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Manual Chapter: Dynamic Routing
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Dynamic Routing

Dynamic routing on the BIG-IP system

By enabling and configuring any of the BIG-IP® advanced routing modules, you can configure dynamic routing on the BIG-IP system. You enable one or more advanced routing modules, as well as the Bidirectional Forwarding Detection (BFD) protocol, on a per-route-domain basis. Advanced routing module configuration on the BIG-IP system provides these functions:

  • Dynamically adds routes to the Traffic Management Microkernel (TMM) and host route tables.
  • Advertises and redistributes routes for BIG-IP virtual addresses to other routers.
  • When BFD is enabled, detects failing links more quickly than would normally be possible using the dynamic routing protocols' own detection mechanisms.
Note: On the BIG-IP system, directly-connected and static routes take precedence over dynamically-learned routes.

Supported protocols for dynamic routing

The BIG-IP® advanced routing modules support these protocols.

Table 1. Dynamic routing protocols
Protocol Name Description Daemon IP version supported
BFD Bidirectional Forwarding Detection is a protocol that detects faults between two forwarding engines connected by a link. On the BIG-IP system, you can enable the BFD protocol for the OSPFv2, BGP4, and IS-IS dynamic routing protocols specifically. oamd IPv4 and IPv6
BGP4 Border Gateway Protocol (BGP) with multi-protocol extension is a dynamic routing protocol for external networks that supports the IPv4 and IPv6 addressing formats. bgpd IPv4 and IPv6
IS-IS Intermediate System-to-Intermediate System (IS-IS) is a dynamic routing protocol for internal networks, based on a link-state algorithm. isisd IPv4 and IPv6
OSPFv2 The Open Shortest Path First (OSPF) protocol is a dynamic routing protocol for internal networks, based on a link-state algorithm. ospfd IPv4
OSPFv3 The OSPFv3 protocol is an enhanced version of OSPFv2. ospf6d IPv6
PIM The Protocol Independent Multicast (PIM) protocol is a dynamic routing protocol for multicast packets from a server to all interested clients. pimd IPv4 and IPv6
RIPv1/RIPv2 Routing Information Protocol (RIP) is a dynamic routing protocol for internal networks, based on a distance-vector algorithm (number of hops). ripd IPv4
RIPng The RIPng protocol is an enhanced version of RIPv2. ripngd IPv6

About the Bidirectional Forwarding Detection protocol

Bidirectional Forwarding Detection (BFD) is an industry-standard network protocol on the BIG-IP® system that provides a common service to the dynamic routing protocols BGPv4, OSPFv2, and IS-IS. Enabled on a per-route domain basis, BFD identifies changes to the connectivity between two forwarding engines, or endpoints, by transmitting periodic BFD control packets on each path between the two endpoints. When either endpoint fails to receive these control packets for a specific duration of time, the connectivity between the endpoints is considered lost, and BFD notifies the associated dynamic routing protocols. In general, BFD detects connectivity changes more rapidly than the endpoints' standard Hello mechanisms, leading to quicker network convergence, which is highly desirable to data center applications.

BFD operates by establishing a session between two endpoints, sending BFD control packets over the link. If more than one link exists between two endpoints, BFD can establish multiple sessions to monitor each link.

A BFD session can operate in one of two modes, either asynchronous mode or demand mode:

  • You configure BFD to operate in asynchronous mode when you want both endpoints to verify connectivity by periodically sending Hello packets to each other. This is the most commonly-used mode.
  • You configure BFD to operate in demand mode when you want the endpoints to use another way to verify connectivity to each other instead of sending Hello packets. For example, the endpoints might verify connectivity at the underlying physical layer. Note, however, that in demand mode, either host can send Hello packets if needed.
Note: BFD failure detection between two BIG-IP systems does not trigger failover.

Configuration overview

The first step in configuring the Bidirectional Forwarding Detection (BFD) protocol on the BIG-IP® system is to use the IMI Shell within tmsh to configure the protocol for the relevant advanced routing modules (BGP4, OSPFv2, and IS-IS):

  • Because BFD does not include a discovery mechanism, you must explicitly configure BFD sessions between endpoints.
  • The BFD protocol requires you to commit a nominal amount of additional system resources, in the form of timers, interface bandwidth, and system memory.

After configuring BFD protocol behavior, you enable the protocol on one or more specific route domains.

Important: You can find detailed documentation on BFD commands in the AskF5™ knowledge base at http://support.f5.com.

Enabling the BFD protocol for a route domain

Before you perform this task, verify that you have configured the Port Lockdown setting on all self IP addresses with which routers must communicate. Specifically, you must configure self IP addresses to allow TCP connections on the relevant service port.

You must enable the Bidirectional Forwarding Detection (BFD) network protocol on a per-route domain basis. Use this task to enable BFD on an existing route domain.

  1. On the Main tab, click Network > Route Domains .
    The Route Domains list screen opens.
  2. In the Name column, click the name of the relevant route domain.
  3. For the Dynamic Routing Protocols setting, from the Available list, select BFD and move it to the Enabled list.
    When you enable BFD, the BIG-IP system starts one BFD session for the route domain, and this session supports the BGP4, IS-IS, and OSPFv2 protocols.
  4. Click Update.
    The system displays the list of route domains on the BIG-IP system.
After you perform this task, the BIG-IP® system starts the daemon oamd. Once enabled, the BFD protocol automatically restarts whenever the BIG-IP system is restarted.

