So we ran into an interesting issue today, and hoping someone might be able to confirm my assumptions / It'll help someone else out if they come across it.
- NX-OS 5.0(3)N2(1)
- Nexus 7010
- N7K-M132XP-12 line cards.
By default the linecards/system use only 2 egress queues for the 32 port M1 cards.
- 1p7q4t-out-pq1 (matches cos 5-7)
- 1p7q4t-out-q-default (matches cos 0-4)
Which really doesn't line up with what wanted so we modify the config on the default vdc to the following.
class-map type queuing match-any 1p7q4t-out-pq1
match cos 5
class-map type queuing match-any 1p7q4t-out-q2
match cos 7
class-map type queuing match-any 1p7q4t-out-q3
match cos 6
class-map type queuing match-any 1p7q4t-out-q4
match cos 3
class-map type queuing match-any 1p7q4t-out-q5
match cos 2
class-map type queuing match-any 1p7q4t-out-q6
match cos 4
class-map type queuing match-any 1p7q4t-out-q7
match cos 0
class-map type queuing match-any 1p7q4t-out-q-default
match cos 1
Create the relevant policy-map which sets the priority queue and bandwidth requirements for each queue/class
Apply the policy map to the interfaces that we wanted.. Viola, everything works..
Well actually no, the system basically started dropping packets on the egress (output discards) on all the ports that didn't have the new policy applied to them.
Now we can't create custom class maps, we have to use the system default ones, and then modify them suit (match cos statements)
It's my assumption, that once we modify these default class maps, it's also being applied to the default policy
Which reads as follows - sh queuing int e x/x
Service-policy (queuing) output: default-out-policy policy statistics status: enabled Class-map (queuing): out-pq1 (match-any)
priority level 1
queue-limit percent 16
queue dropped pkts : 0
Class-map (queuing): out-q2 (match-any)
queue-limit percent 1
queue dropped pkts : 0
Class-map (queuing): out-q3 (match-any)
queue-limit percent 1
queue dropped pkts : 0
Class-map (queuing): out-q-default (match-any)
queue-limit percent 82
bandwidth remaining percent 25
queue dropped pkts : 0
By modifying the default queues it's affected the default egress policy-map, and in order to function correctly, a custom default list needs to be setup.
With the default egress policy, anything not in the above 4 queues gets dropped.
Few things.
- Why doesn't the output queue in the default policy map (out-q3) match the actual class-map name of 1p7q4t-out-q3
- Are my assumptions about the output discards correct relating to the fact there is no relevant mapping for the modified egress queues in the default system policy
- Where in the config guide is this? I've seen some reference that infer it, but don't actually point it out.
- I'm sure someone can explain to me why this is a system wide config item, rather than on a per vdc basis.
Cheers
