Term
What is the range for GLOP addresses?
What are GLOP addresses for?
What are the second and third octets reserved for? |
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Definition
233.0.0.0 - 233.255.255.255
Globally unique addressing
2nd and third octets are for an organization's ASN
"Global P has 2 3s" |
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Term
| What is the range for SSM addresses? |
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Definition
| 232.0.0.0 - 232.255.255.255 |
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Term
| What is the range for private multicast addresses? |
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Definition
"Administratively scoped"
239.0.0.0-239.255.255.255 |
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Term
| What are the two ranges of permanent reserved addresses defined by IANA? |
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Definition
224.0.0.0 - 224.0.0.255 -- local scope
224.0.1.0 - 224.0.1.255 -- routed |
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Term
| What is 224.0.1.39 used for and who sends to this address? |
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Definition
| Sent by candidate RPs in the Auto-RP process. |
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Term
| What is 224.0.1.40 used for and who sends to this address? |
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Definition
| Auto-RP mapping agents send discovered RP mappings to 224.0.1.40. |
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Term
| To what address are IGMP membership reports sent? |
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Definition
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Term
| To what address is a IGMP general query sent? What is the group address in the IGMP header? |
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Definition
| General queries are sent to 224.0.0.1 with a group address of 0.0.0.0 |
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Term
| What is the function of the Maximum Response Time (MRT) in the IGMP General Query? |
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Definition
| Hosts wait random time up to MRT after receiving General Query before sending a report (ensures that only one host sends response). |
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Term
| To what address is the IGMPv2 Leave message sent? |
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Definition
| 224.0.0.2 (all multicast routers) |
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Term
| What is the recommended multicast protocol for general usage? |
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Definition
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Term
| What is the recommended protocol for one-to-many applications? |
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Definition
SSM
"there's one S too many" |
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Term
| What is the recommended protocol for many to many applications? |
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Definition
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Term
| IGMP Leave is supported in which version? |
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Definition
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Term
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Definition
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Term
| Why would a router send a State Refresh message in DM? |
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Definition
| To tell the upstream router to keep pruning. |
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Term
| Are DM Grafts unicast? Acknowledged? |
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Definition
| Grafts are unicast and acknowledged. |
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Term
| What determines if a router becomes IGMPv2 forwarder/querier? |
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Definition
| Router with lowest IP address |
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Term
| What determines if a router becomes IGMPv1 forwarder/querier? |
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Definition
| IGMPv1 does not have a querier function, so it falls to the PIM DR which is the HIGHEST IP address. |
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Term
| If multiple routers can multicast to the same LAN, who actually does it? |
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Definition
| The router with lowest AD to the source (metric if AD equal, highest IP if metric equal) |
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Term
| What features does PIM-SM share with DM? |
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Definition
Hellos
recals of RPF when unicast changes
DR election (only used as querier in DM)
Prune Override
Assert |
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Term
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Definition
Candidate BSRs multicast BSR messages to 224.0.0.13 (automatically flooded)
Highest priority (or IP if priority same) becomes BSR |
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Term
| How are RPs selected in BSR? |
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Definition
Candidate RPs unicast Advertisement to BSR
BSR compiles list of RPs (RP-Set) and sends to all PIM routers (224.0.0.13).
Each router selects an RP from the RP-Set when it needs one. |
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Term
| Which dynamic RP method requires individual routers to select from an advertised list of RPs? |
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Definition
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Term
| Which dynamic RP protocol tells routers which RP to use? |
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Definition
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Term
| Which dynamic RP protocol requires that dense mode be enabled until RP is learned? What is an alternative that results in less flooding? |
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Definition
Cisco's Auto-RP
Use "ip auto-rp listener" (global command) to only allow 224.0.1.39 and 224.0.1.40. |
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Term
| How do Auto-RP Candidate RPs announce themselves? To what address? How often? |
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Definition
| Auto-RP Candidates send RP-Announce messages every 60 seconds to 224.0.1.39. |
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Term
| How do routers learn of RP-group mappings with Auto-RP? |
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Definition
| Routers listen to RP-Discover messages sent from mapping agents to 224.0.1.40. |
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Term
| How many packets does it take on the RPT before a Cisco router will switch to SPT? |
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Definition
1 packet
Change with "ip pim spt-threshold" |
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Term
| What does the J flag on a (*,G) entry signify? |
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Definition
| J flag on (*.G) means SPT threshold has been exceeded (almost always set on Cisco routers since SPT is 1 by default) |
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Term
| Which routers can initiate a switch to SPT by issuing a Join? |
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Definition
| Only the RP and routers with local members. |
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Term
What does the following configure:
ip pim send-rp-announce |
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Definition
An Auto-RP candidate RP.
