SNMP agent enhancements and optimizations

[anand-kumar-subramanian]

Contains support for new RFCs, enhancements to the existing RFCs.

Verified by running SNMP walk at the top

Following are the enhancements and optimizations done in the SNMP agent.

1)Added trap infra support to send db notification as snmp traps.

2)Added support for linkup/linkDown traps.

3)Added support for AgentX NotifyPDU for communicating with master agent.

4)Added support for returning sysObjectId based on platform type.

5)SNMP support for port aliasing

6)Added support for ifPhysAddress

7)Added support ifLastChange

8)Vlan and Loopback interfaces are part of ifTable

9)Supoort for configuration change trap.

10)Support for rfc4188.

Added 1) dot1dBaseBridgeAddress 2) dot1dBaseNumPorts 3) dot1dBaseType 4) dot1dBasePort

5. dot1dBasePortIfIndex 6) dot1dBasePortDelayExceededDiscards 7) dot1dBasePortMtuExceededDiscards

6. dot1dTpAgingTime

11)Support for rfc4363

1. dot1qBase 2) dot1qFdbTable 3) dot1qTpFdbTable 4) dot1qVlanNumDeletes 5) dot1qVlanCurrentTable

2. dot1qVlanStaticTable 7) dot1qPvid

[svc-acs]

Can one of the admins verify this patch?

[lgtm-com]

This pull request introduces 16 alerts when merging 3dfd9b4 into 381ae47 - view on LGTM.com

new alerts:

• 10 for Unused import
• 3 for Except block handles 'BaseException'
• 1 for Unnecessary pass
• 1 for Variable defined multiple times
• 1 for Redundant assignment

[lgtm-com]

This pull request introduces 5 alerts when merging 70619e3 into 025483a - view on LGTM.com

new alerts:

• 2 for Unused import
• 1 for Unnecessary pass
• 1 for Syntax error
• 1 for Variable defined multiple times

[lgtm-com]

This pull request introduces 4 alerts when merging 4ce8e46 into 025483a - view on LGTM.com

new alerts:

• 2 for Unused import
• 1 for Unnecessary pass
• 1 for Syntax error

[lgtm-com]

This pull request introduces 3 alerts when merging ac918c2 into 025483a - view on LGTM.com

new alerts:

• 2 for Unused import
• 1 for Unnecessary pass

[lguohan]

can you provide more descriptions? what are the new rfc? improvements?

[qiluo-msft]

Please resolve the conflicts

[qiluo-msft]

I read quickly the code and see lots of great contribution mixed into one PR. Could you please split into multiple individual PRs on each topics?

The topics 4~8 looks incremental and relative easy to be reviewed.
The topics 10~11 introduces new MIBs and need more effort to review.
The topics 1~3 are quite new use cases and we need careful study the design and investigate the code in close details.