Some time ago I published article about BGP local preference attribute. Today I’d like to show you how to configure BGP MED attribute.
What is it for?
The multi-exit discriminator MED determines an optimal route for incoming traffic of an AS. When a BGP device obtains multiple routes to the same destination but with different next hops from EBGP peers, the BGP device selects the route with the smallest MED value as the optimal route. Simply saying, configuring MED attribute, we would like to show the next hop for traffic coming from EBGP peer. The MED attribute is exchanged only between two neighboring ASs. The AS that receives the MED attribute does not advertise it to any other ASs.
Let’s look at typical scenario for MED attribute configuration:
Why might we want to assign multiple IP addresses to the same interface? The following are the most common scenarios:
- hosts in the network segment use IP addresses on different networks
- there are not enough host addresses on a logical network segment, suppose a /24 address space and 300 hosts
How to configure multiple IP addresses on Huawei devices?
Let’s configure a pair of routers connected via a Gigabit Ethernet link and use four different logical networks.
[labnarioR1]int gi 0/0/0 [labnarioR1-GigabitEthernet0/0/0]ip add 192.168.12.1 255.255.255.0 [labnarioR1-GigabitEthernet0/0/0]ip add 10.0.12.1 255.255.255.0 sub [labnarioR1-GigabitEthernet0/0/0]ip add 10.0.22.1 255.255.255.0 sub [labnarioR1-GigabitEthernet0/0/0]ip add 10.0.32.1 255.255.255.0 sub
As you know I try to avoid products descriptions here, on this blog. But last time I had possibility to see ATN905 boxes, available in the indoor and outdoor types. You can install them in various environment. The application scenarios of ATN905 are divided into the small-cell base station bearer scenario and the Ethernet demarcation device (EDD) scenario.
Let’s look at the pictures of the two types of this router:
Very useful command, especially when you are preparing and executing upgrade of a software of Huawei carrier class devices, like NE40E and CX600. Let’s look what can be checked by this command:
<labnario>check ? hardware-compatibility hardware compatibility startup Check the version of the resource file system-software system-software version check version
I personally use “check hardware-compatibility” before all planned upgrades. During a preparation phase of an upgrade, you have to read software release notes, to be sure that all software and hardware components will be compatible with the new software. You can check hardware compatibility by the command, instead of searching software documents.
Imagine that you’ve just uploaded a new software to CFcard of a router. The new software is v600r006c00spc300.
<labnario>check hardware-compatibility v600r006c00spc300.cc Slot# BoardType Result Detail - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 3 CR57LAXFB00 Compatible NA 4 CR57LAXFB00 Compatible NA 5 CR57EMGFB20 Compatible NA 6 CR57EMGFB20 Compatible NA 9 CR57SRU200A5 Compatible NA 10 CR57SRU200A5 Compatible NA 11 CR57SFU200C0 Compatible NA 12 FRA200A Compatible NA 13 FRA200A Compatible NA
It’s very simple, isn’t it?
Some time ago I described how to display electronic labels. As you probably could see, the displayed information looked illegibly, especially for budding engineers.
Starting from V6R6 software of carrier class devices (like Huawei NE40E, CX600), it looks much better. You have all the information at a glance:
<labnario>display elabel brief Slot BoardType BarCode Description ================================================================================ LPU 1 CR52LPUF40A 030KWD10AB000351 LPUF-40-A PIC 0 CR52L2XXN0 03675210A9000134 P40-2x10GBase LAN/WAN-XFP PIC 1 CR52L2XXN0 03675210A9000115 P40-2x10GBase LAN/WAN-XFP LPU 2 CR52LPUF40A 030KWD10B7000867 LPUF-40-A PIC 0 CR52L2XXN0 03675210B7001018 P40-2x10GBase LAN/WAN-XFP PIC 1 CR52L2XXN0 03675210B7001188 P40-2x10GBase LAN/WAN-XFP LPU 3 CR52LPUKD0 030KJY10A8000126 LPUF-21-A PIC 0 CR52L1XX0 030GSK10A9002012 PIC 1 CR52L1XX0 030GSK10B7001228 LPU 7 CR52LPUKD0 030KJY10B1000383 LPUF-21-A PIC 0 CR52L1XX0 030GSK10A2001595 PIC 1 CR52EBGF0 030GSH10B1000971 LPU 8 CR52LPUKD0 030KJY10CC001471 LPUF-21-A PIC 0 CR52L1XX0 030GSK10A2001005 PIC 1 CR52EBGF0 030GSH10B1000795 MPU 9 CR57SRU40A4 030KSR10AA000258 SRUA4-40 MPU 10 CR57SRU40A4 030KSR10AA000175 SRUA4-40 SFU 11 CR57SFU40C0 030KSY10A9000472 SFUI-40-C SFU 12 SFU 13