Common commands for BFD base configuration

There are two common BFD commands that you can use to perform BFD base configuration. To use these commands, you use the IMI Shell within tmsh.

Sample command line sequence Result
bigip (config-if)# bfd interval 100 minrx 200 multiplier 4 Sets desired Min Tx, required Min Rx, and detect Multiplier.
bigip (config)# bfd slow-timer 2000 Sets BFD slow timer to two seconds.

Common commands for BFD routing configuration

There are a number of common BFD commands that you can use to perform BFD routing configuration. To use these commands, you use the IMI Shell within tmsh.

Protocol Sample command line sequence Result
BGP4 bigip (config-if)# neighbor 1.1.1.1 fallover bfd multihop Enables multi-hop bidirectional forwarding detection to BGP neighbor 1.1.1.1.
OSPFv2 bigip (config)# bfd all-interfaces Enables single-hop bidirectional forwarding detection for all OSPF neighbors.
OSPFv2 bigip (config)# area 1 virtual-link 3.3.3.3 fallover bfd Enables multi-hop bidirectional forwarding detection to OSPF router 3.3.3.3.
IS-IS bigip (config-if)# bfd all-interfaces Enables bidirectional forwarding detection for all IS-IS neighbors.

About the Protocol Independent Multicast protocol

The Protocol Independent Multicast (PIM) protocol (which is available with licensed ZebOS® dynamic routing on the BIG-IP® system) comprises a group of carrier-class multicast routing protocols for the distribution of data. Within this group, the BIG-IP system supports the PIM Dense Mode (PIM-DM) protocol, which provides dense multicast routing, where it uses shortest-path trees by flooding IPv4 or IPv6 multicast traffic throughout the domain and pruning those branches without receivers.

About using PIM dense mode

You can configure a BIG-IP® system non-default route domain to use the Protocol Independent Multicast (PIM) protocol dense mode (DM), which is available with licensed ZebOS® dynamic routing. This configuration provides an effective multicast solution for networks that are configured with listeners at most locations.

For example, in a PIM-DM configuration, you can configure the Local Traffic Manager™ (LTM) to use a wildcard forwarding virtual server to flood the network. Interested listeners, located downstream from a PIM router, use the Internet Group Management Protocol (IGMPv3) protocol for IPv4 traffic or Multicast Listener Discovery (MLDv2) protocol for IPv6 traffic to join the multicast group. When the LTM® receives traffic, it sends that traffic to all active PIM routers, which then forward the packets toward the interested listeners. PIM routers without interested listeners prune themselves from the multicast group. When a listener leaves the multicast group, the upstream router sends a PIM prune message to the LTM, which removes that router from the group's forwarding list, thus enabling the LTM to send group traffic only to active PIM routers.

Additionally, a PIM-DM configuration applies reverse path forwarding functionality, using the unicast routing information base (RIB), to provide loop-free forwarding of multicast traffic.

About reverse path forwarding functionality

The Protocol Independent Multicast (PIM) protocol dense mode (DM) configuration applies reverse path forwarding (RPF) functionality, which uses a unicast routing information base (RIB) to provide loop-free forwarding of multicast traffic.

For example, an RPF router is located on an interface that sends unicast packets to the source. When a multicast packet arrives on an RPF router, the router forwards the packet to the interfaces specified by the unicast RIB. If a multicast packet arrives on a non-RPF interface, the packet is discarded, thus preventing a loop condition.

About Maximum Multicast Rate functionality

Maximum Multicast Rate functionality provides a packets-per-second rate limit intended for non-broadcast multicast functionality. You can disable this functionality to optimize performance and throughput for multicast functionality. Click System > Configuration > Local Traffic > General , and then clear the Maximum Multicast Rate check box.

Configuration overview

The first step in configuring Protocol Independent Multicast (PIM) protocol on the BIG-IP® system is to use the IMI Shell within tmsh to configure the protocol for the relevant advanced routing module (PIM).

After configuring PIM protocol behavior, you enable the protocol on one or more specific route domains.

Important: You can find detailed documentation on PIM commands in the AskF5™ knowledge base at http://support.f5.com.

Enabling a PIM protocol for a route domain

Before you configure a BIG-IP® system route domain to use Protocol Independent Multicast (PIM) network protocol functionality, you need to license and configure ZebOS multicast functionality.
You must enable the PIM network protocol on a per-route domain basis. Use this task to enable PIM on an existing route domain.
  1. On the Main tab, click System > Configuration > Local Traffic > General .
    The Local Traffic General settings screen opens.
  2. Clear the Maximum Multicast Rate check box.
  3. Click Update to apply the changes.
  4. On the Main tab, click Network > Route Domains .
    The Route Domains list screen opens.
  5. In the Name column, click the name of the relevant route domain.
  6. For the Dynamic Routing Protocols setting, from the Available list, select PIM and move it to the Enabled list.
    When you enable PIM, the BIG-IP system starts one PIM session for the route domain, and this session supports the IGMPv3 for IPv4 and MLDv2 for IPv6 protocols.
  7. Click Update.
    The system displays the list of route domains on the BIG-IP system.
After you perform this task, the BIG-IP® system starts the daemons mribd and pimd. Once enabled, the PIM protocol automatically restarts whenever the BIG-IP system is restarted.