"Candidates announce, mappers discover." |
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Term
What is the function of "30" in the command below?
ip pim bsr-candidate Loop0 30 100 |
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Definition
ip pim bsr-candidate Loop0 30 100
"30" is the hash mask. It instructs routers to assign Groups to RPs by hashing the mask against the multicast groups. So with hash 30, 30 bits are masked, and 2 bits are used to assign group addresses to RPs (so 4 groups to an RP). |
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Term
| By default, if two equal-cost routes exist, what will the RPF be? |
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Definition
The RPF will use the highest IP address if costs are equal.
Multicast traffic is not load-shared by default. |
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Term
| What command enables equal cost multicast? How is traffic distributed among multiple paths by default? |
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Definition
ip multicast multipath
With ECMP enabled, PIM Joins will be distributed across multiple paths based on a hash of the source address. |
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Term
| How often do DM Prune entries expired? |
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Definition
| DM Prunes expire in 3 minutes. |
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Term
| When do DM OID forwarding entries expire? |
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Definition
| Never. DM will forward until Pruned. |
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Term
| Why are point-to-point links preferred in the core for multicast? |
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Definition
Faster convergence on link failure
Don't need PIM Snooping
Don't need PIM Asserts (which can cause loops) |
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Term
What can you deduce about the source of this mroute?
(1.1.1.1, 224.1.1.1), 00:14:56/00:02:59, flags: CT
Incoming interface: Ethernet0/1, RPF nbr 0.0.0.0 |
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Definition
| It's directly connected (CT flags plus RPF neighbor 0.0.0.0) |
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Term
| How is traffic forwarded in PIM-BIDIR? |
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Definition
| Always on the RPT, according to the (*,G) mroutes. |
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Term
| Which multicast protocol requires IGMPv3? |
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Definition
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Term
What does the following command do?
int e0
ip multicast boundary 10 |
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Definition
int e0
ip multicast boundary 10
Configures an administratively scoped IPv4 multicast boundary.
Only multicast groups permitted by the ACL are permitted on that interface (both directions). To restrict in one direction, specify "in" or "out" keyword. |
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Term
| What protocol allows RP in one domain to learn multicast sources in another domain? |
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Definition
| Multicast Source Discovery Protocol (MSDP) |
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Term
| When an MSDP RP receives a Register, what does it do? |
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Definition
| The RP sends a source active (SA) message to all peers. |
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Term
| What feature enables RP load-sharing? |
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Definition
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Term
| What kind of address should the Anycast loopback be? |
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Definition
| Anycast loopback should be a host /32 address |
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Term
| If the source and receiver for a group join different Anycast RPs, how can they communicate? |
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Definition
| Anycast RPs need to be MSDP peers. |
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Term
| What are two ways to control multicast traffic to hosts? |
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Definition
CGMP (router sends messages to switch)
IGMP snooping (switch uses IGMP to decide where to flood traffic) |
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Term
| What are two methods for control traffic to multicast routers? |
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Definition
RGMP (router sends messages to switch, switch doesn't flood host traffic there)
PIM snooping (switch snoops PIM to determine where routers sit and don't flood there) |
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Term
| Does IGMP snooping break Report Suppression? |
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Definition
| Yes for v1 and v2. IGMPv3 is not affected. |
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Term
| What multicast address are not forwarded? |
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Definition
| 224.0.0.0 - 224.0.0.255 are reserved and not forwarded |
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Term
| What interface command controls the multicast groups that hosts on the subnet serviced by an interface can join? |
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Definition
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Term
In the following, is loop0 the IP address of the anycast RP?
ip msdp peer 20.0.0.2 connect-source Loopback0
ip msdp originator-id Loopback0 |
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Definition
No, Loop0 is the originator-id and connect-source.
The RP is still configured the usual way (could be IP address of Loop1, though)
ip pim rp-address 20.0.0.1
ip msdp peer 20.0.0.2 connect-source Loopback0
ip msdp originator-id Loopback0 |
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Term
| Which distribution tree does SSM use? |
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Definition
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Term
| If an IGMPv2 host sends a group-specific Leave on a segment with v1 and v2 hosts, what will the router do? |
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Definition
| Router ignores the leave. The router does this because the Version 1 clients would ignore a Group-Specific Query anyways. |
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Term
| What is the default multicast TTL used by Cisco for their routers? What is the implication of this value? |
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Definition
The default TTL value is 0. This means that the router will ignore the TTL value found in multicast packets by default.
