Labnario Huawei From Scratch

Let’s check today how a Designated Intermediate System (DIS) is elected in broadcast network.

Unlike in OSPF, in ISIS, routers of the same level, in a network segment, set up adjacencies (including non-DIS routers). DIS, as a pseudo node also generates LSPs, to describe available routers in the network. A pseudo node is indentified by the system ID of the DIS and the 1-byte circuit ID, which is always not 0. The main task of DIS is to reduce the number of generated LSPs. Even though all routers set up adjacencies in an ISIS broadcast network, LSDBs are synchronized by the DISs. One router can be DIS either for Level -1 or Level 2 routers. It depends on DIS priority configured. You can configure different DIS priority for different levels. The highest priority means the router is elected as DIS. In case that all routers have the same DIS priority, the one with the highest MAC address is chosen as DIS. By default DIS priority is set to 64 and can be changed manually. Comparing to OSFP DR, the router with the priority 0 also takes part in DIS election. Each time you connect a new router with higher DIS priority, the new router is elected as the new DIS, which causes LSPs flooding.

Let’s leave theory and carry out a test of DIS election in ISIS broadcast network.

Based on the below topology configure, IP addresses for physical and loopback interfaces (it is omitted here).

As a continuation of the STP Root Protection feature I want to describe additional STP protection functions and show you, where these functions should be implemented, in a typical campus LAN environment.

BPDU Protection feature can be used to protect switches against STP BPDU attacks. It should be implemented on every switch, which has ports directly connected to end-user workstations. This is because we do not expect receiving STP BPDU from user workstations. When STP BPDUs are received on the edge port, STP topology recalculation occurs, causing network flapping. If the port is configured with BPDU Protection and the switching device receives STP BPDUs, then the port is placed into shutdown state, protecting STP topology from recalculation. By default BPDU Protection feature is disabled on Huawei switches. To enable it:

<labnario_sw>system-view 
[labnario_sw]interface Ethernet 0/0/1
[labnario_sw-Ethernet0/0/1]stp edged-port enable 
[labnario_sw-Ethernet0/0/1]quit
[labnario_sw]stp bpdu-protection

When a switch port is configured as a STP Edged and STP BPDU is received, the port is placed into shutdown state:

May 13 2013 20:17:00-08:00 labnario_sw%%01MSTP/4/BPDU_PROTECTION(l)[4]:This edged-port Ethernet0/0/1 that enabled BPDU-Protection will be shutdown, because it received BPDU packet!

[labnario_sw-Ethernet0/0/1]dis cur int e0/0/1
#
interface Ethernet0/0/1
 shutdown
 stp edged-port enable

[labnario_sw-Ethernet0/0/1]dis int eth0/0/1
Ethernet0/0/1 current state : Administratively DOWN
Line protocol current state : DOWN

Based on the release notes of eNSP:

New features:

• supports TAB key switch when filling IP address of SimPC
• provides one key register function of AR_Base.

Modified features:

• improves the stability when starting AR
• reduces memory usage of AR
• fixes distribution service for AR
• fixes the dysfunction of MPLS L3VPN.

A new Huawei Enterprise Network Simulation Platform has been released.

Download, test and enjoy!

Let’s keep going and try to configure ISIS route aggregation based on the following topology:

If you want to recall how to configure ISIS adjacency on Huawei routers, just go to ‘ISIS on Huawei routers‘.

To avoid DIS election, configure all physical interfaces as ISIS point-to-point (p2p) links (Router 1 as an example):

[1-Ethernet0/0/8]isis circuit-type p2p

[1]dis isis interface 

                       Interface information for ISIS(1)
                       ---------------------------------
 Interface       Id      IPV4.State          IPV6.State      MTU  Type  DIS   
 Eth0/0/8        003         Up                 Down         1497 L1/L2 -- 
 Loop0           001         Up                 Down         1500 L1/L2 -- 
 Loop100         002         Up                 Down         1500 L1/L2 -- 

ISIS is a link-state IGP protocol. It gathers routing information from adjacent neighbors and uses the SPF algorithm to determine the best paths to destinations.

I wouldn’t like to focus on the theory because you can find it in many sources.

Let’s configure ISIS protocol based on the following topology:

Configure IP addresses of physical and loopback interfaces on all routers (it is omitted here):