ARISTA-NEXTHOP-GROUP-MIB

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Organization: Arista Networks, Inc.

Last Updated: 2016-04-17

Category: Vendor: Arista

Description: Arista EOS next-hop group configuration for ECMP and policy-based forwarding management.

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What Is ARISTA-NEXTHOP-GROUP-MIB?

ARISTA-NEXTHOP-GROUP-MIB is an Arista Networks vendor MIB for EOS-based switches/routers, covering next-hop group (NHG) configuration used for ECMP (Equal Cost Multipath) and policy-based forwarding. It exposes the configured next-hop groups, their names and types, along with per-entry packet and byte counters that track traffic forwarded through each next-hop within a group. Administrators use it to monitor software/forwarding-plane status — checking that traffic is being load-balanced as expected across ECMP paths or policy-routed next-hops, and detecting an imbalanced or zero-traffic next-hop that would indicate a failed or misconfigured path. The module is self-contained around Arista's own object tree but conceptually complements standard routing MIBs (e.g., IP-MIB, IP-FORWARD-MIB) for full routing visibility, though no explicit standard dependency is stated. It is typically deployed in data center or service-provider networks running Arista EOS switches that use ECMP or manual next-hop-group forwarding policies. Engineers can download the ARISTA-NEXTHOP-GROUP-MIB file directly to load it into their MIB browser.

IPNetwork Monitor allows you to monitor SNMP objects defined in ARISTA-NEXTHOP-GROUP-MIB. Use the built-in SNMP Monitoring Browser to explore available variables, view their current values and descriptions, and select the objects you want to monitor. You can then create SNMP monitors, configure thresholds, and receive alerts when monitored values change.

Supported Devices

Arista Networks EOS switch/router

Monitoring Examples

An operator would poll aristaNexthopGroupTable (via aristaNexthopGroupEntry) to see each group's aristaNexthopGroupName and aristaNexthopGroupType, then check aristaNexthopGroupCounterTable entries for aristaNexthopGroupCounterPacketCount and aristaNexthopGroupCounterByteCount per next-hop, indexed by aristaNexthopGroupEntryIndex and aristaNexthopGroupCounterIndex. A next-hop showing zero or stalled packet/byte counts while its siblings in the same group carry traffic would reveal that ECMP path has silently failed or been withdrawn from forwarding. These objects are drawn directly from the sample objects provided for this MIB.

What Can Be Monitored

next-hop group configuration
next-hop group type
per-next-hop packet count
per-next-hop byte count
ECMP path traffic distribution

Imported Objects

From ARISTA-SMI-MIB

aristaMibs

OBJECT-IDENTITY

From SNMPv2-CONF

MODULE-COMPLIANCE
OBJECT-GROUP

From SNMPv2-SMI

Counter64
MODULE-IDENTITY
OBJECT-TYPE
Unsigned32

From SNMPv2-TC

TEXTUAL-CONVENTION

How to Use in IPNetwork Monitor

Example using aristaNexthopGroupCounterPacketCount OID:

Select an Arista Networks EOS switch as the target host to create a monitor — the SNMP service should be up and running on it. Click New Monitor, then check SNMP Custom on the Favorites tab, click Next, and confirm the host. On the next page, click Select... to open the built-in SNMP MIB Browser and type aristaNexthopGroupCounterPacketCount into the Find box to locate it in the OID tree, selecting the specific row/instance you want to monitor since this is a table column, then select it and click OK. The number of packets forwarded through the specific nexthop. On the monitor's Main parameters page you can set the target's SNMP port (default 161), credentials, polling interval, and other settings — see the SNMP Monitor help for details. On the State conditions and Alerting tabs, configure when the monitor should change state and trigger an alert; since this is a Counter64-type OID, Value bounds is the most useful condition here — trigger an alert if the counter increases sharply between polls relative to its normal baseline, since an unexpected spike often reflects a real change in traffic or activity. Click Finish to create the monitor; you can adjust any parameter later.

