phones switchport voice vlan #]Choices for port security switchport nonegotiate disables negotiation

switchport mode access disables trunkingUse a parking lot vlan – unused vlan

Shutdown interface shutdown interface commandShutdown VLAN shutdown vlan #Clear vlan database delete flash:vlan.datCheck port statistics show macCheck MAC to port relationships show cam

Clear revision number by1. Changing mode to transparent [vtp server|client|transparent] and then back again to whatever it was previously2. Deleting vlan.dat file [delete flash:vlan.dat] and reloading switch


First half of all MAC Addresses 01-00-5eAll hosts multicast address 224.0.0.1All routers multicast address 224.0.0.2EIGRP sends Hello Packets to 224.0.0.10RIP sends Hello Packets to 224.0.0.9AllSPFDR 224.0.0.6AllSPFRouters 224.0.0.5ISL Multicast address (note this is a 40bit value) 01:00:0c:00:00CDP sends to Destination MAC: 01:00:0c:cc:cc:ccIGMP Membership query process runs how often? Runs every 60 secsMaximum value for TTL 255In 802.1q what is TPID Ethertype field always set to? 0x81-00VTP domain name limitation on 4000 series switch 32Bits allocated to ToS in an 802.1p frame 3Minimum BGP Message length 19 OctetsMaximum BGP Message length 4096 OctetsBits in an IPv4 address 32Bytes in an IPv4 address 4Always assign NSAP address in IS-IS as… 00Maximum paths EIGRP can load-balance across 6OSPF POINT-POINT and BROADCAST hello/dead timers 10/40OSPF POINT-MULTIPOINT and NON-BROADCAST hello/dead timers 30/120Maximum NEW routes a BGP UPDATE message can advertise 1Current OSPF version v2Current BGP version v4Protocol number assigned to EIGRP 88No. of bytes in System ID for IS-IS NET for Cisco Devices 6 bytesWhich IOS version were Prefix lists introduced 12.0Which routing algorithm do OSPF AND IS-IS use? DijkstraMaximum metric for IS-IS 1023Maximum no. of equal cost paths IS-IS can support for load-balancing 6Default Admin distance for IS-IS 115Default Admin distance for EIGRP summary route 5Default Admin distance for iBGP 200Default Admin distance for eBGP 20Default Admin distance for static route 1Default Admin distance for connected route 0Default Admin distance for RIP 120Default Admin distance for OSPF 110

Valid LMI Types: Cisco, ITU-T, ANSIFrame Relay Encapsulation Types: Cisco, IETF


BSCI STUFF: IP helper addresses manage the forwarding of UDP-based broadcasts 3 types of IS-IS Hello PDUs: Level1 LAN, Level2 LAN and point-to-point 4 components of EIGRP: PDMs, RTP, Neighbor discovery/recovery, DUAL IS-IS LSP advertises routing information IS-IS CSNP will be used at initialisation IS-IS adjacency levels: Level 1 and Level 2 IS-IS pseudonode is the Designated IS (DIS) If BGP hold time is set to 0 (zero) a KEEPALIVE will never be sent IS-IS Level 1 routing is not in the Backbone. Level 2 is routing between areas IS-IS Network common items: Area ID, system ID, NSAP Selector IS-IS router types: Level 1, Level 1/2, and Level 2 IS-IS NET (Network Entity Title) uniquely defines each router on the network and has a

network address made up of a system ID and an area ID IS-IS (created by ISO) relies on CLNS as it’s layer 3 protocol for transport IS-IS PSNP is used on a broadcast network to request an LSP it doesn’t have and on a non-

broadcast network it’s used to acknowledge receipt of an LSP IS-IS PSNP contains a list of all the LSPs for the broadcast network IS-IS network types supported are Broadcast and Point-to-Point IS-IS: By default, the Dead-Timer is 3 times the Hello-Timer

BSCI router IOS commandsChange OSPF network type (config-if)#ip ospf network <network-type>Make Area 1 a NSSA area (must place on all routers) (config)#area 1 nssaVerify detailed OSPF configuration information #show ip ospfAllow interface to borrow and IP address from another interface on the router

ip unnumbered

Create a peer group neighbor <peer-group_name> peer-groupEnable policy-based routing (not local) ip policy route-map <route-map>


OSPF:OSPF States:Down Hello packets can be sent from this router to the neighbor but none, so far, have been receivedAttempt (Only valid for manually configured neighbors in NBMA network) same situation as aboveInit Router has received hello from the neighbor but this (receiving) routers ID was not included2Way Bi-directional comms have been established (each router has seen the others hello packet).

