Instructions:

• Answer 50 questions in 15 minutes.
• If you are not ready to take this test, you can study here.
• Match each statement with the correct term.
• Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.

1. What is the signifigance of the neighbor address when establishing BGP neighbor in the context of network that has multiple paths to the neighbor?
The neighbor expects to see the updates from the source address configured in the neighbor statement. BGP
'Periodic Flood and Prune.'<br />Initially floods multicast traffic (received on its RPF) to all its PIM neighbors. Traffic that arrives back at the router via a non-RPF is discarded.<br />Prune messages are sent on all non-RPF interfaces and RPF int
Cluster - combination of RR and its clients. Can have multiple clusters in an AS. <br />Originator ID - carries router ID of the route's originator<br />Cluster ID - configured when multiple RR in a cluster.<br />Cluster list - sequence of cluster ID
Router#(config) ip pim spt-threshold {rate | infinity} [group-list access-list] Multicast


2. What is a BGP black hole and how is it avoided?
Reverse Path Forwarding is the forwarding logic multicast of multicast. <br />It is the opposite of unicast in that is forwards AWAY from source as opposed to towards the receiver.<br /> Multicast
When not all routers within a transit AS have consistent routing information - due to not running BGP or misconfiguration or BPG speakers. Routing information is advertised but since not all routers within AS can reach the destination traffic is halt
Router(config-router)# neighbor 192.168.1.1 remote-as 65000<br />Router(config-router)# neighbor 192.168.1.1 route-reflector-client<br /> BGP
Cluster - combination of RR and its clients. Can have multiple clusters in an AS. <br />Originator ID - carries router ID of the route's originator<br />Cluster ID - configured when multiple RR in a cluster.<br />Cluster list - sequence of cluster ID


3. IOS command to configure router to be a member of an IGMP group or statically connected member.
Session description &amp; announcement.<br />Transport session announcement via 224.2.127.254.<br />Creation of new sessions.<br /> Multicast
RFC 1112<br />Sends membership query every 60 - 120 seconds to 224.0.0.1<br />Hosts send membership report in response to the query<br /> Multicast
Member of a group:<br />Router#(config) ip igmp join-group group-address<br />Statically connected:<br />Router#(config) ip igmp join-group group-address<br />In this mode router forwards (fast switches) group packets but itself does not accept group
Determines upstream and downstream interfaces.<br />Uses the unicast routing table to insure that only one interface is considered to be and incoming interface for the source.<br />RPF makes sure that if data is looped around is not forwarded. <br />


4. What entities are responsible for allocating BGP AS numbers?
0100.5e00.0000 - 0100.5e7f.ffff - IANA reserved. Multicast
WM<br /><br />List of AS numbers pre-pended with a list of AS numbers that the route has traversed and the originating AS at the end. 'Path to 192.168.1.0 is (65500 - 65420 - 65874)'<br /><br />This insures a loop-free environment. If BGP receives a
Router(config-router)# neighbor 192.168.1.1 remote-as 65000<br />Router(config-router)# neighbor 192.168.1.1 route-reflector-client<br /> BGP
IANA delegates to Regional Internet Registries (RIRs):<br />ARIN - AfriNIC - APNIC - LACNIC and RIPE NCC<br /> BGP


5. Explain the contents of the BGP update message.
Path Vector - policy based routing protocol.<br />Uses BGP attributes are the 'metric'. <br />Path it decides it based on 'hops' where hop is Autonomous Systems.<br /> BGP
Variable length sequence of path attributes<br />Attribute Type -1 byte flag field - 1 byte type code<br />Attribute Length <br />Attribute Value<br />Attribute flag field = 0000 0000<br />W | O - T | N - P | C<br /> BGP
When not all routers within a transit AS have consistent routing information - due to not running BGP or misconfiguration or BPG speakers. Routing information is advertised but since not all routers within AS can reach the destination traffic is halt
This should only be for ISP's<br />An improperly configured AS (that is not meant to be a transit) could inadvertently become one.<br /> BGP


6. Explain the AS format and ranges?
Group of BGP routers being configured that have the same update policy.<br />Similar to a 'template'; members then assigned to the peer group.<br /> BGP
16 bit number 1 to 65535<br />1-64511: Public AS<br />64512-6535: Reserved for private AS<br /> BGP
Sends a leave message to 224.0.0.2<br />Router then sends a group specific query<br />Remaining member(s) send a report so group remains active.<br /> Multicast
Since IBGP learned routes are never propagate to other IBGP peer - full mesh of IBPG peers is required within an AS. THIS IS NOT SCALABLE. <br />RR allow the propagation of routes learned by IBGP to other IBGP peers without having a full mesh of IBGP


