> ## Documentation Index
> Fetch the complete documentation index at: https://docs.megaport.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Configuring an MCR

> This help topic describes how to edit and configure a Megaport Cloud Router (MCR) and Virtual Cross Connect (VXC).

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This topic describes how to edit and configure a Megaport Cloud Router (MCR) and Virtual Cross Connect (VXC). Before you begin, you need to create an MCR and configure a VXC, as described in [Creating an MCR](/mcr/creating-mcr) and [Creating an MCR VXC](/mcr/mcr-vxc).

<Anchor name="editmcr" />

## Editing an MCR

For each MCR, you can edit any field on the MCR Configuration page, except the rate limit, which is fixed for the duration of the service. The Megaport Marketplace service availability must also be set in your Megaport Marketplace profile.
For more information about how to make your service visible to the Megaport Marketplace, see [Adding services to your profile](/marketplace/profile#adding-services-to-your-profile).

<Note>
  You can edit the MCR ASN after deployment, but only when there are no VXCs attached. You will need to move or remove all VXCs before editing the ASN. For more information, see [Moving VXCs](/connections/move-vxc).
</Note>

**To edit an MCR**

1. Log in to the <Link href="https://portal.megaport.com">Megaport Portal</Link> and choose **Services**.

2. Select the MCR you want to edit.
   <Image src="/images/mcr/mcr-edit-existing.png" alt="Edit MCR" shadow={true} width={600} />

3. Edit any field on the MCR Configuration page as required, except for the MCR Rate Limit, Megaport Marketplace visibility, and MCR ASN (depending whether a VXC is attached).

   * The **Initial BGP State** lets you select whether newly created BGP connections are enabled or shut down by default. Select Enabled (the default) if you want any new BGP sessions you configure to be live as soon as you save the configuration. Select Shut Down if you want any new BGP sessions you configure to be left in a shut down state when you save the configuration.

     For example, you might want to select the Shut Down option if you are planning to add several BGP sessions across your Virtual Cross Connects (VXCs) but know that you want to do some other router setup before you want them exchanging route information. When you are finished configuring your routers, you can then go into the relevant BGP sessions and enable them.

   * The setting you choose here just sets the default state for the new BGP session. You can override this in the MCR Connection detail screen. For more information about overriding the BGP state for an individual connection, see [Shutting down a BGP connection](/mcr/configuring-mcr#bgpshut).

   For more information, see [Creating an MCR](/mcr/creating-mcr).

4. Click **Save**.

<Anchor name="editing-a-vxc" />

## Editing a VXC

For each VXC connected to an MCR you can configure one or more interfaces, IP addresses, BGP connections, or static routes. You can also select a NAT source IPv4 address and specify the IP MTU value.

Depending on the VXC destination or CSP provider, the MCR connection settings might have been auto-configured during VXC creation. Follow the steps in this task to configure the connection settings as required.

<Note>
  If the VXC provisioning status is LIVE, CONFIGURED, or DEPLOYABLE, the connection configuration fields will be available when editing a VXC regardless of provider.
</Note>

**To edit a VXC interface**

1. Select the MCR VXC you want to edit.

2. Select the VXC A-End or B-End.

   <Image src="/images/mcr/mcr-a-end-vxc.png" alt="Edit MCR VXC" shadow={true} width={600} />

3. Enter a description for the connection.

4. Enter one or more interface IP addresses and subnet masks to configure on the A-End interface.

5. (Optional) Select a NAT source IPv4 address from the **Network Address Translation (NAT)** drop-down list.\
   All packets leaving this interface will have their source NAT rewritten to this address.

   <Gloss term="Network Address Translation (NAT)" anchor="nat" /> allows flexibility in designing a scalable and secure multi-vendor, multicloud, or hybrid cloud scenario. Source NAT translates the source IP address of a packet leaving the MCR. When you assign a NAT IP address in MCR, all packets leaving the interface use that IP address as their source IP address. Enable this feature when NAT is required for a connection, for example, when you need to translate several private IP addresses into a single public IP address to meet Cloud Service Provider (CSP) requirements.

   For more information about how MCR performs NAT to support public peering types to cloud service providers, see [How MCR performs NAT](/mcr/mcr-nat/).

