IS-IS is an Interior Gateway Protocol (IGP) for routing OSI. IS-IS packets are not encapsulated in CLNS or IP but are encapsulated directly in the data-link layer. The IS-IS protocol family is OSI, and values such as 0xFE and 0xFEFE are used by the data-link protocol to identify the Layer 3 protocol as OSI.
Venous blood collected during blood donation. Venous blood is deoxygenated blood which travels from the peripheral vessels, through the venous system into the right atrium of the heart.eoxygenated blood is then pumped by the right ventricle to the lungs via the pulmonary artery which is divided in two branches, left and right to the left and right lungs respectively. Blood is oxygenated in the lungs and returns to the left atrium through the pulmonary veins.
It is the job of our veins to carry deoxygenated blood back to the heart. Healthy veins have valves which open and close to assist the return of blood to the heart. Venous disease (also called vein insufficiency or venous reflux), occurs if these valves become damaged, allowing the backward flow of blood in the legs.