7. Explain the Origin attribute.

Warning: Invalid argument supplied for foreach() in /var/www/html/basicversity.com/show_quiz.php on line 183


8. What are two methods of establishing a gateway of last resort?
WM<br />Next hop address is entry point into the next AS along the path to that destination network. It does a recursive lookup to the routing table which should have learned the route from its IGP.<br />in IBGP the next hop advertised by EBGP should
Bidirection PIM mode - designed for many to many applications.<br />Source Specific Multicast (SSM) ; builds only source specific shortest path trees.<br /> Multicast
Default-Network<br />Static route<br /> BGP
Contains information on ONE path only<br /><br />Withdrawn routes - List of IP prefixes for routes being withdrawn.<br />Path attributes - AS-Path - etc.<br />Network layer reachability information - List of IP prefixes reachable by this path. BGP


9. What is the BGP Synchronization requirement and What does is prevent? When should it be left disabled? When should it be enabled?

Warning: Invalid argument supplied for foreach() in /var/www/html/basicversity.com/show_quiz.php on line 183


10. How is the BGP network command differ from IGP's?
WD<br />Dictates which path is preferred to exit the AS.<br />Higher is is preferred - default is 100 on Cisco.<br />Obviously for this to be relevant there must be multiple exit points for the route.<br />'Influences outbound traffic for an AS'<br /
'Periodic Flood and Prune.'<br />Initially floods multicast traffic (received on its RPF) to all its PIM neighbors. Traffic that arrives back at the router via a non-RPF is discarded.<br />Prune messages are sent on all non-RPF interfaces and RPF int
Sends a leave message to 224.0.0.2<br />Router then sends a group specific query<br />Remaining member(s) send a report so group remains active.<br /> Multicast
It actually determines which networks are advertised. BGP


11. What block of multicast MAC addresses belong to multicast?
Update from client peer - sends update to all non-client peers and client peers except for originating peer.<br />Update from non-client peer - send update to all clients in the cluster.<br />Update from EBGP peer - update sent to all client peers an
0100.5e00.0000 - 0100.5e7f.ffff - IANA reserved. Multicast
WD<br />Dictates which path is preferred to exit the AS.<br />Higher is is preferred - default is 100 on Cisco.<br />Obviously for this to be relevant there must be multiple exit points for the route.<br />'Influences outbound traffic for an AS'<br /
RFC - 3376<br />Ability to filter multicast source (can be picky)<br />IGMPv3 membership report goes to 224.0.0.22 and may include the multicast hosts it will accept or deny.<br /> Multicast


12. What does a '*' and '&gt;' mean in the BGP table?
IGMP Snooping - requires special ASICS can degrade performance with it; is supported by multiple vendors.<br />CGMP - Cisco proprietary - only work on Cisco hardware; resource friendly<br />GMRP - Replaced by MRP; obscure<br />Manually - Performance
* = Best route<br />&gt; = Route has been inserted into the routing table<br /> BGP
Path Vector - policy based routing protocol.<br />Uses BGP attributes are the 'metric'. <br />Path it decides it based on 'hops' where hop is Autonomous Systems.<br /> BGP
EBGP is an adjacency between BGP peers in different AS; iBGP peers are in same AS. BGP


13. What command used to perform the following:<br />A) Reset all neighbors session ('bounce')<br />B) Soft inbound reset<br />C) Soft outbound reset<br />D) Soft inbound reset of neighbor 10.1.1.1<br /><br />R1# clear ip bgp <br />R1# clear ip bgp soft
R1# clear ip bgp <br />R1# clear ip bgp soft in<br />R1# clear ip bgp * soft out<br />R1# clear ip bgp 10.1.1.1 soft in<br /><br /> BGP
BGP specifies that it can advertise to its peers in neighboring AS's only routes that it uses.<br />BGP cannot influence how a neighboring AS will route your traffic BUT it can influence how your traffic gets to the neighboring AS. <br /> BGP
* = Best route<br />&gt; = Route has been inserted into the routing table<br /> BGP
Well-known Mandatory - Must be supported and propagated.<br />Well-known Discretionary - Must be supported; propagation optional.<br />Optional Transitive - Marked as partial if unsupported by neighbor.<br />Option Nontransitive - Deleted is unsuppor