Common commands for enabling multicast routing

There are several commands that you can use to enable multicast routing. To use these commands, you access the IMI Shell within tmsh.

Sample command line sequence Result
bigip (config-if)>en Enables multicast functionality.
bigip (config-if)#conf t Enables configuration functionality.
bigip (config-if)#ip pim dense-mode Enables IPv4 PIM dense-mode functionality.
bigip (config-if)#ipv6 pim dense-mode Enables IPv6 PIM dense-mode functionality.

Common commands for configuring PIM interfaces

There are a number of common PIM commands that you can use to perform PIM routing configuration. To use these commands, you access the IMI Shell within tmsh.

Sample command line sequence Result
bigip (config-if)#interface external Specifies configuration of external port.
bigip (config-if)#ip pim dense-mode Configures PIM dense mode for external port.

Common tmsh commands for PIM interfaces

There are a number of common tmsh commands that you can use to assess Protocol Independent Multicast (PIM) interfaces.

Sample commands Results
bigip (config-if)# tmsh show net mroute Lists multicast sources, groups, incoming interfaces, and outgoing interfaces.
bigip (config-if)# tmsh show sys ip-stat | grep Multicast Summarizes multicast statistics.
   

PIM protocol supported tunnel types

Protocol Independent Multicast (PIM) protocol functionality, available with licensed ZebOS® dynamic routing, supports several types of tunnels.

  • etherip
  • fec
  • gre
  • ip4ip4
  • ip4ip6
  • ip6ip4
  • ip6ip6
  • ipip
  • ppp
  • vxlan

About ECMP routing

Some of the advanced routing modules on the BIG-IP® system include support for Equal Cost Multipath (ECMP) routing. ECMP is a forwarding mechanism for routing a traffic flow along multiple paths of equal cost, with the goal of achieving equally-distributed link load sharing. By load balancing traffic over multiple paths, ECMP offers potential increases in bandwidth, as well as some level of fault tolerance when a path on the network becomes unavailable.

Advanced routing modules that support ECMP

The BIG-IP® system deploys Equal Cost Multipath (ECMP) routing with these advanced routing modules:

  • BGP4
  • IS-IS
  • OSPFv2
  • OSPFv3
  • PIM
  • RIPv1
  • RIPv2

The ECMP protocol is enabled by default for all of these advanced routing modules except BGP4. For BGP4, you must explicitly enable the ECMP forwarding mechanism.

Enabling the ECMP protocol for BGP4

You can enable the Equal Cost Multipath (ECMP) forwarding mechanism for the BGP4 advanced routing module, using the Traffic Management Shell (tmsh) command line interface. When you enable ECMP for BGP4, the BIG-IP® system provides multiple paths for a traffic flow to choose from, in order to reach the destination.

Important: For all other advanced routing modules, the ECMP protocol is enabled by default.
  1. Open a console window, or an SSH session using the management port, on a BIG-IP system.
  2. Use your user credentials to log in to the system.
  3. At the command prompt, type tmsh.
    This opens the tmsh shell.
  4. Type this command: run /util imish -r ID .
    The ID variable represents the route domain ID.
    This command invokes the IMI shell.
  5. Type enable.
  6. Type configure terminal.
  7. Type router bgp as-number .
  8. Type this command: bgp max-paths (ebgp|ibgp|) 2-64
After you perform this task, the ECMP forwarding mechanism is enabled for the BGP4 advanced routing module.

Viewing routes that use ECMP

You can perform this task to view the dynamic routes on the system that are using the Equal Cost Multipath (ECMP) forwarding mechanism.
  1. Open a console window, or an SSH session using the management port, on a BIG-IP® system.
  2. Use your user credentials to log in to the system.
  3. At the command prompt, type tmsh show net route.
The system displays all dynamic routes and indicates the routes that are using ECMP.

Location of startup configuration for advanced routing modules

When you enable advanced routing modules for a route domain, the BIG-IP system creates a dynamic routing startup configuration. Each route domain has its own dynamic routing configuration, located in the folder /config/zebos/rdn , where n is the numeric route domain ID.

Warning: F5 Networks strongly discourages manual modifications to the startup configuration (such as by using a text editor). Doing so might lead to unexpected results.

Accessing the IMI Shell

Perform this task when you want to use IMI Shell (imish) to configure any of the dynamic routing protocols. Note that if you are using the route domains feature, you must specify the route domain pertaining to the dynamic routing protocol that you want to configure.

  1. Open a console window, or an SSH session using the management port, on a BIG-IP device.
  2. Use your user credentials to log in to the system.
  3. At the command prompt, type tmsh.
    This opens the tmsh shell.
  4. Type this command: run /util imish -r ID .
    If the route domain for the protocol you want to configure is the default route domain for the current partition, you do not need to use the -r option to specify the route domain ID.
    This command invokes the IMI shell.
You can now use any of the IMI shell commands.