OIDs

OID symbolic	OID numeric	Type	Access	Description
aristaNexthopGroupMIB	1.3.6.1.4.1.30065.3.21			This MIB contains information about NextHop Groups (NHG). General L3 routing creates routing table entries, each of which are associated with a nexthop. If multiple paths exist for a specific route, the route points to a set of nexthops (commonly referred as ECMP or Equal Cost MultiPath). Arista devices support a feature which allows customers to manually create a nexthop list, and use this list to route packets to the specified set of nexthop addresses. Customers can associate a tunnel type (GRE, for example) with the nexthop group, allowing relevant packets to be tunneled as well. The packet forwarding or routing decision happens in hardware. Nexthop group feature gives customers full control of how a route should be forwarded (tunneled or otherwise). The number of entries in the nexthop group is also determined by the user, and directly translates to the number of nexthop entries in the hardware for the specified route. Let's provide an example, looking at EOS CLI example. nexthop-group foo type ip-in-ip ttl 64 entry 0 tunnel-destination 10.1.1.1 entry 1 tunnel-destination 20.1.1.1 ! ip route 30.1.1.0/24 Nexthop-Group foo In the above configuration, any packet destined to 30.1.1.0/24 will be forwarded by the nexthop group 'foo'. Each entry inside the nexthop group specifies a particular nexthop ('tunnel destination') chosen by the customer. In this example, packets can be forwarded via either of the nexthop (traffic split equally between the 2 entries). This MIB module provides information relevant to the nexthop group feature, specifically the status of various nexthop groups configured, and traffic statistics.
aristaNexthopGroupMibObjects	1.3.6.1.4.1.30065.3.21.1
aristaNexthopGroupTable	1.3.6.1.4.1.30065.3.21.1.1		not-accessible	This table contains information about the nexthop groups that are present in the device.
aristaNexthopGroupEntry	1.3.6.1.4.1.30065.3.21.1.1.1		not-accessible	A conceptual row, containing information for a specific nexthop group.
U32 aristaNexthopGroupId	1.3.6.1.4.1.30065.3.21.1.1.1.1	Unsigned32	not-accessible	Unique index identifying a nexthop group.
NEX aristaNexthopGroupName	1.3.6.1.4.1.30065.3.21.1.1.1.2	NexthopGroupName	read-only	Unique name identifying a nexthop group.
NEX aristaNexthopGroupType	1.3.6.1.4.1.30065.3.21.1.1.1.3	NexthopGroupType	read-only	The type of the nexthop group. The encapsulation information provided for each entry in the nexthop group corresponds to the type.
aristaNexthopGroupCounterTable	1.3.6.1.4.1.30065.3.21.1.2		not-accessible	Each nexthop group contains several entries - each entry specifies a particular nexthop through which a packet can be forwarded. There is packet and byte counter information associated with each such nexthop. This table represents the per nexthop counter information for every nexthop group.
aristaNexthopGroupCounterEntry	1.3.6.1.4.1.30065.3.21.1.2.1		not-accessible	A conceptual row, containing counter information for every nexthop defined inside the nexthop group.
U32 aristaNexthopGroupEntryIndex	1.3.6.1.4.1.30065.3.21.1.2.1.1	Unsigned32	not-accessible	As described in the beginning of the MIB module each nexthop group can have multiple entries, one per 'destination' or 'nexthop'. Each entry within a nexthop group has a number or index as configured by the user. This MIB object represents the entry index within the nexthop group.
U32 aristaNexthopGroupCounterIndex	1.3.6.1.4.1.30065.3.21.1.2.1.2	Unsigned32	read-only	For every nexthop within a nexthop group, packet and byte counters are maintained by the device. Counters can be shared by multiple such nexthops and the counter index will be the same for all of those nexthops.
C64 aristaNexthopGroupCounterPacketCountEx	1.3.6.1.4.1.30065.3.21.1.2.1.3	Counter64	read-only	The number of packets forwarded through the specific nexthop. Note that since counters are shared with multiple nexthops, the packet count is an aggregate of packets forwarded through all the relevant nexthops.
C64 aristaNexthopGroupCounterByteCount	1.3.6.1.4.1.30065.3.21.1.2.1.4	Counter64	read-only	The byte count of packets forwarded through the specific nexthop. Note that since counters are shared with multiple nexthops, the byte count is an aggregate of packets forwarded through all the relevant nexthops.
aristaNexthopGroupMibConformance	1.3.6.1.4.1.30065.3.21.2
aristaNexthopGroupMibCompliances	1.3.6.1.4.1.30065.3.21.2.1
aristaNexthopGroupMibCompliance	1.3.6.1.4.1.30065.3.21.2.1.1			The compliance statement for Arista switches that implement the ARISTA-NEXTHOP-GROUP-MIB.
aristaNexthopGroupMibGroups	1.3.6.1.4.1.30065.3.21.2.2
aristaNexthopGroupGroup	1.3.6.1.4.1.30065.3.21.2.2.1			The collection of objects that provide nexthop group information in the system.
aristaNexthopGroupCounterGroup	1.3.6.1.4.1.30065.3.21.2.2.2			The collection of objects that provide counter information for every nexthop in the nexthop group.

RFC description

Defines management objects for Arista NextHop Groups (NHG), which allow manual creation of nexthop lists for routing decisions with tunnel support (such as GRE) for packet forwarding in hardware.

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Download ARISTA-NEXTHOP-GROUP-MIB