Traffic is flowing through the interfaces in the exhibit as follows:
On ge-0/0/2.0, IPv4 traffic has a throughput rate of 4 Mbps, and the burst size counter is at 200 KB.
On ge-0/0/2.0, IPv6 traffic has a throughput rate of 7 Mbps, and the burst size counter is at 550 KB.
On ge-0/0/3.0, IPv4 traffic has a throughput rate of 5 Mbps, and the burst size counter is at 250 KB.
On ge-0/0/3.1, IPv6 traffic has a throughput rate of 12 Mbps, and the burst size counter is at 450 KB.
Which statement describes what is happening?
A.
IPv6 traffic on ge-0/0.3.1 is being dropped; all other traffic is unaffected.
B.
IPv4 traffic on ge-0/0/2.0 is unaffected; IPv6 traffic on ge-0/0/2.0 is being dropped; IPv4 traffic on ge-0/0/3.0 is unaffected; IPv6 traffic on ge-0/0/3.1 is being dropped.
C.
IPv4 traffic on ge-0/0/2.0 is being dropped; IPv6 traffic on ge-0/0/2.0 is being dropped; IPv4 traffic on ge-0/0/3.0 is unaffected; IPv6 traffic on ge-0/0/3.1 is unaffected.
D.
All IPv4 and IPv6 traffic on ge-0/0/2 and ge-0/0/3 is being dropped.
I think that the corret answer is B) What do you think?
Why? i think, that correct answer is A. ipv6 on ge-0/0/2 not droped by answer B. What do you think ?
In all the dumps ans is C.
But i also think that ans should be B.
Please some one confirm.
I also think the answer should be B.
I think B is correct. Here is sample configuration from Juniper
Discard any packet that exceeds a bandwidth of 300 kilobits per second (Kbps) and a burst-size limit of 500 kilobytes (KB):
[edit firewall]
policer p1 {
if-exceeding {
bandwidth-limit 300k;
burst-size-limit 500k;
}
then {
discard;
}
}
On ge-0/0/2.0
Option B is the correct answer… No doubt about that
http://www.juniper.net/techpubs/software/junos/junos93/swconfig-network-interfaces/applying-policers.html
IMSHO there is no correct answer.
ge-0/0/2.0 IPV4+IPV6 are limited to 10m with burst 500k
ge-0/0/2.1 IPV4 is limited to 10m with burst 500k
ge-0/0/3.0 IPV4+IPV6 are limited to 10m with burst 500k
ge-0/0/3.1 IPV4+IPV6 are limited to 10m with burst 500k
i have reread the question and think i have found a most close to right answer.
if we change the B as followed it would be a right answer:
IPv4 traffic on ge-0/0/2.0 is unaffected; IPv6 traffic on ge-0/0/2.1 is being dropped; IPv4 traffic on ge-0/0/3.0 is unaffected; IPv6 traffic on ge-0/0/3.1 is being dropped.
the bucket in policer on ge-0/0/3.1, is not full
so until it wouldn’t reach 500 no traffic will be lost.
because the policer contains the “logical-interface-policer” statement,
the two policers under the same subinterface are aggregated into one.
Instead of a bandwidth threshold of 10
Mbps per protocol family, the threshold now applies to traffic for both protocol families combined.
and i agreed with dev-null, that there is no correct answer, but if i found the same answers inside the exam, i will choose B.
I think the answer C is the correct one:
IPv4 traffic on ge-0/0/2.0 and IPv6 traffic on ge-0/0/2.0 are being dropped because total traffic rate is 7+4=11Mbps so we need to see if the sufficient tokens remain in the single token bucket but it is not the case as 200+550k burst size exceeds the burst-size-limit (500k).
IPv4 traffic on ge-0/0/3.0 is unaffected as rate is below the bandwidth-limit.
Although we exceed the bandwidth-limit, IPv6 traffic on ge-0/0/3.1 is unaffected as the burst (450k) is still below the burst-size-limit.
ans B is right..
A logical interface policer can be a two-color policer, not a three-color policer. When you apply a logical inteface policer to multiple protocol families on the same logical interface, multiple instances of the policer are created, meaning that traffic for each protocol family is policed separately. You apply a logical interface policer directly to a logical interface configuration (and not by referencing the policer in a stateless firewall filter and then applying the filter to the logical interface).
So ge-0/0/2.0 ipv4 and ge-0/0/3.0 ipv4 are unaffected.
ge-0/0/2.0 ipv6 is unaffected because even the burst is larger than 500k but the total traffic is always be in “Green” zone.
ge-0/0/3.0 ipv6 is getting dropped because of “out-of-profile”
What’s the right answer?
A or B or C?
Any expert please confirm?
I think that Pedro did an excellent explanation, I just want to add to his explanation that the traffic calculation of both families of ge-0/0/2.0 has to be added because of the logical-interface-policer command included in the policer definition.
However, with Pedro´s explanation, I can´t understand how can I have a burst size counter of 550+200 if I have defined a burst size limit of 500
Answer B should be correct.
https://forums.juniper.net/t5/Routing/Difference-Between-Simple-Policer-logical-bandwidth-policer/td-p/201201
Logical interface policers are aggregated on a per-logical-interface basis; the typical example is when you want to rate-limit both IP and IPv6 traffic so that their sum does not exceed the customer contracted rate. So you would define a logical-interface-policer and apply it to both family inet and family inet6.
[edit firewall]
policer 10m {
logical-interface-policer;
if-exceeding {
bandwidth-limit 10m;
burst-size-limit 100k;
}
then discard;
}
[edit interfaces ge-0/0/0]
unit 0 {
family inet {
policer {
input 10m;
}
}
family inet6 {
policer {
input 10m;
}
}
}
The aggregate ingress traffic will be rate-limited to 10m, no matter if it is IPv4, IPv6 or a mix of the two.
C Cannot be correct because it is currently over the policers bandwidth level.
B would be correct because ge-0/0/2.0 is in profile, and under the 10mb policer aggregate. Now the aggregate would get reached when the ipv6 traffic starts pumping and because of that, ipv6 would start getting dropped. (If it were in that order i believe plus its going over the burst limit) I think if both started at the same time, it is plausible that they could both be dropped.
ge-0/0/3.0 is fine because its within the profile and its own logical interface. ge-0/0/3.1 it out of spec at 12mbps and would be dropped.