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1. Why Can I Ping But HTTP/DNS Fails? (Frame Relay - Connected With Cisco)
Answer: Make sure that Frame-Relay payload compression is OFF on the Cisco Router.
 


2. When Running Zebra OSPF over WANPIPE, when I start zebra, OSPF has inactive routes, why? 
Answer: If OSPF comes back with inactive routes, problem lies with the wanpipe netmask address.

         The Netmask address has to be set to 
         255.255.255.255 for pointopoint links.


3. How do I enable ip_forwarding on RedHat 8.0 or greater?
Answer: 

    Edit /etc/sysctl.conf

    To enable ip forwarding on boot up set variable 
    net.ipv4.ip_forward to 1. 
       
    net.ipv4.ip_forward = 1


4. How do I loadbalance multiple T1/E1/56K WANPIPE® lines?
Answer: Linux offers numberous ways to loadbalance multiple WAN lines. Below is the options available on Linux.           

          TEQL:  Round robin packet equalization between multiple links.
                      Refer to README.loadbalancing

          PPP MULTILINK:  True loadbalancing protocol.
                                      However, MULITLINK protocol must be supported by both sides of the link.
                                      Refer to README.multilink

          IPROUTE2: Equal Cost Multi-Path routing. Attaches weights to each path,
                             useful when two lines are not the same baud rate.
           
    


5. How do I bind an irq to a single or multiple CPUs?
Answer: SMP Affinity Bit Map 

The /proc/irq directory contains all available IRQ's.  Each IRQ directory contains a irq to cpu mapping file called 'smp_affinity'.  For example to view irq to cpu mapping for irq 20 (irq 20 is a virtually mapped irq):

cat /proc/irq/20/smp_affinity
    
(eg: output)    ffffffff

The smp_affinity contains the CPU bitmap.  Each bit is used to enable or disable a specific CPU.

eg: bit 1 : enables/disables CPU0
      bit 2 : enables/disables CPU1 
       ... etc

By default, for all IRQ's all CPUs are enabled.  As we can see from
the above smp_affinity     output (ffffffff) all CPUs are enabled.

NOTE: One first 8 bits are used. i.e. XXXXXXff  (X is not used) 

Bind IRQ 20 to CPU 0
    echo 1 > /proc/irq/20/smp_affinity

Bind IRQ 20 to CPU1
    echo 2 > /proc/irq/20/smp_affinity                            

Bind IRQ 20 to both CPUs
    echo 3 > /proc/irq/20/smp_affinity

A good idea would be to bind eth0 irq and wanpipe irq to a different CPUs.  By running a interrupt on a single CPU instead of multiple CPUs a cache coherency can be improved, thus a boost in performance can be achieved by reducing cache misses.

Note: if you are runing irqbalance daemon, the smp_affinity will be overwritten by irqbalance daemon.

 


6. Wanpipe interfaces don't come up on wanrouter start? 
Answer:
Problem: HOTPLUG 

The hotplug driver, automatically starts up the
interface and then brings it down.  This conflicts
with our driver.

Possible Solutions:

1) Insert wanpipe interface name into the hotplug
   interface list, and restart hotplug.
    
    vi /etc/hotplug/net.agent
    
        Insert wanpipe interface name into 
        the ignore list:
    
        ...ppp*|lo*|w*)

        Where w* relates to all wanpipe interfaces 
        starting with letter "w"

 


7. How do I enable SNMP Support?
Answer:

if you are having trouble finding the Wanpipe interface with net-snmp, a modification needs to be done to make snmp work with wanpipe interfaces:

In the snmp source directory,
in agent/mibgroup/mibII/interfaces.c

Look for the line
nnew->if_type ==24 ? 10000000 :

this line is to monitor interfaces of type “Ethernet”, add an interface type for wanpipe:

nnew->if_type ==23? 10000000 :
so your interfaces.c file would have both:

nnew->if_type ==24 ? 10000000 :

nnew->if_type ==23 ? 10000000 :

There is a patched version for version 5.3 there: ftp://ftp.sangoma.com/linux/utilities/net-snmp-5.3.tgz
 

Documentation about net-snmp is located at: http://www.net-snmp.org

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