6. (Optional) Enter an <Gloss term="IP MTU (Maximum Transmission Unit)" anchor="ipmtu" /> value (in bytes) for the VXC.\
   The IP MTU can range from 1280 to 9070 (9074 if Q-in-Q is disabled). The default value is 1500.\
   For more information, see [MCR Advanced VLAN and Routing Features](/mcr/mcr-version-two/) and [Using IPsec with MCR](/mcr/ipsec-mcr/).

7. (Optional) If IPsec has been enabled on your MCR, you can configure IPsec tunnels.

   Click **+ Add IPsec Tunnel Interface**.\
   Add the IPsec tunnel details:

   * **Description** -- Enter a description of the IPsec tunnel for your reference.
   * **Source IP Address** -- Click the box and select the address from the drop-down list.\
     This is a list of interface IP addresses defined on this VXC.
   * **Destination IP Address** -- Add the destination IP address.\
     The destination IP address of the tunnel must not be an IP address configured on the same MCR.
   * **Pre-shared key** -- Add a key that is common to both the IKE2 (Internet Key Exchange version 2) initiator and responder. The length must be between 8 and 100 characters.
   * **Local Identifier** (optional) -- Enter the identifier used for IKE authentication. This allows you to override the default source IP address with a non-IP address, which is required for some configurations. By default, the source IP address is used. Valid values include IPv4/IPv6 addresses, domain names, and email addresses (lowercase, 5-100 characters). For example, `megaport.com` or `user@example.com`.
   * **Remote Identifier** (optional) -- Enter the identifier used for IKE authentication. This allows you to override the default destination IP address with a non-IP address, which is required for some configurations. By default, the destination IP address is used. Valid values include IPv4/IPv6 addresses, domain names, and email addresses (lowercase, 5-100 characters). For example, `megaport.com` or `user@example.com`.
   * **Start Action** -- Select either active or passive.	Passive indicates that the local MCR is an IPsec responder waiting for the remote to perform IKE2 initiation.
   * **Phase 1 Lifetime** -- Enter a value between 300 and 604800 seconds. This is the lifetime of IKE2 session in seconds. The default value is 28800 seconds (8 hours). When it expires, rekeying will occur.
   * **Phase 2 Lifetime** -- Enter a value between 300 and 86400 seconds. This is the lifetime in seconds of the IPsec Security Association (SA). The value must be less than the Phase 1 Lifetime. The default value is 3600 seconds (1 hour). When it expires, rekeying will occur.

     <Image src="/images/mcr/ipsec-config.png" alt="IPsec config details" shadow={true} width={800} />

8. Enter any details specific to the VXC type.
   * For more information about configuring IPsec, see [Using IPsec with MCR](/mcr/ipsec-mcr/).
   * For more information about using packet filters, see [Using Packet Filters](/mcr/packet-filters/).
   * For more information about adding a BGP connection, see [Configuring BGP](/mcr/configuring-mcr/#configbgp).
   * For more information about enabling Bidirectional Forwarding Detection (BFD) settings, see [Enabling the BFD protocol](/mcr/mcr-bgp-advanced/#bfd).
   * For more information about adding a static route, see [Configuring static routes](/mcr/configuring-mcr/#static).
   * For more information about configuring a DHCP server, see [Configuring a DHCP pool](/mcr/configuring-mcr/#dhcp).

9. Click **Save**.

<Anchor name="packetfilter" />

## Using packet filter lists

Packet filters are used to manage the traffic that is allowed to flow through your MCR. You can apply packet filter lists to your VXC if they have been defined on the MCR. Using packet filter lists is optional.\
For more information, see [Using Packet Filters](/mcr/packet-filters).

**To apply packet filter lists**

1. In the <Link href="https://portal.megaport.com">Megaport Portal</Link>, go to the **Services** page.

2. Select the VXC and select the A-End or B-End.

3. Select the packet filter lists to apply from the drop-down lists.\
   You can select inbound and outbound filters.

4. Click **Save**.

<Anchor name="configbgp" />

## Configuring BGP

The <Gloss term="Border Gateway Protocol (BGP)" anchor="bgp" /> allows dynamic route table updates from the MCR across the VXC to the port. Enable one or more BGP peers for the MCR, up to a maximum of five.

