Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
49 Cards in this Set
- Front
- Back
|
How does distance vector use hold down timers to prevent routing loops? |
in the condition where connectivity to a particular network is unstable the routers wait for the hold down time and during that time ignore updates regarding the route.
this keeps triggered updates from reinstating a route too soon
and allows for all routers to updated that the route is down. |
|
|
If the outgoing interface for a static route specifying a next hop address (as opposed to i/f) goes down will the route stay in the routing table or get removed? |
The route is removed because the router will look for a connected route for the subnet of the next hop when using a next hop. |
|
|
how can you make the router keep a static route regardless of the interface state? |
"permanent" keyword
sample... ip route 10.1.2.0 255.255.255.0 10.1.4.2 permanent |
|
|
Do router ACLs filter packets generated by the router? |
No
eg - if an outgoing ACL blocks ping to a destination then the router can still ping that destination |
|
|
What happens if a self ping is issued to the router's own serial interface for point to point link? |
For the ping to succeed the physical link must be working, the local router needs the correct configuration and the neighboring device needs the correct configuration.
If the self ping succeds the packet actually leaves the router, goes the neighboring device which sends the packet back.
The originating router receives it's echo request at which time it needs to reply to the request.
|
|
|
How do ACLs impact self pings over serial point to point links? |
The request and reply are subject to originating routers ingress ACL and neighbor routers ingress and egress ACL |
|
|
What happens when a router self pings the IP of its own ethernet interface |
the interface must be in an up/up state or the ping will fail.
The request does not physically go out the interface. Security on neighboring switches (port security) or routers (ACL) cannot filter ping request.
an ingress IP ACL on router can filter the echo reply` |
|
|
How can OSPF router with an Internet connection advertise a default route? |
router ospf 2 default-information originate
...and
ip route 0.0.0.0 0.0.0.0 10.1.1.1
default-information originate always will keep route whether router's default route is working or not |
|
|
What is another way to add an interface to OSPF aside from a "network" command? |
(config-if) ip ospf 1 area 10
where 1 is process id and 10 is area number |
|
|
How does "show ip protocols" display OSFP routing information when...
..."network" command is used?
..."ip ospf" interface subcommand is used?
|
Network Routing for Network 10.0.0.0 0.255.255.255 area 10
"ip ospf" i/f subcommand Routing on Intefaces Configured Explicitly (Area 10) Serial0/0/1 |
|
|
How does "show ip ospf interface g0/0" differ when...
..."network" command is used?
..."ip ospf" interface subcommand is used? |
Network... "Attached via Network Statement"
"ip ospf" i/f subcommand.... "Attached via Interface Enable" |
|
|
If the DR and BDR have already been selected for a LAN and new router comes online that would win a DR/BDR election what will happen? |
The new router will NOT preempt the DR or BDR. DR and BDR will stay the same |
|
|
Split Horizon Defaults and recommendations for Frame Relay for (sub)interface type...
Physical
Point-multi-point
Point-to-point |
physical default is on, recommended is off Point-multi-point is on, recommended is off Point-to-point is on, recommended is on |
|
|
How do you disable split horizon for a serial interface or sub interface? |
(config-if)# no split-horizon eigrp 10
where 10 is the asn |
|
|
Describe the Area Border Router |
Area Border Router(ABR) is an OSPF router connected to the backbone area and at least one other area |
|
|
Describe Backbone router(ospf) |
Router in one area that is the backbone area |
|
|
describe an Internal router (ospf) |
a router in one area (not the backbone area) |
|
|
Area (ospf) |
A set of routers and links that share the same detailed Link State Database (LSDB) information with each other, but not with routers in other areas, for better efficiency |
|
|
Backbone area (ospf) |
a special OSPF area (area 0) that all other areas must connect to |
|
|
Intra-area route |
A route to a subnet within the same area as the router |
|
|
Interarea route |
A route to a subnet in an different area than the router |
|
|
describe the Router LSA |
LSA #1 primary purpose: describe a router
Contents: RID, interfaces, IP address/mask, current interface state (status) |
|
|
describe the network LSA |
LSA #2 primary purpose: describe a network that has a DR
Contents: DR and BDR IP addresses, subnet ID and mask |
|
|
describe summary LSA |
LSA #3 primary purpose: describe a subnet in another area
contents: Subnet ID and mask, RID of ABR that advertises the LSA |
|
|
Default administative distances |
Connected 0 Static 1 EIGRP summary 5 BGP external 20 EIGRP (internal) 90 IGRP 100 OSPF 110 IS-IS 115 RIP 120 EIGRP (external) 170 BGP internal 200 unusuable 255 |
|
|
OSPF cost calculation examples for i/f... serial ethernet Fast ethernet
faster.... |
formula for cost is 100,000/(default i/f bandwidth)
default bandwidth OSPF cost Serial 1544k 64 Ethernet 10,000k 10 Fast Ethernet 100,000k 1
faster speed are rounded up to 1 and have same default ospf cost as FastEthernet (1gb, 10gb, 100gb) |
|
|
RIPv2 EIGRP OSPFv2
Does routing protocol send periodic full updates? |
RIPv2 - Yes EIGRP - No OSPF - No |
|
|
RIPv2 EIGRP OSPFv2
Does routing protocol send periodic Hello messages? |
RIPv2 - No EIGRP - Yes OSPF - Yes |
|
|
RIPv2 EIGRP OSPFv2
Does routing protocol use route poisoning for failed routes? |
RIPv2 - Yes EIGRP - Yes OSPF - Yes |
|
|
RIPv2 EIGRP OSPFv2
Does routing protocol use split horizon to limit updates about working routes? |
RIPv2 - Yes EIGRP - Yes OSPF - No |
|
|
What is required for two EIGRP routers to become neighbors?