Router will remain in 2Way state with all but the DR and BDR in a BC or NBMA network. Otherwise it will continue…DR and BDR elected at the end of this stageNB: receiving a DBD (Database Descriptor Packet) will also cause a transition to 2Way state

Exstart DR/BDR elections complete and exchange of link state information begins. Master/Slave relationship formed between each neighbor relationship based on highest Router IDNB: DR could conceivably be a slave if it was elected DR by virtue of its priority and the neighbor happens to have a higher router ID

Exchange Neighbors are exchanging DBD packets with each other. DBDs have sequence number which can only be incremented by the Master (as determined during the ExStart state)NB: DBD packets contain LSA headers and describe the contents of the entire link-state database

Loading Actual exchange of link-state information is happening here. Based on the LSA headers received within the DBD packets received during the Exchange state, the router sends LSRs (Link-State Requests) packets to it’s neighbor who responds with LSU (Link-State Update) packets. All LSU packets are acknowledged

Full All routers are fully adjacent with each other and link-state databases are fully synchronised

OSPF LSA Type Sent by1 Router All routers in an area to describe their directly attached links (Intra-area

routes). These do not leave the area2 Network DR of a broadcast or Nonbroadcast segment to describe the neighbors

connected to the segment. These do not leave the area3 Summary ABR to describe a route to neighbors outside the area4 Summary ABR to describe a route to an ASBR to neighbors outside the area5 External ASBR to describe routes redistributed into the area. These routes appear as

E1 or E2 in the routing table. E2 (default) uses a static cost throughout the OSPF domain as it only takes the cost into account that is reported at redistribution. E1 uses a cumulative cost of the cost reported into the OSPF domain at redistribution plus the local cost to the ASBR

6 Multicast Not supported on Cisco Routers7 NSSA External ASBR inside a NSSA to describe routes redistributed into the NSSA. LSA 7 is

translated into LSA 5 as it leaves the NSSA. These routes appear as N1 or N2 in the ip routing table inside the NSSA. Much like LSA 5, N2 is a static cost while N1 is a cumulative cost that includes the cost up to the ASBR

OSPF categories of operation: 1. Neighbor and adjacency initialization2. LSA flooding3. SPF tree calculation

OSPF Hello message contents: Router ID, Area ID, Auth info, network mask, Hello interval, options, router priority, router dead interval, DR, BDR, neighbor router IDs

Two steps required to change an OSPF neighbor to an adjacent OSPF router:1. Two-Way communication© 2011. Terry Roswell – CCNP

2. Database synchronization


BGP Attributes:Well Known Mandatory: ORIGIN, AS_PATH, NEXT_HOPWell-known discretionary: LOCAL_PREF, ATOMIC_AGGREGATEOptional Transitive: AGGREGATOR, COMMUNITYOptional Non-transitive: MULTI_EXIT_DISCRIMINATOR (MED) BGP has four well-known communities:

1. Internet2. NO_EXPORT3. NO_ADVERTISE4. LOCAL_AS

BGP Message types(value): OPEN(1), UPDATE(2), KEEPALIVE(4), NOTIFICATION(3), ROUTE-REFRESH(5)

BGP Attribute Type codes and descriptions:Value Attribute Type Classification Description1 Origin Well-Known

MandatorySpecifies the origin of the path information. This attribute indicates whether the path came originally from an interior routing protocol, the older exterior routing protocol EGP, or some other source

2 AS_Path Well-Known Mandatory

A list of autonomous system numbers that describes the sequence of ASes through which this route description has passed. This is a critically important attribute, since it contains the actual path of autonomous systems to the network. It is used to calculate routes and to detect routing loops

3 Next_Hop Well-Known Mandatory

The next-hop router to be used to reach this destination

4 Multi_Exit_Discriminator (MED)

Optional Non-Transitive

When a path includes multiple exit or entry points to an AS, this value may be used as a metric to discriminate between them (that is, choose one exit or entry point over the others.)

5 Local_Pref Well-Known Discretionary

Used in communication between BGP speakers in the same AS to indicate the level of preference for a particular route.

6 Atomic_Aggregate

Well-Known Discretionary

In certain circumstances, a BGP speaker may receive a set of overlapping routes where one is more specific than the other. For example, consider a route to the network 34.15.67.0/24 and to the network 34.15.67.0/26. The latter network is a subset of the former, which makes it more specific. If the BGP speaker uses the less-specific route (in this case, 34.15.67.0/24) it sets this path attribute to a value of 1 to indicate that this was done

7 Aggregator Optional Transitive Contains the AS number and BGP ID of the router that performed route aggregation; used for troubleshooting.


