Cavium Network, Brocade & Broadcom Interview Questions

Kindly find below the Interview questions asked in "cavium network, Brocade, Broadcom" company. Basically I haven't remember which question asked in which company and in which round, So instead or sharing company wise and round wise, I am sharing a collection of question by topics.

We hope It will help, job seeker to crack the Interview.... 

VLAN:
=====

1. What is use for VLAN_XLATE table, How it work? Design a data structure for VLAN_XLATE table?
2. How do you stop learning per VLAN bases? Where do you apply in pipeline? 

QoS:
===

Mapping:
========

1. How mapping is work?
2. How do create Decoding and Encoding profile?
3. Is there way to modify a packet internal priority?

Police and Shape:
================

1. Were do use police?
2. Were do use shape?
2. Why police is used at ingress and what is the burst and inter packet delay will be handled by police?
3. Why shaping is used at egress, Why can't be ingress? 
4. Write algorithm for police and shape?  

Bandwidth and Shape :
=====================

1. Configure minimum guaranteed bandwidth on Queue0 70% and Queue1 30% and level 1 scheduler shape with 10%, 
    Generate both the traffic 50:50 percent from ingress, what will be the expected output?
    
LAG:
====

1. Different between LAG and ECMP ? Why they are configure directly connection node being LAG, why cannot ECMP?
2. What we need dynamic LAG, why cannot use static lag instead of dynamic LAG ? (Mean why we need LACP) ?
3. 
  
MPLS:
=====

1. Why do you go for MPLS, why cannot we can manage with Ethernet/IP which is currently supported in h/w level forwarding?
2. How pseudo wire packet flowing in network?
3. Do you map MPLS packet to queue? 

C:
===

1. Write a program to toggle a bit location n and m (toggle_bits(int data, int n_loc, int m_loc))?
2. Find a second largest number in array ?
3. int i = 10 and int j, which is declaration and which is definition ?
4. Add a 2 number with out using + operator ?
5. Multiply a number with 8 with out using * operator ?
6. int * ptr = 1000; char *ch = 1000; int **pptr = 1000; void *vd = 1000; ptr++, ch++, pptr++, vd++; printf("all value ") ?
7. Write a program to print range value separated(using -)and single value separated(using ,)in following format(2,4,6-9,11,)?
8. Write a program to insert_sorted_list(),delete_sorted_list(), delete_entire_list() and write program to test inset, delete and delete entire ?
9. Add a given number using program a + b ? (indirectly mean of this question handle overflow) ?
10. Define a data structure for the node should contain list, left child and right child ?
11. Define a data structure for to implement malloc ?
12. Write link list library for insert/delete ?
12. Write a program to delete a n'th node from last ?

13. Make a number to be zero without assign zero direly ? 1. while(n) n = (n & (n-1)); 2. n = n-n;
14. Define a data structure to handle 1 lakh of timer ?
15. How to a mask range of bits in integer? int mask_bits(int data, int s_bit, int e_bit) {.... return mask_data;};
16. Delete a node form double link list?
17. Write program to store vlan, vlan range in short memory?
18. Find a link list is inter junction ?
19. Find a word "CAT" and replace a word with "APPLE" in a file ?
20. Write a program to delete a link list node using recursion?
21. AVL tree insert 9,6 and 7 will this is balance ? how do balance?
22. In you mobile you would have seen, when you type first letter it will show all contexts start with that letter as well as start with number.
    How will you get, can you write a algorithm to get the same way? 
23. Reverse ever alternate node in a link list. mean List: 1->2->3->4->5->6->   after reverse 2->1->4->3->6->5->
24. N number of element("ab", "zb", "cd", "wx", "ab","gv","cd",..."ab", ...."cd") stored in a contagious memory. Element size is 2 byte character.
    Remove the alternate repeated elements(("ab", "zb", "cd", "wx", "--","gv","--",..."ab", ...."cd")). 
    Write an algorithm should meat time complexity O(1) and space complexity constant. 
25. N step staircases are there where you can claim 1 or 2 step at time. How many possible way to reach you a top.
26. Given you N litter milk can, M litter milk can and expect R litter to be deliverer? 
    > you have unlimited milk to pore.
    > Possible way: Fill M can or N can
                    Shift M can to N can until it get fill. Keep remaining in M.
                    Shift N can to M can until it get fill. Keep remaining in N.
    example1: N = 3, M = 4 and R = 1;   
    example2: N = 2, M = 4 and R = 3; 
    Some time it can't be possible to deliver, it require infinite time to loop ? How to you approach this problem ?
27. Write a program to increment a pointer by 10 bytes.
28. Write a program to implement add 2 numbe add(int a, int b), indirectly he ask to handle overflow ....
29. Write a program to implement tcam or ACL in software ?
30. Write a program to convert tree to circular linked lists?