Relationship of advanced routing modules and BFD to route domains

For each route domain on the BIG-IP system (including route domain 0), you can enable one or more dynamic routing protocols, as well as the network protocol Bidirectional Forwarding Detection (BFD). For example, you can enable BGP4 and OSPFv3 on a specific route domain. Use of dynamic routing protocols for a route domain is optional.

When you enable dynamic routing on a specific route domain, the BIG-IP system creates a dynamic routing instance. This dynamic routing instance is made up of the core dynamic routing daemons (imi and nsm), as well each relevant dynamic routing protocol daemon. If you enable BFD, the BFD instance is made up of the oamd protocol daemon. Thus, each dynamic routing instance for a route domain has a separate configuration. You manage a dynamic routing configuration using the IMI shell (imish).

Enabling a protocol for a route domain

Before you perform this task, verify that you have configured the Port Lockdown setting on all self IP addresses with which routers must communicate. Specifically, you must configure self IP addresses to allow TCP connections on the relevant service port. For example, for BGP4, you must configure self IP addresses to allow TCP connections for port 179, the well-known port for BGP4.

The first step in configuring dynamic routing protocols on the BIG-IP system is to enable one or more routing protocols, as well as the optional the Bidirectional Forwarding Detection (BFD) network protocol. A protocol is enabled when at least one instance of the protocol is enabled on a route domain.

Important: The BIG-IP system does not synchronize enabled protocols at runtime during configuration synchronization in a redundant system configuration. This can adversely affect the OSPFv2 and OSPFv3 protocols. To prevent these effects, always enable the protocol on an active device. Then synchronize the configuration to a standby device.
  1. On the Main tab, click Network > Route Domains .
    The Route Domains list screen opens.
  2. In the Name column, click the name of the relevant route domain.
  3. For the Dynamic Routing Protocols setting, from the Available list, select a protocol name and move it to the Enabled list.
    You can enable any number of listed protocols for this route domain.
    Important: When you enable BFD, the BIG-IP system starts one BFD session for the route domain, and this session supports the BGP4, IS-IS, and OSPFv2 protocols only.
  4. Click Update.
    The system displays the list of route domains on the BIG-IP system.
After performing this task, the BIG-IP system starts an instance of the specified protocol daemon for the specified route domain, and starts the core daemons nsm and imi. If BFD is enabled, the system also starts the daemon oamd. Once enabled, a protocol automatically restarts whenever the BIG-IP system is restarted.

Disabling a protocol for a route domain

Perform this task to disable an instance of a routing or network protocol that is currently associated with a route domain other than route domain0.

Important: The BIG-IP system does not synchronize disabled protocols at runtime during configuration synchronization in a device service clustering (redundant) configuration. This can adversely affect the OSPFv2 and OSPFv3 protocols. To prevent these effects, always disable the protocol on a standby device. Then synchronize the configuration to an active device.
  1. On the Main tab, click Network > Route Domains .
    The Route Domains list screen opens.
  2. In the Name column, click the name of the relevant route domain.
  3. For the Dynamic Routing Protocols setting, from the Enabled list, select a protocol name and move it to the Available list.
    You can disable any number of listed protocols for this route domain.
  4. Click Update.
    The system displays the list of route domains on the BIG-IP system.

After disabling a dynamic routing protocol for a route domain, the BIG-IP system stops the daemon of the specified protocol, resulting in these effects:

  • If the specified protocol was the only protocol enabled on the system, the system stops the common daemons nsm and imi, and possibly the oamd daemon. You will no longer see these daemons running on the system.
  • The relevant configuration is removed from the runtime configuration, but the configuration is stored on the system until you explicitly save the running configuration.
  • If restarted later, the BIG-IP system does not automatically re-enable the protocol. In this case, you must explicitly re-enable the protocol after the system restarts.

Displaying the status of enabled protocols

Perform this task to display the status of instances of any dynamic routing protocols (including the Bidirectional Forwarding Detection (BFD) protocol) that are enabled for a specific route domain.
  1. Open a console window, or an SSH session using the management port, on a BIG-IP device.
  2. Use your user credentials to log in to the system.
  3. At the command prompt, type tmsh.
    This opens the tmsh shell.
  4. Type run util zebos check
    This displays the status and process IDs of any enabled dynamic routing protocols or BFD protocol for the specified route domain.
After performing this task, you can see the status and process IDs of any enabled protocols. The following shows sample output:
        bgpd    is running [22320]          
        

About Route Health Injection

Route Health Injection (RHI) is the system process of advertising the availability of virtual addresses to other routers on the network. You can configure two aspects of RHI: route advertisement and route redistribution.

About route advertisement of virtual addresses

Route advertisement is the function that the BIG-IP® system performs when advertising a route for a virtual address to the Traffic Management Microkernel (TMM) routing table. You must configure route advertisement to ensure that the dynamic routing protocols propagate this route to other routers on the network.

When configuring route advertisement for a virtual address, you can specify the particular condition under which you want the BIG-IP system to advertise the address. The available conditions that you can choose from, and their descriptions, are:

When any relevant virtual server is available
If the system has multiple virtual servers for that virtual address and at least one of them is available, the system advertises the route for the virtual address.
When all relevant virtual servers are available
The system only advertises the route for the virtual address when all of the relevant virtual servers are available.
Always
The system can advertise the route even when all relevant virtual servers are unavailable. For example, the system can advertise the route when the virtual server is disabled but the virtual address is enabled and the assigned pool is available.

