September 2011

TIL: Exchange 2010 – Managing A User’s Calendar with Powershell

I can’t count how many times users will email me with a request to have access to another user’s calendar. I initially got rid of some of the requests by having everyone with “reviewer” privileges to a user’s calendar

After you get through the privacy hoops, the only way I knew to give someone access (such as editing and publishing) to another’s calendar was to give them full permission to their mailbox. Not the ideal solution, especially depending on the user you’re changing.

The other option was to give them instructions on how they can share their calendars etc.

Nowadays users request access because the other user is not available.

Today I Learned (TIL) that you can manage calendar permissions through powershell.

The command:

add-mailboxfolderpermission -identity target-user:\Calendar -user requesting-user -accessrights PublishingEditor

add-mailboxfolderpermission - this is the verb that tells Exchange what we’re doing

-target-user:\Calendar - Replace target-user with the user you are trying to edit. the “:Calendar” is the folder in which we are modifying permissions to.

-requesting-user - Replace requesting-user with the user account that needs permission

Here are the different values for the access rights:

  • None
  • Owner
  • PublishingEditor
  • Editor
  • PublishingAuthor
  • Author
  • NonEditingAuthor
  • Reviewer
  • Contributor
If you want to see what the command will do just add the -whatif parameter at the end of the command:
add-mailboxfolderpermission -identity jdoe:\Calendar -user bdole -accessrights editor -whatif
The -whatif parameter will tell you what you’re about to do. When you’re ready, just remove the -whatif parameter.
To verify the added permission you can run the command:
get-mailboxfolderpermission -identity target-user:\Calendar

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EIGRP and It’s Tables

The following notes are based off of the CCNP ROUTE Foundation Learning Guide.

In the last post I summarized some basic EIGRP operations that you need to know before moving on. This post we talk about the different Tables and the associated terms important to EIGRP operation.

Neighbor table 

Routers that form adjacencies will be included in this table. Neighbors are found using the Hello packet.

 

Topology table

When a router becomes a neighbor, the new neighbor will send the routes it knows to the local router which then gets put into the Topology table.

 

Routing table

The routing table has all the best routes to each destination and is used by the router to forward packets. Successor routes are sent to the IP routing table from the topology table.

 

*EIGRP routes only shown in the IP routing table

Advertised distance

The advertised distance (AD) is the lowest cost route between the next hop router and the destination.

Feasible distance

The feasible distance is calculated by taking the sum of the AD + the cost between the local router and next hop router.

Successor

A successor is a loop free lowest cost route to a destination. Successors are sent to the routing table and can have multiple successors.

Feasible successor

These are backup paths to destinations. To become a feasible successor, the neighboring router must have an advertised distance that is less than the feasible distance of the current successor route to maintain a loop free topology. Feasible successors are kept in the topology table and don’t make it to the routing table unless the successor route fails. The feasible successor allows EIGRP to have fast convergence. If there is no feasible successor and the successor route fails then EIGRP begins a query for a loop free route to the failed destination.

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Understanding EIGRP

The following notes are based from the text book CCNP Route Foundation Learning Guide.

The first routing protocol of the CCNP Foundation Learning Guide is EIGRP. It’s a large chapter that needs to be broken down into sections. What I’ve done is taken pieces of the chapter and created my own summary of what I’ve read to help solidify my knowledge.

So we begin learning about the characteristics of EIGRP. First off, the routing process uses protocol number 88 in the IP header. It’s not using TCP (protocol number 6) or UDP (protocol number 17). EIGRP is a Cisco proprietary routing protocol. Most networks will not use this protocol because of this. One such example is ISPs. You can only use other Cisco devices with EIGRP.

So why use EIGRP? It’s fast to converge. EIGRP uses DUAL (diffusing update algorithm) to calculate loop free routes. Backup routes are inserted into the topology table (more on this) so if the destination in the IP routing table fails, EIGRP can quickly converge to the loop free backup route.

During normal operation, EIGRP will only send partial updates when changes occur – such as links changing. When sending updates, EIGRP will communicate using multicast or unicast addresses. EIGRP packets are sent to the multicast address of 224.0.0.10. Unicast addresses are those of the destination router.

Another advantage of EIGRP is that it supports Variable Length Subnet Masking (VLSM) which advertises the subnet mask for each destination network and allows EIGRP to support discontinuous networks.

The metric used by EIGRP is the same algorithm used by IGRP which supports unequal cost load balancing.

Each EIGRP packet is transmitted reliably through RTP (reliable transport protocol). This guarantees the delivery of EIGRP packets to neighbors (except for Hello packets).

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