14. What is the layer 2 multicast address and how is it formed? What potential problem is there with this?
The Source and Share Tree models are the working model of how the tree is built; all multicast routing protocols fit into one or both. This is the 'theory' or model.<br />PIM-DM's operational falls in the source tree model and PIM-SM is classified an
Concatenation of the first (high order) 25 bits of the reserved MAC address range with the last (low order)23 bits of the multicast group IP address. 5 bits of overlap allowing for 32 address (2^5) for each multicast MAC address. 25 bits + 23 bits<br
O<br />Cisco only.<br />Routes with higher weight are preferred (0 - 65535) . Paths that the router originates have 32768; other paths have default of 0.<br /> BGP
The neighbor expects to see the updates from the source address configured in the neighbor statement. BGP


15. Explain the multicast routing table distribution tree notations.

Warning: Invalid argument supplied for foreach() in /var/www/html/basicversity.com/show_quiz.php on line 183


16. What is the key difference between how a multicast routing protocol forwards packets versus a unicast routing protocol?
Unicast uses a routing table looking and forwards towards the destination address.<br />Multicast forwards out multiple interfaces and away from the source and towards multiple destinations using a distribution tree.<br /> Multicast
Session description &amp; announcement.<br />Transport session announcement via 224.2.127.254.<br />Creation of new sessions.<br /> Multicast
When AS has more than one connection to the Internet it is called multihoming.<br />Inbound reliability<br />Better performance by selecting more optimal paths<br />Multihoming can be to one ISP or to several.<br /> BGP
EBGP will only peer to direclty connected neighbors and a loopback is considered one hop away.<br /><br />With eBGP peering to a loopback you must enable eBGP Multihop.<br /><br />R1(config-router)# neighbor 192.168.1.1 ebgp-multihop 2 BGP


17. What is the IBGP Split Horizon rule? What does this accomplish?
Links = n(n-1)/2 BGP
Class D address space<br />First bits are ALWAYS 1110<br />224.0.0.0 - 239.255.255.255<br /> Multicast
Routes learned through IBPG are never propogated to other IBGP speakers.<br /><br />This is a loop prevention mechanism. BGP
IGMP is a layer 3 protocol<br />Switches treat multicast just like broadcast (forward out all ports except the one one which is was received)<br />By definition a pure layer 2 devices do not have a mechanism to see IGMP packets or facilitate the rela


18. What are the 6 BGP Neighbor states?
Idle - Router looking in routing table to see if route exists to neighbor. <br /><br />[Active - When no response to Open message] <br /><br />Connect - Router found route to neighbor and has performed the TCP three-way handshake<br /><br />Open Sent
Router(config-router)# neighbor 192.168.1.1 remote-as 65000<br />Router(config-router)# neighbor 192.168.1.1 route-reflector-client<br /> BGP
IANA delegates to Regional Internet Registries (RIRs):<br />ARIN - AfriNIC - APNIC - LACNIC and RIPE NCC<br /> BGP
The unicast routing table.<br />No routing updates are sent between PIM routers.<br /> Multicast


19. What config would be used to configured an outbound BGP distribute list to block all routes from being advertised except ones from 192.168.0.0 /24 network to neighbors 10.1.1.1 and 10.1.1.2?
<img src='9618cf01b9422f541fc213b74a3bd9de.png' /> Multicast
Router#show ip igmp interface fa0/0<br /> Multicast
Path Vector - policy based routing protocol.<br />Uses BGP attributes are the 'metric'. <br />Path it decides it based on 'hops' where hop is Autonomous Systems.<br /> BGP
R2(config)# access-list 1 permit 192.168.0.0 0.0.0.255<br />R1(config-router)# neighbor 10.1.1.1 distribute-list 1 out<br />R1(config-router)# neighbor 10.1.1.2 distribute-list 1 out<br /> BGP


20. What command will produce the following output and What is it displaying?<br /><br /><img src='5d3c9233dd205ee4319ef0ac2fc07460.jpg' />
WM<br />Next hop address is entry point into the next AS along the path to that destination network. It does a recursive lookup to the routing table which should have learned the route from its IGP.<br />in IBGP the next hop advertised by EBGP should
The BGP Table<br /><br />Command = show ip bgp BGP
Group of BGP routers being configured that have the same update policy.<br />Similar to a 'template'; members then assigned to the peer group.<br /> BGP
EBGP = 20<br />iBGP = 200<br /> BGP


