Question No : 13
What is the effect of turning on all available downstream carrier tones in a DMT DSL transmission systems?
A. Downstream RS error correction effectiveness is reduced.
B. The downstream line rate and throughput remains unchanged, but FEC efficiency is reduced.
C. The upstream DSL bandwidth is reduced, since less carriers become available for upstream traffic.
D. The downstream DSL bandwidth is increased.
Correct Answer: D
Friday, 8 April 2016
Friday, 1 April 2016
350-029 Sample Question
Question No : 12
In which two ways does the BGP graceful capability preserve prefix information during a restart? (Choose two)
A. The peer router immediately removes the BGP routers that it learned from the restarting router from its BGP routing tables.
B. The router establishes BGP sessions with other routers and relearns the BGP routes from others that are also capable of graceful restart. The restarting router waits to receive updates from the neighboring routers.
C. The peer router sends an end-of-RIB message to the restarting router.
D. The restarting router removes any stale prefixes after the timer for stale entries expires.
E. The restarting router does not remove any stale prefixes after the timer for stale entries expires.
Correct Answer: BD
Explanation:
BGP Graceful Restart for NSF
When an NSF-capable router begins a BGP session with a BGP peer, it sends an OPEN message to the peer. Included in the message is a declaration that the NSF-capable or NSF-aware router has graceful restart capability. Graceful restart is the mechanism by which BGP routing peers avoid a routing flap following a switchover. If the BGP peer has received this capability, it is aware that the device sending the message is NSFcapable.
Both the NSF-capable router and its BGP peer(s) (NSF-aware peers) need to exchange the graceful restart capability in their OPEN messages, at the time of session establishment. If both the peers do not exchange the graceful restart capability, the session will not be graceful restart capable.
If the BGP session is lost during the RP switchover, the NSF-aware BGP peer marks all the routes associated with the NSF-capable router as stale; however, it continues to use these routes to make forwarding decisions for a set period of time. This functionality means that no packets are lost while the newly active RP is waiting for convergence of the routing information with the BGP peers. After an RP switchover occurs, the NSF-capable router reestablishes the session with the BGP peer. In establishing the new session, it sends a new graceful restart message that identifies the NSF-capable router as having restarted.
At this point, the routing information is exchanged between the two BGP peers. Once this exchange is complete, the NSF-capable device uses the routing information to update the RIB and the FIB with the new forwarding information. The NSF-aware device uses the network information to remove stale routes from its BGP table. Following that, the BGP protocol is fully converged.
If a BGP peer does not support the graceful restart capability, it will ignore the graceful restart capability in an OPEN message but will establish a BGP session with the NSF-capable device. This functionality will allow interoperability with non-NSF-aware BGP peers (and without NSF functionality), but the BGP session with non-NSF-aware BGP peers will not be graceful restart capable.
Pass4sure 300-115
Pass4sure 400-101
Pass4sure 500-006
Pass4sure 400-051
Pass4sure 640-875
Pass4sure
In which two ways does the BGP graceful capability preserve prefix information during a restart? (Choose two)
A. The peer router immediately removes the BGP routers that it learned from the restarting router from its BGP routing tables.
B. The router establishes BGP sessions with other routers and relearns the BGP routes from others that are also capable of graceful restart. The restarting router waits to receive updates from the neighboring routers.
C. The peer router sends an end-of-RIB message to the restarting router.
D. The restarting router removes any stale prefixes after the timer for stale entries expires.
E. The restarting router does not remove any stale prefixes after the timer for stale entries expires.
Correct Answer: BD
Explanation:
BGP Graceful Restart for NSF
When an NSF-capable router begins a BGP session with a BGP peer, it sends an OPEN message to the peer. Included in the message is a declaration that the NSF-capable or NSF-aware router has graceful restart capability. Graceful restart is the mechanism by which BGP routing peers avoid a routing flap following a switchover. If the BGP peer has received this capability, it is aware that the device sending the message is NSFcapable.
Both the NSF-capable router and its BGP peer(s) (NSF-aware peers) need to exchange the graceful restart capability in their OPEN messages, at the time of session establishment. If both the peers do not exchange the graceful restart capability, the session will not be graceful restart capable.
If the BGP session is lost during the RP switchover, the NSF-aware BGP peer marks all the routes associated with the NSF-capable router as stale; however, it continues to use these routes to make forwarding decisions for a set period of time. This functionality means that no packets are lost while the newly active RP is waiting for convergence of the routing information with the BGP peers. After an RP switchover occurs, the NSF-capable router reestablishes the session with the BGP peer. In establishing the new session, it sends a new graceful restart message that identifies the NSF-capable router as having restarted.
At this point, the routing information is exchanged between the two BGP peers. Once this exchange is complete, the NSF-capable device uses the routing information to update the RIB and the FIB with the new forwarding information. The NSF-aware device uses the network information to remove stale routes from its BGP table. Following that, the BGP protocol is fully converged.
If a BGP peer does not support the graceful restart capability, it will ignore the graceful restart capability in an OPEN message but will establish a BGP session with the NSF-capable device. This functionality will allow interoperability with non-NSF-aware BGP peers (and without NSF functionality), but the BGP session with non-NSF-aware BGP peers will not be graceful restart capable.
Pass4sure 300-115
Pass4sure 400-101
Pass4sure 500-006
Pass4sure 400-051
Pass4sure 640-875
Pass4sure
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