How does Route Monitoring enables the MAS to monitor the L3 uplink status ?

Aruba Employee

Introduction :

 

Problem Statement
 

  • Branch deployments need to detect L3 failure when L2 is still up.
  • Dynamic routes are taken care by the respective protocols
  • Static routes needs a mechanism to detect the L3 failure and update routing table accordingly.

Solution

  • Route Monitoring provides an ability to remove a route based upon probe status.
  •  In addition to basic route monitoring feature, it also brings in multiple default gateway support.
  • This article is applicable only to MAS code running 7.4.0.0 and above.

 

Feature Notes :

 

 

  • Route Monitoring enables the MAS to monitor the L3 uplink status  .
  • Ping probe destined to a server IP address is sent on the uplink interface which is under monitoring.
  • Based on the status of ping reply, probe status of the interface is updated to up or down.
  • Interface probe status is changed from up to down, when there are consecutive unacknowledged pings.
  • When the probe status of the interface is down, static routes are removed from the routing table for respective interface
  • Interface probe status is changed from down to up when there are acknowledged pings.
  • When the probe status of the interface is up again, network routes are added back. 

 

Environment :

 

 

Any typical environment of MAS deployment and have the requirement of monitoring the L3 Uplink status
 
Network Topology :
 
No specific network diagram applied to this as this is going to be route monitoring the L3 uplink status
 
Configuration Steps :
 
By default Route Monitoring is disabled on the Mobility Access Switch.
Enabling Route Monitoring
Route Monitoring can be enabled on the Mobility Access switch using the following steps in the CLI:
  • Configure a probe profile
  • Apply the profile to the uplink VLAN interface.
 
Important Points to Remember
  • Only one probe-profile can be associated per VLAN interface.
  • Same probe-profile can be associated with multiple VLAN interfaces.
  • Up to four probe-profiles can be configured.
  • Up to two IP addresses can be configured. When there are multiple hosts, probe status of the interface is changed to up if ping succeeds to at least one of the configured hosts.
Sample Configuration

Configure a probe profile
(host) (config) #probe-profile L3Monitoring
(host) (probe profile "L3Monitoring") #destination 10.1.10.1
(host) (probe profile "L3Monitoring") #pkt-found-cnt 16
(host) (probe profile "L3Monitoring") #pkt-lost-cnt 16
(host) (probe profile "L3Monitoring") #pkt-send-freq 11
(host) (probe profile "L3Monitoring") #protocol icmp
 
Apply the profile to the uplink VLAN interface
(host) (config) # interface vlan 10
(host) (vlan “10") # probe-profile L3Monitoring
 
pkt-found-cnt: Minimum number of ping responses to keep the probe status up
Default:6 Allowed range: 2-32
pkt-lost-cnt: Minimum number of packet loss in the ping to mark
the interface probe status as down
Default:6 Allowed range: 2-32
pkt-send-freq : Frequency at which ping packets are sent
Default:5 Allowed range: 1-32
protocol : Protocol used for the probe operation
This release provides support only for ping probe and hence the only option available to choose is ICMP
 
 
Use the following command to view the configuration on a probe-profile:

(host) #show probe-profile L3Monitoring
probe profile "L3Monitoring" (N/A)
----------------------------------
Parameter Value
--------- -----
Destination IP 10.1.10.1
Destination Host Name N/A
Packet Lost Count 16
Packet Found Count 16
Packet Send Frequency (Secs) 11
Protocol icmp
 
 
Use the following command to view the list of probe-profiles configured and their references:
(host) #show probe-profile
probe profile List
------------------
Name          References  Profile Status
----          ----------  --------------
default       0            N/A
L3Monitoring  1            N/A
test          0            N/A
 
Sample output to depict that probe is Up until at least one destination server is reachable.

(host) (vlan "200") #show probe
IPV4 PROBE Table
----------------
Vlan     Server      Protocol  Port   Probe-State  Sent  Received
-----    ------      --------  ----   -----------  ----  --------
vlan10  40.40.40.3  ICMP      N/A    Up           11    10
vlan10  60.60.60.3  ICMP      N/A    Up           11    10
Total Probe host entries: 2
(host) (vlan "200") #show ip interface brief
Flags: S - Secondary IP address
Probe: U - Up, D - Down, U/O - Up & Own IP, N/A - Not Applicable
Interface                   IP Address / IP Netmask        Admin   Protocol Probe  Flags
vlan 1                         1.1.1.1 / 255.255.255.0     Up      Down     N/A
vlan 10                   20.20.20.254 / 255.255.255.0     Up      Up       U

(host) (vlan "200") #show probe
IPV4 PROBE Table
----------------
Vlan     Server      Protocol  Port   Probe-State  Sent  Received
-----    ------      --------  ----   -----------  ----  --------
vlan10   40.40.40.3  ICMP      N/A    Down         57    34
vlan10   60.60.60.3  ICMP      N/A    Up           57    56
Total Probe host entries: 2
(host) (vlan "200") #show ip interface brief
Flags: S - Secondary IP address
Probe: U - Up, D - Down, U/O - Up & Own IP, N/A - Not Applicable
Interface                   IP Address / IP Netmask        Admin   Protocol Probe  Flags
vlan 1                         1.1.1.1 / 255.255.255.0     Up      Down     N/A
vlan 10                   20.20.20.254 / 255.255.255.0     Up      Up       U
 
