R# sh buffer- sh buffer stat, sh int- sh all int config, sh proto: sh all layer3 proto config, sh ip proto- IP proto in detail

Cisco Discovery Protocol (CDP): allows access config info on other routers with single command, uses SNAP broadcasts at DLLayer. CDP starts by default (ver10.3/later) & discovers neighboring routers running CDP thro data link broad. updates: 60 sec, holdtime: 180 sec, # config t, # cdp timer 60, # cdp holdtime 180 (global), R# sh cdp int: int stat, config info, encaps, cdp timers. R# sh cdp entry */ routerA: * shows info recd from all routers / only router A. R# sh cdp neighbors: shows cdp updates (device ID, local int/port, holdtime, capability, platform5000, neibhor port ID) (capa- R router, T trans bridge, B source route bridge, S switch, H host, I igmp), R# sh cdp neighbors detail: shows cdp enrty+ sh cdp neighbors

R# sh cdp traffic: reveals amount of pkts sent & recd among neighbors; config t, # no cdp run (cdp off-all int-router),

# config int, # no cdp enable (cdp off- single int)

Telnet : Virtual Term conns: part of tcp/ip proto allows to connect to remote hosts and routers. Cisco supports 5 simultaneous (vty 0 4) telnet sessions. R# telnet [ip add], ip add of any active int on the router. R# exit: to close session.

Ctrl+shift+6 X : return to org router w/o closing telnet. # 1, return: takes back to telnet session

R# sh sessions : sh all telnet sessions/conn no, host, add, byte, idle, conn name.

Hostnames: router can resolve ip add to hostnames. Config t, # ip host routerC 23 172.16.40.2 (23 telnet port- optl),

R # sh host / s: sh all> hosts, flags (perm/temp, ok/ex), age (hrs), type (proto), ip add, t# no ip domain-lookup: disables router DNS lookup (enabled by default), to re-enable DNS lookup, t# ip domain-lookup, t# ip name-server 172.16.30.8 (max 6 add)

IP Add config: config t, # int s0, # IP address [ ip-add] [ subnet-mask] - config IP add, Subnet mask for serial int s0.

# sh interfaces-shows all interface types & their associtd IP adds. use CDP command to see IP add of neighbor routers.

Inter Network Testing : R# telnet : shows all layers are working, verify appl layer commn between the hosts.

R# Ping 172.16.10.1- uses IP & ICMP proto to verify commn at Inet layer between hosts (! echo replay recd, . time out,

U dest un reachable, C congested exp pkt, | ping interupted, ? pkt type unknown, & pkt TTL exceeded.)

R# trace ip 172.16.40.2 uses TTL values (!H-recd probe not forward due to access list, P proto un reach, N net unreach,
U port unreach,* time out, (trace used in IP, AppleTalk, CLNS, Vines, Old Vines), R# sh int so : shows 
line & data link
proto status, R# debug all, # undebug all,
IP Routing : Source and Destn. Hardware add keeps changing, but IP add remains same as pkt travels thro?routers.
Dest IP remains same, frame keeps changing at each hope b’cos source, destn h/w add keeps changing.
Static Routing config t, # ip route [rem net ID] [subnetmask] [def Gway,next hop add / interface][distance]- cisco book
# no ip route [remote net ID]- to cancel a route, # sh ip route-sh R table/all routes, # sh ip route static-sh only static routes,
# ip classless global command to use def routing with static routing to forward pkts destd to obscure subnets to best route. Default Routing : default route = router or gateway of last resort, # ip route [0.0.0.0] [0.0.0.0] [gateway IP/next hop add] # ip default-network 192.68.17.0 : Default route as per Cisco book, # no ip routing (disable), # ip routing (re enable)

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