After you specify the desired behavior of the system with respect to route advertisement, the tmrouted daemon attempts to comply. The daemon only succeeds in advertising the route for the virtual address when the relevant virtual servers, pool, and pool members collectively report their status in specific combinations.

Note: When you configure RHI in a device group configuration, only devices with active traffic groups attempt to advertise routes to virtual addresses.

Determination of UP state for a virtual address

The tmrouted daemon within the BIG-IP® system considers a virtual IP address to be in an UP state when any one of the following conditions are true:

  • The BIG-IP Configuration utility shows blue, green, or yellow status for the virtual address.
  • The virtual address is a member of an active traffic group.
  • The virtual address is enabled and is currently being advertised.

Conditions for route advertisement of virtual addresses

This table shows the ways that Local Traffic Manager™ (LTM®) object status affects whether the BIG-IP® system advertises a route to a virtual address. In the table, the colors represent object status shown on the Local Traffic screens within the BIG-IP Configuration utility. The table also summarizes the collective LTM object status that determines route advertisement.

Table 2. Route advertisement for virtual addresses based on LTM object status
LTM object status
Route advertised? Pool member Pool Virtual server Virtual address Status summary
Yes green circle status icon green circle status icon green circle status icon green circle status icon Pool members are monitored and UP. The virtual address is UP.
Yes blue square status icon blue square status icon blue square status icon blue square status icon Pool or pool members are unmonitored. The virtual address is enabled.
Yes black circle status icon black diamond status icon green circle status icon green circle status icon green circle status icon Pool members are disabled. Other objects are enabled.
Yes black circle status icon black diamond status icon green circle status icon black circle status icon black diamond status icon green circle status icon Virtual server is disabled. Virtual address is enabled.
Yes N/A yellow triangle status icon yellow triangle status icon yellow triangle status icon The pool has no members. The virtual address is enabled.
Yes N/A N/A blue square status icon blue square status icon Virtual server has no pool assigned.
No red diamond status icon red diamond status icon red diamond status icon red diamond status icon Pool members are monitored and DOWN.
No black circle status icon black diamond status icon green circle status icon black circle status icon black diamond status icon black circle status icon black diamond status icon Virtual server and virtual address are disabled.
No green circle status icon green circle status icon gray circle status icon gray square status icon gray triangle status icon black circle status icon black diamond status icon Virtual address is disabled. Other objects are enabled.

LTM object status indicators

The BIG-IP® Configuration utility displays various colored icons to report the status of virtual servers, virtual addresses, pools, and pool members.

Green circle green circle status icon
The object is available in some capacity. The BIG-IP system services traffic destined for this object.
Blue square blue square status icon
The availability of the object is unknown. Sample causes of this status are when the object is not configured for service checking, the IP address of the object is misconfigured, or the object is disconnected fromthe network.
Yellow triangle yellow triangle status icon
The object is not currently available but might become available later with no user intervention. For example, an object that has reached its configured connection limit might show yellow status but later switch to green when the number of connections falls below the configured limit.
Red diamond red diamond status icon
The object is not available. The BIG-IP system cannot service traffic destined for this object. A sample cause of this status is when a node fails service checking because it has become unavailable. This status requires user intervention to restore the object status to green.
Black circle black circle status icon
A user has actively disabled an available object.
Black diamond black diamond status icon
A user has actively disabled an unavailable object.
Gray icons gray circle status icon gray square status icon gray triangle status icon
A parent object disabled the object, or the object is enabled but unavailable because of another disabled object.

Configuring route advertisement on virtual addresses

Before performing this task, verify that you have created the relevant virtual server on the BIG-IP system. Also, the virtual address that you want to advertise must have a status of Up, Unavailable, or Unknown.

Perform this task to specify the criterion that the BIG-IP system uses to advertise routes for virtual addresses. You must perform this task if you want the dynamic routing protocols to propagate this route to other routers on the network.

  1. On the Main tab, click Local Traffic > Virtual Servers .
    The Virtual Server List screen displays a list of existing virtual servers.
  2. On the menu bar, click Virtual Address List.
  3. Click the name of the virtual server you want to configure.
  4. For the Advertise Route setting, select an option:
    • When any virtual server is available
    • When all virtual server(s) are available
    • Always
  5. Click Update.
After you perform this task, properly-configured dynamic routing protocols can redistribute the advertised route to other routers on the network.

Displaying advertised routes for virtual addresses

Before you perform this task, depending on the dynamic routing protocol, you might need to configure the protocol's router definition to redistribute the kernel.
Perform this task when you want to display routes for virtual addresses that the BIG-IP system has advertised to other routers on the network.
  1. Open a console window, or an SSH session using the management port, on a BIG-IP device.
  2. Use your user credentials to log in to the system.
  3. At the command prompt, type tmsh.
    This opens the tmsh shell.
  4. Type run /util imish -r ID
    The variable ID is the ID of the relevant route domain. This ID must be an integer.
    This opens the IMI shell.
  5. At the prompt, type show ip route kernel.