21. What is the command to configure a BGP RR?<br />
Determines upstream and downstream interfaces.<br />Uses the unicast routing table to insure that only one interface is considered to be and incoming interface for the source.<br />RPF makes sure that if data is looped around is not forwarded. <br />
Router(config-router)# neighbor 192.168.1.1 remote-as 65000<br />Router(config-router)# neighbor 192.168.1.1 route-reflector-client<br /> BGP
Reverse Path Forwarding is the forwarding logic multicast of multicast. <br />It is the opposite of unicast in that is forwards AWAY from source as opposed to towards the receiver.<br /> Multicast
Dense mode interfaces are always added to the table. <br /><br />Sparse mode interfaces are added to the table only when periodic join messages are received from downstream routers - or when a directly connected member is on the interface<br /> Multi


22. What are some of the obstacles with IGMP and multicast in general as it relates to layer 2/switches?
Places it in the routing table. BGP
Router#show ip igmp group<br />Group address - interface - uptime - expires - and last reporter.<br /> Multicast
Must insure loopback is reachable in the routing table. BGP
IGMP is a layer 3 protocol<br />Switches treat multicast just like broadcast (forward out all ports except the one one which is was received)<br />By definition a pure layer 2 devices do not have a mechanism to see IGMP packets or facilitate the rela


23. What is the terminology for BGP route reflector?

Warning: Invalid argument supplied for foreach() in /var/www/html/basicversity.com/show_quiz.php on line 183


24. What is the command to enable BPG authentication?
R1(config-router)#neighbor 192.168.1.1 password MyPassword<br /><br />OR<br /><br />R1(config-router)#neighbor MyPeerGroup password MyPassword<br /> BGP
When using the <span style='font-style:italic;'>classful</span> method - at least one subnet of the classful range must reside in the IP routing table.<br /><br />When using the <span style='font-style:italic;'>classless</span> method the exact subne
RFC 1112<br />Sends membership query every 60 - 120 seconds to 224.0.0.1<br />Hosts send membership report in response to the query<br /> Multicast
The is the multicast bit. Multicast


25. What effect will placing a route to null0 have on BGP?
BPG will find an exact match. BGP
EBGP is an adjacency between BGP peers in different AS; iBGP peers are in same AS. BGP
RFC 2236<br />Leave and join latency resolved<br />Group specific query to G instead of 224.0.0.1<br />Leave group message<br />Election of querier (lowest IP) on broadcast medium with multiple routers <br /> Multicast
O<br />Cisco only.<br />Routes with higher weight are preferred (0 - 65535) . Paths that the router originates have 32768; other paths have default of 0.<br /> BGP


26. What type of protocol is BGP classified as? What is its decision engine?

Warning: Invalid argument supplied for foreach() in /var/www/html/basicversity.com/show_quiz.php on line 183


27. Describe how and IGMPv2 host leaves. What is the interaction between host and router look like?
Sends a leave message to 224.0.0.2<br />Router then sends a group specific query<br />Remaining member(s) send a report so group remains active.<br /> Multicast
Default-Network<br />Static route<br /> BGP
SPT (S -G) consume more memory because there is an entry for each source BUT traffic is sent over optimal path to receiver.<br />Shared distribution tree state entries (* -G) consume less CPU but may take suboptimal path to receiver.<br /> Multicast
BPG will find an exact match. BGP


28. What is the command to configure a BGP RR?
Using a Distribute List to filter outbound routing updates. BGP
Router(config-router)# neighbor 192.168.1.1 remote-as 65000<br />Router(config-router)# neighbor 192.168.1.1 route-reflector-client<br /> BGP
Since IBGP learned routes are never propagate to other IBGP peer - full mesh of IBPG peers is required within an AS. THIS IS NOT SCALABLE. <br />RR allow the propagation of routes learned by IBGP to other IBGP peers without having a full mesh of IBGP
R1(config-router)# neighbor 192.168.1.1 next-hop-self<br /><br />Cause each routers outgoing interface that the route traverse wihtin the AS (iBPG peers) to annouce itself as the 'next hop' instead of the next hop into the neighboring AS.<br /><br />