If it's non-zero, the router will drop any packets with TTL equal to or less than the configured value. |
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Term
| Name two features new to IGMPv2 |
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Definition
Leave
Group specific query |
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Term
| What is the root of the (*,G) tree? |
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Definition
| The root of the (*.G) tree is the RP. |
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Term
| What is the root of the (S,G) tree? |
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Definition
| The root of the (S,G) tree is the Source. |
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Term
| What is the destination IP address of a (*,G) Join? |
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Definition
| (*,G) Joins are sent to 224.0.0.13 (all PIM Routers) |
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Term
| Why do switches that support IGMPv3 feature a proxy-reporting mode? |
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Definition
Because IGMPv3 does not have report suppression.
All the hosts send their complete membership information to the router in response to queries. The switch receives these responses, updates the database and forwards the reports to the router. In proxy reporting mode, the switch forwards only the first report for a channel to the router and suppresses all other reports for the same channel. |
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Term
| What is the function of a PIM DR? |
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Definition
| PIM DR is the IGMP Querier for IGMP v1. |
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Term
| Name one advantage of Auto-RP over BSR. |
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Definition
Auto-RP RP Announcements are multicast to 224.0.1.39 with a TTL that can be decremented and hence controlled with TTL scoping.
BSR routers send RP-set list to all routers using PIM messages which are link-local (no TTL so no TTL scoping) |
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Term
| What kind of multicast routing tables entries are used by PIM-BIDIR? |
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Definition
| PIM-BIDIR uses only (*,G) entries. |
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Term
| What are two transitional solutions for PIM-SSM? |
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Definition
IGMPv3lite lets app developers create SSM receivers before IGMPv3 is available.
URD lets IP multicast receiver applications to be used with SSM without the need to modify the application and change or add any software on the receiver host running the application. |
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Term
| Do auto-RP and BSR support IPv6? |
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Definition
| Only BSR supports IPv6. Auto-RP does not support IPv6. |
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Term
| What is the embedded RP address of the following multicast packet? FF76:0:0130:1234:5678:9abc::4321 |
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Definition
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Term
| What addresses are reserved for administrative scoping? |
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Definition
| 239.0.0.0-239.255.255.255 |
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Term
What is the purpose of the following configuration?
ip msdp sa-filter in list 111 ip msdp sa-filter out list 111
ip msdp redistribute list 111
access-list 111 deny ip any host 224.0.2.2
access-list 111 deny ip any host 224.0.1.3 ! Rwhod
access-list 111 deny ip any host 224.0.1.24 ! Microsoft-ds
access-list 111 deny ip any host 224.0.1.22 ! SVRLOC
access-list 111 deny ip any host 224.0.1.2 ! SGI-Dogfight
access-list 111 deny ip any host 224.0.1.35 ! SVRLOC-DA
access-list 111 deny ip any host 224.0.1.60 ! hp-device-disc !--- Auto-RP groups.
access-list 111 deny ip any host 224.0.1.39
access-list 111 deny ip any host 224.0.1.40 !--- Scoped groups.
access-list 111 deny ip any 239.0.0.0 0.255.255.255 !--- Loopback, private addresses (RFC 1918). a
ccess-list 111 deny ip 10.0.0.0 0.255.255.255 any access-list 111 deny ip 127.0.0.0 0.255.255.255 any access-list 111 deny ip 172.16.0.0 0.15.255.255 any access-list 111 deny ip 192.168.0.0 0.0.255.255 any !--- Default SSM-range. Do not do MSDP in this range. access-list 111 deny ip any 232.0.0.0 0.255.255.255 access-list 111 permit ip any any |
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Definition
To improve the scalability of MSDP in the native IP multicast Internet, and to avoid global visibility of domain local (S,G) information, the msdp-filter list will reduce unnecessary creation, forwarding, and caching of some of these well-known domain local sources. |
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Term
| What protocol does MVPN require? |
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Definition
| MVPN is based on mLDP which can be used to build P2MP and MP2MP LSPs in an MPLS network. |
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Term
| Name 3 benefits of LSM (label-switched multicast) mLDP-based MVPN? |
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Definition
1) common MPLS data plane for unicast and multicast
2) Applies MPLS benefits (like FRR) to multicast
3) eliminates complexity of PIM |
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Term
True or False.
IOS XR IPv6 multicast supports OOR, Auto-RP and MSDP. |
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Definition
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Term
True or False.
IOS XR IPv6 multicast supports PIM-SSM, PIM-BIDIR and Multicast NSF. |
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Definition
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