Multicast configuration commandsEnable PIM on an interface ip pim <pim method>Configure a IP for Rendezvous Point (RP) ip pim rp-address <ip-address>

Other config commandsEnable mls on a router mls rp ipConfigure int to send mlsp frames to a switch mls rp management-interface

Configuration 2950 Commands 4000 CommandsEnable etherchannel set port channelSet int fa0/1 to run full duplex duplex fullChange spanning tree priority spanning-tree port priorityEnable port 2 on card 3 set port enable 3/2Verify duplex setting on fa0/24 show interface fa0/24Set port 4 on card 3 to full duplex set port duplex 3/4 fullSet port 3 on card 2 name to sales set port name 2/3 salesSet hostname to CT4h hostname CT4h set system name CT4hSet port 3 of card 2 to 100Mbps set port speed 2/3 100Delete startup-config erase startup-config clear config allIdentify port 3 show interface fa0/3 or sh int descSet enable mode password enable password|secret set enablepassSet user mode password set passwordDisplay IP configuration show interfaceSet IP address on switch int vlan # ip address <ip-address mask> set interface sc0 <ip-address mask> Set default gateway Ip default gateway <ip-address>Make ports 3/1-12 part of vlan 3 set vlan 3 3/1-12VTP information show vtp status show vtp domainClear prune eligibility for vlans clear vtp pruneeligible <vlan>Display cached IP-to-Ethernet translations

show ip arp

Limit multicast network scope ttl-thresholdEnable mls on a switch set mls enableDefault Route Ip route <dest-ip mask> <next-hop-ip> set route default <dest-ip>

set route 0.0.0.0 <dest-ip>

Maximum Cable distancesMulti-Mode Fibre (MMF) 62.5-micron Gigabit Ethernet <260mSingle-mode 9-micron Gigabit Ethernet fibre with 1300nm laser <10kmMulti-Mode Fibre (MMF) 62.5-micron core with 125-micron outer cladding (62.5/125) using fast ethernet

<400m

From patch-panel to switch using 10BT <5m


Troubleshooting Methodologies:

1. Gather Symptoms2. Isolate the Problem3. Fix the problem4. Document the Problem Resolution

When gathering symptoms try to get as granular as possible. If a user says “I can’t get to host X”, that is not enough. You need to also find out the following:

1. What service are they actually trying to use to get to host X (ftp, mail, telnet, web etc)2. Can they reach other hosts in the destination subnet using the same service?3. Can other hosts in the users subnet access host X using the same service?4. Can the user reach other hosts in the destination network at all?, using other services?5. Can they reach other hosts in their own subnet using the same service?6. Can they reach other hosts in their own subnet at all?7. Are they experiencing any other difficulties?8. Have they EVER been successful at getting to host X?, if so, when were they last successful

Table for Gathering Symptoms:Information ExampleSymptoms Can’t telnet, ftp or get to WWWReproducibility Is this a one-time ocurrence, or does it always happen? Reproduce it as exactly as possibleTimeline When did it start? How long did it last? How often does it occur? Has the current configuration

ever worked properly?Scope What are you able to access successfully via telnet or ftp? Which WWW sites can you reach, if

any? Who else does this affect?Baseline info Were any recent changes made to the network configurations?

When isolating the problem use all the tools you can:1. Ping2. Traceroute3. Check config of source machine (default gateway, correct subnet address etc)4. Check router logs to see if any recent changes were made to the config or if any previously active interfaces

etc went down5. Check config of routers in the path for ACLs that could be blocking the user

When Correcting the problem you should:1. Assemble a list of the possible problems and a resolution for each2. Put them in order of most likely to least likely3. Apply a further filter that puts non/low network impact resolutions at the top4. Peer Review your plan5. Implement transparent and non-network impacting changes first6. Make ONE change at a time and check impact and results. If unsuccessful, backout of the change and move on

to the next one7. Implement transparent and non-network impacting changes first (Yes, this is here twice!)8. Invoke change notification prcedures when appropriate (eg. when changes you are going to make may impact

on currently functional services)9. Implement each change through your list until the problem is resolved.10. If none of your proposed changes resolved the issue then you will have to start again with the Gathering

symptoms stage

Upon completing the problem resolution part successfully you should:1. Document your changes2. Update all affected Network diagrams and other documentation3. If applicable, create a troubleshooting procedure for the next time the issue recurs


ISDN Troubleshooting Commands: Ping Clear interface bri X Show interface bri X Show interface bri X 1 2 Show controller bri Show isdn status Show dialer Show ppp multilink

ISDN Debugging Commands: Debug bri Debug isdn q921 Debug dialer Debug isdn q931 Debug ppp negotiation Debug ppp packet