29. Describe how PIM-Sparse-Dense operates.

Warning: Invalid argument supplied for foreach() in /var/www/html/basicversity.com/show_quiz.php on line 183


30. How does RPF avoid routing loops?
Session description &amp; announcement.<br />Transport session announcement via 224.2.127.254.<br />Creation of new sessions.<br /> Multicast
The Source and Share Tree models are the working model of how the tree is built; all multicast routing protocols fit into one or both. This is the 'theory' or model.<br />PIM-DM's operational falls in the source tree model and PIM-SM is classified an
Determines upstream and downstream interfaces.<br />Uses the unicast routing table to insure that only one interface is considered to be and incoming interface for the source.<br />RPF makes sure that if data is looped around is not forwarded. <br />
IANA delegates to Regional Internet Registries (RIRs):<br />ARIN - AfriNIC - APNIC - LACNIC and RIPE NCC<br /> BGP


31. What is a BGP route reflector - What is it purpose?
The neighbor expects to see the updates from the source address configured in the neighbor statement. BGP
BGP specifies that it can advertise to its peers in neighboring AS's only routes that it uses.<br />BGP cannot influence how a neighboring AS will route your traffic BUT it can influence how your traffic gets to the neighboring AS. <br /> BGP
TCP port 179<br />Reliability; uses sliding window<br />Triggered - incremental updates made very efficient<br /> BGP
Since IBGP learned routes are never propagate to other IBGP peer - full mesh of IBPG peers is required within an AS. THIS IS NOT SCALABLE. <br />RR allow the propagation of routes learned by IBGP to other IBGP peers without having a full mesh of IBGP


32. Explain the Next-Hop attribute. How does this differ from IGP's? In what environment might this be problematic?
WM<br />Next hop address is entry point into the next AS along the path to that destination network. It does a recursive lookup to the routing table which should have learned the route from its IGP.<br />in IBGP the next hop advertised by EBGP should
When using the <span style='font-style:italic;'>classful</span> method - at least one subnet of the classful range must reside in the IP routing table.<br /><br />When using the <span style='font-style:italic;'>classless</span> method the exact subne
R1(config-router)#neighbor 192.168.1.1 password MyPassword<br /><br />OR<br /><br />R1(config-router)#neighbor MyPeerGroup password MyPassword<br /> BGP
Update from client peer - sends update to all non-client peers and client peers except for originating peer.<br />Update from non-client peer - send update to all clients in the cluster.<br />Update from EBGP peer - update sent to all client peers an


33. What are the commands to configure a BGP peer group?
Bidirection PIM mode - designed for many to many applications.<br />Source Specific Multicast (SSM) ; builds only source specific shortest path trees.<br /> Multicast
The unicast routing table.<br />No routing updates are sent between PIM routers.<br /> Multicast
The neighbor expects to see the updates from the source address configured in the neighbor statement. BGP
R1(config-router)#neighbor MyPeers peer-group<br />R1(config-router)#neighbor 10.1.1.1 remote-as 64513<br />R1(config-router)#neighbor 10.1.1.1 peer-group MyPeers<br /> BGP


34. Explain the BGP route decision process? How many routes does it select? Where do they go? Where do the ones go that are not used?
Idle - Router looking in routing table to see if route exists to neighbor. <br /><br />[Active - When no response to Open message] <br /><br />Connect - Router found route to neighbor and has performed the TCP three-way handshake<br /><br />Open Sent
RFC - 3376<br />Ability to filter multicast source (can be picky)<br />IGMPv3 membership report goes to 224.0.0.22 and may include the multicast hosts it will accept or deny.<br /> Multicast
BGP not designed for load balancing (by default). <br />BGP selected the SINGLE best path to a destination and places it in the routing table; the rest are kept in the BGP Table.<br />Paths are chosen based on policy. BGP eliminates paths until one p
This router originated the route. BGP


35. State how IGMPv1 operates.
BPG will find an exact match. BGP
EBGP is an adjacency between BGP peers in different AS; iBGP peers are in same AS. BGP
RFC 1112<br />Sends membership query every 60 - 120 seconds to 224.0.0.1<br />Hosts send membership report in response to the query<br /> Multicast
Cisco Proprietary - between router and switch<br />'Client/Server': Router = CGMP Server - Switch = CGMP Client<br />When router sees IGMP control message it creates a CGMP packet with the mutlicast MAC + client MAC; sends this to 'All CGMP Devices M


