Verifying limit-resource memory per VDC instance on N7K

Recently, I came across the situation where one of my DCI links started to flap after introduction of EIGRP. At the end it was the service provider issue on the long haul but one of the health checks I’ve done was to verify limit-resource on that particular VDC.

When carving up new VDC you are being presented with default resource limits for non default VDC.

Default resource limit as an example on my N7K:

vdc CORE id 4
limit-resource module-type f2 f2e
allow feature-set fabricpath
cpu-share 5
allocate interface Ethernet3/17-32,Ethernet3/45-48
allocate interface Ethernet5/17-32,Ethernet5/45-48
allocate interface Ethernet6/17-32,Ethernet6/45-48
boot-order 1
limit-resource vlan minimum 16 maximum 4094
limit-resource monitor-session minimum 0 maximum 2
limit-resource monitor-session-erspan-dst minimum 0 maximum 23
limit-resource vrf minimum 2 maximum 4096
limit-resource port-channel minimum 0 maximum 768
limit-resource u4route-mem minimum 8 maximum 8
limit-resource u6route-mem minimum 4 maximum 4
limit-resource m4route-mem minimum 8 maximum 8
limit-resource m6route-mem minimum 5 maximum 5
limit-resource monitor-session-inband-src minimum 0 maximum 1
limit-resource anycast_bundleid minimum 0 maximum 16
limit-resource monitor-session-mx-exception-src minimum 0 maximum 1
limit-resource monitor-session-extended minimum 0 maximum 12

Please note that the integer after minimum # and maximum # represents MB size.

In order to verify if you are hitting the limit-resource on your VDC login to that particular VDC and perform the following command:

show routing memory estimate routes #

# represents amount of routes you are considering to have on that particular VDC.

Here is the memory usage on my suspected VDC:

N7K1-CORE# show routing memory estimate routes 1000
Shared memory estimates:
Current max 8 MB; 2649 routes with 32 nhs
Current max 8 MB; 2322 routes with 32 IPv6 nhs
in-use 1 MB; 176 routes with 1 nhs (average)
in-use 1 MB; 176 routes with 0 IPv6 nhs (average)
Configured max 8 MB; 2649 routes with 32 nhs
Configured max 8 MB; 2322 routes with 32 IPv6 nhs
Estimate memory with fixed overhead: 1 MB; 1000 routes with 0 nhs and 0 IPv6 nhs
Estimate with variable overhead included:
– With MVPN enabled VRF: 1 MB
– With OSPF route (PE-CE protocol): 1 MB
– With EIGRP route (PE-CE protocol): 1 MB

From the output above we can see VDC is only using 1MB out of 8MB assigned.  The estimate of 1000 routes will only take 1MB.

In case your routing table will increase i.e. to 100K your estimate will change drastically:

N7K1-CORE# show routing memory estimate routes 100000
Shared memory estimates:
Current max 8 MB; 2649 routes with 32 nhs
Current max 8 MB; 2322 routes with 32 IPv6 nhs
in-use 1 MB; 176 routes with 1 nhs (average)
in-use 1 MB; 176 routes with 0 IPv6 nhs (average)
Configured max 8 MB; 2649 routes with 32 nhs
Configured max 8 MB; 2322 routes with 32 IPv6 nhs
Estimate memory with fixed overhead: 20 MB; 100000 routes with 0 nhs and 0 IPv6 nhs
Estimate with variable overhead included:
– With MVPN enabled VRF: 20 MB
– With OSPF route (PE-CE protocol): 20 MB
– With EIGRP route (PE-CE protocol): 20 MB

As you can see, default resource limit on your VDC will need to be adjusted accordingly. In that case, please follow configuration guide for vdc template in order to accommodate your requirement.

In my scenario I was underutilized (1MB) so this was not my issue.

Regards,

Bart

 

Resources:

Tags:,

Add a Comment

Your email address will not be published. Required fields are marked *