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Configuring OMP & Its attributes

Configuring OMP & Its attributes

Posted on Jan 27, 2020 (0)

Configuring OMP & Its attributes

OMP protocol is enabled by default and OMP graceful restart is a process which enables OMP peers to continue sending data traffic even though one of the Peer become unavailable for some unknown reason.
Let’s suppose, if vSmart is unavailable, vEdge will continue sending data traffic based on last known OMP routing information received from vSmart controller , likewise , if vEdge is unknown , the vSmart will use its last known routing information it received .

OMP graceful restart is enabled by default on vEdge and vSmart and its default restart time is 12 hrs. This timer indicates that how long the devices will cache the information. When timer expires, the cache routes are no longer valid. As soon as it is enabled, vEdge and vSmart will cache the OMP information received from their peer. This information is OMP routes, TLOC routes, Service Routes, IPSEC SA parameters, centralized data policies.

When any device between vEdge and vSmart is unavailable, they periodically check whether vSmart is available again or not, when they come up, they re-establish the connection and then flush their old routing and other information and cache the latest information received.
To modify the default timer:

Viptela(config-omp)# timers graceful-restart-timer seconds

Timer range is 1 to 604800 seconds (7 days)
It is recommended to enable the same timer in all vEdge and vSmart devices.

To Disable OMP graceful start:

Viptela(config-omp)# no omp graceful-restart

Advertise Routes to OMP

By default, vEdge router advertises connected, static, OSPF (intra area and inter area) routes to OMP and router does not advertise BGP and OSPF external routes to OMP.

To advertise and configure so that vEdge advertise those routes to OMP:

vEdge(config-omp)# advertise (bgp | connected | ospf type | static)

To enable vEdge to advertise routes to OMP for specific VPN

vEdge(config-vpn-omp)# advertise (aggregate prefix [aggregate-only] | bgp | connected | network prefix | ospf type | static)

if you want to advertise specific network instead of advertising all routes use Network command and specify particular prefix.

If aggregation is also used then by default all aggregated and specific routes are advertised, if the requirement is to only advertise aggregated routes, use aggregate-only option.

OMP advertise command will advertise all routes across all VPN, and vpn omp advertise command will advertise routes for that VPN only.

By default, when BGP advertises routes into OMP, BGP advertises each prefix's metric. BGP can also advertise the prefix's AS path when you configure below command.

vEdge(config)# vpn vpn-id router bgp
vEdge(config-bgp)# propagate-aspath

After you configure the above command, the vEdge router will send the AS path information to those router which are behind this vEdge router that is service side network and running BGP and also it receives the AS path information from them.

Once BGP route are redistributed to OMP, AS path information is included in routes, using this command avoids the BG running routing loops.
If in any network , other Overlay ( Viptela ) and underlay ( MPLS ) network are present , that means when any vEdge is connected by MPLS and Viptela Overlay network , it is possible to assign AS number to OMP itself if vEdge router running BGP and this AS number will be included in BGP routing updates.

vEdge(config)# omp
vEdge(omp)# overlay-as as-number ( 1 to 65535 )

Configure the Number of Advertised Routes

As soon as any vEdge learns the network, it advertise to vSmart and vSmart further advertises to rest of vEdge in Overlay network. These routes are advertised as tuple (routes and TLOC associated with routes)


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