36. Explain the concept of RPF.
Links = n(n-1)/2 BGP
AS-Path<br />Next Hop<br />Origin BGP
Language between local router interface and hosts.<br />IGMP - ICMP - similarities <br />TTL is usually 1; RFC states it should never leave local subnet.<br />Creates and maintains group membership for hosts wishing to participate in a multicast grou
Reverse Path Forwarding is the forwarding logic multicast of multicast. <br />It is the opposite of unicast in that is forwards AWAY from source as opposed to towards the receiver.<br /> Multicast


37. What advantage is there it establishing a neighbor relationship using a loopback interface?
Since IBGP learned routes are never propagate to other IBGP peer - full mesh of IBPG peers is required within an AS. THIS IS NOT SCALABLE. <br />RR allow the propagation of routes learned by IBGP to other IBGP peers without having a full mesh of IBGP
ISP passes only default route to AS.<br />ISP passes default route and provider owned select routes to AS.<br />ISP passes all routes to AS.<br /> BGP
Use loopback interface to establish the neighbor. (i.e. peer to a loopback interface)<br />Tell BGP to use the lookback interface as teh source of updates<br /><br />R1(config-router)# neighbor 192.168.1.1 update-source loopback0<br /> BGP
Loopback more resilient than physical interfaces. BGP


38. Describe how PIM-DM operates.

Warning: Invalid argument supplied for foreach() in /var/www/html/basicversity.com/show_quiz.php on line 183


39. Explain the IGMPv3 membership process and new features.
ON<br />Displayed as metric in Cisco IOS; lower is preferred. Default is 0. Indicated to external AS the preferred path into the AS.<br />'Influence inbound traffic to an AS'<br />By default ONLY compares if neighbors AS is same for all routes being
EBGP will only peer to direclty connected neighbors and a loopback is considered one hop away.<br /><br />With eBGP peering to a loopback you must enable eBGP Multihop.<br /><br />R1(config-router)# neighbor 192.168.1.1 ebgp-multihop 2 BGP
Unicast uses a routing table looking and forwards towards the destination address.<br />Multicast forwards out multiple interfaces and away from the source and towards multiple destinations using a distribution tree.<br /> Multicast
RFC - 3376<br />Ability to filter multicast source (can be picky)<br />IGMPv3 membership report goes to 224.0.0.22 and may include the multicast hosts it will accept or deny.<br /> Multicast


40. What does a 0.0.0.0 signify in the Next Hop column in the BGP Table?
Loopback more resilient than physical interfaces. BGP
This router originated the route. BGP
Router#show ip igmp group<br />Group address - interface - uptime - expires - and last reporter.<br /> Multicast
O<br />Cisco only.<br />Routes with higher weight are preferred (0 - 65535) . Paths that the router originates have 32768; other paths have default of 0.<br /> BGP


41. Explain the relationship between MBone - DVMRP - PIM - IGMP - CGMP hosts - routers and switches?

Warning: Invalid argument supplied for foreach() in /var/www/html/basicversity.com/show_quiz.php on line 183


42. What is a BGP peer group?

Warning: Invalid argument supplied for foreach() in /var/www/html/basicversity.com/show_quiz.php on line 183


43. Explain the path selection process for BGP? What is the order and what preference does it take?
* = Best route<br />&gt; = Route has been inserted into the routing table<br /> BGP
EBGP will only peer to direclty connected neighbors and a loopback is considered one hop away.<br /><br />With eBGP peering to a loopback you must enable eBGP Multihop.<br /><br />R1(config-router)# neighbor 192.168.1.1 ebgp-multihop 2 BGP
AS-Path<br />Next Hop<br />Origin BGP
1. Weight - Administrative preference (Highest)<br /><br />2. Local Preference - Communicated between peers within AS (Highest)<br /><br />3. Self-originated - Prefer path originated locally (True)<br /><br />4. AS Path - Minimize AS hops (Shortest)<


44. Name 4 verification commands for BGP and what they display?
Show ip bgp - Shows entire BGP topology database (BGP table)<br /><br />show ip bgp rib-failure - Displays BGP routes not installd into the routing information base (RIB) and reason they were not installed.<br /><br />show ip bgp neighbors - Displays
MOSPF<br />DVMRP<br />CBT<br />PIM Dense Mode<br />PIM Sparse Mode<br />PIM Sparse-Dense Mode<br /> Multicast
BGP peer BGP
SPT (S -G) consume more memory because there is an entry for each source BUT traffic is sent over optimal path to receiver.<br />Shared distribution tree state entries (* -G) consume less CPU but may take suboptimal path to receiver.<br /> Multicast