After performing this task, you should see the advertised routes for virtual addresses. For example, advertised routes for virtual addresses 10.1.51.80/32 and 10.2.51.81/32 appear as follows:

             K       10.1.51.80/32 is directly connected, tmm0
             K       10.1.51.81/32 is directly connected, tmm0
             

The /32 netmask indicates that the IP addresses pertain to individual hosts, and the tmm0 indicator shows that protocols on other routers have learned these routes from the Traffic Management Microkernel (TMM).

Delaying the withdrawal of RHI routes

Perform this task to delay the withdrawal of RHI routes when operation status changes. Delaying route withdrawal prevents short route flaps that might occur due to both the short period during failover when both devices are in a standby state, and the periodic housekeeping processes in routing protocol daemons (specifically bgpd).

  1. Open a console window, or an SSH session using the management port, on a BIG-IP device.
  2. Use your user credentials to log in to the system.
  3. At the command prompt, type tmsh.
    This opens the tmsh shell.
  4. Set the bigdb variable to the needed delay by typing this command: modify /sys db tmrouted.rhifailoverdelay value delay_in_seconds
The BIG-IP system now delays the withdrawal of RHI routes by the number of seconds that you specified.

Redistribution of routes for BIG-IP virtual addresses

You can explicitly configure each dynamic routing protocol to redistribute routes for advertised virtual addresses, to ensure that other routers on the network learn these routes. For purposes of redistribution, the dynamic routing protocols consider any route generated through Route Health Injection (RHI) to be a host route.

Note: For all dynamic routing protocols, you must configure route redistribution for IPv4 addresses separately from that of IPv6 addresses.

This example shows an entry in the OSPF configuration. When you add this statement to the OSPF configuration, the BIG-IP system redistributes the route for the virtual address.

                     
router ospf
   redistribute kernel
                  

You can optionally specify a route-map reference that specifies the route map to use for filtering routes prior to redistribution. For example:

                     
redistribute kernel route-map external-out
                  

Route maps provide an extremely flexible mechanism for fine-tuning redistribution of routes using the dynamic routing protocols.

Advertisement of next-hop addresses

The BIG-IP system advertises all self IP addresses, including floating self IP addresses, to the dynamic routing protocols. The protocols store floating addresses so that the protocols can prefer a floating address as the advertised next hop. This applies only to protocols that allow explicit next-hop advertisement.

IPv6 next-hop address selection (BGP4 only)

When you are using BGP4 and IPv6 addressing, you can advertise one or two next-hop addresses for each route. The BIG-IP system selects the addresses to advertise based on several factors.

Parameter combinations for next-hop address selection

For BGP-4 only, you can choose from several combinations of configuration parameters to control the selection of next-hop IPv6 addresses.

Table 3. P = Peering, X = Configured
Link-local autoconf. (LL-A) Link-local (LL) Link-local floating (LL-F) Global (G) Global floating (G-F) EBGP multihop Advertised nexthop addresses
P           LL-A
X P         LL
X P X       LL-F
X P   X     G, LL
X     P     G, LL-A
X X X P   X G
X X X P     LL-F
X     P X   G-F
X P   X X   GF, LL
X X   P X   GF
X P X X X   LL-F
X X X P X   GF-F

Visibility of static routes

The dynamic routing protocols view Traffic Management Microkernel (TMM) static routes as kernel routes. (TMM static routes are routes that you configure using tmsh or the BIG-IP Configuration utility.) Because TMM static routes are viewed as kernel routes, a TMM static route has a higher precedence than a dynamic route (with an identical destination).

Management routes and addresses are not visible to the dynamic routing protocols and cannot be advertised. Routes to the networks reachable through the management interface can be learned by dynamic routing protocols if they are reachable through a VLAN, VLAN group, or tunnel.

About dynamic routing for redundant system configurations

If the BIG-IP system that you are configuring for dynamic routing is part of a redundant system configuration, you should consider these factors:

  • You must configure the dynamic routing protocols on each member of the device group.
  • For protocols that include the router ID attribute, you should verify that each member of the device group has a unique router ID.
  • When you configure Route Health Injection (RHI), only active device group members advertise routes to virtual addresses.

Special considerations for BGP4, RIP, and IS-IS

For the BGP, RIP, RIPng, and IS-IS protocols, you no longer need to specifically configure these protocols to function in active-standby configurations. Each member of the device group automatically advertises the first floating self IP address of the same IP subnet as the next hop for all advertised routes. This applies to both IPv4 and IPv6 addresses.

Advertising a next-hop address that is always serviced by an active device guarantees that all traffic that follows routes advertised by any device in the redundant pair is forwarded based on the active LTM® configuration.

Special considerations for OSPF

For OSPF protocols, the BIG-IP system ensures that standby device group members are the least preferred next-hop routers. The system does this by automatically changing the runtime state as follows:

Table 4. Dynamic routing protocols
Protocol Name Runtime state change
OSPFv2 The OSPF interface cost is increased on all interfaces to the maximum value (65535) when the status of the device is Standby. Also, all external type 2 Link State Advertisements (LSAs) are aged out.
OSPFv3 The OSPF interface cost is increased on all interfaces to the maximum value.