EIGRPv6?
|
interfaces must be in up/up state Must pass authentication if used Must use same Autonomous System Number interfaces must be in the same subnet K Values must match ACLs must NOT filter routing protocol messages
EIGRPv6 sames as v4 EXCEPT interfaces do NOT have to be in the same subnet
|
|
|
RIPv2 EIGRP OSPFv2
What address does routing protocol use to send messages to? |
RIPv2 - 224.0.0.9 EIGRP - 224.0.0.10 OSPFv2 - 224.0.0.5 (allSPF) and 224.0.0.6 (all DRouters which include DR and BDR) |
|
|
RIPv2 EIGRP OSPFv2
What metic value is considered infinite for routing protocol? |
RIPv2 - 16 EIGRP - 2 to the 32nd power -1 or 56th power -1 OSPFv2 - 2 to the 24th power - 1 |
|
|
Requirements for OSPF routers to become neighbors |
Hello and hold/dead timers must match RIDs must be unique must be in the same area
-----same for EIGRP--------- i/f's must be in up/up state i/f's must be in same subnet ACLs must not filter routing protocol messages must pass neighbor auth if config'd |
|
|
Useful show commands for EIGRP simlets |
show ip eigrp topology show ip eigrp neighbors show ip eigrp interfaces show ip protocols show ip route show ip interface brief debug eigrp packets (neighbor auth) |
|
|
Useful show commands for OSPF simlets |
show ip ospf interface brief show ip ospf database show ip ospf neighbor show ip ospf (check if RID unique) debug ip ospf hello debug ip ospf adj
show ip route show ip interface brief show interfaces |
|
|
Neighbor relationship requirements for OSPFv2
how does OSPFv3 differ? |
OSPFv2 i/f's must be up/up i/f's must be in same subnet ACLs must not filter routing protocol messages must pass neighbor auth if config'd hello and dead timers must match RIDs must be unique
process IDs do NOT have to match
OSPFv3 All the same EXCEPT interfaces do NOT have to be in the same subnet. |
|
|
how can you isolate OSPF neighbor authentication problem |
show ip ospf interface or debug ip ospf hello
OSPFv3 show ipv6 ospf interface |
|
|
Useful commands to troubleshoot OSPFv3 neighbor issues |
show ipv6 ospf interface brief show ipv6 ospf interface show ipv6 ospf show ipv6 protocols |
|
|
EIGRP command to create process, define ASN
EIGRPv6? |
EIGRPv4 router eigrp 1
EIGRPv6 ipv6 router eigrp 1 |
|
|
command to EIGRPv4 Define RID explicitly
EIGRPv6? |
EIGRPv4 eigrp router-id 1.1.1.1
EIGRPv6 same as v4 |
|
|
command to change EIGRPv4 number of concurrent routes
EIGRPv6? |
EIGRPv4 (config-router)# maximum-paths 3
EIGRPv6 same as v4 |
|
|
command to change EIGRPv4 variance
EIGRPv6? |
EIGRPv4 (config-router)# variance 3
EIGRPv6 same as v4 |
|
|
command to change EIGRPv4 bandwidth and delay
EIGRPv6? |
EIGRPv4 (config-if)# bandwidth (config-if)# delay
EIGRPv6 same as v4 |
|
|
command to change EIGRPv4 hello time
EIGRPv6? |
EIGRPv4 (config-if)# ip hello-interval 1 5 where 1 is ASN and 5 is seconds
EIGRPv6 (config-if)# ipv6 hello-interval 1 5 where 1 is ASN and 5 is seconds
|
|
|
command to change EIGRPv4 hold time
EIGRPv6? |
EIGRPv4 (config-if)# ip hold-time 1 10 where 1 is ASN and 10 is seconds
EIGRPv6 (config-if)# ipv6 hold-time 1 10 where 1 is ASN and 10 is seconds |
|
|
command to enable EIGRPv4 on an interface?
EIGRPv6? |
EIGRPv4 (config-router)# network 10.0.0.0
EIGRPv6 (config-if)# ipv6 eigrp 1 ...for each interface |
|
|
command to enable/disable auto-summary in EIGRPv4?
EIGRPv6? |
EIGRPv4 (config-router)# auto-summary (config-router)# no auto-summary
EIGRPv6 not needed |
|
|
Why is OSPF so resource intensive? |
OSPF is quite CPU and memory intensive due to SPF algorithm and maintenance of multiple copies of routing information |