                                   10
                                       
                              6         15
                              
                            3   8    12    18 
                            
            output:|------------------------------|    
                   |-> 3->6->8->10->12->15->18----|

  
int Add(int x, int y)
{
   int carry;
    // Iterate till there is no carry 
    while (y != 0)
    {
        // carry now contains common set bits of x and y
        carry = x & y; 

        // Sum of bits of x and y where at least one of the bits is not set
        x = x ^ y;

        // Carry is shifted by one so that adding it to x gives the required sum
        y = carry << 1;
    }
    return x;
}

int 
mask_bits(int data, int s_bit, int e_bit) 
{
  int n_mask = 0, mask = 0;
  int n = 0;
  n_mask = ((e_bit - s_bit)+1);
  n =(0x1<<n_mask);
  mask = ~((n-1) << (s_bit-1));
  data =  data & mask;
  return data;
}

23. Reverse ever alternate node in a link list. mean List: 1->2->3->4->5->6->   after reverse 2->1->4->3->6->5->
     Reverse_Alternate_Node(LIST ** head)
       {
         LIST *prev = *head;
         LIST *curr = NULL;
         LIST *to_be_link = NULL; 
         
         if(!prev) return ;
         curr = prev->next;
         
         while(curr) {
          to_be_link = curr->next;
          curr->next = prev;
          prev = to_be_link;
          to_be_link = curr->next;
          if(!prev) break;
            curr = prev->next;
          if(curr) to_be_link->next = curr;    
         }
         
         if(to_be_link) to_be_link->next = prev; 
         return ;
       }
       
24. N number of element("ab", "zb", "cd", "wx", "ab","gv","cd",..."ab", ...."cd") stored in a contagious memory. Element size is 2 byte character.
    Remove the alternate repeated elements(("ab", "zb", "cd", "wx", "--","gv","--",..."ab", ...."cd")). 
    Write an algorithm should meat time complexity O(1) and space complexity constant. 
     > Solution 1: 2 dimension array (array[26][26]) require 676 byte storage.
     > Solution 2: Use Bit-map(size = ((26*26)/8)+1; bitmap[size];) requite 85 byte storage
                    /*Bit map location is calculate with the assumption, 
                      bitmap- 0 bit is map to "aa" 26 bit is map to "ba" so on..*/
                    void
                    get_bitloc(char *str, int *array_loc, int *bit_loc)
                     {
                       /*Assume always str, array_loc and bit_loc is valid*/
                       int base = str[0] - 'a';
                       int base_bit_pos = (base*26)%8;
                       int bit_pos  = (str[1] - 'a');                       
                       *array_loc = (base*26)/8;              
                        base = base_bit_pos + bit_pos;
                       *array_loc += (base/8); 
                       *bit_loc = (base%8);
                     }
                    /*First visit a set a bit second visit unset a bit and remove the element from storage.*/
                    int remove_element(char **mem)
                        {
                           int loc = 0, bit_loc = 0;
                           int is_set = 0;
                           char *ptr[2] = *mem;
                           while(ptr) {
                             get_bitloc(ptr, &loc, &bit_loc);
                             is_set = bitmap[loc]&(0x80>>bit_loc);
                             if(is_set) { remove content in memory}
                             bitmap[loc] = bitmap[loc]^(0x80>>bit_loc);     
                             ptr++;
                           }
                        }
     
    
25. N step staircases are there where you can claim 1 or 2 step at time. How many possible way to reach you a top.
     Solution:
      > if N = 1 , Possible way(1) = 1
      > if N = 2 , Possible way(2) = (1,1) (2)
      > if N = 3 , Possible way(3) = (1,1,1) (2,1) (1,2)
      > if N = 4 , Possible way(5) = (1,1,1,1)(2,1,1) (1,2,1) (1,1,2) (2,2)
      > if N = 5 , Possible way(8) = (1,1,1,1,1) (2,1,1,1)(1,2,1,1) (1,1,2,1) (1,1,1,2) (2,2,1) (2,1,2) (1,2,2) 
      int 
      Fibonacci(int n)
       {
         if ( n == 0 )
           return 0;
         else if ( n == 1 )
           return 1;
         else
           return ( Fibonacci(n-1) + Fibonacci(n-2) );
       } 
       
       

LAG:
====
1. Different between LAG and ECMP ? Why they are configure directly connection node being LAG, why cannot ECMP?
    Directly connected routers can be connect way ecmp path, but there will be a unnecessarily reserve IP address which can be connect way L2 itself.  
2. What we need dynamic LAG, why cannot use static lag instead of dynamic LAG ? (Mean why we need LACP) ?
    Dynamic LAG is require to avoid loop between the node. 
              ____            ____
    example: |    |----------|    |
             | S1 |----------| S2 |
             |____|----------|____|
             
              In "S1" static lag is configured  and S2 normal STP is running on the port which is directly connected.  
3. 

L2 Learning packets indication to CPU:
*************************************

> Polling method  --> For station moument, first it will send add and delete call to CPU. 
> FIFO method     --> For station moument, send as updated.


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