No relevant resource is found in the selected language.

This site uses cookies. By continuing to browse the site you are agreeing to our use of cookies. Read our privacy policy>Search

Reminder

To have a better experience, please upgrade your IE browser.

upgrade

Fat AP and Cloud AP V200R008C00 CLI-based Configuration Guide

Rate and give feedback :
Huawei uses machine translation combined with human proofreading to translate this document to different languages in order to help you better understand the content of this document. Note: Even the most advanced machine translation cannot match the quality of professional translators. Huawei shall not bear any responsibility for translation accuracy and it is recommended that you refer to the English document (a link for which has been provided).
Principles

Principles

This section describes the implementation of Static Routes.

Basics of Static Routes

A router forwards data packets based on routing entries containing route information. The routing entries can be manually configured or calculated by dynamic routing protocols. Static routes refer to the routes that are manually added to the routing table.

Static routes use less bandwidth than dynamic routes. No CPU resource is used for calculating or analyzing routing update. When a fault occurs on the network or the topology changes, static routes cannot automatically change and must be changed manually. The configuration of a static route includes destination IP address and mask, outbound interface and next-hop address, and preference.

Destination Address and Mask

The destination IPv4 address is expressed in dotted decimal notation. The mask can be expressed either in dotted decimal notation or by the mask length, that is, the number of consecutive 1s in the mask. When the destination and mask are set to all 0s, the default static route is configured.

Outbound Interface and Next-Hop IP Address

When configuring a static route, you can specify the outbound interface and the next-hop IP address based on outbound interfaces types.

  • Configure the outbound interface for point-to-point (P2P) interfaces. For a P2P interface, the next-hop address is specified after the outbound interface is specified. That is, the address of the remote interface (interface on the peer device) connected to this interface is the next-hop address. For example, the protocol used to encapsulate 10GE is the Point-to-Point protocol (PPP). The remote IP address is obtained through PPP negotiation. You need specify only the outbound interface.

  • Configure the next hop for Non Broadcast Multiple Access (NBMA) interfaces. You need to configure the IP route and the mapping between IP addresses and link-layer addresses.

  • Configure the next hop for broadcast interfaces (for example, Ethernet interfaces). The Ethernet interface is a broadcast interface. If the Ethernet interface is specified as the outbound interface, multiple next hops exist and the system cannot decide which next hop is to be used. Therefore, this configuration is not recommended.

Static Route Preference

Different static routes can be configured with different preferences. A smaller preference value indicates a higher priority of static routes. If you specify the same preference for the static routes to the same destination, you can implement load balancing among these routes. If you specify different preferences for the static routes, you can implement route backup among the routes..

Permanent Advertisement of Static Routes

Permanent advertisement of static routes provides a low-cost and simple link detection mechanism and improves compatibility between Huawei devices and non-Huawei devices. If service traffic needs to be forwarded along a specified path, you can ping the destination addresses of static routes to detect the link connectivity.

Link connectivity determines the stability and availability of a network. Therefore, link detection plays an important role in network maintenance. BFD, as a link detection mechanism, is inapplicable to certain scenarios. For example, a simpler and more natural method is required for link detection between different ISPs.

After permanent advertisement of static routes is configured, the static routes that cannot be advertised are still preferred and are added to the routing table in the following cases:

  • If an outbound interface configured with an IP address is specified for a static route, the static route is always preferred and added to the routing table regardless of whether the outbound interface is Up or Down.

  • If no outbound interface is specified for a static route, the static route is always preferred and added to the routing table regardless of whether the static route can be iterated to an outbound interface.

In this way, you can enable IP packets to be always forwarded through this static route. The permanent advertisement mechanism provides a way for you to monitor services and detect link connectivity.

A device enabled with this feature always stores static routes in its IP routing table, regardless of whether the static routes are reachable. If a path is unreachable, the corresponding static route may become a blackhole route.

Applications

In Figure 7-104, BR1, BR2, and BR3 belong to ISP1, ISP2, and ISP3 respectively. Between BR1 and BR2 are two links, Link A and Link B. ISP1, however, requires that service traffic be forwarded to ISP2 over Link A without traveling through ISP3.

Figure 7-104  Networking for applying permanent advertisement of static routes

The External Border Gateway Protocol (EBGP) peer relationship is established between BR1 and BR2. For service monitoring, a static route destined for the BGP peer (BR2) at 10.1.1.2/24 is configured on BR1, and permanent advertisement of static routes is enabled. The interface that connects BR1 to BR2 is specified as the outbound interface of the static route. Then, the network monitoring system periodically pings 10.1.1.2 to determine the status of Link A.

If Link A works properly, ping packets are forwarded over Link A. If Link A becomes faulty, although service traffic can reach BR2 over Link B, the static route is still preferred because permanent advertisement of static routes is enabled. Therefore, ping packets are still forwarded over Link A, but packet forwarding fails. This scenario is also applicable to BGP packets. That is, a link fault causes the BGP peer relationship to be interrupted. The monitoring system detects service faults as returned in the ping result and prompts maintenance engineers to rectify the faults before services are affected.

Translation
Download
Updated: 2019-01-11

Document ID: EDOC1000176006

Views: 115878

Downloads: 309

Average rating:
This Document Applies to these Products
Related Documents
Related Version
Share
Previous Next