**To configure BGP**

1. On the MCR Connection detail page, click **Add BGP Connection**.

   <Image src="/images/cloud/megaport/aws/mcr-add-bgp.png" alt="IP details" shadow={true} width={950} />

2. Specify these values:

   * **Local IP** -- Select the IP address on this interface that communicates
     with the BGP peer. The drop-down menu is auto-populated based on the address
     you specified in the connection detail.

   * **Peer IP** -- Specify the IP address for the BGP peer. For example, if the
     local IP is 198.162.100.1, the peer IP address would be
     198.162.100.2.

   * **Peer ASN** -- The ASN of the target routing device that will terminate the BGP connection. The ASN range is from 2 to 4294967294. 4-byte ASNs are supported in the asplain format.

   * **BGP Password** -- The shared key to authenticate the BGP peer. A shared key is optional when creating the VXC, but is required to set up the BGP peering. You can add it after you create the VXC. The shared key length is from 1 to 25 characters. The key can include any of these characters:\
     a-z\
     A-Z\
     0-9\
     ! @ # . \$ % ^ & \* + = - \_

     <Tip>
       Click the eye icon to see the password as you type. The view persists until you click the eye icon again to hide the password.
     </Tip>

   * **Description** (optional) -- Enter a description that will help identify this connection. The description length can range between 1 and 100 characters.

   * **BGP State** -- Shuts down the connection without removing it. The initial setting will be taken from the setting on the A-End of the MCR. Enabling or shutting down the BGP state does not affect existing BGP sessions. The BGP state only affects new VXCs. This setting overrides the MCR state for an individual connection. For more information, see [Shutting down a BGP connection](#bgpshut) and [Creating an MCR](/mcr/creating-mcr).

   <Note>
     - If you have entered multiple CIDR ranges, the IP addresses are available for selection.
     - Use a CIDR calculator to ensure that all data is valid and within range.
   </Note>

3. Click **Add**.

4. Click **Next**.

**To edit a BGP connection**

1. Select the VXC and select MCR A-End or MCR B-End.
2. Next to the BGP connection, click **Edit**.
3. Make your changes.
4. Click **Update**.

For information on the BGP Advanced tab settings, see [Configuring BGP Advanced Settings](/mcr/mcr-bgp-advanced).

<Anchor name="static" />

## Configuring static routes

Static routes establish reachability to peers in place of BGP connections that provide dynamic routing. You configure static routes to provide connectivity to a customer device that doesn't support BGP or to a target device that requires manually configured addressing and routes. With static routes, you need to manually update any topology changes.

An MCR supports up to 100 static routes.

**To add a static route**

1. Select the VXC and select MCR A-End.
2. In the MCR Connection detail page, under Static Routes, specify the IPv4 or IPv6 destination network address in CIDR notation.
3. Specify the IPv4 or IPv6 address of the next-hop router.\
   The address must be in the same subnet as the interface but it cannot match the interface IP address.
4. (Optional) In the Description field, include any notes that will help identify this static route.\
   The description range is from 1 to 100 characters.
5. Click **Next**.
6. Update the MCR B-End, if necessary.
7. Click **Next**.
8. Click **Update**.

To view static routes, see [Viewing Traffic Routing through the MCR Looking Glass](/mcr/mcr-looking-glass).

<Anchor name="dhcp" />

## Configuring a DHCP pool

You can configure a <Gloss term="DHCP" anchor="dhcp" /> pool on an MCR VXC interface to assign IPv4 addresses to devices connected through that interface.\
When configured, the MCR acts as a <Gloss term="DHCP server" anchor="dhcp-server" /> for the connected network.

<Note>
  DHCP pools are not available on IPsec tunnel interfaces, connections to Megaport Internet, or connections to an Internet Exchange.
</Note>

**To add a DHCP pool**

1. Select the gear icon on the VXC, then select MCR A-End.

2. Under DHCP Pool, click **+ Add Pool**.

3. Specify these values:
   * **Network** -- The IPv4 network in Classless Inter-Domain Routing (<Gloss term="CIDR" anchor="cidr" />) notation for the DHCP pool. The network must be a valid IPv4 address and must be a subnet of the interface's IPv4 prefix. The minimum prefix length is /30. For example, `192.168.1.0/30`.\
     For more information, see [Classless Inter-domain Routing (CIDR)](https://en.wikipedia.org/wiki/Classless_Inter-Domain_Routing).
   * **Start Address** -- The first IPv4 address in the range to assign to DHCP clients. The address must be within the specified network.
   * **End Address** -- The last IPv4 address in the range to assign to DHCP clients. The address must be within the specified network and greater than or equal to the start address.