45. Explain the Community attribute.

Warning: Invalid argument supplied for foreach() in /var/www/html/basicversity.com/show_quiz.php on line 183


46. What are the 4 BGP packet types? What do they contain?
'Periodic Flood and Prune.'<br />Initially floods multicast traffic (received on its RPF) to all its PIM neighbors. Traffic that arrives back at the router via a non-RPF is discarded.<br />Prune messages are sent on all non-RPF interfaces and RPF int
Open - Version - AS - Hold Time - BGP Router ID - Optional Parameters<br />Keepalive - Sent every 60 seconds by default; hold time 180 Seconds.<br />Update - Information on only ONE path; <br />Notification - When error condition detected<br /> BGP
The BGP Table<br /><br />Command = show ip bgp BGP
Path Vector - policy based routing protocol.<br />Uses BGP attributes are the 'metric'. <br />Path it decides it based on 'hops' where hop is Autonomous Systems.<br /> BGP


47. Name the Well-known mandatory attributes.
Router#(config) router bgp 1<br />Router#(config-router) neighbor 192.168.1.1 remote-as 1<br />Router#(config-router) network 192.168.0. mask 255.255.255.0<br /> BGP
R1(config-router)# neighbor 192.168.1.1 next-hop-self<br /><br />Cause each routers outgoing interface that the route traverse wihtin the AS (iBPG peers) to annouce itself as the 'next hop' instead of the next hop into the neighboring AS.<br /><br />
The router will not accept a routing update that includes its AS number in the path. BGP
AS-Path<br />Next Hop<br />Origin BGP


48. What does BGP use for communication? What advantage does it offer?
Router(config-router)# neighbor 192.168.1.1 remote-as 65000<br />Router(config-router)# neighbor 192.168.1.1 route-reflector-client<br /> BGP
The Source and Share Tree models are the working model of how the tree is built; all multicast routing protocols fit into one or both. This is the 'theory' or model.<br />PIM-DM's operational falls in the source tree model and PIM-SM is classified an
Source Tree - Source-based tree's are rooted at the source. Source tree created for each new group. Also called shortest path tree (SPT's). <br />Shared Tree - Single tree that is shared between all sources; single common root called the rendezvous p
TCP port 179<br />Reliability; uses sliding window<br />Triggered - incremental updates made very efficient<br /> BGP


49. What effect does (S -G) and (* -G) entries have on router CPU?
Show ip bgp - Shows entire BGP topology database (BGP table)<br /><br />show ip bgp rib-failure - Displays BGP routes not installd into the routing information base (RIB) and reason they were not installed.<br /><br />show ip bgp neighbors - Displays
WM<br /><br />List of AS numbers pre-pended with a list of AS numbers that the route has traversed and the originating AS at the end. 'Path to 192.168.1.0 is (65500 - 65420 - 65874)'<br /><br />This insures a loop-free environment. If BGP receives a
This will advertise the entire classful network:<br />R1(config-router)# network 10.1.1.0<br /><br />This will advertise the the classless network:<br />R1(config-router)# network 10.1.1.0 mask 255.255.255.0<br /><br /> BGP
SPT (S -G) consume more memory because there is an entry for each source BUT traffic is sent over optimal path to receiver.<br />Shared distribution tree state entries (* -G) consume less CPU but may take suboptimal path to receiver.<br /> Multicast


50. Name the Well-known discretionary attributes.
EBGP will only peer to direclty connected neighbors and a loopback is considered one hop away.<br /><br />With eBGP peering to a loopback you must enable eBGP Multihop.<br /><br />R1(config-router)# neighbor 192.168.1.1 ebgp-multihop 2 BGP
Local preference<br />Atomic Aggregate BGP
Members leave through attrition; no leave group message. This keep traffic flowing for a period of time even with no group members. Multicast
Allow router to operate in sparse mode and dense mode at the same time.<br />Supports multiple RP's and automatic RP selection for each multicast source.<br />Support auto-RP - bootstrap router (BSR) or statically defined RP's with minimal configurat