Network Baseline commands: (Router) Show version Show ip interface brief Show interface Show ip protocols Show ip interface

Network Baseline commands: (Switch)CatOS IOSshow version show versionshow interface show interfaceshow vtp domain show vtp statusshow port show interfaceshow trunk show interface trunkshow spantree vlan show spanning-tree vlan

End System Troubleshooting commands: ipconfig (WinXP/NT/2000) – winipcfg (Win9x) ifconfig (Unix) netstat nbtstat route ping traceroute arp


Serial lines Troubleshooting commands: clear counters serial show interface serial show controllers serial show buffers debug serial interface

Interface troubleshooting symptoms and causes:

Symptom Possible causes<interface> is up, line protocol is up Everything is workingInterface is up, line protocol is up (looped) The circuit is in loopback somewhereInterface is down, line protocol is down Improper cabling

No carrier signal from local provider HW failure (interface or CSU/DSU; cabling) Clocking (or lack thereof)

<interface> is up, line protocol is down Failed CSU/DSU Router interface problems Mismatched timing on CSU/DSU or carrier network Misconfigured interface Keepalive sequencing not incrementing Carrier Problem, noisy line L2 issues such as LMI

Large number of interface resets Queued packets not sent for several seconds HW problem (eg, router interface, cable or CSU/DSU) Mismatched clocking signals Looped interface Interface shutdown Line protocol down and interface resetting periodically

Carrier Transitions incrementing Unstable signalling coming from local provider Faulty cabling HW failure (eg. interface or CSU/DSU)

Incrementing interface resets Faulty cabling HW failure Line congestion

Input drops, errors, CRC, and framing errors Line speed oversubscribes the router interface capacity Local Provider problem Noisy line Faulty cabling Improper cabling HW failure

Output drops Interface is capable of transmitting at higher than line speedExcessive errors on controller Possible faulty hardwareFree buffers at 0 (show buffers int #) Interface is being overutilised as memory available for buffering

incoming and outgoing packets is running lowInterface is showing ignore errors The hardware buffer is full

The RX interface is running faster than the SP can send them to the interface

The IP hardware buffers cannot copy frames to the SP buffers

Interface Troubleshooting Problems and Action Plans:© 2011. Terry Roswell – CCNP

Problem Resolution Action PlanLocal Provider problems 1. Check the CSU/DSU for a CD signal. Check for other signals, such as RX

and TX clocking, to see if the circuit is transmitting and receiving information

2. If you don’t get a CD signal or have other problems, contact the local service provider to troubleshoot and fix the problem

Improper or faulty cabling 1. Make sure you are using the proper cable for the equipment being used

2. Use a breakout box to check the control leads3. Swap faulty cables

Misconfigured interface 1. View the interface configuration using the show running-config command

2. Make sure that the same encapsulation type is used at both endsof the circuit by using the show interface command

Keepalive problems 1. Verify that keepalives are being sent (show interface)2. If the configuration says that keepalives are being sent, you may want

to enable debug serial interface for the interface3. Verify that the sequence numbers are incrementing4. If the sequence numbers don’t increment, run loopback tests on the

local and remote sites5. If the sequences don’t increment even when the CSU/DSU is in

loopback, you have a HW problem. Replace faulty HWHardware failure Replace the hardwareInterface is in loopback mode

1. Check the interface configuration2. If there is a loopback entry ni the interface configuration, remove it

with the no form of the command3. If the interface configuration is clean, check the CSU/DSU to see if it is

placed in loopback.4. If the CSU/DSU is in loopback, remove it from loopback mode5. If the CSU/DSU is not in loopback mode, contact the local provider; it

may have placed the circuit in loopbackInterface is administratively down

1. Check the configuration. Verify that the IP address is not a duplicate2. Enter the configuration and issue the no shutdown command within

the interfaceLind speed is larger than the interface capacity

1. Reduce input queue size by using the hold-queue in command2. Increase output queues on exiting interfaces

Interface speed is larger than the line speed

1. Reduce broadcast traffic2. Increase output queue3. Implement queuing algorithms, if necessary


Frame Relay Troubleshooting commands show interface show frame-relay lmi show frame-relay pvc show frame-relay map

Frame Relay: Symptoms and problemsSymptoms Associated Problem(s)Frame Relay link is down Faulty Cabling

Faulty Hardware Local Service Provider problem LMI/DLCI/Encapsulation type mismatch Keepalives not being sent

Cannot ping remote host across a FR Network DLCI assigned to wrong interface Encapsulation mismatch Access list issue Interface misconfiguration

Frame Relay: Problems and Action PlansProblem Action PlanFaulty cabling 1. Check the cabling and use a breakout box to test the control leads