4. (Optional) Click **Add DNS Server** to specify one or more DNS resolver IP addresses provided to DHCP clients. You can add up to 5 DNS servers.

5. (Optional) Click **Add Default Gateway** to specify the default gateway IP address provided to DHCP clients.

6. (Optional) Click **Add Description** to enter a description for the DHCP pool. The description can be up to 100 characters.

7. Click **Save**.

**To delete a DHCP pool**

1. Select the gear icon on the  VXC, then select MCR A-End.
2. Under DHCP Pool, click **Delete**.
3. Click **Save**.

## Verifying the BGP configuration

The MCR Looking Glass provides single-screen visibility into the BGP configuration. For more information, see [Viewing Traffic Routing through MCR Looking Glass](/mcr/mcr-looking-glass).

**To view the BGP status**

1. In the <Link href="https://portal.megaport.com">Megaport Portal</Link>, go to the **Services** page.
2. Select the VXC.
3. Choose **Details**.\
   The Configuration Details page shows the provisioning, service, and BGP status.
   <Image src="/images/mcr/mcr-bgp-status.png" alt="View the BGP status in the Configuration Details page" shadow={true} width={950} />

## Troubleshooting BGP

If the Services > Connection Detail page displays a status issue, verify these items:

1. Select the VXC and select MCR A-End or B-End.
2. Under BGP Connections, verify that the correct local ASN is in use for the A-End of the VXC.
3. Verify that the correct peer IP address is in use.
4. Verify that the correct BGP MD5 password is in use for the A-End of the VXC.

If the BGP configuration looks correct:

* Make sure that a BGP peer is not blocking ingress or egress from TCP port 179 (BGP) and other relevant ephemeral ports.

* Verify that a BGP peer is not advertising more than 100 prefixes to AWS. The maximum number of advertised routes to AWS is 100. The BGP session is disabled if it exceeds the prefix limit of 100 advertised routes.

<Anchor name="bgpshut" />

### Shutting down a BGP connection

Use this setting to temporarily disable the BGP session without removing it. BGP shutdown provides a way to administratively shut down a BGP connection while setting up a new route, performing maintenance, troubleshooting, and so on.

**To temporarily disable a BGP connection**

1. In the <Link href="https://portal.megaport.com">Megaport Portal</Link>, go to the **Services** page.

2. Select the VXC and select the A-End or B-End.

3. After the BGP connection details, click **Shut Down**.

4. Click **Yes** to confirm.

<Anchor name="bgp-notification" />

### Setting up MCR BGP notifications

You can receive email notifications whenever a <Gloss term="Border Gateway Protocol (BGP)" anchor="bgp" /> session status changes on your MCR.  These changes can include BGP going up, down, or flapping. If a session is flapping, only one email per hour will
be sent.

You can opt in or out of receiving these email notifications.

**MCR BGP notifications email specifications**

The MCR BGP notification system is designed to provide timely notifications for BGP up, down, or flapping events while minimizing alert noise.

The notification system implements rate limiting for rapidly changing status, as described below.

* The initial notification is sent immediately.
* Subsequent events within one hour are suppressed.
* The email body will indicate if the event has repeated during the suppression period.

**To receive BGP email notifications**

1. Visit the <Link href="https://portal.megaport.com">Megaport Portal</Link> and log in.
2. Choose User Menu > User Settings > Notifications.
3. Click the Service Status notification group to view the BGP email notification types.
4. Select the notification group check box to subscribe to all notifications in that group, or subscribe to individual notification types. Any notification subscription changes are automatically saved.

