Lists I've Memorized Flashcards
What are the 13 BGP Path Attributes?
- Highest weight
- Highest Local pref
- Locally originated over externally originated
- AIGP
- Shortest AS path
- Lowest origin type
- Lowest MED
- eBGP over iBGP
- Lowest IGP next hop cost
- If eBGP then oldest route
- Lowest peer router ID
- Shortest Cluster List
- Lowest neighbor IP address
What are 5 enhancements introduced by DUAL?
- Rapid Convergence
- Sends updates only when there’s a change
- Uses Hellos and forms Neighborships
- Uses bandwidth, delay, reliability, load and MTU
- can Load Balance across equal or un-equal cost links
What are the 5 packet types used by EIGRP when communicating with other routers?
- Hello
- Query
- Request
- Update
- Reply
What are the 5 message types used by OSPF?
- Hello
- DD
- Link State Request (LSR)
- Link State Update (LSU)
- Link State Ack
What are 9 fields in an OSPF Hello packet?
- Router ID
- Authentication options
- Area ID
- Interface mask
- Interface priority
- Hello Interval
- Dead Interval
- DR and BDR IP addresses
- Active neighbors
What are the 8 OSPF neighbor states?
- Down
- Attempt
- Init
- 2-way
- ExStart
- Exchange
- Loading
- Full
What are the 9 requirements for OSPF routers to become neighbors?
- Unique router IDs
- Authentication matches
- Area ID matches
- Area flags match
- Interfaces on a common subnet
- MTUs match
- Hello timer matches
- Dead timer matches
- DR enablement matches
What are 3 OSPF interface costs?
- T1 = 64
- 10 Mbps Ethernet = 10
- 100 Mbps Ethernet and faster = 1
What are the 5 OSPF media types?
- Broadcast
- Non-broadcast
- Point-to-point
- Point-to-multipoint
- Loopback
What are the 6 LSA types called?
- Type 1 - Router LSA
- Type 2 - Network LSA
- Type 3 - Summary LSA
- Type 4 - ASBR Summary LSA
- Type 5 - AS External LSA
- Type 7 - NSSA External LSA
What are 9 ways that OSPFv3 is different from OSPFv2?
- Multiple:
- Address Families
- OSPF instances per interface
- Removed:
- Number of fields in the packet has been reduced
- Address Semantics from OSPF headers
- Authentication removed
- LSAs:
- New LSA types
- LSA Flooding scope is identified
- Router ID - must be manually assigned
- Neighbor adjacencies - handled by link-local addressing
What are the 8 LSA Types in OSPFv3?
- 0x2001 Router
- 0x2002 Network
- 0x2003 InterArea Prefix
- 0x2004 InterArea Router
- 0x4005 AS External
- 0x2007 NSSA
- 0x0008 Link
- 0x2009 IntraArea Prefix
What are the 2 blocks of private AS numbers?
- 64,512 to 65,535
- 4,200,000,000 to 4,294,967,294
What are the 4 BGP message types?
- OPEN - establishes adjacency
- UPDATE - advertises, updates, or withdraws routes
- NOTIFICATION - indicates an error condition to a BGP neighbor
- KEEPALIVE - ensures that the BGP neighbor is still alive
What 5 things are in an OPEN message?
- BGP version number
- Originating router’s ASN
- Hold time
- BGP Router ID
- Other optional parameters for session capabilities
What 4 things have to match in the OPEN Message that is received in the OpenSent State?
- BGP versions must match
- Source IP and ASN must match what has been configured locally
- Router IDs must be unique
- Security Parameters (password and TTL) must be set appropriately
What 3 Path Attributes are set when a Connected Network is added to the Loc-RIB table?
- Next Hop BGP Attribute set to 0.0.0.0
- BGP Origin Attribute set to I (for IGP)
- BGP weight set to 32,768
What 4 Path Attributes are set when a Static Route or a route from a Routing Protocol is added to the Loc-RIB table?
