Labnario Huawei From Scratch

I have come across link flapping protection feature recently. It is available on S5700 switches. It looks like it is a new feature on Huawei switches. I had not met it in older hardware versions. That’s why I decided to write a few words about it. Unfortunatelly, although this command is available in Huawei network simulator eNSP, it does not work properly. But maybe you will have possibility check it on your real devices.

Port flapping (port going UP and DOWN continually) can be caused by a faulty cable, link failure, active/standby switchover, port hardware failure, etc. Frequent status changes on an interface can lead to:

• STP topology recalculation and changes,
• ARP entries updates,
• dynamic routing instability and convergence problems.

All these issues can negatively affect switch performance and should be avoided.

Link Flapping Protection is a feature that can be implemented on an interface to solve problems caused by the flapping port or link. It checks the interface flapping frequency and link flapping detection interval. If the number of interface flapping times reaches the limit, in a specified period, the interface is shut down.

Let’s keep going and try to configure BGP local preference attribute using route-policy.

We can take full advantage of topology and configuration from the last post: “BGP default local preference in Huawei CLI“.

1. Assure full connectivity based on the attached topology (look at the previous article).
2. Configure Loopback 10 and Loopback 20 on router AR4.
3. Import all Loopback interfaces of router AR4 to BGP.

Let’s assume that we have a topology like in below picture:

1. AR1, AR2 and AR3 are in AS 100.
2. AR4 is in AS 200.
3. Loopback 100 of router AR1 and loopback 0 of router AR4 are advertised by BGP.

What we want to do is to configure default local preference attribute, which will determine the optimal route, for traffic that leaves AS 100. In our case, the whole traffic leaving AS 100 will go through AR3.

If a BGP device obtains multiple routes from different IBGP peers and these routes have different next hops to the same destination, the BGP device will select the route with the greatest Local_Pref value.

Huawei devices support generic MAC (GMAC) ping and trace on Layer 2 networks. Network administrators can use GMAC ping and trace functions to detect Layer 2 network faults, without configuring CFM.

ping mac mac-address vlan vlan-id [ interface interface-type interface-number | -c count | -s packetsize |-t timeout | -p priority-value ]

GMAC ping works at the same manner like 802.1ag MAC ping. It uses the Loopback Message and Loopback Reply (LBM/LBR) and is similar to ICMP ping function. GMAC ping can be used without configuring the MD (Maintenance Domain), MA (Maintenance Association), or MEP (Maintenance association End Point) on the source device, intermediate device, and destination device, as it is required when using 802.1ag. You only need to enable the GMAC function on the intermediate device. Therefore, GMAC ping is applicable to part of or a whole network without reference to MD, MA, and MEP configurations.

trace mac mac-address vlan vlan-id [ interface interface-type interface-number | -t timeout ] *

GMAC trace works at the same manner like 802.1ag MAC trace and uses Link Trace Message/Reply (LTR/LTM), so its function is similar to “trace route”. But GMAC trace can be implemented without configuring the MD, MA, or MEP on the source device, intermediate device, and the destination device. All the intermediate devices can respond with an LTR. Therefore, GMAC trace is applicable to part of or a whole network without reference to MD, MA, and MEP configurations.

1. CE1 and CE5 are in VPN labnario_1
2. CE2 and CE8 are in VPN labnario_2
3. ISIS level -2 as IGP
4. Connections CE1—PE3 and CE5—PE4 – static routes
5. Connection CE2—PE3 – OSPF
6. Connection CE8—PE4 – EBGP
7. Users in different VPNs cannot access each other.

A BGP/MPLS IP VPN uses the Border Gateway Protocol (BGP) to advertise VPN routes and the Multiprotocol Label Switching (MPLS) to forward VPN packets on backbone networks.