 
 
Configuring multiple default gateways along with metrics option introduced in the CLI. The multiple default gateways can be configured in two different ways:
  • You can configure multiple routes with metrics under the IP profile to support multiple default gateways.
(host) (config) #ip-profile
(host) (ip-profile) #route 0.0.0.0 0.0.0.0 <next-hop> <metrics>
  •  When DHCP import is configured for the default gateway, you can configure the metrics value under the
   (host) (ip-profile) #default-gateway import dhcp
(host) (ip-profile) #exit
(host) (config) #interface vlan <id>
(host) (vlan "<id>") #metric <cost>
  • ECMP with static routes is supported.
 
Sample Configuration
The following example configures multiple default gateways under the IP profile as static routes:
(host) (config) #ip-profile
(host) (ip-profile) #route 0.0.0.0 0.0.0.0 192.168.1.1 10
(host) (ip-profile) #route 0.0.0.0 0.0.0.0 172.168.1.1 20
The following example configures multiple default gateways under the VLAN interface when the default gateway is obtained from DHCP:
(host) (config) #ip-profile
(host) (ip-profile) #default-gateway import dhcp
(host) (ip-profile) #exit
(host) (config) #interface vlan 10
(host) (vlan "10") #metric 10
 
 
Use the following command to view the configuration under the IP profile:
 
(host) #show ip-profile
ip-profile "default"
--------------------
Parameter Value
--------- -----
Default Gateway N/A
Import DHCP Gateway Disabled controller-ip loopback1
route 0.0.0.0 0.0.0.0 192.168.1.1 10
route 0.0.0.0 0.0.0.0 172.168.1.1 20
 
Answer : The above configuration steps gives the idea of configuring route moniroing on MAS switch.
 
Verification :
 
Here are the commands to verify metric configuration.
==========================================


Verifying Metric Configuration
Use the following command to view the configuration under the interface vlan:
(host) #show interface vlan 10
VLAN10 is administratively Up, Line protocol is Down
Hardware is CPU Interface, Address is 00:1a:1e:08:6d:80
Description: 802.1Q VLAN
Internet address is unassigned
IPV6 link-local address is fe80::1a:1e00:a08:6d80
Global Unicast address(es):
Routing interface is enabled, Forwarding mode is enabled
Directed broadcast is disabled, BCMC Optimization disabled
Encapsulation 802, Loopback not set
Interface index: 50331658
MTU 1500 bytes
Metric 10

The Default Route with least metric is added in the routing table
(host) #show ip route
Codes: C - connected
       O - OSPF, O(IA) - OSPF inter area
       O(E1) - OSPF external type 1, O(E2) - OSPF external type 2
       O(N1) - OSPF NSSA type 1, O(N2) - OSPF NSSA type 2
       M - mgmt, S - static, * - candidate default
       D - DHCP
Gateway of last resort is 20.20.20.2 to network 0.0.0.0 at cost 200
S       * 0.0.0.0  /0 [10] via 192.168.1.1
M        10.16.74.0/26 is directly connected: mgmt
M        10.16.74.42/32 is directly connected: mgmt
C        20.20.20.0/24 is directly connected: vlan200
C        20.20.20.254/32 is directly connected: vlan200
C        50.50.50.0/24 is directly connected: vlan500
C        50.50.50.254/32 is directly connected: vlan500

 
Troubleshooting :
 
In the following scenarios the probe status will be immediately marked as ‘Down’ as probes can’t be sent out
  • IP address is not assigned for the interface where the probe is applied
  • Protocol is down for the interface.
  • Route is not present for the probe destination.
  •  

For viewing the logs related to ‘route not present’ & ‘MAC not resolved’, enable ‘probe’  flag  
(host)(support)#configure t
(host)(config) #traceoptions
(host)(traceoptions) #routing flags probe



Viewing the Logs
(host) #show trace routing
 
 
Jul 21 07:49:27 [L3MGR_PROBE] probe_icmp_receive: Probe recvmsg received bytes: -1 Errno: 11
Jul 21 07:49:27 [L3MGR_PROBE] probe_icmp_send_dest_all vlan_id 500
Jul 21 07:49:27 [L3MGR_PROBE] probe_icmp_send Mac binding is not resolved yet
Jul 21 07:49:27 [L3MGR_PROBE] probe_icmp_send Mac binding is not resolved yet
Jul 21 07:49:27 [L3MGR_PROBE] probe_state_change: ip_resolved[0]: 40.40.40.3 id: 0x0000a1f4 seq: 0x00000000 window: 0x00000000 current: 0x00000000
Jul 21 07:49:27 [L3MGR_PROBE] probe_state_change: ip_resolved[1]: 60.60.60.3 id: 0x0000a1f4 seq: 0x00000000 window: 0x00000000 current: 0x00000000
Jul 21 07:49:32 [L3MGR_PROBE] probe_icmp_receive: Probe recvmsg received bytes: -1 Errno: 11
 
 

 

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Revision #:
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Last update:
‎11-10-2014 04:04 AM
Updated by:
 
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