- Next Hop BGP Attribute set to Next Hop int the RIB
- BGP Origin Attribute set to I (for IGP)
- BGP weight set to 32,768
- MED attribute set to the IGP metric
What are the 6 BGP neighbor states?
- Idle
- Connect
- Active
- OpenSent
- OpenConfirm
- Established
Formula to calculate EIGRP metrics
256 * ((107 / least_bandwidth_kbps) + (cumm delay/10))
Formula to calculate EIGRP variance
Feasible successor FD/successor FD and round up
Formula to calculate number of links in a full mesh
n(n-1)/2
What 4 components of Flexible Netflow?
- Flow Records
- Flow Monitors
- Flow Exporters
- Flow Samplers
What are the 5 steps in configuring a Flow Exporter?
- Define the Exporter name
- Set a useful description
- Specify the destination IP to export to
- Specify the flow version
- Specify the UDP port
What are the 5 steps in configuring a Flow Monitor?
- Define the Flow Monitor name
- Set a useful description
- Assign the Flow Record to be used
- Specify a cache timeout of 60 for active connections
- Assign the Exporter to the Monitor
What are the 8 syslog severity codes?
- 0 emergency
- 1 alert
- 2 critical
- 3 error
- 4 warning
- 5 notification
- 6 informational
- 7 debugging
Valid numbers for standard and extended access-lists
- Standard
- 1 - 99
- 1300 - 1999
- Extended
- 100 - 199
- 2000 - 2699
Which OSPF network types do not require a DR/BDR?
- Point-to-point
- Multipoint
Regarding BFD:
- what does BFD stand for?
- what does it require in order to operate?
- how does it work?
- which 2 places is it enabled?
- Bidirectional Forwarding Detection
- CEF
- Sends small fixed-length keepalive packets detecting failures in less than a second
- it is enabled on the interfaces and under the routing protocol
OSPF Summarization Commands:
- for ABR
- NULL0 route auto-installed and with what AD?
- for ASBR
- NULL0 route auto-installed and with what AD?
- area 0 range 172.16.0.0 255.255.0.0
- yes
- summary-address 172.16.0.0 255.255.0.0
- yes with metric of 254
EIGRP Summarization Commands
- Classic mode
- Named mode
- Route to NULL0 installed?
- on the interface “ip summary-address eigrp 4 172.16.0.0 255.255.0.0
- under AF-Interface “summary-address 172.16.0.0/16
- Yes
BGP Summarization Commands:
- Route to NULL0 auto-installed?
- aggregate-address 172.16.0.0 255.255.0.0 summary-only as-set
- yes
Regarding uRPF:
- what does uRPF stand for
- what does it do
- what does it require
- what modes does it operate in
- Unicast Reverse Path Forwarding
- it compares the source address of a packet and checks to see if the packet came in the same interface the router would use to get to the source
- CEF
- Strict, Loose, and VRF
In OSPF, for each of the following stub area types list 1) prohibited LSA types, 2) whether a default route is automatically installed and 3) whether an ASBR is allowed
- Stub Area
- Totally Stubby Area
- NSSA
- Totally NSSA
- Stub Area- no Type 4 or 5 LSAs, gets a Type 3 default route automatically installed, no ASBR allowed
- Totally Stubby Area -No Types 3s, 4s or 5s, default route automatically installed, no ASBR allowed
- NSSA - No Type 4s or 5s,Type 7s instead, default route optional, ASBR allowed
- Totally NSSA - No Types 3, 4, or 5, default route automatically installed, ASBR allowed
What protocol numbers are used by the following:
- OSPF
- EIGRP
- BGP
- IP 89
- IP 88
- TCP 179
What multicast addresses do the following use:
- EIGRP
- OSPF
- EIGRP - 224.0.0.10
- OSPF - 224.0.0.5 and 224.0.0.6
In EIGRP, which show command would display authentication parameters such as authentication mode and keychain being used?
“show ip eigrp interfaces detail”
What is the source and destination of:
- EIGRPv6 Hello Messages?
- EIGRPv6 Update Messages?
