We've recently upgraded a WAN link to a DS3. Encapsulation is Frame-Relay.
The link is an MPLS link, with a 2MB guaranteed delivery ("GoldCAR") rate.
We're seeing utilization on the link up to 20Mbps, yet we're also seeing tail drops. We want to match our voice traffic in our policy map (we're doing that successfully) and let all other traffic share the remaining bandwidth.
Here's the relevant policy statements:
class-map match-all MarkGold match access-group name GoldCARService class-map match-any Gold-CAR match ip dscp ef ! ! policy-map Traffic-Engineering class Gold-CAR priority 1024 class class-default fair-queue policy-map Marking class MarkGold set ip dscp ef
interface GigabitEthernet0/0 ip address 188.8.131.52 255.255.252.0 duplex auto speed auto media-type rj45 service-policy input Marking
interface Serial1/0 no ip address no ip redirects encapsulation frame-relay IETF load-interval 30 dsu bandwidth 44210 scramble service-policy output Traffic-Engineering ! interface Serial1/0.101 point-to-point bandwidth 44210 ip address 184.108.40.206 255.255.255.252 frame-relay interface-dlci 101 IETF !
A useful command to see if a link is really suffering congestion is "show queue ", in your case: show queue serial1/0. If you see any active conversation in tha output of this command it means there is congestion at that moment. It is a good practice to repeat this command several times to check active conversations.
I would change two thing to reduce your drops:
1. I would make class Gold-CAR match your real CAR with "priority 2048"
2. I would implement WRED on the class-default with a more granular QoS (different AFxx allocations for different traffic classes). This way the the less important traffic would be discarded randomly following a 1/10 discard rate before being tail dropped.
The total offered rate, at 277,000 + 7,503,000 is well below the total bandwidth available of 44,210,000. It doesn't make sense that we'd have a significant drop rate -- we're not in a congested state.
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Queues are probably too shallow for DS3. Recommend individual flow queue be able to support about half your BDP.
Hi everyone, I would like to thank you in advance for any help you can provide a newcomer like myself!
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