2. Replace cabling as neededFaulty Hardware 1. Isolate hardware problems by performing loopback tests

2. Change the cable to a new interface on the router and configure the new interface to match the old interface. If the link comes up you know that you must replace the HW

Local Service Provider problem If loopback tests bring the LMI state up, but you cannot connect to the remote site, contact the local carrier.Problems can include carrier problems as well as FR mis-configuration such as DLCI mismatch or encapsulation mismatch

LMI type mismatch 1. Verify that the LMI type on the router matches the LMI type for every device in the PVC

2. If you’re using a public provider network, you won’t have access to the LMI information; contact the carrier

Keepalive problems 1. Use the show interface command to see whether keepalives are disabled or to verify that they are configured properly

2. If the keepalive is not set, enter conf mode and specify the keepalive interval on the proper interface

Encapsulation type mismatch 1. Verify the encapsulation type is the same on both routers. If non-Cisco equipment is used, the encapsulation must be set to IETF. Show frame-relay map command displays this information

2. To change the encapsulation, use the encapsulation frame-relay ietf command

DLCI mismatch 1. Use the show running-config command to display the DLCI number assigned to the proper interface. The show frame-relay pvc command can also display the DLCI assigned to the interface.

2. If the correct DLCI number is configured on the proper interface, contact the local carrier to verify that it has the same DLCI configured on their FR switch

Access list problem 1. Use the show ip interface command to display the access list applied to the interface

2. Analyse the ACL, then remove and modify, if necessary


Troubleshooting VLANs on Routers: Show vlans Show arp Show interface Show cdp neighbor Debug vlan packet Debug spantree (check this..could be “debug spanning-tree”)

5 guidelines for creating Network Documentation1. Determine the scope2. Know the objective3. Keep it consistent4. Make it accessible5. Maintain it

Global buffers: small, middle, big, very big, large, huge

4 categories for SHOW commands:1. Global2. Interface3. Process4. Protocol

3 categories for DEBUG commands:1. Global2. Interface3. Protocol

2 Protocols used for dynamic IP address assignment:1. BootP2. DHCP

Standard ACL filters on… Source addressExtended ACL filters on… Source, destination, protocol, port number

EIGRPIn order for a route to become a feasible successor, it’s Advertised (Reported) Distance must be less than the Feasible Distance of the Successor. The feasible distance of the successor is the advertised distance of that route plus your distance to that router (?????) NOT CLEAR ENOUGH!!!


Further Study:

Fields contained in the BGP OPEN Message. (Version, My AS, Hold time, BGP ID, Optional Parameters length, Optional Parameters)

BGP Attribute flag settings (eg. 1st high-order bit is 0, attribute is well-known, set to 1 means it is optional

BGP NOTIFICATION Error codes (eg. 2 is “Error is an OPEN message error”)

1. Idle is the initial state of a BGP connection. The BGP speaker is waiting for a start event, generally either the establishment of a TCP connection or the re-establishment of a previous connection. Once the connection is established, BGP moves to the next state.

2. Connect is the next state. If the TCP connection completes, BGP will move to the OpenSent stage if the connection does not complete, BGP goes to Active.

3. Active indicates that the BGP speaker is continuing to create a peer relationship with the remote router. If this is successful, the BGP state goes to OpenSent. You'll occasionally see a BGP connection flap between Active and Connect. This indicates an issue with the physical cable itself, or with the configuration.

4. OpenSent indicates that the BGP speaker has received an Open message from the peer. BGP will determine whether the peer is in the same AS (iBGP) or a different AS (eBGP) in this state.

5. In OpenConfirm state, the BGP speaker is waiting for a keepalive message. If one is received, the state moves to Established, and the neighbor relationship is complete.

6. It is in the Established state that update packets are actually exchanged.

BGP: Multiple Route-Reflectors being used for redundancy MUST ALL have the CLUSTER ID configured.

BGP: confederations must have confederation ID and confederation peers configured.

BGP distribute-list filters incoming and outgoing routes for a BGP session

BGP route-maps filter and/or manipulate routes and/or traffic

BGP Attribute Flags

Attribute Flag Flag Name Description

Highest bit Optional bit Defines whether an attribute is well known (0) or optional (1).Second highest bit Transitive bit Defines whether an optional attribute is nontransitive (0) or transitive (1).Third highest bit Partial bit Defines whether an optional transitive attribute is complete (0) or partial (1).Fourth highest bit Extended Length bit Defines whether the attribute length is 1 octet (0) or 2 octets (1). This flag is

only used (set to 1) when the attribute length is greater than 255 octets


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