- Hello’s are sourced from Link Local address FE80::/10 and destined for FF02::A
- Update messages are sourced and destined for link local addresses
In OSPF, which state do routers send LSRs and LSUs to each other?
Loading
In OSPF, which area types do not permit ASBRs?
- Stub
- Totally Stubby
In OSPF, what show command displays the timers configured on an interface?
“show ip ospf interface”
In OSPF, can neighbors with different network types form a full neighborship?
Yes, as long as the timers match
In OSPF, what do the following option bits mean:
- E-bit
- DC-bit
- N-bit
- MC-bit
- V6-bit
- R-bit
- E-bit - capable of processing external LSAs
- DC-bit - capable of suppressing future Hellos
- N-bit - supports Type 7 LSAs
- MC-bit - supports Multicast
- V6-bit - router is participating in IPV6 routing
- R-bit - router actively participates in forwarding traffic
In OSPFv3, which ‘show’ command will display whether the area is participating in authentication?
“show ospfv3”
In OSPFv3, which ‘show’ command will display the reference bandwidth?
“show ipv6 ospf”
In OSPFv3, which command will display whether the local router has injected a default route?
“show ospfv3”
In EIGRP Named Mode, what command enables EIGRP for an interface?
“network” command
In EIGRP, by default, what is the maximum amount of bandwidth that EIGRP is allowed to use on a link?
50%
In classic EIGRP, where do you modify the Hello and Hold timers/
On the interface.
In EIGRPv6, what show command can you use to determine if a remote router is a stub router?
“show ipv6 eigrp neighbors detail”
In OSPFv3, which 2 show commands display whether a router is an ABR?
- “show ipv6 ospf”
- “show ipv6 protocols”
In BGP, which ‘show’ command can verify the incoming and outgoing TTL values?
“show bgp ipv4 unicast neighbors”
When using a route-map for redistribution, there are 3 conditions that can be used to match prefixes. What are they?
- Route type
- Outbound interface
- Prefix List
In EIGRP for IPV4, which 2 ‘show’ commands can you use to determine the value of K-6?
- “show ip protocols”
- “show eigrp protocols”
In OSPF, how is the cost of a link calculated?
Reference bandwidth/Interface bandwidth
The assumption was that reference bandwidth would always be greater than interface bandwidth. Today it’s not.
What are the 4 well-known communities and what do they mean?
- Internet - advertise the prefix to all BGP neighbors
- No-advertise - don’t advertise the prefix to any BGP neighbors
- No-export - don’t advertise the prefix to any eBGP neighbors (other ASs)
- Local-as - don’t advertise the prefix outside the confederation
When redistributing from BGP into OSPF what kind of routes will be redistributed?
Only eBGP routes.
Which OSPF network types set the Hello timer to 30 sec?
- Non-broadcast
- Point-to-multipoint
In OSPFv3 which instance numbers are valid for IPv6 and which are valid for IPV4?
- IPV6 - 0 to 31
- IPV4 - 64 to 95
In LFA FRR, What are the 8 tie-breakers?
- SRLF
- ECMP Primary
- Interface Disjoint
- Lowest Metric
- Linecard Disjoint
- Node Protecting
- Broadcast Interface Disjoint
- Load Sharing
What authentication types do each of the following routing protocols support?
- EIGRP
- OSPF
- OSPFv3
- BGP
- EIGRP
- MD5
- SHA-2 (named mode)
- OSPF
- Plain text
- MD5
- HMAC SHA
- OSPFv3
- IPsec with AH or ESP
- BGP
- MD5
Route Reflector Rules:
Who can the RR advertise routes to when:
- learned from an RR client
- learned from a non-client
- learned from eBGP
- from an RR client it can be reflected to clients and non-clients
- from a non-client it can only be reflected to clients
- from eBGP it can be reflected to clients and non-clients
What happens when BGP synchronization is turned on?
A router cannot consider an iBGP route in the BGP table as “best” unless the exact prefix was learned through an IGP and is currently in the routing table.