Displaying OSPF interface status

When you display OSPF interface status, you can see the effect of runtime state changes.
  1. Open a console window, or an SSH session using the management port, on a BIG-IP device.
  2. Use your user credentials to log in to the system.
  3. At the command prompt, type tmsh.
  4. Type this command: run /util imish -r ID .
  5. Type sh ip ospf interface.
    The variable id is the ID of the relevant route domain.

Listing the OSPF link state database

When you list the contents of the OSPF link state database, you can see the effect of runtime state changes.
  1. Open a console window, or an SSH session using the management port, on a BIG-IP device.
  2. Use your user credentials to log in to the system.
  3. At the command prompt, type tmsh.
  4. Type this command: run /util imish -r ID
  5. Type sh ip ospf database external self-originate.
    The variable id is the ID of the relevant route domain.

Dynamic routing on a VIPRION system

If you have a VIPRION® system, it is helpful to understand how the cluster environment affects the dynamic routing functionality.

VIPRION appearance as a single router

On a VIPRION® system, the dynamic routing system behaves as if the cluster were a single router. This means that a cluster always appears as a single router to any peer routers, regardless of the dynamic routing protocol being used.

From a management perspective, the VIPRION system is designed to appear as if you are configuring and managing the routing configuration on a single appliance. When you use the cluster IP address to configure the dynamic routing protocols, you transparently configure the primary blade in the cluster. The cluster synchronization process ensures that those configuration changes are automatically propagated to the other blades in the cluster.

Redundancy for the dynamic routing control plane

The dynamic routing system takes advantage of the redundancy provided by the cluster environment of a VIPRION® chassis, for the purpose of providing redundancy for the dynamic routing control plane. Two key aspects of dynamic routing control plane redundancy are the VIPRION cluster’s appearance to the routing modules as a single router, and the operational modes of the enabled dynamic routing protocols.

Operational modes for primary and secondary blades

Enabled dynamic routing protocols run on every blade in a cluster in one of these operational modes: MASTER, STANDBY, or SLAVE.

This table shows the operational modes for primary and secondary blades, on both the active cluster and the standby cluster.

Table 5. Operational modes for dynamic routing protocols per blade type
Blade Type Active Cluster Standby Cluster Notes
Primary MASTER mode STANDBY mode The dynamic routing protocols:
  • Actively participate in dynamic routing protocol communication with peer routers.
  • Maintain TMM and host route tables on all blades in the cluster.
Secondary SLAVE mode SLAVE mode The dynamic routing protocols:
  • Do not transmit any dynamic routing protocol traffic.
  • Track communication between a module and the peer routers, or wait for transition to MASTER or STANDBY mode.

In MASTER and STANDBY modes, all routes learned by way of dynamic routing protocols on the primary blade are (in real-time) propagated to all secondary blades. The difference between MASTER and STANDBY mode is in the parameters of advertised routes, with the goal to always make the active unit the preferred next hop for all advertised routes.

The transition from SLAVE to MASTER or STANDBY mode takes advantage of standard dynamic routing protocol graceful restart functionality.

Viewing the current operational mode

Perform this task to display the current operational mode (MASTER, STANDBY, or SLAVE) of a blade.

  1. Open a console window, or an SSH session using the management port, on a BIG-IP device.
  2. Use your user credentials to log in to the system.
  3. At the command prompt, type tmsh.
  4. Type run /util imish -r ID .
    If the route domain for the protocol you want to configure is the default route domain for the current partition, you do not need to use the -r option to specify the route domain ID.
    This command invokes the IMI shell.
  5. Type show state.
The BIG-IP system displays a message such as Current operational state: MASTER.

About graceful restart on the VIPRION system

With the graceful restart function, the dynamic routing protocol control plane moves from one blade to another without disruption to traffic. Graceful restart is enabled for most supported protocols and address families by default.

To operate successfully, the graceful restart function must be supported and enabled on all peer routers with which the VIPRION® system exchanges routing information. If one or more peer routers does not support graceful restart for one or more enabled dynamic routing protocols, a change in the primary blade causes full dynamic routing reconvergence, and probably traffic disruption. The traffic disruption is caused primarily by peer routers discarding routes advertised by the VIPRION system.

The BIG-IP system always preserves complete forwarding information (TMM and host route tables) on VIPRION systems during primary blade changes, regardless of support for graceful restart on peer routers.

Runtime monitoring of individual blades

The BIG-IP system automatically copies the startup configuration to all secondary blades and loads the new configuration when the running configuration is saved on the primary blade.

You can display information about the runtime state of both the primary and secondary blades. However, some information displayed on secondary blades might differ from the information on the primary blade. For troubleshooting, you should use the information displayed on the primary blade only, because only the primary blade both actively participates in dynamic routing communication and controls route tables on all blades.

Troubleshooting information for dynamic routing

Dynamic route propagation depends on a BIG-IP® system daemon named tmrouted. The BIG-IP system starts the tmrouted daemon when you enable the first dynamic routing protocol. and restarts the daemon whenever the BIG-IP system restarts.

In the rare case when you need to manage the tmrouted daemon due to a system issue, you can perform a number of different tasks to troubleshoot and solve the problem.