<Image src="/images/snippets/service-status-notification-box.png" alt="Service Status Notification" shadow={true} width={750} />

## Configuring flow export

Flow export enables IP Flow Information Export (<Gloss term="IPFIX" anchor="ipfix" />) on MCR services, allowing you to export network flow records to external collectors for traffic analysis, capacity planning, and security monitoring.

You can configure up to three flow export targets for each MCR. Flow records are exported using either the UDP or TCP transport protocol.

A flow export target specifies the destination to which flow records are sent.

### Requirements

Before configuring flow export, ensure that your service meets these requirements:

* The MCR must be in a *Live* or *Configured* provisioning state.
* You must have a flow collector ready to receive IPFIX data.
* The MCR must have an active route to the collector via any attached VXC.

### Validation rules

These validation rules apply when configuring flow exporters:

* **Maximum Targets** -- Each service supports up to three flow export targets.
* **Target IP Address** -- Cannot be a reserved or loopback address (for example, 127.0.0.1).
* **Target Port** -- Must be between 1 and 65535.
* **Address Family** -- If you specify a Local IP Address, it must be the same address family (IPv4 or IPv6) as the Target IP Address.
* **Uniqueness** -- The combination of Target IP Address, Target Port, and Protocol must be unique within the service.

**To configure flow export**

1. In the <Link href="https://portal.megaport.com">Megaport Portal</Link>, go to the **Services** page.

2. Click the gear icon next to the MCR.

3. On the MCR Configuration page, select the **Flow Export** tab.

   <Image src="/images/mcr/mcr-flow-export-config.png" alt="MCR config flow export" shadow={true} width={600} />

4. Click **Add Export Target**.

   The Add Export Target page appears.

   <Image src="/images/snippets/add-export-target-fields.png" alt="Add export target fields" shadow={true} width={400} />

   1. Specify the configuration details:
      * **Description** -- Enter a name to identify this flow export target.
      * **Local IP Address (optional)** -- The source IP address on the service for the flow export stream. Select an address configured on the service, or leave blank to use the default.
      * **Target IP Address** -- Enter the IPv4 or IPv6 address of your flow collector.
      * **Target Port** -- The port number of the flow collector (1-65535). Enter the port number your collector listens on.
      * **Protocol** -- Select **UDP** or **TCP**.

   2. Click **Add**.
      The new flow export target configuration details are displayed in the table.

<Image src="/images/mcr/mcr-flow-export-3-targets.png" alt="MCR 3 flow export targets setting" shadow={true} width={900} />

<Note>
  A maximum of three IPFIX export targets can be configured per service. Each target must have a unique combination of the Local IP Address and collector targets (Target IP Address, Target Port and Protocol).
</Note>

**To edit a flow export configuration**

1. In the <Link href="https://portal.megaport.com">Megaport Portal</Link>, go to the **Services** page.

2. Click the gear icon next to the MCR.

3. On the MCR Configuration page, select the **Flow Export** tab.

4. In the row for the flow export configuration you want to edit, click **Edit**.
   <Image src="/images/mcr/mcr-flow-export-edit.png" alt="MCR mcr flow export edit" shadow={true} width={900} />

5. Update the configuration details as required.

6. Click **Save**.

**To delete a flow export configuration**

<Warning>
  Deleting a flow export target immediately stops exporting flow records to that collector. This action cannot be undone.
</Warning>

1. In the <Link href="https://portal.megaport.com">Megaport Portal</Link>, go to the **Services** page.

2. Click the gear icon next to the MCR.

3. On the MCR Configuration page, select the **Flow Export** tab.

4. In the row for the flow export configuration you want to remove, click **Delete**.
   <Image src="/images/mcr/mcr-flow-export-delete.png" alt="MCR mcr flow export delete" shadow={true} width={900} />

5. In the confirmation prompt, click **Delete Target**.

## Helpful references

* [Creating an MCR ](/mcr/creating-mcr)
* [Creating an MCR VXC](/mcr/mcr-vxc)
* [Managing IPFIX Targets with the API](/api/api-ipfix-targets)
* [MCR Route Filtering](/mcr/route-filtering)
* [Using IPsec with MCR](/mcr/ipsec-mcr)
* [Using Packet Filters](/mcr/packet-filters)
* [Viewing Traffic Routing through MCR Looking Glass](/mcr/mcr-looking-glass)