Checking the status of the tmrouted daemon

Use this procedure to verify that the tmrouted daemon is running. This daemon must be running for the enabled dynamic routing protocols to propagate routes.
  1. Open a console window, or an SSH session using the management port, on a BIG-IP device.
  2. Type your user credentials to log in to the system.
  3. If the system has granted you access to the BASH shell prompt, type tmsh. Otherwise, skip this step.
  4. Type show /sys service tmrouted.
The BIG-IP system displays information about tmrouted such as: tmrouted run (pid 5113) 1 days

Stopping the tmrouted daemon

Before you can stop an instance of the tmrouted daemon, the associated protocol instance must be enabled on the BIG-IP system. Also, the BIG-IP system mcpd and tmm daemons must be running on the system.

You perform this task to stop an instance of the tmrouted daemon.

Important: Manage the tmrouted daemon using the tmsh utility only. Attempting to manage tmrouted using a Linux command or with invalid parameters might cause the daemon to fail.
  1. Open a console window, or an SSH session using the management port, on the BIG-IP device.
  2. Type your user credentials to log in to the system.
  3. If the system has granted you access to the BASH shell prompt, type tmsh. Otherwise, skip this step.
  4. At the tmsh shell prompt, type stop /sys service tmrouted.
This command stops any instances of tmrouted that are running on the system, causing the associated protocol instance to stop propagating routes.

Restarting the tmrouted daemon

Before restarting an instance of the tmrouted daemon, verify that the associated protocol instance is enabled on the BIG-IP system. Also, verify that the BIG-IP system mcpd and tmm daemons are running on the system.

You perform this task to restart an instance of the tmrouted daemon. Whenever the BIG-IP system reboots for any reason, the BIG-IP system automatically starts an instance of tmrouted for each instance of an enabled dynamic routing protocol.

Important: Manage the tmrouted daemon using the tmsh utility only. Attempting to manage tmrouted using a Linux command or with invalid parameters might cause the daemon to fail.
  1. Open a console window, or an SSH session using the management port, on the BIG-IP system.
  2. Type your user credentials to log in to the system.
  3. If the system has granted you access to the BASH shell prompt, type tmsh. Otherwise, skip this step.
  4. At the tmsh shell prompt, type restart /sys service tmrouted.
This command restarts any instances of tmrouted that are currently stopped. The daemon also communicates with the nsm daemon to propagate dynamically-learned routes to other BIG-IP system processes that need to direct application traffic.

Configuring tmrouted recovery actions

Use this task to configure recovery actions when the tmrouted daemon restarts.
  1. Open a console window, or an SSH session using the management port, on a BIG-IP device.
  2. Use your user credentials to log in to the system.
  3. At the command prompt, type tmsh.
  4. Type modify /sys daemon-ha tmrouted running [enabled|disabled]
    • If you want to enable the running-timeout and non-running-action options, type enabled.
    • If you want to disable the running-timeout and non-running-action options, type disabled.
    Typing this command with the enabled option causes the active BIG-IP device to fail over to another device in the device group whenever the tmrouted daemon restarts.
  5. Type modify /sys daemon-ha tmrouted heartbeat [enabled|disabled]
    • If you want to enable monitoring for the tmrouted heartbeat, type enabled.
    • If you want to disable monitoring for the tmrouted heartbeat, type disabled.
    When you type this command with the enabled option and the tmrouted heartbeat is subsequently lost, the system behaves according to the action specified by the heartbeat-action option.

Location and content of log files

For each dynamic routing protocol, the BIG-IP system logs messages to a file that pertains to the route domain in which the protocol is running. An example of the path name to a dynamic routing log file is /var/log/zebos/rd1/zebos.log file, where rd1 is the route domain of the protocol instance.

The system logs additional messages to the files /var/log/daemon.log and /var/log/ltm. The system logs protocol daemon information for protocol-specific issues, and logs nsm and imi daemon information for core daemon-related issues.

If a core dynamic routing daemon exits, the system logs an error message similar to the following to the /var/log/daemon.log file:

                     
Mar  5 22:43:01 mybigip LOGIN: Re-starting tmrouted
                  

In addition, the BIG-IP system logs error messages similar to the following to the /var/log/ltm file:

                     
mcpd[5157]: 01070410:5: Removed subscription with subscriber id bgpd
mcpd[5157]: 01070533:3: evWrite finished with no byte sent to connection 0xa56f9d0 (user Unknown) - connection deleted
                  

Creating a debug log file

Perform this task to create a log file for debugging. With a debug log file, you can more effectively troubleshoot any issues with a dynamic routing protocol.

  1. Open a console window, or an SSH session using the management port, on a BIG-IP device.
  2. Use your user credentials to log in to the system.
  3. At the command prompt, type tmsh.
    This opens the tmsh shell.
  4. At the tmsh prompt, type this command: run /util imish -r ID .
    If the route domain for the protocol you want to configure is the default route domain for the current partition, you do not need to specify the route domain ID.
    This command invokes the IMI shell.
  5. Type the command log file /var/log/zebos/rdn/zebos.log.
    The variable n represents the relevant route domain ID. This ID must be an integer.
    The system creates a debug log file.
  6. Type write.
    This action saves the log file.
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